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Use of fauna road-crossing structures in northern New South Wales
Abstract
The vast network of roads around the world has had a significant effect on wildlife and ecosystems through habitat fragmentation, reduced dispersal and mortality by collision with vehicles. Road agencies worldwide now frequently install dedicated structures to facilitate the safe crossing of roads by wildlife. We conducted surveys to determine the use of dedicated wildlife overpasses and nearby underpasses at two locations on the Pacific Highway in north-eastern New South Wales. Road-kill surveys were conducted to provide some understanding of the species commonly killed and whether the rate of road-kill was lower at one location where crossing-structures were located. Use of the crossing-structures by wildlife was monitored with sand-transects. The most frequent users were macropods, bandicoots and rodents. Macropods made greater use of overpasses (n≤104 tracks) than underpasses (n≤36), whereas underpasses were used more by bandicoots (n≤87) and rodents (n≤82) than were overpasses (n≤28, n≤15, respectively). We identified 78 road-kills of 21 species on two sections of the Pacific Highway over a 7-week period. Bandicoots (n≤16) and macropods (n≤9) were the most frequently observed victims. The mortality of wildlife was lower along the highway section with the crossing-structures (0.04road-killskm-1) than it was along the highway section without structures (0.15road-killskm-1). The lack of replication precludes any firm conclusion that the crossing-structures reduced road mortality but the high level of use of the crossing-structures by species that were common victims of road-kill suggests an influence. © 2009 Australian Mammal Society
... Nine mammal species used the crossing. Most crossings were by rabbits Sylvilagus palustris (69 crossings), racoons Procyon lotor (61), armadillos Dasypus novemcinctus (36), opossums Didelphis virginiana (36), foxes Vulpes vulpes (29) and bobcats Lynx rufus (27). The number of mammals of squirrel size or larger killed on the fenced road section was not significantly different in the 11 months after fence installation (13 animals) relative to the 11 months before (10 animals). ...
... Nine mammal species used the crossing. Most crossings were by rabbits Sylvilagus palustris (69 crossings), racoons Procyon lotor (61), armadillos Dasypus novemcinctus (36), opossums Didelphis virginiana (36), foxes Vulpes vulpes (29) and bobcats Lynx rufus (27). The number of mammals of squirrel size or larger killed on the fenced road section was not significantly different in the 11 months after fence installation (13 animals) relative to the 11 months before (10 animals). ...
... A site comparison study in 2006 along a Highway in New South Wales, Australia (36) found that two underpasses were used by mammals and that presence of crossing-structures along with barrier fencing reduced road-kills. There were fewer road-kills over seven weeks along the section with crossing-structures (0.02/km of survey) than along a section without crossings (0.09/km of survey). ...
Terrestrial Mammal Conservation provides a thorough summary of the available scientific evidence of what is known, or not known, about the effectiveness of all of the conservation actions for wild terrestrial mammals across the world (excluding bats and primates, which are covered in separate synopses). Actions are organized into categories based on the International Union for Conservation of Nature classifications of direct threats and conservation actions. Over the course of fifteen chapters, the authors consider interventions as wide ranging as creating uncultivated margins around fields, prescribed burning, setting hunting quotas and removing non-native mammals.
This book is written in an accessible style and is designed to be an invaluable resource for anyone concerned with the practical conservation of terrestrial mammals.
The authors consulted an international group of terrestrial mammal experts and conservationists to produce this synopsis. Funding was provided by the MAVA Foundation, Arcadia and National Geographic Big Cats Initiative.
Terrestrial Mammal Conservation is the seventeenth publication in the Conservation Evidence Series, linked to the online resource www.ConservationEvidence.com. Conservation Evidence Synopses are designed to promote a more evidence-based approach to biodiversity conservation. Others in the series include Bat Conservation, Primate Conservation, Bird Conservation and Forest Conservation and more are in preparation. Expert assessment of the evidence summarised within synopses is provided online and within the annual publication What Works in Conservation.
... Within Australia, wildlife underpasses have been increasingly adopted over the last 20 years, particularly in conjunction with upgrades to the Pacific Highway along the eastern seaboard (Taylor and Goldingay 2010). A consistent finding of the relatively few published studies describing fauna use of underpasses has been their regular use by bandicoots (Taylor and Goldingay 2003;Bond and Jones 2008;Hayes and Goldingay 2009;Harris et al. 2010). ...
... Harris et al. (2010) reported relatively frequent use (0.1-0.4 traverses per day) of two underpasses 35-45 m long, though greater use of one that was 20 m long (0.1-0.9 traverses per day). Hayes and Goldingay (2009) recorded frequent use by bandicoots near the entrance of one underpass 42 m long (2.5 tracks per day) but no use of one 63 m long. Goosem et al. (2005) also reported frequent use (rate not described) by bandicoots of underpasses at least 40 m long. ...
... Harris et al. (2010) attributed a decline in the local abundance of southern brown bandicoots (Isoodon obesulus fusciventer) and their use of underpasses to the presence of foxes. Whilst bandicoot decline may occur at some locations (and also in the absence of underpasses), this observation is not universal in other Australian studies (see Abson and Lawrence 2003;Goosem et al. 2005;Bond and Jones 2008;Hayes and Goldingay 2009). In the current study, the pattern of underpass usage by foxes (detected in 9 of 13 monitoring periods) and bandicoots revealed no clear association. ...
