Article

Mitigating Roadway Impacts to Migratory Mule Deer-A Case Study With Underpasses and Continuous Fencing

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Abstract

Wildlife–vehicle collisions pose a major safety concern to motorists and can be a significant source of mortality for wildlife. Additionally, roadways can impede movements and reduce habitat connectivity. For migratory ungulates, these problems can be exacerbated when roadways bisect migration routes, as is the case in Southwest Wyoming, USA, where a 21-km section of U.S. Highway 30 overlaps with a critical winter range and migration route used by thousands of mule deer (Odocoileus hemionus). In an effort to reduce deer–vehicle collisions (DVC) and maintain migratory connectivity, the Wyoming Department of Transportation installed 7 concrete box-culvert underpasses with continuous game-proof fencing between each crossing structure. To evaluate the effectiveness of this mitigation project, we used remote cameras to quantify the number of mule deer that used the underpasses, estimate passage rates through time, and compare rates of DVCs before and after underpass construction. Through 3 years of monitoring (which encompassed autumn migration [2008, 2009, and 2010], winter use, and spring migration [2009, 2010, and 2011] for 3 migration cycles), we documented 49,146 mule deer move through the underpasses. Passage rates of deer approaching underpasses steadily increased from 54% in Year 1 to 92% in Year 3. Peak movements during the autumn migration occurred in mid-December, while peak spring movements were in mid-March and early May. Underpass and fence installation effectively reduced DVCs by 81%. Had fence gates remained closed and cattle guards clear of snow, DVCs could be eliminated altogether. Our results suggest that underpasses, combined with game-proof fencing, can improve highway safety for motorists while providing safe and effective movement corridors for large populations of migratory mule deer. © 2012 The Wildlife Society.

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... [11][12][13][14][15][16] Crossing structures (highway under-or over-passes), in combination with fences, typically reduce collisions by 60-90 percent, but can cost millions of dollars to implement. [16][17][18][19] Crossing structures have been installed in a number of locations around Wyoming. However, these structures are not suitable or feasible in all locations. ...
... For example, a before-after comparison of the Nugget Canyon project in southwestern Wyoming showed a dramatic 81 percent decrease in deer-vehicle collisions after highway underpasses and extensive fencing were installed. 19 In the present study, however, the effects of wildlife warning reflectors on DVC rates appear to be more subtle or simply reveal the limitations of before-after comparisons. Results from our before-after comparison at four sites were inconclusive, with some sites showing an increase in DVCs after reflectors were installed, some showing a decrease, and some showing no change. ...
... 57 A similar set of underpasses and fencing was completed along US 30 west of Kemmerer (Nugget Canyon Area) in 2008 and reduced DVC rates by 81 percent within the first several years. 19 Both the occurrence and number of DVC were most strongly related to total traffic volume. The effect of traffic volume was logarithmic. ...
Technical Report
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The purpose of this study was to provide the Wyoming Department of Transportation with information about (1) the effectiveness of Streiter-Lite wildlife warning reflectors that had been installed in three locations within Wyoming’s District 5, and (2) preliminary analysis of patterns of deer-vehicle collisions across Wyoming and the habitat and road variables associated with collision hotspots. We evaluated reflector effectiveness in terms of their ability to reduce deer-vehicle collisions and modify deer road-crossing behavior. Using a series of experimental manipulations of reflectors, we showed that reflectors reduced deer-vehicle collisions by 32 percent and significantly reduced the number of high-risk deer road crossings (those in which deer ran into the road as a car was approaching). However, covering reflectors with white canvas bags – initially done with the intent of creating a control treatment that neutralized the reflectors – proved even more effective than leaving the reflectors exposed. White bags on posts resulted in 33 percent fewer collisions than when reflectors were exposed and significantly reduced the number of high-risk deer road crossings. It is likely that the white bags are more visible or reflective to deer than the red wildlife warning reflectors. A cost-benefit analysis suggests that the benefits of reflectors outweigh their initial materials and installation costs, but may not outweigh the net costs once maintenance is taken into account. Analysis of patterns of deer-vehicle collisions across the state showed that traffic volume, proximity to agricultural land, proximity to deer winter range and migration routes, and high speed limits are all strongly associated with high collision rates. On average, areas with a 55 mph speed limit have 36 percent and 55 percent fewer deer-vehicle collisions than areas with speed limits of 65 and 75 mph, respectively. Reducing nighttime speed limits in high collision areas may be a cost-effective strategy for mitigating deer-vehicle collisions in Wyoming.
... Woods (1990) reported a 94 to 97% reduction in ungulate-vehicle collisions in Alberta following implementation of wildlife crossing structures and funnel fencing. Bissonette and Rosa (2012) and Sawyer et al. (2012) documented 98% and 81% reductions in mule deer (Odocoileus hemionus) mortalities, respectively, following installation of funnel fencing and wildlife crossing structures. Collisions with Florida Key deer (Odocoileus virginianus claviu) were reduced by 73 to 100% following fencing and underpass construction (Parker et al. 2008(Parker et al. , 2011. ...
... Gagnon et al. (2013) noted that though frequent crossers accounted for 8.4% of the collared elk, they accounted for 60% of the elk-vehicle collisions involving collared elk (Gagnon et al. 2007a). Incentives that would potentially cause more elk to push through the heightened right-of-way fencing could include: vegetation within the right-of-way, making it substantially preferable to the surrounding habitat Graves 1971, Puglisi et al. 1974); juxtaposition to preferred resources (e.g., riparian meadows, agriculture) in relation to elk movement patterns (Dodd et al. 2007a); and newly fenced roads that intersect migratory paths (Sawyer et al. 2012). In cases where these motivations to cross roads exceed the deterrent of the barrier effect of the highway, 2.4 m woven-wire fence should be used to connect wildlife crossing structures (Clevenger and Waltho 2000, Gagnon et al. 2011, Bissonette and Rosa 2012, Sawyer et al. 2012. ...
... Incentives that would potentially cause more elk to push through the heightened right-of-way fencing could include: vegetation within the right-of-way, making it substantially preferable to the surrounding habitat Graves 1971, Puglisi et al. 1974); juxtaposition to preferred resources (e.g., riparian meadows, agriculture) in relation to elk movement patterns (Dodd et al. 2007a); and newly fenced roads that intersect migratory paths (Sawyer et al. 2012). In cases where these motivations to cross roads exceed the deterrent of the barrier effect of the highway, 2.4 m woven-wire fence should be used to connect wildlife crossing structures (Clevenger and Waltho 2000, Gagnon et al. 2011, Bissonette and Rosa 2012, Sawyer et al. 2012. ...
Article
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Collisions with large ungulates cause serious human and animal injuries and significant property damage. Therefore, wildlife crossing structures are increasingly included in new road construction to reduce wildlife-vehicle collisions, while still allowing wildlife to safely cross roads. Recently, state and federal transportation budgets have declined, concomitantly reducing the construction of wildlife crossing structures, which are generally tied to large-scale reconstruction projects that are delayed for decades into the future. Nevertheless, even during times of fiscal constraint or temporal delay, it is still necessary to reduce collisions with wildlife and maintain habitat connectivity. Therefore, it is important to find cost-effective and functional alternatives. Retrofitting roadways with wildlife exclusion fencing that directs animals to existing highway structures (e.g., sufficiently sized bridges and culverts) is a possible costeffective, interim solution that needs further testing. Along Interstate-17 in northern Arizona, we heightened 9.17 km of right-of-way barbed wire fence to 2.4 m to guide elk (Cervus canadensis) to 2 large bridges and 2 modified transportation interchanges. We evaluated occurrence of elk-vehicle collisions, elk use of existing structures, and GPS movements of elk pre-and post-fencing retrofit. Post retrofit, there was a 97% reduction in elk-vehicle collisions for the 9.17 km stretch of road. There were also no increases in collisions at the fence termini (area within 1.61 km from fence ends) nor in the remaining sections, indicating that elk were not simply forced to those areas. We documented a 217% and 54% increase in elk use of the 2 large bridges, but no elk use of the transportation interchanges. GPS relocation data from 31 elk showed a statistically insignificant decrease, from 0.07 to 0.03 crossings per approach pre-and post-fence modification, respectively. Elk road crossings, determined through GPS relocations, were concentrated around the bridge structures rather than being evenly distributed across the treatment sections, and similar to collisions, crossings did not increase on adjacent fence termini. Using the Huijser et a. (2009) estimate of $17,483 for the cost to society of an elk-vehicle collision, the level of collision reduction on this stretch of road will recoup project costs in <5 years. Our results indicate that, under certain circumstances, retrofits can in the short-term reduce wildlife-vehicle collisions on roadways that are not scheduled to be reconstructed in the near future. However, for the long-term, areas with significant wildlife-vehicle collisions or habitat fragmentation should have appropriately designed, located, and maintained wildlife crossings with exclusionary funnel fencing.
... Grade-level crossings may be adequate along roads with relatively low traffic volumes, especially if right-of-way fencing is absent or designed as wildlifefriendly. However, maintaining functional migration routes across roads with high traffic volumes, multiple lanes, or impermeable right-of-way fencing requires careful transportation planning that incorporates wildlife crossing structures (e.g., underpasses or overpasses) into proposed or existing infrastructure (Gagnon et al. 2007b, Sawyer et al. 2012, Clevenger et al. 2015. ...
... Wildlife crossing structures can provide an effective means to reduce wildlife-vehicle collisions (WVC) and maintain connectivity between seasonal ranges (Romin and Bissonette 1996, Clevenger et al. 2001, McCollister and Van Manen 2010, Sawyer et al. 2012. For ungulates, crossing structures typically consist of some sort of underpass (e.g., box culvert or span bridge) and adjacent fencing to funnel animals underneath the roadway. ...
... Although underpasses have proven effective for a variety of wildlife (Foster and Humphrey 1995, Clevenger and Waltho 2000, Forman et al. 2003, they may not be conducive for moving large numbers of pronghorn (Antilocapra americana) or other species (e.g., Mongolian gazelle [Procapra gutturosa]) that live in open habitats and rely on vision to detect and avoid predators. Although pronghorn are known to use underpasses on occasion (Plumb et al. 2003, Sawyer et al. 2012, it is presumed they would move more freely over roadways via overpasses where their vision is not impaired and movement is less constrained. Although this assumption is biologically intuitive, there have been no studies that support this assertion. ...
Article
The seasonal migrations of ungulates are increasingly threatened by various forms of anthropogenic disturbance, including roads, fences, and other infrastructure. Although roadway impacts (e.g., wildlife–vehicle collisions and landscape permeability) to species such as mule deer (Odocoileus hemionus) can largely be mitigated with underpasses and continuous fencing, similar mitigation may not be effective for pronghorn (Antilocapra americana) or other ungulate species that are reluctant to move through confined areas. The Wyoming Department of Transportation recently installed 6 underpasses and 2 overpasses along 20 km of U.S. Highway 191 in western Wyoming, USA, where we evaluated species-specific preferences by documenting the number of migratory mule deer and pronghorn that used adjacent overpasses and underpasses for 3 years (autumn 2012 to spring 2015) following construction. We also measured the amount of back-and-forth movement across the highway for each species through time. We documented 40,251 crossings of the highway by mule deer and 19,290 crossings by pronghorn. Of those highway crossings, 79% of mule deer moved under, whereas 93% of pronghorn moved over the highway. These strong species-specific differences were evident at both sites and support the notion that overpasses are more amenable to pronghorn than underpasses. Concurrently, we documented a 64–306% increase in the amount of back-and-forth movement of mule deer and pronghorn across the highway during migration periods. Such movement flexibility is presumed to improve their ability to respond to changing environmental conditions by easily accessing habitats on either side of the highway. Our results highlight that species-specific preferences are an important consideration when mitigating roadway impacts with wildlife crossing structures.
... Measures aimed at reducing WVCs and creating safe crossing opportunities for wildlife vary widely in both cost and effectiveness. WVCs can typically be reduced by >80% through the use of wildlife-exclusion fencing to prevent animals from entering the highway, coupled with overpasses and underpasses that allow wildlife to cross safely (Huijser et al., 2009;Rytwinski et al., 2016;Sawyer et al., 2012;Sawyer et al., 2016). The combination of fencing and crossing structures is also very effective at maintaining, and potentially even improving, habitat connectivity for large mammals Sawyer et al., 2016). ...
... At the same time, the state is home to some of the longest-distance and most intact large ungulate migrations in the world (Berger, 2004;Kauffman et al., 2018;Middleton et al., 2019). While fencing and crossing structures have been installed in several locations in Wyoming and shown to be highly effective at reducing WVCs and connecting habitat for a variety of large mammals (Sawyer et al., 2012, the public continues to exert pressure to try other, less costly measures such as reducing the posted speed limit at night. ...
... For higher traffic volume roads, separated crossings (highway underpasses and overpasses) with wildlife fencing are the only proven way to ensure that roads do not obstruct large mammal movements, while also reducing WVC rates. Separated crossing structures with >3 mi (5 km) of fencing are consistently >80% effective at reducing WVCs Rytwinski et al., 2016;Sawyer et al., 2012Sawyer et al., , 2016 and once accustomed to them, large mammals cross them regularly . In the long-term, crossing structures with fencing, though costly, are the most effective way to increase road safety for large mammals and the traveling public alike and to also allow wildlife to continue to move across the road. ...
Article
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Roads obstruct wildlife movements, and wildlife‐vehicle collisions are a hazard to both animals and humans. Wildlife and transportation managers often consider reducing the speed limit to reduce wildlife‐vehicle collisions, but there is little empirical data to support or refute this measure. We experimentally reduced the nighttime speed limit from 70 to 55 mph on six stretches of highway that cross mule deer (Odocoileus hemionus) winter range or migration paths. Drivers consistently reduced their speeds, but only by 3–5 mi/h. Reduced speed limit did not make it any easier for deer to cross the road, indicating no benefit for habitat connectivity. At winter sites, the number of deer‐vehicle collisions was not affected by the reduced speed limit whereas at migration sites, collisions were modestly lower under the reduced speed limit. Given the small reduction in vehicle speeds, it is not surprising that there was little benefit of reduced speed limit for deer or people. We conclude that reduced nighttime speed limit is not an effective way to reduce wildlife‐vehicle collisions or make roads more permeable to wildlife due to poor compliance from motorists. Roads obstruct wildlife movements, and wildlife‐vehicle collisions are a hazard to both animals and humans. Managers often consider reducing the speed limit to mitigate the effects of roads on wildlife, but there is almost no empirical data to support or refute this measure. We experimentally reduced the nighttime speed limit from 70 to 55 mph on six stretches of highway that interset mule deer movement paths and found minimal reduction in driver speed, no evidence for any improvement in habitat connectivity, and modest to no reduction in risk of collisions to animals.
... Puglisi et al. 1974;Falk et al. 1978). Fencing can prevent WVC and is particularly effective when combined with properly designed and located crossing structures that allow faunal movement across roads (Dodd Jr. et al. 2004;Huijser et al. 2007;Dodd et al. 2012;Sawyer et al. 2012). Fence designs and standards differ among regions and species, and for some species, alternatives to traditional fences are available. ...
... There is clear evidence from around the world that the effectiveness of wildlife crossing structures is improved when animals are funnelled towards them, and fencing is the most effective way to achieve this for most species (excluding birds, bats and some arboreal animals) (Jackson & Tyning 1989;Gagnon et al. 2010a;McCollister & Van Manen 2010;Sawyer et al. 2012; Textbox 20.1). Crossing structures and fencing that are designed and installed simultaneously are 20.5 Fence ends and planned breaks in fences must be designed to reduce the rate of WVC. ...