Roads may create filters or barriers to animal movement and adversely affect population processes. Underpasses are now commonly installed during highway construction to mitigate barrier effects and link habitat patches. We used sand-tracking to investigate use of six underpasses by bandicoots along a section of the Pacific Highway in northern New South Wales before, during and after road duplication (i.e. expansion from two to four lanes). Trapping revealed that the northern brown bandicoot (Isoodon macrourus) and the long-nosed bandicoot (Perameles nasuta) were equally abundant prior to highway expansion. Five years before highway widening, bandicoots frequently used 18-m-long underpasses (>1 traverses per day). Twelve months before road widening, underpass use by bandicoots declined to ∼0.5 traverses per day and continued near this level during construction. This declined to 0.03 traverses per day after duplication with underpasses extended to ≥49 m in length. Few crossings were recorded after expansion of the road corridor, which may indicate a shift from regular foraging traverses before duplication to infrequent dispersal movements after duplication.
... Following trials in North Queensland rainforest, canopy bridges are increasingly being incorporated into the construction of Australian highways passing through other habitats (van der Ree 2006; . Faunal underpasses are a common feature elsewhere in Australia (Hunt et al. 1987;Mansergh & Scotts 1989;Hayes & Goldingay 2009), and large culvert underpasses now incorporate a variety of movement routes, escape opportunities and cover similar to Wet Tropics designs (Bond & Jones 2008). More expensive options such as bridges for fauna above the road (overpasses) have been constructed elsewhere in Australia (Bond & Jones 2008;Hayes & Goldingay 2009). ...
... Faunal underpasses are a common feature elsewhere in Australia (Hunt et al. 1987;Mansergh & Scotts 1989;Hayes & Goldingay 2009), and large culvert underpasses now incorporate a variety of movement routes, escape opportunities and cover similar to Wet Tropics designs (Bond & Jones 2008). More expensive options such as bridges for fauna above the road (overpasses) have been constructed elsewhere in Australia (Bond & Jones 2008;Hayes & Goldingay 2009). Fencing designed to exclude a variety of vertebrates from the road and encourage overpass and underpass use appears at least partially successful, although occasional fence damage still results in road kill (Bond & Jones 2008;Hayes & Goldingay 2009). ...
... More expensive options such as bridges for fauna above the road (overpasses) have been constructed elsewhere in Australia (Bond & Jones 2008;Hayes & Goldingay 2009). Fencing designed to exclude a variety of vertebrates from the road and encourage overpass and underpass use appears at least partially successful, although occasional fence damage still results in road kill (Bond & Jones 2008;Hayes & Goldingay 2009). Such fencing could be trialled further in appropriate areas of the Wet Tropics. ...
Summary Research into mitigation of the ecological impacts of rainforest roads in North Queensland has a long history, commencing during the formative years of Australian road ecology. In Queensland’s Wet Tropics and throughout Australia, installation of engineered structures to ameliorate ecological road impacts is now common during larger construction projects, but unusual in smaller road projects. Retro‐fitting of engineering solutions to roads that are causing obvious impacts is also uncommon. Currently, Australian mitigation measures concentrate on two important impacts: road mortality and terrestrial habitat fragmentation. Unfortunately, other important ecological impacts of roads are seldom addressed. These include edge effects, traffic disturbance, exotic invasions and fragmentation of stream habitats. In North Queensland, faunal underpasses and canopy bridges across rainforest roads have been monitored over long periods. These structures are used frequently by multiple individuals of various species, implying effectiveness for movements and dispersal of many generalist and specialised rainforest animals. However, without addressing population and genetic implications, assessment of effectiveness of these connectivity structures is not holistic. These aspects need sufficient long‐term funding to allow similar systematic monitoring before and after construction. Throughout Australia, more holistic approaches to mitigation of road impacts would routinely examine population and genetic connectivity, consider mitigation against more ecological impacts where appropriate and include landscape‐scale replication.
... This study aimed to investigate whether roadways impacted on the movement patterns of Eastern-Grey Kangaroos along the Coffs Harbour Northern Beaches region, through three main objectives: (1) Determine the home ranges of EGKs located near different types of roadways (major highway, minor highway, residential roadway); (2) Determine, on average, how far individuals were located with regards to different types of roads; and (3) Determine the level of road utilisation by EGKs. It is hypothesised that: (1) Roads will affect the movement patterns of EGKs; (2) Males will have larger home ranges than females irrespective of road type, as previous studies observed males to have greater dispersal patterns (Coulson, 1997;Coulson et al., 2014); (3) EGKs will be in closer proximity to residential roads than highway-style roads, as highways can present greater noxious stimuli, increasing avoidance behaviours (Frid & Dill, 2002); and (4) Road utilisation will be greater along residential roadways, as these roads are more accessible, therefore enabling more successful crosses (Lode, 2000;Hayes & Goldingay, 2009;Wilson et al., 2015;Mimet et al., 2016;Rytwinski et al., 2016). ...
... Highways are mandated to have wildlife exclusion fences erected for approximately 200 metres on either side of a wildlife crossing (Taylor et al., 2017), although subject to financial and structural constraints. It has also been established that wildlife exclusion fences and wildlife crossings have variable degrees of effectiveness and depend on the species in focus (Bond & Jones, 2008;Hayes & Goldingay, 2009;Taylor & Goldingay, 2014;Chambers & Bencini, 2015). Although not directly examined in the study, majority of road crosses were assumed to occur through wildlife corridors at HP (based on the position of the GPS points relative to wildlife corridors). ...
Understanding how spatial and temporal movement patterns of individuals change in relation to the development of road infrastructure is crucial for effective kangaroo population management in peri-urban environments. In this study, we assessed the impact of three types of roadways (major highway, minor highway, residential roadway), on the movement patterns of Eastern-Grey Kangaroos (Macropus giganteus). We examined the home range of individuals located near different types of roadways and quantified the impacts of the roads on individuals based on the number of crosses and proximity to the roadway. The kangaroo movement patterns were tracked using GPS collars collecting fixes at 15 minutes intervals, in multiple deployments on individuals between 2017-2018. GPS data was statistically analysed in R to determine home range size and location using the ‘adehabitatHR’ package and the number and location of road crossings was determined by visualisation of GPS tracks in ArcGIS Pro. Males were found to have larger average home ranges (13.3 ha) than females (6.0 ha). Males moved significantly further and incorporated more of the roadways into their home ranges than females, which seemingly influenced the number of times they interacted with a roadway. The proximity to roadways changed depending on the study site and type of roadway, with kangaroos having a smaller average distance from residential roads (217 m). The degree of road use differed depending on the road type, with the greatest total number of crosses occurring along residential roadways (257, 49%). Roadways are likely to act as barriers to movement for female kangaroos more than males, however, this appears to be the case only for major and minor highway structures. The female movement was relatively unencumbered by residential roadways. Further, whilst proximity to roads was relatively similar between study sites, individuals were located, on average, closer to residential roadways than major or minor highways. The findings conform to predictions regarding movement patterns of Eastern-Grey Kangaroos, where males were expected to move more than females and that highway-style roadway would act as barriers to movement more than smaller residential-style roads. Movement patterns of wildlife can be impacted by the introduction of urban infrastructure, particularly roads, and as such management strategies should be based on ecological and behavioural data regarding the spatial and temporal movement patterns of animals in relation to these urban structures.
... Fauna overpasses are the largest and most effective crossing structures, as they able to benefit the greatest diversity of species (Glista et al., 2009;Hayes and Goldingay, 2009). Traditionally, many of these structures were designed primarily to facilitate the movements of larger mammals. ...
... Despite the dramatic increase of purpose designed fauna crossing structures in Australia over the last decade , only five fauna overpasses have been constructed to date. Although all are fully vegetated, only two have been monitored (Hayes and Goldingay, 2009). The most intensively studied of the Australian fauna overpasses is that at Compton Road ( Fig. 1), located on the outskirts of Brisbane in subtropical Queensland (Veage and Jones, 2007;Bond and Jones, 2008). ...
The ecological impact of roads and traffic is now widely acknowledged, with a variety of mitigation strategies such as purpose designed fauna underpasses and overpasses commonly installed to facilitate animal movement. Despite often being designed for larger mammals, crossing structures appear to enable safe crossings for a range of smaller, ground dwelling species that exhibit high vulnerability to roads. Less attention has been paid to the extent to which fauna overpasses function as habitat in their own right, an issue particularly relevant to reptiles and amphibians. The Compton Road fauna array (Brisbane, Australia) includes a vegetated fauna overpass which connects two urban forest reserves and traverses a major four lane arterial road. The aim of this study was to quantify the extent to which colonisation of the Compton Road fauna overpass by reptile and amphibian species living in adjacent forests occurred. Pitfall sampling at seven sampling sites occurred between June 2005 and February 2010, starting approximately six months after overpass construction, with additional observational detections throughout this period. The overpass yielded higher species diversity and capture rates compared with the forest areas. Species accumulation curves demonstrated a strong and consistent colonisation rate of the overpass throughout the six year monitoring period, while persistent occupation by species on the overpass throughout the six years suggests permanent colonisation of the vegetated structure as an extension of the natural forest habitat. These outcomes demonstrate that the fauna overpass at Compton Road provides suitable habitat for diverse local herpetofauna communities and suggest enhanced habitat connectivity across the road.
... Although wallabies and kangaroos used fauna culverts as small as 1.2 m high  2.4 m wide (Taylor and Goldingay 2003), a minimum of 3 m in height should be recommended to allow animals to stand upright and hop unimpeded (Figs 3, 4). The influence of the length of the underpasses has only been assessed on a few occasions, but one culvert 62.5 m in length has been used, suggesting that wallabies and kangaroos may not be deterred by long structures (Hayes and Goldingay 2009). Unidentified kangaroos or wallabies have also been detected using viaducts and culverts for creek and drainage flow on the Gold Coast, Queensland, although no dimensions for these structures were reported (Leopold-Wooldridge 2008). ...
... The red Strieter-Lite reflectors elicited significantly increased vigilance in red kangaroos and increased flight from the road in red-necked wallabies . However, despite these results being statistically significant, overall responses to the wildlife warning reflectors were very low, and therefore were deemed ineffective (Ramp and Taylor and Goldingay (2003); 11, Goosem et al. (2005); 12, Bond and Jones (2006); 13, Bond and Jones (2008); 14, Hayes and Goldingay (2009);15, Jones et al. (2012); 16, Jones et al. (2013). ...