... Fencing is usually focused at high-risk localities and crossing structures and often includes breaks to allow traffic from side roads to enter the fenced road. Gates are the most effective approach at containing larger fauna; however, they are impractical when traffic volume on the lateral road is high and gates can be unintentionally left open (Sawyer et al. 2012). When gates are not an option, wildlife guards and electrified mats ( Fig. 20.11) can be effective (Reed et al. 1974b;Seamans & Helon 2008;Allen et al. 2013). ...
Chapter
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Fences prevent animals from accessing roads, thereby reducing the rate of wildlife-vehicle collisions (WVC). Fences also funnel animals towards crossing structures, making them an essential component of the success of this form of mitigation. Fencing can be used for a variety of species, ranging from frogs and turtles to deer and bears. Consequently, fence designs are almost as varied as the species they target. 1 Fencing is an essential component of mitigation and must be comprehensively integrated into the mitigation programme for it to be effective. 2 Fencing must be designed for the target species. 3 Consider alternatives to traditional fences. 4 Animals inevitably breach fences, and when they do, they must be able to exit the roadway. 5 Fence ends and planned breaks in fences must be designed to reduce the rate of WVC. 6 Fences need to be maintained forever. Appropriately designed fences and crossing structures can cost-effectively reduce or eliminate WVC. The potential negative effects of fences must also be considered, including increasing the barrier effect when installed without crossing structures and mortality of wildlife at fence ends and if poorly designed or maintained. Careful consideration of a small number of design and maintenance parameters is essential to achieve and maintain effectiveness.
... With anticipated growth of the human population and ongoing investment in highways, there is an increasing effort to exclude wildlife from roadways while maintaining landscape connectivity, especially with respect to migratory populations (Forman et al. 2003, Bissonette andAdair 2007). Previous studies have reported that installation of crossing structures, and exclusionary fencing to funnel wildlife to those structures, decreased wildlife-vehicle collisions up to 80% (Clevenger et al. 2001, Bissonette and Rosa 2012, Sawyer et al. 2012. Consequently, conservation biologists and transportation agencies have begun to incorporate crossing structures into road upgrades to reduce the risk of wildlife-vehicle collisions and to restore connectivity among habitats and movement corridors for animals (Clevenger and Waltho 2005, Jaarsma et al. 2007, Huijser et al. 2009, Sawaya et al. 2014). ...
... Exclusionary fencing was included to funnel wildlife to the entrance of each structure and to exclude animals from the roadway (Dodd and Gagnon 2010, Sawyer et al. 2012, Fairbank 2013, Sawyer et al. 2013). The fencing was 2.4 m tall and made of 12.5-gauge woven wire animal fencing. ...
... The fencing was 2.4 m tall and made of 12.5-gauge woven wire animal fencing. Escape ramps (i.e., jump-outs) were incorporated into the fencing, 6 at each study site, to allow individuals trapped within the fencing to jump out and away from the roadway (Sawyer et al. 2012). Fencing spanned the entire length of each study site between the structures to prevent wildlife from entering the roadway. ...
Article
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Maintenance of movement corridors is a fundamental component of the conservation of biological diversity, and is especially critical for terrestrial species that migrate extended distances. Highways and interstate freeways fragment corridors and often result in increased mortality of terrestrial migrants from collisions with vehicles. Wildlife crossing structures are an important tool in multiple ecosystems to allow safe passage for wildlife across roadways. Indeed, crossing structures have been used extensively in Europe and with increasing frequency in North America to reconnect fragmented habitats for numerous species. Few projects, however, have documented responses to >1 structure type simultaneously that are close to one another. We used mule deer (Odocoileus hemionus), a widespread species across diverse bioregions in western North America, to test hypotheses about efficacy of 2 different types of crossing structures for ungulates. We documented behavioral responses and use of overpasses and underpasses by mule deer. Our metrics to evaluate success included passage rates and the number of animals that crossed each structure. Crossing structures were used by mule deer immediately following construction and although all of the crossing structures were used, we observed greater passage rates at overpasses than underpasses. Wildlife crossing structures reduced habitat fragmentation and enhanced connectivity by allowing safe passage across US 93. More importantly, those structures succeeded in removing a large number of mule deer from the roadway making US 93 safer for wildlife and motorists.
... Roadways affect wildlife via mortalities, fragmentation of movement corridors, and degradation of habitat (Jackson 2000, Trombulak and Frissell 2000, Huijser et al. 2008, Fahrig and Rytwinski 2009, Brunton et al. 2018. For migratory wildlife, roadways may impede annual migrations, particularly for large terrestrial species, such as ungulates (Lendrum et al. 2012, Sawyer et al. 2012, Seidler et al. 2015. Wildlife-vehicle collisions (WVCs) are also costly for humans, resulting in human fatalities and injuries, and an estimated economic cost of 8.4 billion dollars annually in the United States (Conover et al. 1995, Huijser et al. 2008. ...
... To reduce WVCs and improve migration corridors across roadways, crossing structures (i.e., underpasses and overpasses) are an effective solution in many countries (Clevenger and Waltho 2000, Olsson et al. 2008, Smith et al. 2015, Sawyer et al. 2016b, Caldwell and Klip 2020. Researchers have reported that wildlife crossing structures are effective at reducing mortalities and improving permeability along wildlife corridors, particularly for large migratory species, such as mule deer (Odocoileus hemionus; Mata et al. 2008, Sawyer et al. 2012, Stewart 2015, Simpson et al. 2016. Mule deer migrations can range 15-200 km, and migration paths often cross developed areas and roadways (Sawyer and Kauffman 2011, Lendrum et al. 2012, Sawyer et al. 2016a. ...
... Roadways that bisect traditional migration routes often have higher levels of deer-vehicle collisions during migration (Coe et al. 2015). Areas with high levels of WVCs are logical candidates for crossing structures (Sawyer et al. 2012, Simpson et al. 2016. Crossing structures, such as overpasses and underpasses, are successful at decreasing deer-vehicle collisions at migration corridors, and the combination of wildlife highway fencing and crossing structures is considered one of the most effective strategies to promote connectivity and reduce WVCs (Huijser et al. 2009, Sawyer et al. 2012. ...
Article
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Roadways may pose barriers to long‐distance migrators such as some ungulates. Highway underpasses mitigate wildlife‐vehicle collisions and can be an important management tool for protecting migration corridors. In northern California, 3 underpasses were built on United States Route 395 (Route 395) in Hallelujah Junction Wildlife Area (HJWA) in the 1970s for a migratory mule deer (Odocoileus hemionus) herd that had been negatively affected by highway traffic. To determine whether these underpasses were still reducing mule deer mortalities >40 years after construction, we investigated deer use of the underpasses from 2006–2019 using cameras, global positioning system (GPS) collars, and roadkill records. We used occupancy models, approximations of GPS‐collared mule deer movement paths, and roadkill locations to estimate the highway crossing patterns of deer. From camera data, there was higher use of the underpasses by deer during migration (spring [Mar–Jun], fall [Oct–Dec]) than in summer (Jul–Sep), when only resident deer were present. Higher underpass usage occurred in the spring compared to fall migrations. Eleven of 21 GPS‐collared migrating mule deer crossed Route 395. We estimated 30% of the crossings (by 7 of the 11 deer) occurred south of the underpasses where deer could easily access the highway because of short (1‐m high) and deteriorating highway fencing. Roadkill data confirmed that deer‐vehicle collisions were occurring south of the underpasses and at the underpasses. This was likely due to deteriorating infrastructure at the underpasses that allows wildlife access to the highway. Overall, our study indicated that although underpasses can provide safe passage for migratory deer decades (>40 yr) after their construction, deteriorating infrastructure such as fencing and gates can lead to wildlife mortalities on highways near underpasses. © 2021 The Wildlife Society. The results of our study indicate the importance of long‐term maintenance and monitoring of roadway crossing structures and highway fencing to prevent wildlife‐vehicle collisions. Migratory mule deer still used underpasses built over 40 years ago, but deer roadkills near the underpasses were attributed to deterioration of infrastructure including highway fencing.
... Roads, especially primary highways, threaten wildlife survival not only via vehicular collisions but by fragmenting and reducing available habitat, isolating populations, and disrupting daily and seasonal movements (Forman and Alexander 1998, Coffin 2007, Delaney et al. 2010). These negative effects may be mitigated by the presence of wildlife-friendly underpasses, which can allow safe movement across barriers and provide connectivity (Clevenger et al. 2001, Forman et al. 2003, Dodd Jr. et al. 2004, Sawyer et al. 2012, Riley et al. 2014. Certain parameters of an underpass (e.g., size, vegetation presence/type) may determine its effectiveness and the importance of those parameters may vary depending on frequency of use by humans Waltho 2000, Glista et al. 2009). ...
... The population densities and extensive home ranges of American badger and mountain lion require habitat connectivity for individuals to locate mates, access foraging habitat, and maintain a diverse gene pool (Beier 1995, Crooks 2002, Jager et al. 2006, Wilmers et al. 2013, Vickers et al. 2015. Although underpass use by American badger has been documented in Arizona (Gagnon et al. 2011), Utah (Cramer 2013), Wyoming (Sawyer et al. 2012), Montana (Allen 2011), and California (Ordeñana et al. 2010), information is sparse regarding the rate of use. Mountain lions use underpasses for dispersal, but tend to avoid areas with artificial lighting and obvious human activity (Beier 1995). ...
Article
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Environmental planners often rely on transportation structures (i.e., underpasses, bridges) to provide connectivity for animals across developed landscapes. Environmental assessments of predicted environmental impacts from proposed developments often rely on literature reviews or other indirect measures to establish the importance of wildlife crossings. Literature-based evaluations of wildlife crossings may not be accurate, and result in underestimation of impacts or establishment of inappropriate mitigation measures. To investigate the adequacy of literature-based evaluations, we monitored wildlife use of a freeway underpass that had been identified as critically important to wildlife connectivity, and which was evaluated in an environmental review document. Photographs were obtained from a network of trail cameras over 3 years. Six mid-to large-sized native mammal species used the underpass and two other mammal species were photographed near the underpass but not using it. American badger (Taxidea taxus) was photographed at a higher rate in the underpass than in the surrounding area. Gray fox (Urocyon cinereoargenteus) was rarely detected in the underpass relative to surrounding habitats, whereas the absence of mule deer (Odocoileus hemionus) in the underpass was unexpected, given relatively frequent detection in adjacent habitats. These results differed from the environmental assessment in that American badger was listed as "potentially" present while mule deer were expected to use the underpass. Results underscore importance of gathering data to document wildlife use of corridors, because some species do not or rarely take advantage of apparently suitable corridors, while others may be present when assumed to be absent.
... Wildlife fencing in combination with wildlife crossing structures is commonly regarded as the most effective and robust strategy to reduce these types of collisions while also maintaining connectivity across highways for wildlife (review in Huijser et al., 2009). If wildlife fencing and crossing structures are designed based on the requirements of the target species, and if they are implemented and maintained correctly, the measures can reduce large mammal-vehicle collisions by 80-97% (Clevenger et al., 2001;Gagnon et al., 2015;Sawyer et al., 2012). In addition, the number of animal movements across overpasses or through underpasses, as well as the percentage of animals out of a local population that use the structures, can be substantial (Clevenger and Waltho, 2000;Sawaya et al., 2013;Sawyer et al., 2012). ...
... If wildlife fencing and crossing structures are designed based on the requirements of the target species, and if they are implemented and maintained correctly, the measures can reduce large mammal-vehicle collisions by 80-97% (Clevenger et al., 2001;Gagnon et al., 2015;Sawyer et al., 2012). In addition, the number of animal movements across overpasses or through underpasses, as well as the percentage of animals out of a local population that use the structures, can be substantial (Clevenger and Waltho, 2000;Sawaya et al., 2013;Sawyer et al., 2012). ...
... The wildlife crossing structures allow wildlife to cross the highway without being exposed to potential collisions with vehicles. Wildlife use of underpasses and overpasses can be substantial and meaningful at a population level (Clevenger and Waltho 2000, Sawyer et al. 2012, Sawaya et al. 2013. Wildlife crossing structures can also help reduce intrusions of wildlife into the fenced road corridor as wildlife may choose to use the crossing structures rather than breach the wildlife fence to access the other side of the highway. ...
... If wildlife fences and crossing structures are designed based on the requirements of the target species, if the road length fenced is at least 3.1 mi (5km) long, and if the fences and structures are implemented and maintained correctly, the measures can reduce large mammal-vehicle collisions by more than 80 percent (see Chapter 3, Huijser et al. 2016). In addition, the number of animal movements across overpasses or through underpasses, as well as the percentage of animals out of a local population that use the structures, can be substantial (Clevenger and Waltho 2000, Sawaya et al. 2013, Sawyer et al. 2012). ...
Technical Report
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The US Highway 93 North reconstruction project on the Flathead Indian Reservation in northwest Montana represents one of the most extensive wildlife-sensitive highway design efforts to date in North America. The reconstruction of the 56 mile (90 km) long road section included the installation of wildlife crossing structures at 39 locations and approximately 8.71 miles (14.01 km) of road with wildlife exclusion fences on both sides. The mitigation measures were aimed at improving safety for the traveling public through reducing wildlife-vehicle collisions and allowing wildlife to continue to move across the road. This report summarizes research conducted between 2002 and 2015. The research focused on the effectiveness of the mitigation measures in reducing collisions with large mammals, and the use of the crossing structures (specifically by white-tailed deer, mule deer, and black bear). In addition, the effectiveness of wildlife guards (similar to cattle guards), wildlife jump-outs and a human access point was evaluated. Finally, the researchers conducted cost-benefit analyses and formulated recommendations.
... Although motorized activity can disrupt important migration corridors, note that this disruption is more strongly influenced by highway traffic than is typical of trail-based motorized recreation (Lendrum et al. 2013, Sawyer et al. 2012 ...
... OHVs have been found to indirectly reduce food sources by facilitating the spread of invasive species(Knisley and Hill 2001, Laabs 2006, Wilson et al. 2009). Mule deer may shift their distribution to lower quality habitats farther from roads(Northrup et al. 2015, Sawyer et al. 2012, Webb et al. 2011, and grouse have been displaced from preferred habitat(Hovick et al. 2014). Roads or hardened surfaces associated with motorized recreation can negatively affect the resources provided by amphibian habitat(Guderyahn et al. 2016). ...
... Due to the strong fidelity migrating artiodactyls have to their migration routes, new construction such as underpasses can play a pivotal role in decreasing the likelihood of potential collisions and help to maintain the previously discussed movement corridors these animals utilize. Sawyer et al. (2012) found a decrease in deer-vehicle collisions of 81% in a 21 km stretch of US Highway 30 after construction of an underpass. Although other variables will likely need to be taken into account, such as available vegetation, terrain, and other human activity, these changes strongly benefit both migrating artiodactyls and humans themselves (Lendrum et al. 2012;Reimoser and Putman 2011;Sawyer et al. 2012). ...
... Sawyer et al. (2012) found a decrease in deer-vehicle collisions of 81% in a 21 km stretch of US Highway 30 after construction of an underpass. Although other variables will likely need to be taken into account, such as available vegetation, terrain, and other human activity, these changes strongly benefit both migrating artiodactyls and humans themselves (Lendrum et al. 2012;Reimoser and Putman 2011;Sawyer et al. 2012). ...