Understanding the impacts of roads on wildlife and the natural environment is of increasing importance. Macropods (mostly kangaroos and wallabies) are a diverse and widespread taxon in Australia that has been significantly affected by the presence of roads in various ways. We reviewed the available literature on macropods and roads, assessing 60 scientific journal articles, reports and theses. Studies on road mortalities were the most prevalent (n = 29, with 12 on macropods only), revealing both spatial and temporal patterns in occurrence. Behavioural studies in relation to the road environment are limited (n = 2) yet could help our understanding of patterns of road-kill and other impacts. Some macropod populations are critically affected by the presence of roads (e.g. brush-tailed rock-wallaby, Petrogale penicillata) due to either proportionately high road mortalities and/or population fragmentation, and may face continued decline unless effective road-mitigation measures are implemented. Investigations of various types of road mitigation focussed on wildlife-exclusion fencing and road crossing structures as the most effective option, although the high cost of these measures appears to limit their implementation. Further research into several areas was identified, particularly on species where severe road impacts are likely to result in population declines.
... We also observed that snake mortality was comparatively less near an underpass (water channel). Underpasses and overpasses are used for safe movement of wild animals (Hayes and Goldingay, 2009;Glista et al., 2009;McCollister and Van Manen, 2010;Rytwinski et al., 2016). Fencing, overpass, underpass and wildlife warning signs can contribute to minimise wildlife killing due to road accidents. ...
... This removal or lack of complex habitat at crossing structures has been shown to influence wildlife use more than noise levels caused by traffic volume (Iglesias et al., 2012). Vegetation near structure entrances provides cover and increased use of underpasses for small to medium sized mammals and reptiles (Chambers and Bencini, 2015;Goosem, 2001;Hayes and Goldingay, 2009). So too, for birds and forest microbats, as shown with a large vegetated overpass in southeast Queensland (Jones and Bond, 2010;McGregor et al., 2017;Pell and Jones, 2015). ...
Crossing structures are frequently installed worldwide to ameliorate the impacts of road and rail infrastructure on wildlife populations, yet their effectiveness is often uncertain. We monitored various species at multiple drainage culverts, dedicated wildlife underpasses, and a large viaduct, as well as in adjacent bushland over 12 months along a 13 km section of a new highway in eastern Australia. We quantified the frequency that species approached each structure relative to their presence in adjacent bushland, and compared species’ utilisation preferences between the three types of crossing structure. Of the 46 species detected, only 28 were detected at crossing structures. Brush turkeys (Alectura lathami), echidnas (Tachyglossus aculeatus), European brown hares (Lepus europaeus), rats (Rattus spp.), red-necked wallabies (Macropus rufogriseus) and swamp wallabies (Wallabia bicolor) were less frequently observed at crossing structures than in adjacent bushland. Feral cats (Felis catus) and European red foxes (Vulpes vulpes) were observed 3.5 and 2.7 times more frequently at crossing structures than in adjacent bushland. Culverts, underpasses and the viaduct performed equally for all species except for swamp wallabies and hares, which preferred the viaduct. Feral cats, foxes, dingoes (Canis familiaris), and hares were responsible for 76% of the successful crossings, and individually identified feral cats and foxes repeatedly crossed the road during the study period. We recommend increased use of experimental study designs to evaluate the effectiveness of crossing structures and provide construction authorities with reliable information on structure performance.
... Only two studies extended for more than 2 years (Taylor & Goldingay, 2014;van der Ree et al., 2009). Most studies investigated fewer than five underpasses (Bateman et al., 2017;Bond & Jones, 2008;Chachelle et al., 2016;Goosem et al., 2005;Harris et al., 2010;Hayes & Goldingay, 2009;Koehler & Gilmore, 2014;van der Ree et al., 2009) and were focused on a single study area. Only two studies (Chambers & Bencini, 2015;van der Ree et al., 2009) had knowledge of wildlife populations in the habitat surrounding the underpasses, while another two studies radio-tracked animals to describe their use of the underpasses and the surrounding habitat (Bateman et al., 2017;Chachelle et al., 2016). ...
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.
... By examining koala movements in relation to risks and preventative measures, Goldingay and Dobner (2014), in their radio-tracking study of koalas in an urban area (Lismore) of north-east NSW, found that all the koalas crossed roads. They noted that the installation of floppy-top fencing along major roads in NSW appears to be reasonably successful in reducing koala roadkill, and they cite Taylor and Goldingay (2003), Lassau et al. (2008) and Hayes and Goldingay (2009). They added that fencing may have limited application in Lismore where driveways occur at regular intervals. ...
This 6-year study aimed to monitor a local koala population and koala protection/mitigation measures before, during and after a major upgrade to the Pacific Highway at Lindsay’s cutting near Coffs Harbour in northern coastal New South Wales. This represents the scale of the individual koala interacting with traffic on a primary road within a well-studied Local Government Area for koalas. We also collected records of koala road injury and death from local wildlife carers. The principal findings were that, before the upgrade or any mitigation provisions, koalas were regularly killed on this 1 km stretch of highway flanked by primary koala habitat (26 records 1991–97). Koala exclusion fences largely eliminated the roadkill here, but the benefits were highly localised. Koalas made occasional use of a wildlife underpass below the highway. Two problems were identified: a farm gate left open in the fence allowed koalas onto the highway, and koalas could walk around the fence ends onto the highway. On the positive side, we have shown the value of local-scale research and mitigation, such as koala exclusion fences, and the value of examining the koala population of the surrounding area to assess the effectiveness of this mitigation at a larger scale.
... Two studies since 2001 have described the use of underpasses containing timber railings but neither documented the use of this 'furniture' (Bond and Jones 2008;Hayes and Goldingay 2009). Two underpasses at Coffs Harbour containing timber railings were monitored for 2.4 years (AMBS 2012). ...
Wildlife underpasses in Australia are commonly fitted with timber railings to facilitate the passage of arboreal and scansorial mammals but there are no published accounts of railing use. We compared detections of such mammals on railings in two underpasses to detections on the ground in these and other underpasses. The brown antechinus (Antechinus stuartii) and the black rat (Rattus rattus) were detected on a closely monitored railing on 12-14% of nights over three years. These species were detected on the ground of underpasses on <1% of nights. Koalas (Phascolarctos cinereus) and brushtail possums (Trichosurus spp.) were infrequently detected, koalas only on the ground and brushtail possums mostly on the ground. These observations suggest that road crossings by small scansorial mammals can be facilitated by timber railings.
... A practical start has been undertaken in NSW by the Environment Branch of the Roads and Traffic Authority (RTA; now Roads and Maritime Services) in producing biodiversity guidelines (RTA 2011). While various mitigation options have attracted considerable research attention in recent years ( Bender 2001;Dique et al. 2003;Goldingay 2003, 2010;Magnus et al. 2004;Bond and Jones 2008;Hayes and Goldingay 2009;van der Ree et al. 2010;Soanes et al. 2013;van der Grift et al. 2013), there remains much to be done. Although overpasses, for example, have been touted as an effective solution, they make little sense from an ecological standpoint. ...
Wildlife roadkill is a tragic blind spot in public perception, both internationally and in Australia. Despite an increasing body of data documenting the frequency and distribution of roadkill, and its consequences for specific animal populations, scientists and engineers alone have been unable to develop solutions that challenge the prevailing indifference to the problem. This points to an urgent need to develop approaches to roadkill which engage the general public, and which draw from the insights of a range of scholarly communities. This paper contends that a broader response to the problem, and to the conceptual basis of its solution, is required if we are to effect substantial change. The author, an ecologist, has attempted to draw on the work of humanities scholars on the subject of roadkill in order to demonstrate the value of their ideas for enriching our understanding of the problem. This essay also aims to develop a deeper understanding of the significance of roadkill by exploring the different ways it is understood by specific groups, such as those interested in its consumption, its artistic portrayal, and educational potential. The diverse perspectives from the humanities, combined with the quantitative and species-specific approach of research scientists, promises to overcome the current impasse and build a more robust and wide-ranging public discussion.
... It has been shown that the provision of exclusion fencing along roads, together with 244 underpasses, effectively reduces koala and other wildlife mortalities(Hayes & Goldingay 2009). A 245 recent study by the NSW Roads and Maritime Services found that fencing (with or without 246 underpasses) was able to reduce koala deaths along roads by approximately 80% (Semeniuk et al. 247 2011). ...
1. As threats to biodiversity from environmental change increase, assessing priorities for mitigation
action becomes increasingly important. However, there have been few attempts to schedule actions
across broad spatial extents that explicitly account for dynamic ecological processes and threats.
2. We combined a dynamic occupancy model with a decision analysis framework to spatially
allocate multiple recovery actions to maximize species’ probability of occupancy under threats
posed by climate and land-use change. We used the koala Phascolarctos cinereus across the Australian
state of New South Wales (810000 km2) to illustrate this approach. We considered four
actions implemented on a 10x10 km2 grid: reduce domestic dog attacks through dog control,
reduce vehicle collisions through fencing highways, protect habitat through land acquisitions and
restore Eucalyptus forest. We used the occupancy model to predict ecological responses to recovery
actions and simulated annealing to identify spatio-temporal priorities for each action. We contrasted
the results against priorities generated using a traditional static distribution model.
3. To maximize the probability of koala occupancy in 50 years’ time, with an annual budget
of up to AU$20 million, investment priorities were located in the eastern part of koala’s
range, focusing on dog control with some investment in habitat protection and restoration.
With higher budgets, investment priorities shifted towards habitat protection and restoration
in the western part of the range. However, priorities based on the static distribution model,
which had a lower predictive accuracy than the dynamic model, were different. Regardless of
budget, priorities derived from the static model were predominantly located in the western
part of koala’s range, focusing on highway fencing with some investment in dog control.
4. Synthesis and applications. Our approach for integrating spatio-temporal dynamics into conservation
prioritization across broad spatial extents provides a significant advance on existing
approaches based on static distribution models. The finding that the inferior static model produced
different priorities to the dynamic model cautions against the use of static models for conservation
planning in dynamic landscapes. Additionally, the substantial changes in priorities with
budget indicate that conservation planning under dynamic landscape and climate change must
carefully consider priority actions and locations relative to the conservation resources available.
... Koala crossing signs that aimed to reduce vehicle speed were ineffective in south-east Queensland (Dique et al. 2003). In contrast, the installation of floppy-top fencing along major roads in New South Wales appears to be reasonably successful in reducing koala road-kill (Taylor and Goldingay 2003;Lassau et al. 2008;Hayes and Goldingay 2009). Fencing may have limited application in Lismore where driveways occur at regular intervals. ...