... The focus on ungulates may be partly due to their relationship with humans in terms of hunting and potential conflict (e.g. road collisions; Sawyer, Lebeau & Hart, 2012). The dominance of research on altitudinal migration of birds could be due to a higher proportion of migratory species within this group, or a strong history of research on bird migration in general. ...
... For example, landscape-level conservation strategies to facilitate movements of altitudinal migratory ungulates by creating overpasses and underpasses on highways have resulted in frequent usage of these structures (Sawyer et al., 2009;Sawyer & Kauffman, 2011). When combined with fencing, these underpasses reduced deer-vehicle collisions by 81% (Sawyer et al., 2012). ...
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Animal migration has been the subject of intensive research for more than a century, but most research has focused on long‐distance rather than short‐distance migration. Altitudinal migration is a form of short‐distance migration in which individuals perform seasonal elevational movements. Despite its geographic and taxonomic ubiquity, there is relatively little information about the intrinsic and extrinsic factors that influence altitudinal migratory behaviour. Without this information, it is difficult to predict how rapid environmental changes will affect population viability of altitudinal migrants. To synthesize current knowledge, we compiled literature on altitudinal migration for all studied taxa, and identified the leading hypotheses explaining this behaviour. Studies of animal altitudinal migration cover many taxonomic lineages, with birds being the most commonly studied group. Altitudinal migration occurs in all continents except for Antarctica, but about a third of the literature focused on altitudinal migration in North America. Most research suggests that food and weather are the primary extrinsic drivers of altitudinal migration. In addition, substantial individual‐level variation in migratory propensity exists. Individual characteristics that are associated with sex, dominance rank, and body size explain much of the variation in migratory propensity in partially migratory populations, but individual‐level correlates are poorly known for most taxa. More research is needed to quantify the effects of habitat loss, habitat fragmentation, and climate change on altitudinal migrants. Demographic studies of individually marked populations would be particularly valuable for advancing knowledge of the cascading effects of environmental change on migratory propensity, movement patterns, and population viability. We conclude our review with recommendations for study designs and modelling approaches that could be used to narrow existing knowledge gaps, which currently hinder effective conservation of altitudinal migratory species.
... Modifying the fences (e.g., raising the lowest wire) might be effective, because the gazelles can cross these barriers, but larger livestock, such as horses, cows, and camels, cannot [24]. Creating new passages for the animals, such as the over-and under-passes created along the Qinghai-Tibetan Railway in China [36] and along highways in North America [37,38,39], would be also effective, but this approach would be expensive. For new railroads that are currently being planned or are under construction, no fence zones or passages for animals with a suitable structure should be created at frequent intervals. ...
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Habitat loss and habitat fragmentation caused by anthropogenic activities are the main factors that constrain long-distance movement of ungulates. Mongolian gazelles (Procapra gutturosa) and Asiatic wild asses (Equus hemionus) in Mongolia are facing habitat fragmentation and loss. To better understand how their movements respond to potential anthropogenic and natural barriers, we tracked 24 Mongolian gazelles and 12 wild asses near the Ulaanbaatar-Beijing Railroad and the fenced international border between Mongolia and China between 2002 and 2012. None of the tracked gazelles crossed the railroad, even though gazelles were captured on both sides of the tracks at the start of the study. Similarly, we did not observe cross-border movements between Mongolia and China for either species, even though some animals used areas adjacent to the border. The both species used close areas to the anthropogenic barriers more frequently during winter than summer. These results suggest strong impacts by the artificial barriers. The construction of new railroads and roads to permit mining and other resource development therefore creates the threat of further habitat fragmentation, because the planned routes will divide the remaining non-fragmented habitats of the ungulates into smaller pieces. To conserve long-distance movement of the ungulates in this area, it will be necessary to remove or mitigate the barrier effects of the existing and planned roads and railroads and to adopt a landscape-level approach to allow access by ungulates to wide ranges throughout their distribution.
... Identifying suitable design, spacing and locations for crossing structures and movement corridors along the migration routes are a mitigation measure for minimizing the landscape-scale impacts of linear barriers on migratory ungulates (Bastille-Rousseau, Wittemyer, Douglas-Hamilton, & Wall, 2018;Sawyer, Lebeau, & Hart, 2012). ...
Article
1.Conservation of nomadic species presents significant conservation challenges because of unpredictability in their movements and space use. Long‐term studies on nomadic species offering insights into the variability in space use within and between years are largely missing but are necessary to develop effective conservation strategies. 2.We examined the temporal variability in space‐use of Mongolian gazelle, a species of nomadic ungulate. We tracked 22 individuals for one to three years with GPS and used the resulting movement patterns to evaluate conservation strategies associated with their nomadic movements in the intact open plain grasslands of Mongolia. Individuals exhibited a high degree of variability in space use within and between years, often using different wintering areas in different years. The individual range size varied as much as threefold between years, with an estimated average annual individual range size of ~19,000 km2 and a lifetime range of ~100,000 km2. 3.Comparing simulated and empirical GPS trajectories for the Mongolian gazelle showed that they avoided disturbed areas (e.g., oil fields) and did not prefer protected areas. Importantly, no single protected area in the region was large enough to cover the annual range of any of the tracked gazelle. 4.Because of their wide‐ranging movements, the presence of linear infrastructure and the resulting barrier effects are a particular concern. We found that fences along the national border were absolute barriers affecting movements of about 80% of all tracked individuals. When gazelle encounter the border fence, they moved a median distance of 11 km along fences, suggesting frequent crossing options are needed to make barriers permeable. 5.Synthesis and applications. We show that for nomadic species whose space use varies greatly across years, multi‐year movement data is essential for sound conservation planning. We emphasize that place‐based approaches alone are insufficient to conserve wide‐ranging nomadic species and that linear infrastructure, including fences, highways, and railroads, is of particular concern. Because nomadic species lack defined movement corridors, we advocate integrated land use planning that prioritizes permeability across the entire landscape and facilitates long‐distance movements. We suggest that conservation strategies for nomadic species in arid and semi‐arid regions be reconsidered based on multi‐year connectivity assessments at the landscape scale. This article is protected by copyright. All rights reserved.
... In temperate regions, migration among large herbivores is typified by movement to summer ranges at high elevation in spring following the leading edge of advancing plant phenology, with return movements to low-elevation winter ranges that are prompted by winter weather in autumn (Monteith et al. 2011, Sawyer and Kauffman 2011, Bischof et al. 2012, Jones et al. 2014, Aikens et al. 2017. Therefore, twice each year animals must navigate through a complex and potentially risky landscape to successfully reach their destinations (Nicholson et al. 1997, Lendrum et al. 2012, Sawyer et al. 2012, Seidler et al. 2015. Construction of impermeable barriers along a migratory route can result in the loss of connectivity and benefits obtained from seasonal ranges, which can lead to population collapse (Whyte andJoubert 1988, Benshahar 1993). ...
Article
Long‐distance migration by terrestrial mammals is a phenomenon critical to the persistence of populations, but such migrations are declining globally because of over‐harvest, habitat loss, and movement barriers. Increasingly, there is a need to improve existing routes, mitigate route segments affected by anthropogenic disturbance, and in some instances, determine whether alternative routes are available. Using a hypothesis‐driven approach, we identified landscape features associated with the primary functional attributes, stopovers and movement corridors, of spring migratory routes for mule deer in two study areas using resource selection functions. Patterns of selection for landscape attributes of movement corridors and stopovers mostly were similar; however, landscape features associated with movement corridors aligned better with areas that facilitated movement, whereas selection of stopovers was consistent with sites offering early access to spring forage. For movement corridors, deer selected for dry sites, low elevation, and low anthropogenic disturbance. For stopovers, deer selected for dry sites, with consistently early green‐up across years, south‐southwesterly aspects, low elevation, and low anthropogenic disturbance. Stopovers and movement corridors of a migratory route presumably promote different functions, but for a terrestrial migrant, patterns of habitat selection indicate that the same general habitat attributes may facilitate both movement and foraging in spring. Our findings emphasize the roles of topographical wetness, vegetation phenology, and anthropogenic disturbance in shaping use of the landscape during migration for this large herbivore. Avoiding human disturbance and tracking ephemeral forage resources appear to be a consistent pattern during migration, which reinforces the notion that movement during migration has a nutritional underpinning and disturbance potentially alters the net benefits of migration.
... Conserving suitable landscapes for migratory ungulate populations in areas of increasing human disturbance is a challenging conservation issue in North America (Bolger et al. 2008). Understanding mechanisms affecting migration is critical for avoiding human disturbances from blocking or reducing permeability of migration routes (Sawyer et al. 2012, Benz et al. 2016. The lack of stopover permeability (e.g., reduced likelihood of crossing the road network) could reduce the benefits of migration, and influence the ability of species to modify range due to climate change (Minor and Urban 2008). ...
Article
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Migrations of large ungulates are globally threatened in environments affected by increasing human disturbance, rising large carnivore predation, deteriorating habitat quality, and changing climate. Animals migrating outside of protected areas can be exposed to greater human pressure, and this effect can be stronger when humans are perceived to be a predation risk, such as during hunting seasons. Using four consecutive years of satellite telemetry data (n = 138 migration events), we compared habitat selection, movement, and behavior of a large partially migratory herbivore while migrating through a heterogeneous landscape in spring and fall. We tested the hypothesis that fall hunting exacerbates the response of a large herbivore exposed to human disturbance while migrating through a road network. All elk (Cervus elaphus) selected greater forest cover, reduced movement rates, and avoided roads during fall-day than in any other season or time of day. Avoidance of roads was reduced during spring at night, for example, the time period of no hunting with fewest people on roads. Elk using stopovers in fall displayed different seasonal and diurnal behaviors between sexes in response to the disturbance. Females used steeper terrain during fall-day and males did not use this strategy in fall. Male avoidance of roads was much stronger than females during fall-day and males were less likely to cross a road during fall. Such responses are probably linked to higher hunting pressure on males vs. females. Finally, we found that elk spent more time feeding during spring migration compared to the fall migration and elk vigilance was >3 times higher in the fall hunting season. Our results provide insights into the effect of fear of humans on the ecology of both sexes of a migrating large herbivore when using stopovers. Such changes in behavior and stopover use might affect animal fitness by decreasing foraging, cause displacement from high-quality habitats, or affect the permeability of migration route stopovers.
... Wildlife-vehicle collision mitigation measures range widely in both cost and effectiveness. Highway crossing structures such as overpasses and underpasses, when coupled with extensive wildlife-exclusion fencing to funnel animals toward the crossings, typically reduce wildlife-vehicle collisions by >80% (Huijser et al. 2009(Huijser et al. , 2016Huijser and McGowen 2010;McCollister and Van Manen 2010;Sawyer et al. 2012). They are also very effective at maintaining habitat connectivity for large mammals. ...
... However, disturbances to these migrations affect their ability to obtain nutritional requirements (Sawyer et al. 2009). One primary disturbance to migration is intensive development, which causes mule deer to change migration routes, increasing rates of movement and decreasing stopover use (Sawyer et al. 2012), and therefore compromising their ability to obtain nutritional requirements. Disturbances in the form of human development, including residential and energy development are linked to decreasing recruitment rates in mule deer (Johnson et al. 2017). ...
Article
Advances in technology and availability associated with camera traps have resulted in a rapid rise in their use to monitor wildlife distribution, abundance, and behavior. We focus on assessing body condition, a new application of camera traps. Body condition indices must relate to the percent body fat if they are to be useful. To acquire measurements of body fat, most body condition indices require capture or mortality of animals to estimate, which has limitations when applied to free-ranging animals. We developed a non-invasive, visual body condition index (VBCI) to assess body condition of mule deer that can be applied to camera trap images or videos. The VBCI was based on the visibility of five bone regions, the scapula, spinal ridge, ribs, tuber ischium, and tuber ilium, which are covered in varying amounts of subcutaneous fat. We compared the VBCI to known values of ingesta-free body fat, obtained from ultrasonography and physical palpation of captured mule deer. Our VBCI was positively related to percent ingesta-free body fat (R2=0.23, p<0.001). Additionally, the bone regions evaluated were each correlated with the percent ingesta-free body fat. Using Spearman’s correlation, the scapula is the region most highly correlated to ingesta-free body fat (0.44, p<0.001), followed by the ischium (0.36, p<0.001), ilium (0.35, p<0.001), spinal ridge (0.31, p<0.001), and ribcage (0.12, p<0.01). Based on the relationships between VBCI and ingesta-free body fat, we developed two visual body condition indices, one that requires a broadside orientation to the camera (VBCI-1) and one that is applicable when a deer is quartered towards the camera (VBCI-2). Potential applications of the VBCI include evaluating relationships between body condition and habitat enhancements, habitat disturbances, population performances, and weather.
... Our findings are encouraging and suggest that further development and refinement of a visual index of nutritional condition could be useful, including testing the index with deer captured in the summer to determine applicability when deer have short coats. With rising interest and identification of bottlenecks associated with migration (Sawyer et al. 2012) and the ease of photographing hundreds of animals, noninvasive camera surveys may yield an inexpensive but useful index to tracking nutritional status and recruitment of young within populations over time. ...
Article
Understanding nutritional condition of animals can provide insight into underlying drivers of population dynamics. To estimate nutritional condition, indices require capture or mortality of animals to obtain measurements of body fat. Advances in technology provide an opportunity to acquire estimates of nutritional condition in a noninvasive way if ocular estimates can be validated. We developed and evaluated a noninvasive, visual index of nutritional condition for mule deer (Odocoileus hemionus) intended to be applied to camera‐trap images or videos. Our index was based on the visibility of 4 skeletal regions that are covered in varying amounts of subcutaneous fat depending upon the nutritional condition of the animal. We compared the visual index of nutritional condition to estimates of percent ingesta‐free body fat (IFBFat) obtained from ultrasonography and physical palpation of captured mule deer (n = 89) in western Wyoming, USA, in December 2015, March 2016, and November 2018. Our visual index of nutritional condition related positively to IFBFat (r2 = 0.41). Although further refinement may be warranted to increase predictive power of visual estimates, use of visual approaches to estimate nutritional condition can enhance knowledge that can be gained with a minimal budget, or where more invasive approaches are not possible. © 2020 The Wildlife Society. We developed and evaluated a noninvasive, visual index of nutritional condition for mule deer intended to be applied to camera‐trap images or videos. The index was positively related to percent ingesta‐free body fat, suggesting it may be a useful tool to estimate nutritional condition in mule deer when invasive methods are not feasible.
... Maintaining ecological integrity necessitates a proactive approach of identifying threats to species, communities, and the ecological processes that sustain them. For mule deer (Odocoileus hemionus), a culturally and economically important species (Copeland et al., 2014), habitat fragmentation can present barriers to migration, alter migration routes, or increase mortality through deer-vehicle collisions (Sawyer, LeBeau & Hart, 2012). Highway underpasses have restored connectivity for mule deer in fragmented landscapes (Reed, Woodward & Pojar, 1975; Ng et al., 2004; Clevenger & Waltho, 2005; Braden et al., 2008; Gagnon et al., 2011). ...