Conserving wildlife within urban areas requires knowledge of habitat requirements and population processes, and the management of threatening factors. The koala (Phascolarctos cinereus) is one species that is adversely affected by urban development. Sick and injured koalas in the Lismore urban area are regularly taken into care. We radio-tracked koalas released from care in order to estimate home-range areas and to determine their fate. Koalas were tracked for periods of 90-742 days; 7 of 10 survived for a period of at least one year. Home ranges defined by the minimum convex polygon (MCP100%) were large (mean +/- s.e.=37.4 +/- 8.2ha). Analysis using the 95% Fixed Kernel revealed home-range areas of 8.0 +/- 1.7ha. Analysis of the habitat composition of each MCP home range showed that they included 4.3 +/- 0.9ha of primary habitat (dominated by their primary food trees). These home ranges contained 27.6 +/- 6.8ha of non-habitat (cleared or developed land). Koalas crossed roads within their home ranges at least 5-53 times; one crossed the Bruxner Highway near a roundabout at least 32 times over his 2-year tracking period. Future management should include strategic food tree planting that enhances habitat connectivity and minimises the risk of car strike or dog attack.
... The challenge here is to devise an effective management response. A recent approach to help breach road barriers is the installation of wildlife landbridges (Bond and Jones 2008;Hayes and Goldingay 2009). These are very expensive structures (~$2 million), which is likely to prevent their installation when needed. ...
How we manage National Parks (protected areas or reserves) for their biodiversity is an issue of current debate. At the centre of this issue is the role of ecological research and its ability to guide reserve management. One may assume that ecological science has sufficient theory and empirical evidence to offer a prescription of how reserves should be managed. I use Royal National Park (Royal NP) as a case study to examine how ecological science should be used to inform biodiversity conservation. Ecological research relating to reserve management can be: i) of generic application to reserve management, ii) specific to the reserve in which it is conducted, and iii) conducted elsewhere but be of relevance due to the circumstances (e. g. species) of another reserve. I outline how such research can be used to inform management actions within Royal NP. I also highlight three big challenges for biodiversity management in Royal NP: i) habitat connectivity, ii) habitat degradation and iii) fire management. A key issue for local managers is finding a mechanism to enable their management to be informed by ecological research in their Park in an ongoing way and to be able to encourage further research. If resolved, Royal NP could provide a model to be used by other protected areas.
... Based on these data, we estimated the maintenance cost was the mid-range of these values, i.e. 2.5% of the initial construction cost. It has been shown that the provision of exclusion fencing along roads, together with underpasses, effectively reduces koala and other wildlife mortalities (Hayes & Goldingay 2009). A recent study conducted by the NSW Roads and Maritime Services found that fencing (with or without underpasses) was able to reduce koala deaths along roads by approximately 80% (Semeniuk et al. 2011). ...
... We studied five rope-bridges erected at four locations along the Pacific Highway, in New South Wales (NSW), Australia. This highway has undergone major realignment and expansion during the last 15 years in order to provide dual carriage-way from Sydney to Brisbane (see Taylor and Goldingay 2003; Hayes and Goldingay 2009). The rope-bridges were installed by the NSW Roads and Traffic Authority (now named NSW Roads and Maritime Services) as part of consent conditions for the new highway. ...
Artificial structures designed to promote road-crossing by arboreal mammals are increasingly being installed in Australia but there is a limited understanding of their usefulness. We studied five 50-70-m-long rope-bridges (encompassing three designs) erected across the Pacific Highway, a major freeway in eastern Australia. Native arboreal mammals showed a willingness to explore these structures, being detected by camera traps on four rope-bridges. The vulnerable squirrel glider (Petaurus norfolcensis) crossed on one rope-bridge at least once every 4.5 weeks over a 32-week period. The feathertail glider (Acrobates pygmaeus), common ringtail possum (Pseudocheirus peregrinus) and the common brushtail possum (Trichosurus vulpecula) were detected on one of two rope-bridges that extended under the freeway at creek crossings. The feathertail glider was detected on all three rope-bridge designs. Our results suggest that rope-bridges have the potential to restore habitat connectivity disrupted by roads for some arboreal mammals. Further research is needed to refine the design and placement of rope-bridges as well as to determine whether these structures promote gene flow.
... This is largely due to a lack of replication in many studies, which severely reduced the ability of authors to draw strong conclusions from their results (Roedenbeck et al., 2007; van der Ree et al., 2008; Glista, DeVault & DeWoody, 2009; Grift et al., 2013). To date, studies on underpass use in Australia, with the exception of Harris et al. (2010), have all used either sand pads or motion-activated cameras to determine which species used them (Mansergh & Scotts, 1989; Ecologia Environmental Consultants, 1995; Taylor & Goldingay, 2003; Goosem et al., 2005; Bond & Jones, 2008; Hayes & Goldingay, 2009; Taylor and Goldingay, 2014). Outside of Australia, the pattern is similar with only few studies recording the identities of individual animals using underpasses with the exception of Clevenger & Sawaya (2010), Dodd et al. (2007) and Baxter-Gilbert (2014). ...
The construction of fauna underpasses is becoming increasingly common in road construction projects. However, factors that affect their use by native fauna in Australia are still largely unknown. We monitored 10 fauna underpasses for 13 months to determine factors affecting their use by southern brown bandicoots Isoodon obesulus fusciventer and western bobtail lizards Tiliqua rugosa rugosa. We trapped around each underpass five times to determine the size of the populations of these two species. Bandicoots and bobtail lizards were marked with passive implant transponders (PIT) and PIT readers and motion-activated infrared cameras recorded the number of crossings and the number of individuals that used each underpass. For bandicoots the mean weekly frequency of use corrected for population size and the proportion of the marked population that used each underpass were modelled against factors hypothesized to impact underpass use using generalized linear models. These were underpass length, cross-sectional area, vegetation cover at the entrances, presence or absence of logs and branches in the underpass (furniture), use by introduced predators and time since construction. Underpass length was negatively correlated with the frequency of use by bandicoots and time since construction was negatively correlated with the proportion of the population that used the underpasses. For western bobtail lizards none of the factors tested were strongly correlated with the frequency of use, or the proportion of the population that used the underpass. Based on these results, we recommend that the length of underpasses be kept to a minimum, possibly through the use of vegetated median strips allowing shorter underpasses to connect habitat on either side of the road. This would likely result in greater use than one long underpass spanning the entire width of the road.
... This is largely due to a lack of replication in many published studies of underpass use, which has severely reduced the ability of authors to draw strong conclusions from their results (Roedenbeck et al., 2007, Grift et al., 2013, van der Ree et al., 2008). All studies on underpass use published in Australia with the exception of Harris et al. (Harris et al., 2010) have used either sand pads or motion activated cameras to determine which animals were using them (Bond and Jones, 2008, EcologiaEnvironmental-Consultants, 1995, Taylor and Goldingay, 2003, Mansergh and Scotts, 1989, Hayes and Goldingay, 2009, Goosem et al., 2005). The major drawback of this approach is that these methods do not provide information on the number of individual animals that are utilising the structures. ...
The construction of fauna underpasses is becoming increasingly common in road construction projects in Australia. However, there is a paucity of data relating to the factors associated with their use by native fauna. We monitored 10 fauna underpasses for a period of 13 months in the southern metropolitan area of Perth, Western Australia to determine the factors associated with use by southern brown bandicoots or quenda (Isoodon obesulus fusciventer) and western bobtail lizards (Tiliqua rugosa rugosa), the two native species that mostly used these underpasses. We also trapped in the area directly around each underpass five times in order to determine the size of the populations of these two species around the structures and derive the mean frequency of use and the proportion of the known population that used each crossing structure. All quenda and bobtail lizards were marked with passive implant transponders (PIT tags) and PIT tag readers and motion-activated cameras recorded the total use and the number of individual quenda and bobtails lizards that used each underpass. Mean weekly frequency of use corrected for population size and the proportion of the marked population that used each underpass were modelled using generalized linear models against factors hypothesised to impact underpass use. These were underpass length, cross sectional area, vegetation cover at the entrances, the presence or absence of logs and branches in the underpass (furniture), use by feral predators and time since construction.
Underpass length was found to be negatively related to the frequency of use by quenda and vegetation cover was found to be positively correlated. Time since construction was found to be negatively correlated with the proportion of the population of quenda that used the underpasses. For western bobtail lizards none of the factors tested were found to be related to the frequency of use, but time since construction and vegetation cover were both found to be negatively related to the proportion of the population that used the underpass. Based on these results we recommend that the length of underpasses should be kept to a minimum possibly through the use of vegetated median strips with two short underpasses connecting to habitat on either side of the road. This would be highly likely to result in a greater amount of underpass use than one long underpass connecting the two sides of the road. The cause of the reduction in the proportion of both species using the underpasses over time needs further investigation as it may indicate long term negative consequences of underpass use.
Terrestrial Mammal Conservation provides a thorough summary of the available scientific evidence of what is known, or not known, about the effectiveness of all of the conservation actions for wild terrestrial mammals across the world (excluding bats and primates, which are covered in separate synopses). Actions are organized into categories based on the International Union for Conservation of Nature classifications of direct threats and conservation actions. Over the course of fifteen chapters, the authors consider interventions as wide ranging as creating uncultivated margins around fields, prescribed burning, setting hunting quotas and removing non-native mammals.
This book is written in an accessible style and is designed to be an invaluable resource for anyone concerned with the practical conservation of terrestrial mammals.
The authors consulted an international group of terrestrial mammal experts and conservationists to produce this synopsis. Funding was provided by the MAVA Foundation, Arcadia and National Geographic Big Cats Initiative.
Terrestrial Mammal Conservation is the seventeenth publication in the Conservation Evidence Series, linked to the online resource www.ConservationEvidence.com. Conservation Evidence Synopses are designed to promote a more evidence-based approach to biodiversity conservation. Others in the series include Bat Conservation, Primate Conservation, Bird Conservation and Forest Conservation and more are in preparation. Expert assessment of the evidence summarised within synopses is provided online and within the annual publication What Works in Conservation.
Terrestrial Mammal Conservation provides a thorough summary of the available scientific evidence of what is known, or not known, about the effectiveness of all of the conservation actions for wild terrestrial mammals across the world (excluding bats and primates, which are covered in separate synopses). Actions are organized into categories based on the International Union for Conservation of Nature classifications of direct threats and conservation actions. Over the course of fifteen chapters, the authors consider interventions as wide ranging as creating uncultivated margins around fields, prescribed burning, setting hunting quotas and removing non-native mammals.