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Maintaining ecological integrity necessitates a proactive approach of identifying and acquiring lands to conserve unfragmented landscapes, as well as evaluating existing mitigation strategies to increase connectivity in fragmented landscapes. The increased use of highway underpasses and overpasses to restore connectivity for wildlife species offers clear conservation benefits, yet also presents a unique opportunity to understand how weather conditions may impact movement of wildlife species. We used remote camera observations (19,480) from an existing wildlife highway underpass in Wyoming and daily meteorological observations to quantify weather conditions associated with autumn migration of mule deer in 2009 and 2010. We identified minimal daily temperature and snow depth as proximate cues associated with mule deer migration to winter range. These weather cues were consistent across does and bucks, but differed slightly by year. Additionally, extreme early season snow depth or cold temperature events appear to be associated with onset of migration. This information will assist wildlife managers and transportation officials as they plan future projects to maintain and enhance migration routes for mule deer.
... Alternatively, locations collected with smartphones were accurate enough that relationships with landscape features and infrastructure were readily apparent, providing managers with a clearer understanding of factors associated with WVCs at finer spatial scales. Additionally, patterns in WVCs can be influenced by broad scale landscape processes, such as seasonal changes that trigger long distance migrations of ungulates in temperate climates [40,41]. The seasonal flow of large numbers of migrating ungulates often results in peaks in WVCs in fall and spring [9,42]. ...
Article
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Background: Currently there is a critical need for accurate and standardized wildlife-vehicle collision data, because it is the underpinning of mitigation projects that protect both drivers and wildlife. Gathering data can be challenging because wildlife-vehicle collisions occur over broad areas, during all seasons of the year, and in large numbers. Collecting data of this magnitude requires an efficient data collection system. Presently there is no widely adopted system that is both efficient and accurate. Methodology/principal findings: Our objective was to develop and test an integrated smartphone-based system for reporting wildlife-vehicle collision data. The WVC Reporter system we developed consisted of a mobile web application for data collection, a database for centralized storage of data, and a desktop web application for viewing data. The smartphones that we tested for use with the application produced accurate locations (median error = 4.6-5.2 m), and reduced location error 99% versus reporting only the highway/marker. Additionally, mean times for data entry using the mobile web application (22.0-26.5 s) were substantially shorter than using the pen/paper method (52 s). We also found the pen/paper method had a data entry error rate of 10% and those errors were virtually eliminated using the mobile web application. During the first year of use, 6,822 animal carcasses were reported using WVC Reporter. The desktop web application improved access to WVC data and allowed users to easily visualize wildlife-vehicle collision patterns at multiple scales. Conclusions/significance: The WVC Reporter integrated several modern technologies into a seamless method for collecting, managing, and using WVC data. As a result, the system increased efficiency in reporting, improved accuracy, and enhanced visualization of data. The development costs for the system were minor relative to the potential benefits of having spatially accurate and temporally current wildlife-vehicle collision data.
... While efforts to mitigate disturbance to wildlife arising from transportation infrastructure can be costly (McGuire andMorrall 2000, Huijser et al. 2009), this effort is leading to the restoration of animal movement (Gagnon et al. 2011, Van Manen et al. 2012, Sawaya et al. 2013, Sawyer et al. 2013) and genetic flows (Sawaya et al. 2014) across the landscape and a reduction in the risk of wildlife-vehicle collisions (Clevenger et al. 2001, McCollister and Van Manen 2010, Found and Boyce 2011. Indeed, the large number of wildlife using WC in our study area ) may be interpreted by some observers v www.esajournals.org ...
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Despite the popular perception of protected areas as vestiges of remnant wilderness, the behavior and activity patterns of wildlife in these areas are still subject to many forms of anthropogenic disturbances, such as roads, recreation and resource extraction. In Banff National Park, Alberta, efforts to mitigate the effects of roads on wildlife using wildlife crossing structures (WC) have been successful for a number of large mammal species, when measured as a reduction in mortality from vehicle collisions or the restoration of population connectivity; however, a comprehensive view of mitigation success should also account for the restoration of animal behavior and activity patterns. We evaluated the general hypothesis that existing WC have mitigated the effects of anthropogenic disturbance on wildlife activity, and predicted that the activity patterns of wildlife at WC should be similar to those in areas characterized by little or no human disturbance. We collected data from a long-term monitoring program of activity patterns, in an assemblage of large mammal species, using a network of camera traps throughout Banff National Park. We quantified the inter- and intra-specific overlap of diel activity patterns at 39 engineered wildlife crossings, varying in design (e.g., over and underpasses) and age. We compared activity at WC to baseline conditions at 126 backcountry sites (BC). In general, activity patterns at WC were found to closely match those at BC. Of the eight species we examined, only elk and coyotes showed significantly different peaks in activity. Activity between WC depended on the time of day, the amount of human use and age of the crossing structure; however, the impact of these factors varied among carnivores and ungulates. Our work demonstrates that the impact of people on wildlife activity at WC is highly context dependent and that the restoration of native patterns of activity within protected areas will require management of human activity, even in relatively remote areas.
... There is a large and growing body of evidence that demonstrates wildlife species are capable of using a range of wildlife crossing structure types, thereby reducing mortality and increasing connectivity (Jeffrey W. Gagnon et al. 2011;Van Manen et al. 2012;Sawyer, Lebeau, and Hart 2012). Grizzly bears are a focal species for mitigation where road projects impact their habitats and populations, such as the Highway 68 corridor. ...
Technical Report
Highway 68 in southwestern Alberta may undergo future upgrades including paving gravel sections to facilitate increased traffic from recreational pressures. The highway runs through the Rocky Mountain Forest Reserve with access to a number of small Provincial Recreational Areas (PRAs) between Trans-Canada Highway and Highway 40. Paving would take place from the intersection of Highway 40 to the existing paved section of Highway 68 just east of Camp Cadicasu. An upgrade of this type will result in higher traffic volumes and increased travelling speeds, and subsequently have significant impacts on wildlife. Black and grizzly bears, elk, deer and moose, other smaller mammals and amphibians are currently found in the area thus highway mitigation measures to facilitate road crossings for wildlife would need to be considered as part of any future upgrade of Highway 68. The principle goal for this study was to develop and implement an assessment of wildlife movement patterns along the Highway 68 corridor, and from these findings provide recommendations on the key locations where mitigation would need to take place should an upgrade project occur. To determine wildlife crossing patterns on Highway 68, we undertook a 20-month wildlife study with the following methods and components:  Remote camera detections of species distributions;  Snow-tracking surveys;  Connectivity modeling for grizzly bear and moose; and  Amphibian and reptile surveys.
... By employing GPS technology, we have better understanding of how animals respond to anthropogenic features (Panzacchi et al. 2013;Sawyer et al. 2013), increased knowledge of habitat selection (Leclerc et al. 2016;Valls-Fox et al. 2018) and improved information on predator-prey dynamics (Hebblewhite et al. 2005;DeMars and Boutin 2017). In turn, such information has been imperative for informing successful conservation efforts and evaluating management actions (Wydeven et al. 2009;Sawyer et al. 2012). ...
Article
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Data from animals equipped with global positioning system collars have advanced our understanding of vertebrates, but this technology has rarely been employed to study feral equids. Hesitation to equip feral equids with telemetry collars in the USA can often be attributed to safety concerns stemming from one study from the 1980s, where injuries were sustained by feral horses (Equus ferus caballus) equipped with radio-collars. Improvements in collar design over the ensuing quarter-century may have decreased risk of collar-related complications; however, telemetry-based studies on feral equids continue to be limited. In the present review, studies from wild and feral equids worldwide were systematically reviewed to better understand the mortality and injury risk in application of telemetry collars to equids. Our goals were to: (1) report the number of individual equids fitted with telemetry collars (1979–2017); and (2) document the numberofindividualequidsthatreportedlydiedorsufferedinjuriesfromcollarsorothersources.A comparative review of elk (Cervus canadensis), mule deer (Odocoileus hemionus) and pronghorn (Antilocapra americana) was also conducted to evaluate the relative risk of collar-related complications among equids and routinely collared North American ungulates. In total, 1089 wild and feral telemetered equids were identified across 48studies. Of these, 87(8.0%) were reported to have died, with only one (0.09%) mortality attributable to a collar. Comparatively, 23.0% (1095) of 4761 elk, mule deer and pronghorn fitted with telemetry collars were found to have died in the same number of studies, though no mortalities were reported to be related to the collar. Although wild and feral equids did not experience increased natural mortality compared with the other ungulates, studies have not provided sufficient information to assess relative risk of collar-related complications. Explicit reporting and discussion of telemetry collar impacts in future publications of all animal species are recommended, especially equids, to improve understanding of how telemetry collars can affect study individuals.
... To reduce the negative effects of roads, road mitigation structures (RMS) are commonly incorporated into highway systems (Taylor & Goldingay, 2010) and include structures such as underpasses, overpasses and jumpouts (structures allowing wildlife to escape a fenced road corridor) in conjunction with fencing (Huijser et al., 2009). RMS aim to guide the movement of wildlife away from the road, provide connectivity between habitats and have been shown to protect wildlife from collisions with vehicles (Clevenger et al., 2001;McCollister and Van Manen 2010;Rytwinkski et al. 2016;Sawyer et al., 2012). However, these RMS can negatively impact wildlife. ...
Article
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Human population and economic growth have resulted in roads transecting much of the North American landscape and this has negatively affected wildlife populations by fragmenting habitat, impeding movement between populations and increasing the chance of wildlife‐vehicle collisions. A common conservation tool to counteract these effects is the incorporation of road mitigation structures (RMS, i.e., jumpouts and overpasses/underpasses/fencing) into highway systems. However, gaps remain in our knowledge on RMS efficacy due to a lack of long‐term multispecies studies that can assess temporal and species‐specific variation in use. We investigate the efficacy of the Alberta Environment and Parks and Alberta Transportation RMS on the Trans‐Canada Highway (TCH) in the Bow Valley by analyzing annual reported wildlife‐vehicle collisions over a 23‐year period and wildlife use of the underpasses over a ten‐year period. We found that the incorporation of multiple underpasses and jumpouts, along with fencing, reduced the number of reported wildlife‐vehicle collisions on the TCH. We also found that wildlife use of the RMS exhibited variation with regards to month and location. Overall, our results add to the research supporting RMS effectiveness and suggest that incorporating additional similar infrastructure has the potential to further reduce wildlife‐vehicle collisions on the TCH. A common conservation tool to mitigate for fragmenting habitat, impeding movement between populations, and wildlife‐vehicle collisions is the incorporation of road mitigation structures (i.e., jumpouts and over/underpasses and fencing) into highway systems. In this study, we found in the long‐term that the incorporation of multiple underpasses and jumpouts, along with fencing reduced the number of wildlife‐vehicle collisions on the Trans‐Canada Highway.
... These structures are typically located where roads intersect with identified wildlife corridors and/or wildlife crash hotspots. The reduction in vehicle collisions with deer and elk as a result of these measures is typically greater than 80% (Clevenger et al., 2001;Sawyer et al., 2012) and was 90% or more in several studies (Bissonette and Rosa, 2012;Kintsch et al., 2020;Parker et al., 2011;Woods, 1990). Support for the increasing efforts to identify wildlife corridors and construct wildlife crossings is reflected in a series of wildlife corridor programs and legislation passed in the United States in recent years. ...
Article
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The impact of wildlife-vehicle collisions on drivers and wildlife populations has been gaining increasing attention in the United States. Given the established success of wildlife crossings with fencing in reducing wildlife crashes and connecting habitat, a growing number of states, including Virginia, have enacted wildlife corridor legislation, some of which encourages or requires the construction of wildlife crossings along identified wildlife corridors and/or high-crash areas. Because of the growing interest in wildlife crossing measures, research is needed on cost-effective means of implementation for departments of transportation. When wildlife crossings are constructed, they are often built into new road construction projects as a series of two or more underpasses and/or overpass structures connected by exclusionary fencing. Given limited transportation budgets, enhancing existing underpasses on previously constructed roads has also been recognized as a cost-effective mitigation opportunity. More research is needed, however, on the effects of adding fencing to existing underpasses, particularly those that are too far from one another to be connected with contiguous fencing. The purpose of this study was to determine the effectiveness of enhancing existing isolated underpasses with wildlife fencing. One mile of 8-ft-high wildlife fencing was added to a large bridge underpass and a large box culvert 5 mi apart on Virginia’s I-64. Effectiveness was determined by conducting a 2-year post-fencing camera monitoring study and comparing the findings with those from a 2-year pre-fencing study with regard to the frequency of deer-vehicle collisions (DVCs); the use of the underpasses by deer and other wildlife; and roadside deer activity. The study also used deer behavior and activity data to make comparisons among different fence end designs and jumpout designs applied at the study sites. The study found that the addition of wildlife fencing to certain existing isolated underpasses can be a highly cost-effective means of increasing driver safety and enhancing habitat connectivity for wildlife. After fencing installation, DVCs were reduced by 92% on average (96.5% and 88% at the box culvert and bridge underpass, respectively). Deer crossings increased 410% at the box culvert and 71% at the bridge underpass. Use of the culvert and bridge underpasses by other mammals increased 81% and 165%, respectively. DVCs did not increase at the fence ends, but there was high deer activity at the ends that did not tie into a feature such as right-of-way fencing. At the study sites, the benefits from crash reduction exceeded the fencing costs in 1.8 years, and fencing resulted in an average savings of more than $2.3 million per site. The findings from this study should be considered when DVC mitigation and/or wildlife connectivity measures are needed. Wildlife crossing and fencing guidelines will be developed to provide the Virginia Department of Transportation with a resource for the cost-effective implementation of this wildlife crash mitigation measure.
... Worldwide, there are more than 40 different types of mitigation measures available, but the most common and robust measures are the combination of fences and safe crossing opportunities, such as underpasses and overpasses, which are widely used in North America and Europe (Gloyne and Clevenger, 2001;Cain et al., 2003;Clevenger and Waltho, 2005;Mata et al., 2005;Huijser et al., 2016;Gonzalez-Gallina et al., 2018). When implemented and maintained correctly, these fenced passages were found to reduce up to 97% of the large mammal-vehicle collisions, especially North-American and European ungulates (Sawyer et al., 2012;Gagnon et al., 2015;Huijser et al., 2016). Wildlife passage systems have two distinct roles: first, the fences block the animals' access to the road and thus, guide them to a safe crossing structure; second, the crossing structure has the potential to reestablish the structural and functional connectivity between habitats bisected by roads. ...
Article
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Wildlife road mortality is a worldwide problem. In tropical developing countries, it is urgent to implement and test mitigation measures to reduce wildlife-vehicle collisions, especially because financial resources are limited and alternatives should be considered such as retrofitting of existing underpasses. We assessed herein the use of 12 unfenced crossing structures, including drainage culverts and cattle boxes, by medium and large mammals along a highway in the Brazilian Cerrado. Underpass usage was monitored for 3682 trapping nights from September 2017 to May 2018. We recorded 20 species of medium and large wild mammals in a total of 4212 events. The most frequent mammals were lowland tapirs (Tapirus terrestris, n = 1154), followed by capybaras (Hydrochoerus hydrochaeris, n = 910), and crab-eating foxes (Cerdocyon thous, n = 271). Underpass usage did not differ between drainage culverts and cattle boxes, but species composition differed among the structures, suggesting that terrestrial mammals prefer cattle boxes while some semiaquatic species used only culverts. We identified 28 different individual tapirs using the underpasses and we estimated over 180 tons of tapir biomass crossing under the highway. Tapir underpass usage did not differ between cattle boxes and culverts, but it was negatively associated with the presence of pasture area around the structures. Our study suggests that, although underpasses show high mammal usage suggesting a satisfactory level of connectivity, combining this method with fencing would be critical to substantially decrease wildlife road mortality and increase human safety.
... Many organisms aggregate in winter refugia (hibernacula) that concentrate populations and may make them particularly vulnerable to exploitation and disturbance (Cunjak 1996, Hanson et al. 2007, Taylor et al. 2016. Safe and continuous migratory corridors are also required for animals to reach critical winter habitats (Sawyer et al. 2012, Simpson et al. 2016. Considering winter habitats and corridors are therefore important components of management strategies requiring international collaboration for species that cross through different country boundaries (Nevins et al. 2009, Zmelik et al. 2011. ...
Article
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Frozen winters define life at high latitudes and altitudes. However, recent, rapid changes in winter conditions have highlighted our relatively poor understanding of ecosystem function in winter relative to other seasons. Winter ecological processes can affect reproduction, growth, survival, and fitness, whereas processes that occur during other seasons, such as summer production, mediate how organisms fare in winter. As interest grows in winter ecology, there is a need to clearly provide a thought-provoking framework for defining winter and the pathways through which it affects organisms. In the present article, we present nine maxims (concise expressions of a fundamentally held principle or truth) for winter ecology, drawing from the perspectives of scientists with diverse expertise. We describe winter as being frozen, cold, dark, snowy, less productive, variable, and deadly. Therefore, the implications of winter impacts on wildlife are striking for resource managers and conservation practitioners. Our final, overarching maxim, “winter is changing,” is a call to action to address the need for immediate study of the ecological implications of rapidly changing winters.
... Road crossing structures for wildlife are intended to serve five objectives: reduce vehicle strike and road-kill; improve driver safety; enable wildlife to disperse to maintain gene flow; enable seasonal migration; and enable home range movements (Denneboom et al., 2021;Kusak et al., 2009;Sawyer et al., 2012;Simpson et al., 2016;Taylor & Goldingay, 2010). Structures built under the road (underpasses), which includes modified drainage culverts, have been the most widely installed and studied structures (Denneboom et al., 2021;Taylor & Goldingay, 2010). ...
Article
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Road networks continue to expand globally with predictable effects on ecological systems. Research into the effectiveness of road underpasses and overpasses for wildlife has been concentrated in North America and Europe. In Australia, most studies of underpasses have been of relatively short duration and without reference sites to give context to the measured rates of use. We studied 5-7 road underpasses at two locations in eastern Australia over 2-3 years, comparing camera trap detections of animals in underpasses with those at nearby forest sites. Three species of large macropod (wallabies and kangaroos) were frequently detected in the underpasses, with some underpasses traversed 1-4 times per week, and in many cases exceeded detections in the forest. The lace monitor (Varanus varius) was detected in all underpasses, often once per week during spring and summer, and infrequently in the forest. At each location, a different small macropod species, including one regionally threatened, showed a higher probability of detection in one underpass compared with several of the forest sites. The vulnerable koala (Phascolarctos cinereus) was detected infrequently in underpasses and in the adjoining forest. The short-beaked echidna (Tachyglossus aculeatus) had a high probability of detection in a single underpass. The "prey-trap hypothesis" postulates that predators will exhibit increased activity at underpasses as a consequence of prey being funneled. We found the red fox (Vulpes vulpes) had high activity in some underpasses. However, its activity coincided less than expected with the activity of the mammals most at risk to it. Our results provide no consistent support for the "prey-trap hypothesis." Instead, our study confirms the generic value of underpasses for a range of medium-large mammals as well as one large reptile. Habitat adjoining underpasses exert a strong influence on their use and require greater consideration to maximize underpass use.
... The success of wildlife crossings (overpasses or underpasses) with fencing has been well established in recent decades (Dodd et al. 2007, Gagnon et al. 2010, Clevenger and Huijser 2011, Kintsch et al. 2020, resulting in an increase in their construction in the United States (Vartan 2016). The reduction in vehicle collisions with deer and elk as a result of these measures is typically >80% (Clevenger et al. 2001, Sawyer et al. 2012 and was 90% or more in several studies (Woods 1990, Parker et al. 2011, Bissonette and Rosa 2012, Kintsch et al. 2020. Wildlife crossings also increase highway permeability and promote genetic connectivity. ...
Article
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The impact of wildlife-vehicle collisions on drivers and wildlife populations has been gaining attention in the United States. Given the established success of wildlife crossings with fencing in reducing wildlife crashes and connecting habitat, information is needed on cost-effective means of implementation for departments of transportation. When wildlife crossings are constructed, they are often built into new road projects as a series of 2 or more underpasses and/or overpass structures connected by exclusionary fencing. Given limited transportation budgets and the prevalence of maintenance activities more so than new construction in many states, enhancing existing underpasses on previously constructed roads has been recognized as a cost-effective mitigation opportunity. More research is needed, however, on the effects of adding fencing to existing underpasses, particularly those that are too far from one another to be connected with contiguous fencing. In this study, we evaluated the effectiveness of this measure when applied to isolated underpasses. Approximately 1.6 km of 2.4-m-high wildlife fencing was added to each of 2 existing underpasses, a large bridge underpass and a large box culvert, situated approximately 8 km apart from one another on Interstate 64 in Virginia, USA. We conducted a 2-year post-fencing camera monitoring study and compared the findings from a 2-year pre-fencing study with regard to collision frequencies with white-tailed deer (Odocoileus virginianus) and black bears (Ursus americanus); the use of the underpasses by wildlife; and roadside deer activity. We also evaluated deer activity data to compare different fence end designs applied at the study sites. After fencing installation, deer-vehicle collisions (DVCs) were reduced by 96.5% and 88% at the box culvert and bridge underpass, respectively, and there were no increases in DVCs within 1.6 km of the fence ends. Deer crossings increased 410% at the box culvert and 71% at the bridge underpass. Use of the culvert and bridge underpasses by other mammals increased 81% and 165%, respectively. Although deer use of the underpasses was much greater than their activity at any of the fence ends, there was relatively high deer activity at the fence ends that did not tie into a feature such as right-of-way fencing. Our study found that the addition of wildlife fencing to certain existing isolated underpasses can be a highly cost-effective means of increasing driver safety and enhancing habitat connectivity for wildlife. The benefits from crash reduction exceeded the fencing costs in 1.8 years, and fencing resulted in an average saving of >$2.3 million per site over the 25-year lifetime of the fencing. The results add to the growing body of knowledge about effective ways we can use existing infrastructure to connect wildlife habitat and increase driver safety.
... Wildlife corridors (e.g., underpasses, overpasses, culverts) along highways traversing conservation areas are a valuable mitigation tool for enhancing the permeability of transportation infrastructure for wildlife while preventing wildlife mortalities from vehicle collisions and encouraging connectivity [17][18][19][20] . Several research studies, mostly in North America and Europe, have examined the effectiveness of wildlife underpasses along highways 19,[21][22][23][24][25][26][27][28][29][30] , but limited studies exists for railways 18,[31][32][33] . Moreover, there is a dearth of information on wildlife use of underpasses associated with roads or railways by wildlife in the African continent where these designs and technologies are increasingly being adopted (but see examples [34][35][36] ). ...
Article
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Rail and road infrastructure is essential for economic growth and development but can cause a gradual loss in biodiversity and degradation of ecosystem function and services. We assessed the influence of underpass dimensions, fencing, proximity to water and roads, Normalized Difference Vegetation Index (NDVI), presence of other species and livestock on underpass use by large and medium-sized mammals. Results revealed hyenas and leopards used the underpasses more than expected whereas giraffes and antelopes used the underpasses less than expected. Generalized linear mixed-effects models revealed that underpass height influenced use by wildlife, with several species preferring to use taller underpasses. Electric fencing increased underpass use by funneling species towards underpasses, except for elephants and black-backed jackal for which it reduced underpass passage. We also found that the use of underpasses by livestock reduced the probability of use by nearly 50% for wildlife species. Carnivore species were more likely to cross underpasses used by their prey. Buffalo, livestock, and hyenas used underpasses characterized by vegetation with higher NDVI and near water sources while baboons, dik-diks and antelope avoided underpasses with high NDVI. Our findings suggest a need for diverse and comprehensive approaches for mitigating the negative impacts of rail on African wildlife.
... 22 WYDOT has had significant success in reducing conflicts between wildlife and the traveling public through installing road crossing structures (under-and over-passes) at Nugget Canyon west of Kemmerer, Wyoming, at Trapper's Point, west of Pinedale, Wyoming, and north of Baggs, Wyoming; these structures have reduced collisions by more than 80 percent and enabled thousands of animals to cross these highways safely. [23][24] Crossing structures are widely recognized to be the most effective way to reduce wildlife-vehicle collisions and increase habitat connectivity for large mammals. [25][26][27][28] However, they are also costly, on the order of hundreds of thousands of dollars per mile. ...
Technical Report
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Roads have two major effects on ungulate populations: they can cause direct mortality through wildlife-vehicle collisions, and they can create partial to complete barriers to animal movements, cutting animals off from food and habitat resources they need. Wildlife-vehicle collisions are also dangerous and costly to the traveling public. The most effective way to reduce wildlife-vehicle collisions and the barrier effects of roads is to install wildlife crossing structures with game fencing; these measures are 80-100 percent effective. However, they are costly, and managers are challenged to make informed decisions about where to prioritize their installation. In this report, we developed two key pieces of information to help inform these decisions. We used a gap-acceptance approach to determine the duration of gap between consecutive vehicles that enables deer to safely and consistently cross roads. We found that 60 seconds’ gap is necessary to allow deer to safely cross roads 90 percent of the time. We used traffic data to relate this gap duration to hourly traffic volume and to assess the relative degree to which different hotspots of deer-vehicle collisions in Wyoming are permeable or impermeable to deer. We also conducted cost-benefit analyses for six different methods of reducing wildlife-vehicle collisions for the WYDOT road network.
Article
Wildlife–vehicle crashes (WVCs) pose a significant threat to not only wildlife populations but also highway safety. The most expensive WVC countermeasures include crossing structures with fencing, whereas the least expensive countermeasure is the wildlife warning signs. This study is aimed at estimating the crash modification factors (CMFs) for these two countermeasures using cross-sectional analysis. Two types of WVC data are used in this study: carcass removal data and traditional crash data. A random-intercept Bayesian approach was utilized to incorporate the contributing factors representing traffic volume, roadway geometry, weather conditions, and unobserved heterogeneity resulting from between-site variance. The No-U-Turn Hamiltonian Monte Carlo sampling technique was employed because of its high efficiency in handling complex models. The results suggest that the treatment of implementing wildlife warning signs on hotspots of high WVCs has been ineffective, perhaps because warning signs are passive devices, and the high uncertainty of wildlife interaction still remains. The crossing structures are found to be effective, with an estimated CMF of 0.66 and 0.55 using the carcass data and crash data, respectively. Recommendations could be made to implement more active information dissemination via wildlife-actuated warning signs, where crossing structures may not be feasible. The findings from this study indicate that the carcass removal data are more comprehensive than the crash data, despite the underreporting issue existing in both datasets. Therefore, a unique identifier should be added in both datasets to enable merging the data and obtain more complete results from the analyses.
Thesis
Site fidelity, the behaviour of animals to return to areas where they have been before is a common trait in many species. The Scandinavian moose is known to show fidelity to its range, but to what extent, is little known. The landscape in Sweden changes in a predictable and unpredictable way and hence gives the opportunity to test the existence of fidelity. I used the kernel Brownian bridge method to estimate the home ranges of individual moose over consecutive years and estimated the overlap at the home range level. I also used Euclidian distance to look on calving site fidelity. The moose in Sweden show fidelity to the different parts of their annual range at different levels. The overall pattern is that fidelity towards seasonal range increased with increasing latitude in winter, with a reversed pattern in summer, but the southern populations of moose show high fidelity, all year round. The calving site fidelity also follows the pattern of high fidelity in the south and lower fidelity to the north. This could be explained by the different movement strategies and the predictability of resources vital to the moose across the landscape. The increased knowledge could be used to better manage the Swedish moose population and provide information of the causes of fidelity.
Article
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Conserving migratory ungulates in increasingly human-dominated landscapes presents a difficult challenge to land managers and conservation practitioners. Nevertheless, ungulates may receive ancillary benefits from conservation actions designed to protect species of greater conservation priority where their ranges are sympatric. Greater Sage-Grouse (Centrocerus urophasianus), for example, have been proposed as an umbrella species for other sagebrush (Artemesia spp.)-dependent fauna. We examined a landscape where conservation efforts for sage-grouse overlap spatially with mule deer (Odocoileus hemionus) to determine whether sage-grouse conservation measures also might protect important mule deer migration routes and seasonal ranges. We conducted a spatial analysis to determine what proportion of migration routes, stopover areas, and winter ranges used by mule deer were located in areas managed for sage-grouse conservation. Conservation measures overlapped with 66?70% of migration corridors, 74?75% of stopovers, and 52?91% of wintering areas for two mule deer populations in the upper Green River Basin of Wyoming. Of those proportions, conservation actions targeted towards sage-grouse accounted for approximately half of the overlap in corridors and stopover areas, and nearly all overlap on winter ranges, indicating that sage-grouse conservation efforts represent an important step in conserving migratory mule deer. Conservation of migratory species presents unique challenges because although overlap with conserved lands may be high, connectivity of the entire route must be maintained as barriers to movement anywhere within the migration corridor could render it unviable. Where mule deer habitats overlap with sage-grouse core areas, our results indicate that increased protection is afforded to winter ranges and migration routes within the umbrella of sage-grouse conservation, but this protection is contingent on concentrated developments within core areas not intersecting with high-priority stopovers or corridors, and that the policy in turn does not encourage development on deer ranges outside of core areas. With the goal of protecting entire migration routes, our analysis highlights areas of potential conservation focus for mule deer, which are characterized by high exposure to residential development and use by a large proportion of migrating deer.
Article
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Highways are hazardous to migratory ungulates world-wide, causing direct and indirect impacts to ungulate survival. Moreover, significant financial costs are incurred in damage from wildlife–vehicle collisions and in building and maintaining wildlife passage structures. Information is needed to link ungulate movements to collision occurrence to prioritize needed construction of wildlife crossings on highways. We simultaneously documented mule deer (Odocoileus hemionus) migration corridors and mule deer–vehicle collisions (DVCs) in South-central Oregon, USA, over 6 years (2005–2011). We calculated Brownian Bridge Movement Models for 359 migrating mule deer equipped with Global Positioning System technology. We modeled DVC counts as functions of probability of use during migration, annual average daily traffic (AADT), and habitat characteristics. Probability of use during migration was the strongest predictor of where DVCs occurred (r = 0.93). Predicted DVCs also increased with AADT but peaked at approximately 8,000 and then decreased. Where AADT was above approximately 8,000, fewer deer attempted to cross the highway and DVCs decreased because, over time, deer either abandoned the migration route or were killed trying to cross this busy highway. Our results suggest that managers should focus on migration corridors or high-density DVC locations to identify where fencing and under/overpasses could be most effective for maintaining migratory corridors when confronting increasing traffic and development that bisect seasonal ranges of mule deer. © 2015 The Wildlife Society.
Research
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In an effort to better convey the science to migration stakeholders, the Wyoming Migration Initiative conducted a “migration assessment” of this newly discovered mule deer migration. The assessment identified specific locales of potential risks (e.g., fences, road crossings, bottlenecks, energy development) and considered the complex land-use patterns and associated policies through detailed mapping and analysis. By identifying potential risks to migrating deer, the assessment provides a roadmap for agencies, non-government organizations, landowners, industry, and other stakeholders to improve management and conservation efforts directed at the Red Desert to Hoback migration.