This book is written in an accessible style and is designed to be an invaluable resource for anyone concerned with the practical conservation of terrestrial mammals.
The authors consulted an international group of terrestrial mammal experts and conservationists to produce this synopsis. Funding was provided by the MAVA Foundation, Arcadia and National Geographic Big Cats Initiative.
Terrestrial Mammal Conservation is the seventeenth publication in the Conservation Evidence Series, linked to the online resource www.ConservationEvidence.com. Conservation Evidence Synopses are designed to promote a more evidence-based approach to biodiversity conservation. Others in the series include Bat Conservation, Primate Conservation, Bird Conservation and Forest Conservation and more are in preparation. Expert assessment of the evidence summarised within synopses is provided online and within the annual publication What Works in Conservation.
Although wildlife overpasses have been constructed in many countries to provide safe crossing passages over roads, most have been focused on larger species of mammals. Bird use of these large structures has largely been ignored, although the impact of roads on birds is of increasing concern, especially among smaller, forest-interior species. We studied birds crossing a four-lane road over the road either above the surface or via a vegetated wildlife overpass near Brisbane, Australia, over two years. A total of 14 species were detected crossing the road between the forest edges away from the structure. These were mainly larger species (median weight 110g). In contrast, 25 species of mainly smaller species (median weight 15g) were detected using the wildlife overpass, primarily within the dense planted foliage, with an additional 14 species crossing the road directly above the structure. Although detected only occasionally during the study, the presence of species typically known only from the forest interior in the foliage of the wildlife overpass was especially noteworthy. Moreover, there was strong evidence that the wildlife overpass was being actively used as a corridor. Thus, as many smaller forest-dwelling species appear to be reluctant to cross roads, the construction of this vegetated wildlife overpass appears to have facilitated opportunities for movement that has been exploited by local species. Finally, these results strongly suggest that many of the large number of wildlife overpasses could be converted into safe passages over roads for a much larger proportion of the local biodiversity than has often been previously considered.
Gliding mammals may be susceptible to habitat fragmentation due to increased vulnerability to predators and road mortality if forced to cross roads and other canopy gaps on the ground. We document three trials where 6-12-m-high wooden poles, also known as glide poles, were installed to provide a link for gliding mammals across 50-75-m-wide canopy gaps, over open pasture or over roads. We used hair-traps over periods of 10-42 months to determine whether squirrel gliders (Petaurus norfolcensis) used the poles. Squirrel glider hair was detected on at least one pole during 69-100% of sampling sessions. At two road locations where poles were installed on wildlife land-bridges, hair was detected on poles in the middle of the bridge in 7-18 sessions, suggesting that complete crossings may have occurred. At one road location a camera-trap recorded a squirrel glider ascending a middle pole on five of 20 nights. Repeated use of the wooden poles by squirrel gliders at three locations suggests that tall wooden poles can restore habitat connectivity for a gliding mammal. We recommend further trials to extend our knowledge of the usefulness of this management tool for a range of gliding mammal species.
Context. Urbanisation is recognised as a primary cause of biodiversity loss. Roads are an inherent element of this, creating partial or complete barriers to animal movement. Urban landscapes of eastern Australia are typified by a dense road network interspersed with remnant patches of bushland. Inter-patch movement by tree-dependent gliding mammals may be halted and, consequently, population viability threatened, when canopy gaps over roads exceed gliding ability. Aims. We test the notion that a metapopulation of the squirrel glider (Petaurus norfolcensis) in southern Brisbane can persist within a highly fragmented urban landscape with large road canopy gaps. Methods. We used the population modelling software VORTEX to investigate the influence of inter-patch movement (dispersal) and wildfire on the probability of extinction. Wildfire is an inherent characteristic of this landscape. Key results. Our modelling suggests that a lack of inter-patch movement as a result of road barriers, in tandem with wildfire, is associated with a high probability of local extinction. However, a small rate of inter-patch movement can substantially reduce the likelihood of extinction. Conclusions. Road-crossing structures are the most plausible means available to link remnants to enable inter-patch movement for squirrel gliders in this landscape because of inadequate road-side tree height. Simulation studies such as the present study that test population viability are critical to convince land managers that action must be taken. Implications. The need to conserve urban biodiversity will increase over time, so land managers must consider the likely benefits to population persistence conferred by installing wildlife crossing structures into existing roads.
Tree‐dwelling mammals may be vulnerable to road mortality if forced to cross canopy gaps on the ground. This group of mammals has received scant attention worldwide despite major road projects potentially causing severe fragmentation to their habitat. Gliding mammals may be enabled to cross road gaps that exceed their gliding capability by the installation of tall wooden poles to act as “stepping stones.” We investigated whether such glide poles installed across two land‐bridges in eastern Australia could restore landscape connectivity for small gliding petaurid marsupials. Hair‐traps revealed repeated use of all poles at both locations over periods of 1–3 years. Camera traps at one site suggest a crossing frequency on the poles by the squirrel glider (Petaurus norfolcensis) of once every 3.8 nights. Radio‐tracked animals did not glide directly over the road but instead used the poles to cross on the bridge. Hair‐traps