Article
Exclusion fencing is a common tool used to mitigate a variety of unwanted economic losses caused by problematic wildlife. While the potential for agricultural, ecological and economic benefits of pest animal exclusion are often apparent, what is less clear are the costs and benefits to sympatric non‐target wildlife. This review examines the use of exclusion fencing in a variety of situations around the world to elucidate the potential outcomes of such fencing for wildlife and apply this knowledge to the recent uptake of exclusion fencing on livestock properties in the Australian rangelands. In Australia, exclusion fences are used to eliminate dingo (Canis familiaris dingo ) predation on livestock, prevent crop‐raiding by emus (Dromaius novaehollandiae ), and enable greater control over total grazing pressure through the reduction of macropods (Macropodidae) and feral goats (Capra hircus ). A total of 208 journal articles were examined for location, a broad grouping of fence type, and the reported effects the fence was having on the study species. We found 51% of the literature solely discusses intended fencing effects, 42% discusses unintended effects, and only 7% considers both. Africa has the highest proportion of unintended effects literature (52.0%) and Australia has the largest proportion of literature on intended effects (34.2%). We highlight the potential for exclusion fencing to have positive effects on some species and negative effects on others (such as predator exclusion fencing posing a barrier to migration of other species), which remain largely unaddressed in current exclusion fencing systems. From this review we were able to identify where and how mitigation strategies have been successfully used in the past. Harnessing the potential benefits of exclusion fencing while avoiding the otherwise likely costs to both target and non‐target species will require more careful consideration than this issue has previously been afforded.
Preprint
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The need for conservation action to be cost-effective is widely accepted and this has prompted an increased interest and effort to assess effectiveness. Assessing financial costs of conservation is equally important, yet its measurement and assessment are repeatedly identified as lacking. The healthcare sector however, has made substantial progress in identifying and including costs in decision-making. Here, we consider what conservation can learn from this experience. We present a three-step framework for identifying and recording the relevant financial costs and benefits of conservation interventions where the user 1) describes the costing context, 2) determines which types of cost and benefit to include and 3) obtains values for these costs and benefits alongside metadata necessary for others to interpret the data. This framework is designed to help estimate economic costs, but can also be used flexibly to record direct costs of interventions (i.e. accounting costs), calculate financial benefits, and calculate cost effectiveness. Although recording cost data can be deceptively complex, this framework facilitates the improved recording of financial costs and benefits, and shows how this could enhance the assessment of cost-effectiveness across a broad range of conservation contexts.
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Roadside mineral licks form when road salt used to de-ice highways in winter runs off road surfaces and accumulates in roadside ditches. Some ungulates are attracted to these roadside licks as they seek to satisfy their mineral requirements. Within the distribution of moose (Alces alces (Linnaeus, 1758)) in North America, motorists often encounter moose visiting roadside licks in mid-summer, with many jurisdictions reporting summer peaks in moose-vehicle collisions (MVCs) at these locations. Our research used camera traps to monitor moose visitation of 22 roadside locations (including roadside licks, roadside ponds, and dry roadsides) in central British Columbia, Canada from December 2009–July 2020, tested the efficacy of treatment (decommissioning) methods used to reduce moose visitation to roadside licks, and roughly estimated decommissioning costs. Moose visitation to roadside licks was greatest from May–July. As we hypothesized, untreated licks were visited more often by moose than decommissioned licks, roadside ponds (absent of road salt), and dry roadsides. Decommissioning roadside licks by replacing or mixing lick waters and soils with materials, such as riprap, cedar mulch, pine logs, or dog (Canis lupus familiaris (Linnaeus, 1758)) fur and human (Homo sapiens (Linnaeus, 1758)) hair, is an effective and inexpensive means of reducing moose visitations to roadside areas and should increase motorist safety where roadside licks are visited by moose.
Chapter
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Amphibians and reptiles are vertebrates that are often overlooked in assessments of the importance of sagebrush (Artemisia spp.) ecosystems for wildlife. Given their dependence on water, few amphibians are strongly associated with sagebrush habitats, although several use these uplands for foraging, shelter, or dispersal. Of the 60 amphibian species that are predicted to occur within the sagebrush biome, the Great Basin spadefoot (Spea intermontana) is probably the only species that occupies enough of the biome and lives predominantly in terrestrial habitats (mostly in burrows) to be considered sagebrush associated. Of the 116 reptiles that are predicted to occur within the sagebrush biome, about 5 lizards and 5 snakes were identified as both strongly associated with sagebrush habitats and occupied areas likely to be managed for sage-grouse (Centrocercus spp). However, this list could be lower or higher depending on the specific location within the biome, and there remains considerable uncertainty regarding potential threats to reptiles, as well as basic information on distribution and abundance of most reptile species.
Chapter
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Adaptive management and monitoring efforts focused on vegetation, habitat, and wildlife in the sagebrush (Artemisia spp.) biome help inform management of species and habitats, predict ecological responses to conservation practices, and adapt management to improve conservation outcomes. This chapter emphasizes the adaptive resource management framework with its four stages: (1) problem definition, (2) outcomes, (3) decision analysis, and (4) implementation and monitoring. Adaptive resource management is an evolving process involving a sequential cycle of learning (the accumulation of understanding over time) and adaptation (the adjustment of management over time). This framework operationalizes monitoring a necessary component of decision making in the sagebrush biome. Several national and regional monitoring efforts are underway across the sagebrush biome for both vegetation and wildlife. Sustaining these efforts and using the information effectively is an important step towards realizing the full potential of the adaptive management framework in sagebrush ecosystems. Furthermore, coordinating monitoring efforts and information across stakeholders (for example, Federal, State, nongovernmental organizations) will be necessary given the limited resources, diverse ownership/management, and sagebrush biome size.
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The Tibetan antelope (Pantholops hodgsonii) is a migratory ungulate species that inhabits the Qinghai–Tibet Plateau. In recent years, the population of Tibetan antelope has steadily increased owing to rigorous protection measures to safeguard the species from commercial poaching. Currently, infrastructure development, competition with domestic livestock, and predation are the principal factors threatening the survival of Tibetan antelope. Our study found that migratory Tibetan antelope can adapt to the development of infrastructure over time, decreasing the potential negative impacts of such developments. We, therefore, urge infrastructure development companies to incorporate wildlife corridors that enable free movement of wildlife populations, particularly for migratory species.
Technical Report
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Across the western United States, many ungulate herds must migrate seasonally to access resources and avoid harsh winter conditions. Because these migration paths cover vast landscapes (in other words migration distances up to 150 miles [241 kilometers]), they are increasingly threatened by roads, fencing, subdivisions, and other development. Over the last decade, many new tracking studies have been conducted on migratory herds, and analytical methods have been developed that allow for population-level corridors and stopovers to be mapped and prioritized. In 2018, the U.S. Geological Survey assembled a Corridor Mapping Team to provide technical assistance to western states working to map bison, elk, moose, mule deer, and pronghorn migrations using existing Global Positioning System data. Led by the Wyoming Cooperative Fish and Wildlife Research Unit, the team consists of federal scientists, university researchers, and biologists and analysts from participating state agencies. In its first year, the team has worked to develop standardized analytical and computational methods and a workflow applicable to datasets typically collected by state agencies. In 2019, the team completed analyses necessary to map corridors, stopovers, routes and winter ranges in Arizona, Idaho, Nevada, Utah, and Wyoming. A total of 26 corridors, 16 migration routes, 25 stopovers, and 9 winter ranges were mapped across these states and are included in this report. This report and associated data release provide the means for the habitats required for migration to be taken into account by state and federal transportation officials, land and wildlife managers, planners, and other conservationists working to maintain big-game migration in the western states.
Article
This paper examines whether wildlife crossing structures reduce the number of wildlife–vehicle collisions. Using Washington state crash data from 2011 to 2020, I employed a difference-in-differences methodology at the year level on each of 13 observed wildlife crossing structures in Washington. The treatment area consisted of wildlife–vehicle collisions within 10 mi of a wildlife crossing structure, and the control area included wildlife–vehicle collisions that were 60 to 70 mi from the same wildlife crossing structure. I found evidence that wildlife crossing structures resulted in one to three fewer wildlife–vehicle collisions on average per mile per year. The marginal treatment effect also held within a 5-mi treatment area, a 15-mi treatment area, and when controlling for the presence of other structures within the baseline of a 10-mi treatment area. However, the collision reductions were more consistent among wildlife bridges than culverts, suggesting that not all wildlife crossing structures have the same effect in reducing accidents involving wildlife. Using a back-of-the-envelope approach, each wildlife crossing structure yielded annual benefits of $235,000 to 443,000 in 2021 U.S. dollars.
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United States Highway 30 between Kemmerer and Cokeville, Wyoming bisects the migratory route of the Wyoming Range mule deer (Odocoileus hemionus) herd and is the site of hundreds of deer-vehicle collisions each year. We tested the effectiveness of the FLASH™ (Flashing Light Animal Sensing Host, Victoria Gouch, Meridian, Id.) system, designed to detect deer presence on the highway and warn motorists by triggering flashing lights associated with a sign. We collected data on changes in vehicle speed in response to the warning system and conducted a series of experimental manipulations to determine motorist response to the system with various treatments involving the sign, the lights, and the presence of a deer decoy. Motorists in automobiles traveling at night reduced their speed the most (6%) in response to the normal operation of the system, with a mean speed reduction of 6 km/hour. During experimental manipulations motorists reduced their speed 20% when the deer decoy was present in the crossing, and responded less (7%) to the flashing lights and sign. The system tested may be effective in preventing deer-vehicle collisions in areas with a lower speed limit and more local traffic, but we believe it is not suitable for an application with high-speed traffic (i.e., >100 km/hour) and a high proportion of interstate traffic.
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Migratory ungulates outnumber residents by an order of magnitude in several savanna ecosystems in Africa, as was apparently the case in other grasslands around the world before the intervention of modern man. Migrants may be more numerous because 1) they use a much larger area, 2) they make more-efficient use of resources, or 3) they are less vulnerable to regulation by predators. These hypotheses were examined using simulation models of migratory and sedentary wildebeest Connochaetes taurinus in the Serengeti ecosystem. Simulations suggest that realistic numbers of predators could regulate resident herbivores at low population densities, whereas such regulation is probably rare for migratory herds. When residents and migrants have overlapping ranges, migrants should always outcompete residents, reducing them to low numbers. Results suggest that differences in the modes of regulation explain the predominance of migratory herbivores in some grassland ecosystems. -from Authors
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Transportation planners are increasingly incorporating roadway design features to mitigate impacts of highways on wildlife and to increase driver safety. We used camera and track surveys to evaluate wildlife use before and after construction of 3 wildlife underpasses and associated fencing on a new section of United States Highway 64 in Washington County, North Carolina, USA. We recorded 242 occasions of white-tailed deer (Odocoileus virginianus) use of underpass areas before highway construction began. Following completion of the highway, we collected 2,433 photographs of 9 species with deer representing 93% of all crossings. Adjusting for differences in number of monitoring days, white-tailed deer use of underpass areas averaged 6.7 times greater after the new highway and underpasses were completed. We recorded 3,614 wildlife crossings of ≥20 species based on track counts, representing most medium and large mammals known to occur in the area and several reptiles and birds. After completion of the highway, we documented wildlife mortality due to vehicle collisions during a 13-month period and recorded 128 incidences representing ≥24 species. Within fenced highway segments, mortalities were lowest near underpasses and increased with distance from the underpasses. However, we also documented more mortalities in fenced areas compared with unfenced areas. With greater distance from an underpass, animals with smaller home ranges seemed less likely to reach the underpass and instead attempted to climb over or crawl under fencing. Based on collision reports from adjacent highway sections, the new section of United States Highway 64 experienced approximately 58% fewer wildlife mortalities (primarily white-tailed deer), suggesting underpasses and fencing reduced the number of deer—vehicle collisions. Continuous fencing between underpasses may further reduce the number of vehicle collisions for deer but additional design features (e.g., buried fencing) should be considered for other wildlife species.
Article
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Road mortality can significantly impact some wildlife populations. However, few studies have assessed the effectiveness of measures to reduce wildlife-vehicle collisions (WVCs). We evaluated highway mitigation fencing to reduce WVCs along 3 4-lane sections (phase 1, 2, 3A) of the Trans-Canada highway in Banff National Park, Alberta. We collected data on WVCs and animal intrusions on the fenced right-of-way from 1981 to 1999. We found that WVCs were distributed nonrandomly after fencing and were associated with and close to fence ends. Wildlife-vehicle collisions were greatest within 1 km of fence ends, but proximity to major drainages also likely influenced location of collisions. Post-fencing WVCs were reduced effectively as ungulate-vehicle collisions declined 80%. Wildlife-vehicle collisions and animal intrusions onto the right-of-way were not associated with fence-access points. We recommend methods of modifying motorist behavior and fence design to decrease accident probability at fence ends.
Article
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Wildlife crossing structures are intended to increase permeability and habitat connectivity across roads. Few studies, however, have assessed the effectiveness of these mitigation measures in a multispecies or community level context. We used a null model to test whether wildlife crossing structures serve large mam-mal species equally or whether such structures limit habitat connectivity across roads in species-specific ways. We also modeled species responses to 14 variables related to underpass structure, landscape features, and hu-man activity. Species performance ratios (observed crossing frequency to expected crossing frequency) were evaluated for four large carnivore and three ungulate species in 11 underpass structures in Banff National Park, Alberta, Canada. Observed crossing frequencies were collected in 35 months of underpass monitoring. Expected frequencies were developed from three independent models: radio telemetry, pellet counts, and hab-itat-suitability indices. The null model showed that species responded to underpasses differently. In the pres-ence of human activity carnivores were less likely to use underpasses than were ungulates. Apart from hu-man activity, carnivore performance ratios were better correlated to landscape variables, and ungulate performance ratios were better correlated to structural variables. We suggest that future underpasses de-signed around topography, habitat quality, and location will be minimally successful if human activity is not managed.
Article
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ABSTRACT  We used video surveillance at 4 wildlife underpasses along 27 km of Arizona State Route 260, USA, to monitor elk (Cervus elaphus) responses to traffic volume and traffic type during underpass use. Passage rates at the highest traffic category (>10–27 vehicles/min) were not lower than passage rates when no vehicles were present, whereas passage rates at low, intermittent traffic volume (>0–1 vehicles/min) were 15% lower. Once elk entered an underpass, semi-trailer trucks were 4 times more likely than passenger vehicles to cause flight behavior when traffic levels were intermittent versus when traffic was continuous. Overall, traffic volumes of >10–27 vehicles per minute did not decrease the effectiveness of wildlife underpasses as a means of mitigating elk population subdivision. However, if flight away from underpasses at intermediate traffic levels causes elk to cross the highway at other points and thereby increases the potential for costly elk-vehicle collisions, we recommend that managers consider measures to reduce traffic noise and visual stimuli, especially those caused by semi-trailer trucks.
Article
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ABSTRACT  We used 38,709 fixes collected from December 2003 through June 2006 from 44 elk (Cervus elaphus) fitted with Global Positioning System collars and hourly traffic data recorded along 27 km of highway in central Arizona, USA, to determine how traffic volume affected elk distribution and highway crossings. The probability of elk occurring near the highway decreased with increasing traffic volume, indicating that elk used habitat near the highway primarily when traffic volumes were low (<100 vehicles/hr). We used multiple logistic regression followed by model selection using Akaike's Information Criterion to identify factors influencing probability of elk crossings. We found that increasing traffic rates reduced the overall probability of highway crossing, but this effect depended on both season and the proximity of riparian meadow habitat. Elk crossed highways at higher traffic volumes when accessing high quality foraging areas. Our results indicate that 1) managers assessing habitat quality for elk in areas with high traffic-volume highways should consider that habitat near highways may be utilized at low traffic volumes, 2) in areas where highways potentially act as barriers to elk movement, increasing traffic volume decreases the probability of highway crossings, but the magnitude of this effect depends on both season and proximity of important resources, and 3) because some highway crossings still occurred at the high traffic volumes we recorded, increasing traffic alone will not prevent elk-vehicle collisions. Managers concerned with elk-vehicle collisions could increase the effectiveness of wildlife crossing structures by placing them near important resources, such as riparian meadow habitat.
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Roads are a widespread and increasing feature of most landscapes. We reviewed the scientific literature on the ecological effects of roads and found support for the general conclusion that they are associated with negative effects on biotic integrity in both terrestrial and aquatic ecosystems. Roads of all kinds have seven general effects: mortality from road construction, mortality from collision with vehicles, modification of animal behavior, alteration of the physical environment, alteration of the chemical environment, spread of exotics, and increased use of areas by humans. Road construction kills sessile and slow-moving organisms, injures organisms adjacent to a road, and alters physical conditions beneath a road. Vehicle collisions affect the demography of many species, both vertebrates and invertebrates; mitigation measures to reduce roadkill have been only partly successful. Roads alter animal behavior by causing changes in home ranges, movement, reproductive success, escape response, and physiological state. Roads change soil density, temperature, soil water content, light levels, dust, surface waters, patterns of runoff, and sedimentation, as well as adding heavy metals (especially lead), salts, organic molecules, ozone, and nutrients to roadside environments. Roads promote the dispersal of exotic species by altering habitats, stressing native species, and providing movement corridors. Roads also promote increased hunting, fishing, passive harassment of animals, and landscape modifications. Not all species and ecosystems are equally affected by roads, but overall the presence of roads is highly correlated with changes in species composition, population sizes, and hydrologic and geomorphic processes that shape aquatic and riparian systems. More experimental research is needed to complement post-hoc correlative studies. Our review underscores the importance to conservation of avoiding construction of new roads in roadless or sparsely roaded areas and of removal or restoration of existing roads to benefit both terrestrial and aquatic biota. Resumen: Las carreteras son una característica predominante y en incremento de la mayoría de los paisajes. Revisamos la literatura científica sobre los efectos ecológicos de las carreteras y encontramos sustento para la conclusión general de que las carreteras están asociadas con efectos negativos en la integridad biótica tanto de ecosistemas terrestres como acuáticos. Las carreteras de cualquier tipo ocasionan siete efectos generales: mortalidad ocasionada por la construcción de la carretera; mortalidad debida a la colisión con vehículos; modificaciones en la conducta animal; alteración del ambiente físico; alteración del ambiente químico; dispersión de especies exóticas e incremento en el uso de áreas por humanos. La construcción de carreteras elimina a organismos sésiles y a organismos de lento movimiento, lesiona a organismos adyacentes a la carretera y altera las condiciones físicas debajo ella misma. Las colisiones con vehículos afectan la demografía de muchas especies tanto de vertebrados como invertebrados; las medidas de mitigación para reducir la pérdida de animales por colisiones con vehículos han sido exitosas solo de manera parcial. Las carreteras alteran la conducta animal al ocasionar cambios en el rango de hogar, movimientos, éxito reproductivo, respuesta de escape y estado fisiológico. Las carreteras cambian la densidad del suelo, temperatura, contenido de agua en el suelo, niveles de luz, polvo, aguas superficiales, patrones de escurrimiento y sedimentación, además de agregar metales pesados (especialmente plomo), sales, moléculas orgánicas, ozono y mutrientes a los ambientes que atraviesan. Las carreteras promueven la dispersión de especies exóticas al alterar los hábitats, al estresar a las especies nativas y proveer corredores para movimiento. Las carreteras también promueven el incremento de la caza y la pesca, el hostigamiento pasivo de animales y modificaciones del paisaje. No todas las especies ni todos los ecosistemas son afectados por las carreteras de igual forma, pero en general la presencia de carreteras está altamente correlacionada con cambios en la composición de especies, los tamaños poblacionales y los procesos hidrológicos y geomorfológicos que afectan a la estructura de sistemas acuáticos y reparios. Se necesita más investigación experimental para complementar estudios correlativos post-hoc. Nuestra revisión hace énfasis en que en trabajos de conservación es importante evitar la construcción de nuevas carreteras en áreas carentes de ellas o en áreas con pocas carreteras, además de remover o restaurar carreteras existentes con la finalidad de beneficiar tanto a la biota acuática como la terrestre.
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Roads, especially large highways, can have significant impacts on wildlife movement and survival. This is especially true for wide-ranging species, such as mammalian carnivores. Some of these impacts may be mitigated if wildlife can find and utilize passageways under highways. To determine if underpasses and drainage culverts beneath highways are used by wildlife as movement corridors, we monitored 15 such passages near Los Angeles, California using remotely triggered cameras and gypsum track stations. We found that passages were used by a variety of species, including carnivores, mule deer, small mammals, and reptiles. Many types of undercrossings were utilized, indicating that passages beneath highways, even when not originally designed for wildlife, can provide important safe avenues for animals to cross roads. For mammals of conservation concern, including native carnivores and deer, passage dimensions, surrounding habitat, and the extent of human activity were assessed to determine if these factors influenced passage use by these species. Our results show that while many native mammals used passages beneath highways, the presence of suitable habitat on either side of the passage was a particularly important factor predicting use. For deer and coyotes, passage dimensions were also important and should be considered with the presence of suitable habitat when wildlife passages are planned or evaluated. To increase the likelihood of utilization and to help prevent animals from crossing road surfaces, we suggest that simple improvements such as habitat restoration near crossing points and animal-proof fencing that serves to funnel wildlife to passages, can facilitate animal movement between fragmented habitats that are bisected by roads.
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As habitat loss and fragmentation increase across ungulate ranges, identifying and prioritizing migration routes for conservation has taken on new urgency. Here we present a general framework using the Brownian bridge movement model (BBMM) that: (1) provides a probabilistic estimate of the migration routes of a sampled population, (2) distinguishes between route segments that function as stopover sites vs. those used primarily as movement corridors, and (3) prioritizes routes for conservation based upon the proportion of the sampled population that uses them. We applied this approach to a migratory mule deer (Odocoileus hemionus) population in a pristine area of southwest Wyoming, USA, where 2000 gas wells and 1609 km of pipelines and roads have been proposed for development. Our analysis clearly delineated where migration routes occurred relative to proposed development and provided guidance for on-the-ground conservation efforts. Mule deer migration routes were characterized by a series of stopover sites where deer spent most of their time, connected by movement corridors through which deer moved quickly. Our findings suggest management strategies that differentiate between stopover sites and movement corridors may be warranted. Because some migration routes were used by more mule deer than others, proportional level of use may provide a reasonable metric by which routes can be prioritized for conservation. The methods we outline should be applicable to a wide range of species that inhabit regions where migration routes are threatened or poorly understood.
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Numerous species undergo impressive movements, but due to massive changes in land use, long distance migration in terrestrial vertebrates has become a highly fragile ecological phenomenon. Uncertainty about the locations of past migrations and the importance of current corridors hampers conservation planning. Using archeological data from historic kill sites and modern methods to track migration, we document an invariant, 150 km (one-way) migration corridor used for at least 6000 years by North America's sole extant endemic ungulate. Pronghorn (Antilocapra americana) from the Greater Yellowstone Ecosystem, like other long distant migrants including Serengeti wildebeest (Connochaetes taurinus) and Arctic caribou (Rangifer tarandus), move nearly 50 km d-1, but in contrast to these other species, rely on an invariant corridor averaging only 2 km wide. Because an entire population accesses a national park (Grand Teton) by passage through bottlenecks as narrow as 121 m, any blockage to movement will result in extirpation. Based on animation of real data coupled with the loss of six historic routes, alternative pathways throughout the 60,000 km2 Yellowstone ecosystem are no longer available. Our findings have implications for developing strategies to protect long distance land migrations in Africa, Asia and North America and to prevent the disappearance of ecological phenomena that have operated for millennia.
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Odocoileus hemionus associated with the winter ranges occupied summer ranges spread over a >6000 km 2 area. Most marked animals summered on public lands in mountainous areas E and SE of the winter ranges. Autumn migration occurred in October-November. Spring migration occurred in March-May. Most marked deer migrated along definable corridors and used the same corridors in spring and autumn. Migration corridors followed prominent geographic features; deer selected open vegetation types within corridors. Deer migrating from one of the largest winter concentration areas in SE Idaho were not exposed to excessive hunting pressure during migration nor were their migration corridors immediately threatened by human land use. Areas where deer concentrated in migration corridors were identified, these areas should be protected from overgrazing and excessive conversion of native vegetation to crop production. -from Authors
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We distributed questionnaires to 50 state natural resource agencies in October 1992 to request estimates of deer killed annually on highways, the source of the estimates, and information about methods used to reduce vehicle collisions with deer; 43 agencies responded. Statistics on deer killed by vehicles were highly variable among agencies and were inconsistent among agencies. Despite a limited quantitative basis, the national deer road-kill for 1991 conservatively totaled at least 500,000 deer. Deer road- kills had increased during 1982-1991 in 26 of 29 states that had suitable trend data. Nearly all states had used some type of signs, modified speed limits, fencing, over- and underpasses, reflective apparatus, habitat alteration, or public awareness programs, but few agencies had evaluated performance of those techniques. Approaches that alter deer behavior and movement patterns appear to be the most fruitful for future application anti evaluation.
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Abstract A huge road network with vehicles ramifies across the land, representing a surprising frontier of ecology. Species-rich roadsides are conduits for few species. Roadkills are a premier mortality source, yet except for local spots, rates rarely limit population size. Road avoidance, especially due to traffic noise, has a greater ecological impact. The still-more-important barrier effect subdivides populations, with demographic and probably genetic consequences. Road networks crossing landscapes cause local hydrologic and erosion effects, whereas stream networks and distant valleys receive major peak-flow and sediment impacts. Chemical effects mainly occur near roads. Road networks interrupt horizontal ecological flows, alter landscape spatial pattern, and therefore inhibit important interior species. Thus, road density and network structure are informative landscape ecology assays. Australia has huge road-reserve networks of native vegetation, whereas the Dutch have tunnels and overpasses perforating road barriers to enhance ecological flows. Based on road-effect zones, an estimated 15–20% of the United States is ecologically impacted by roads.
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Seasonal movements of 117 female mule deer (Odocoileus hemionus hemionus) were monitored using radio telemetry from November 1980 through October 1984. All deer migrated in October before significant snow accumulated on summer range. During mid-winter, deer usually moved to lower elevations and shifted use from northerly to southerly aspects. Timing of mid-winter movements varied among years and appeared related to weather severity. In spring, deer concentrated around meadows until migrating to summer range. Timing of spring migration varied annually and was related to winter severity. During summer, deer were generally sedentary. However, of 8 animals that made extended movements, 6 were yearlings. We found little evidence of dispersal as all adult deer demonstrated strong fidelity to seasonal movement patterns, returning to essentially the identical locales occupied on summer and winter ranges in previous years. We suggest that the seasonal movements of migratory mule deer in the intermountain west are driven and controlled by seasonal changes in energetic needs of the animals and by the quantity and quality of forage available within the year-round range of the animals.
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An understanding of the migratory patterns of mule deer (Odocoileus hemionus hemionus) is essential when defining populations and helps wildlife managers select appropriate management strategies. During 1985-89, I used radio telemetry to study movements and migration patterns of mule deer in southeastern Idaho. Migration between summer and winter ranges averaged 19.7 km and did not differ (P > 0.05) between sexes. Twenty-six percent of the marked deer were not migratory. Deer from 1 summer range migrated to 6 discrete winter ranges, and the overall migration pattern formed a complex web among the winter and summer ranges. Deer showed high fidelity to summer ranges; 100% of the females (n = 27) and 92% of the males (n = 12) used the same summer range during each year they were monitored. Fidelity to winter ranges was lower than for summer ranges. Distances traveled between centers of activity during successive winters averaged 1.4 km (n = 38 deer) and did not differ (P > 0.05) between males (n = 12) and females (n = 26). During 2 relatively mild winters, 48% and 19% of marked migratory deer did not use winter range habitat.
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Among Earth's most stunning, yet imperiled, biological phenomena is long-distance migration (LDM). Although the understanding of how and why animals migrate may be of general interest, few site-specific strategies have targeted ways in which to best retain such increasingly rare events. Contrasts among 29 terrestrial mammals from five continents representing 103 populations indicate that remnant long-distant migrants have poor long-term prospects. Nonetheless, in areas of low human density in the Western Hemisphere, five social and nongregarious species, all from the same region of the Rocky Mountains (U.S.A.), still experience the most accentuated of remaining New World LDMs south of central Canada. These movements occur in or adjacent to the Greater Yellowstone region, where about 75% of the migration routes for elk (Cervus elaphus), bison ( Bison bison), and North America's sole surviving endemic ungulate, pronghorn (Antilocapra americana), have already been lost. However, pronghorn still migrate up to 550 km (round-trip) annually. These extreme movements (1) necessitate use of historic, exceptionally narrow corridors (0.1–0.8 km wide) that have existed for at least 5800 years, (2) exceed travel distances of elephants ( Loxodonta africana) and zebras ( Equus burchelli), and (3) are on par with those of Asian chiru ( Pantholops hodgsoni) and African wildebeest (Connochaetes taurinus). Although conservation planners face uncertainty in situating reserves in the most biologically valued locations, the concordance between archaeological and current biological data on migration through specific corridors in these unprotected areas adjacent to the Yellowstone system highlights their retention value. It is highly likely that accelerated leasing of public lands for energy development in such regions will truncate such migrations. One landscape-level solution to conserving LDMs is the creation of a network of national migration corridors, an action in the Yellowstone region that would result in de facto protection for a multispecies complex. Tactics applied in this part of the world may not work in others, however, therefore reinforcing the value of site-specific field information on the past and current biological needs of migratory species. Resumen: Entre los fenómenos biológicos más asombrosos, pero en peligro, de la Tierra está la migración de larga distancia (MLD). Aunque el entendimiento de cómo y porque migran los animales puede ser de interés general, pocas estrategias sitio-específicas han encontrado formas para retener tales eventos cada vez más raros. Los contrastes entre 29 mamíferos terrestres de cinco continentes que representar a 103 poblaciones indican que las MLD remanentes tienen perspectivas pobres a largo plazo. No obstante, en áreas con bajas densidades humanas en el Hemisferio Occidental, cinco especies sociales y no gregarias, todas de las misma región de las Montañas Rocallosas (E.U.A.) aun experimentan las MLD más acentuadas al sur de Canadá. Estos movimientos ocurren en la región de Yellowstone o adyacentes a la misma, donde se han perdido cerca del 75% de las rutas de migración de alces (Cervus elaphus), bisontes ( Bison bison) y el único ungulado endémico sobreviviente de Norteamérica, Antilocapra americana. Sin embargo, Antilocapra americana aun migra hasta 550 km (viaje redondo) anualmente. Estos movimientos extremos (1) necesitan el uso de corredores históricos, excepcionalmente angostos (0.1-0.8 km de ancho) que han existido por lo menos por 5800 años, (2) exceden las distancias de viaje de elefantes ( Loxodonta africana) y cebras ( Equus burchelli) y (3) son similares a los de Pantholops hodgsoni y Connochaetes taurinus. Aunque los planificadores de conservación enfrentan la incertidumbre de situar reservas en las localidades biológicamente más valiosas, la concordancia entre datos arqueológicos y actuales sobre migración por corredores específicos en estas áreas no protegidas adyacentes al sistema Yellowstone resalta su valor de retención. Es altamente probable que las migraciones se trunquen por el arrendamiento acelerado de tierras públicas para el desarrollo energético en tales áreas. Una solución a nivel de paisaje para conservar a las MLD es la creación de una red de corredores nacionales de migración, una acción que resultaría en la protección de hecho de un complejo multi-específico en la región de Yellowstone. Sin embargo, las tácticas empleadas en esta parte del mundo pueden no funcionar en otras, por lo cual se refuerza el valor de la información de campo sitio-específica sobre las necesidades pasadas y actuales de especies migratorias.
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Migratory mule deer (Odocoileus hemionus) and pronghorn (Antilocapra americana) populations rely on seasonal ranges to meet their annual nutritional and energetic requirements. Because seasonal ranges often occur great distances apart and across a mix of vegetation types and land ownership, maintaining migration corridors to and from these ranges can be difficult, especially if managers do not have detailed information on mule deer and pronghorn seasonal movements. We captured, radiomarked, and moni- tored mule deer (n=171) and pronghorn (n=34) in western Wyoming to document sea- sonal distribution patterns and migration routes. Mule deer and pronghorn migrated 20-158 km and 116-258 km, respectively, between seasonal ranges. These distances represented the longest recorded migrations for either species. We identified a number of bottlenecks along the migration routes of mule deer and pronghorn, but the most crit- ical appeared to be the 1.6-km-wide Trapper's Point bottleneck, which was used by both mule deer and pronghorn during their spring and autumn migrations. Housing develop- ments and roadways apparently have reduced the effective width of this bottleneck to
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Roads pose many threats to wildlife including wildlife-vehicle collisions, which are a danger to humans as well as wildlife. Bridges built with provisions for wildlife can function as important corridors for wildlife passage. We used video surveillance to record wildlife passage under a bridge near Durham, North Carolina, USA, to determine whether it functioned as a wildlife underpass. This is particularly important for white-tailed deer (Odocoileus virginianus) because forests associated with the bridge created a corridor between 2 natural areas. We calculated detection probabilities and estimated the number of crossings as observed crossings divided by detection probability. We observed 126 crossings by > 10 species of mammals. Detection probability was 42%; therefore, an estimated 299 wildlife crossings occurred. We observed 75 deer: 17 deer approached the underpass and retreated. We estimated sighting 40% of deer crossings and 92% of deer approaches. Thus, an estimated 185 deer crossings and 18 approaches occurred. As an index of road mortality, we conducted weekly surveys of vehicle-killed animals on a 1.8-km section containing the underpass. We discovered only 5 incidences of animals killed by vehicles. The size and design of the bridge promoted wildlife use of the underpass, providing landscape connectivity between habitats on opposite sides of the highway and likely increasing motorist safety. Thus, bridges in the appropriate landscape context and with a design conducive to wildlife use, can function as a corridor to reduce the effects of fragmentation.
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We evaluated use of 6 wildlife underpasses (UP) using video camera surveillance along State Route 260 in Arizona, USA. We documented wildlife use and compared successful UP crossings by various species and among UP. From 2002 to 2008, we recorded visits by 15,134 animals of 21 species (16 wildlife, 5 domestic) resulting in 72.4% crossing through UP. Elk (Cervus elaphus) accounted for 68% of recorded animals, white-tailed deer (Odocoileus virginianus) and mule deer (O. hemionus) accounted for 13% and 6%, respectively. As elk and white-tailed deer were the only species adequately represented across all UP, we used logistic regression to further evaluate factors associated with successful use of UP. To evaluate habituation over time we limited this analysis to 5 UP monitored for ≥4 yr. For elk, structural attributes and placement, season, time of day, and months monitored were associated with successful elk UP crossing in year 1, however, by year 4 only structural attributes and placement were significant, suggesting that UP structure and placement likely were of primary importance for successful elk passage. By year 4, probabilities of crossing at 4 of 5 UP converged on >0.70, indicating that given sufficient time to allow habituation, most UP we evaluated appeared to be effective for elk, regardless of structural attributes or placement. For deer, only structural attribute and placement were significant, and aside from one structure did not increase in probability of a successful crossing over time. The overall number of animals and species that crossed SR 260 via UP underscores efficacy of UP in promoting multi-species permeability. Long-term monitoring allows wildlife and highway managers to evaluate adaptation to wildlife crossing structures by different species. Results from this study add to our knowledge of mitigating the impact of highways on wildlife. © 2011 The Wildlife Society.
Article
Highways constitute barriers to wildlife passage, or permeability, which fragment populations and habitats. The degree of barrier effect caused by roadways varies by wildlife species, highway type and standard, and traffic volume. We assessed deer–highway relationships along a 27-km stretch of highway in central Arizona, USA. Our research objectives were to 1) assess white-tailed deer (Odocoileus virginianus) highway crossing patterns and permeability, 2) compare deer permeability on 4-lane reconstructed and 2-lane control sections to determine the influence of wildlife underpasses, and 3) assess and compare deer passage relationships to traffic volume. We fitted 13 deer with Global Positioning System (GPS) collars between 2004 and 2007. Eleven deer crossed the highway 395 times. On 2 control sections, deer crossed an average of 0.02 times/day, while on 3 reconstructed sections they averaged 15 times more crossings/day (0.28; t13 = −2.35; P = 0.035). The deer passage rate on control sections averaged 0.03 crossings/approach, approximately 20% of that for reconstructed sections (0.16; t13 = −2.43; P = 0.030). We linked hourly traffic volumes to our GPS data to examine how passage rates and the proportion of deer relocations at different distances from the highway varied with traffic volume. Deer distance from the highway showed minimal shift away from the highway with increased traffic, and at-grade passage rates were low (≤0.1 crossings/approach) across all traffic volumes. Although our linear regression analysis found no relationship between deer passage rate and increasing traffic volume on reconstructed sections with underpasses, there was a strong negative relationship on control sections (r = −0.881; P = 0.05); thus, we conclude that deer passage rates were minimally affected by traffic on reconstructed sections where passage structures facilitated below-grade passage. Further, from the 865 deer groups we recorded on videotape at 5 underpasses, traffic levels did not affect below-grade deer passage at the volumes we studied. Passage structures improved highway permeability across reconstructed sections with underpasses where traffic volume had a much lower impact compared to deer crossing at highway grade on control sections. © 2011 The Wildlife Society.
Article
We used integrated video systems to compare wildlife use of 2 bridged wildlife underpasses (UPs) on a reconstructed highway in central Arizona, USA, from September 2002 to September 2005. Both UPs opened into the same riparian-meadow complex, were situated <250 m apart, and had different below-span characteristics and dimensions. Our objectives were to compare Rocky Mountain elk (Cervus elaphus nelsoni) response to the UPs and test hypotheses that passage rate (crossing frequency/approach frequency), probability of use, and behavioral response at the 2 UPs did not differ. We related differences in elk use and response to UP design characteristics. Elk accounted for >90% of the animals we recorded on videotape, with 3,708 elk in 1,266 groups recorded at the 2 UPs. We used multiple logistic regression to predict the probability of UP use by elk, incorporating the combined effects of UP, season, and year. Season had the greatest effect on UP use, with the probability of UP use in summer (0.81) higher than in winter (0.58), when migratory elk less habituated to the UPs were present. A pattern of high summer (>0.80) and low winter passage rates (<0.40), regardless of UP, existed in all 3 years of video surveillance. Underpass also had an effect on the probability of elk crossing the UPs; the probability of use of the UP with 2 times the openness ratio, one-half the length for elk to traverse, and sloped earthen sides (0.75) was higher than the neighboring UP with concrete walls (0.66). Proportions of elk displaying behaviors indicative of resistance to crossing were dependent on UP and were higher at the UP with concrete walls. In all cases, elk preferred the more open UP with natural earthen sides. We believe that differences in UP length and the concrete walls contributed to differences in elk use and behavioral response. Continued video surveillance of these and other UPs will allow us to evaluate their efficacy in promting wildlife permeability and safer highways.
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The migratory route of the Wyoming Range mule deer (Odocoileus hemionus) herd is bisected by U.S. Highway 30 between Kemmerer and Cokeville, Wyoming, resulting in hundreds of deer-vehicle collisions at this site each year. We tested the effectiveness of the FLASH system, designed to detect deer presence on the highway and warn motorists by triggering flashing lights associated with a sign. We collected data on deer activity, system reliability, and vehicle speed in response to the warning signs. We also conducted a series of experimental manipulations to determine motorist response to the system with the lights flashing or not flashing and with the presence or absence of a realistic deer decoy in the road. It was found that more than 50 percent of the hits registered by the FLASH system were false hits not caused by deer, though a backup deer detection system worked well throughout the study period, with no false hits detected. Vehicles were not found to slow down significantly for the warning signs, although they did slow down in response to deer presence. During the experimental manipulations, vehicles only significantly reduced their speed (11.6 and 6.3 mph on average for passenger vehicles and tractor trailers respectively) when the deer decoy was in the crossing. Vehicles responded to the other treatments by reducing their speed by an average of less than 5 mph. The system tested may be effective in preventing deer-vehicle collisions under different traffic conditions, but is not suitable for this particular site.
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The Tibetan antelope or chiru Pantholops hodgsonii is endemic to the Tibetan plateau and was once abundant over vast areas of high elevation grassland habitat. During the 20th century, however, the population declined greatly in numbers. Hunting used to be the main threat to this species but recent actions by the government and wildlife protection organizations have brought this under control. With the development of north-west China, conflicts between development of transportation facilities and conservation have become more acute, and heavy traffic on the Golmud-Lhasa highway and the construction of the Qinghai-Tibet rail-way across key migration corridors have disturbed the migration of Tibetan antelopes. During June to August 2003 and 2004 we monitored the movement of Tibetan antelopes across the railway and highway and recorded their passes at wildlife crossing structures, which was the first use of such structures in China. Our results show that the efficiency of passages greatly improved between 2003 and 2004, and that use of wildlife corridors was affected by the structure of the passage, presence of wolves, recovery of vegetation following damage during construction, and other factors. The disturbance to mi-gration of Tibetan antelopes included infrastructure, human activities, road traffic, construction of the railway and so on. The impact of infrastructure, especially trans-portation development, on the habitat and migration of Tibetan antelopes are the main factors that threaten this species now and in the future.
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A huge road network with vehicles ramifies across the land, representing a surprising frontier of ecology. Species-rich roadsides are conduits for few species. Roadkills are a premier mortality source, yet except for local spots, rates rarely limit population size. Road avoidance, especially due to traffic noise, has a greater ecological impact. The still-more-important barrier effect subdivides populations, with demographic and probably genetic consequences. Road networks crossing landscapes cause local hydrologic and erosion effects, whereas stream networks and distant valleys receive major peak-flow and sediment impacts. Chemical effects mainly occur near roads. Road networks interrupt horizontal ecological flows, alter landscape spatial pattern, and therefore inhibit important interior species. Thus, road density and network structure are informative landscape ecology assays. Australia has huge road-reserve networks of native vegetation, whereas the Dutch have tunnels and overpasses perforating road barriers to enhance ecological flows. Based on road-effect zones, an estimated 15-20% of the United States is ecologically impacted by roads.
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Statistics from the U.S. or from Continental Europe suggest that damage to persons and property arising from road or railway accidents involving deer amounts to a very significant annual total and is increasing everywhere. Despite this, the relative efficacy or cost-effectiveness of different control options is poorly understood. This review presents an analysis of deer movement patterns in relation to roads in order to try and develop some general conclusions about the probable or expected pattern and behaviour of road crossings. Based on such framework the various possible options available for reducing accident rates are more formally evaluated. The review focuses primarily on deer and roadside management within Europe. Approaches to the management of deer on roads consist either of methods to increase driver awareness of deer (deer warning signs) and/or methods to reduce deer crossing activity or change the pattern of crossings (fences, reflectors or chemical repellents). Effective reduction of deer road-crossings can only be assured in erection of a genuinely impermeable barrier fence. Cost considerations usually result in erection of barriers which are only partially effective. Such fencing must be viewed merely as a deterrent to crossing and not an absolute barrier; effectiveness can be enhanced by providing alternative means of passage, thus reducing the probability of deer intent on crossing, forcing the fence. Some means of exit (one-way gates, deer-leaps) should be provided for animals that do get on to the carriageway and are then unable to escape. Provision of fencing, with the additional structures of one-way gates and underpasses, is likely to be extremely costly; such high costs may only be justified in regard to major roads. For minor roads where traffic flow is lighter and intermittent, deer-mirrors or game-reflectors are a more economical and a more appropriate solution, since the intention is to delay crossing, rather than prevent it. The effectiveness of both fencing and mirrors may be reinforced in especially sensitive areas by erection of appropriate road signs to increase driver awareness.
Article
Studies assessing the efficacy of wildlife crossing structures often lead to spurious results because of their failure to address masking effects of confounding variables. Confounding variables include variation in human activity, density of crossing structures along the highway corridor, and equality of species' perceived access to each crossing structure. We investigated these issues for wide-ranging large carnivores and their prey species in Banff National Park, Alberta, using data obtained from systematic, year-round monitoring of 13 newly constructed crossing structures for wildlife (underpasses and overpasses) for 34 months post-construction. We standardized the first confounding variable by selecting crossing structures remote from areas of human activity. The second confounding variable we standardized by developing probability models of crossing structure usage assuming habitat homogeneity. We standardized the third confounding variable by developing species-specific, performance indices of crossing structures (=observed through passage usage–expected through passage usage). We regressed the species performance indices against 13 crossing structure variables encompassing structural, landscape, and human activity. Our results suggest that in absence of high human activity structural attributes best explained the performance indices for both large predator and prey species, while landscape and human-related factors were of secondary importance. Crossing structures that were high, wide and short in length strongly influenced passage by grizzly bears Ursus arctos, wolves Canis lupus, elk Cervus elaphus, and deer Odocoileus sp. More constricted crossing structures were favoured by black bears Ursus americanus and cougars Puma concolor. Distance to cover was the most important crossing structure landscape attribute for cougars (negative correlation) and was a significant factor determining passage for grizzly bears, elk and deer (all positive correlations). Our findings underscore the importance of: (a) integrating temporal and spatial variability a priori when addressing the efficacy of crossing structures, and; (b) demonstrate that species respond differently to crossing structure features. In light of these results, we suggest that to maximize connectivity across roads for multiple large mammal species, road construction schemes should include a diversity of crossing structures of mixed size classes. Mitigation planning in a multiple-species ecosystem is likely to be a challenging endeavour and long-term research will aid in the decision-making process.prs.rt("abs_end");KeywordsBanff National Park; Habitat fragmentation; Mammals; Road ecology; Wildlife crossing structureFigures and tables from this article: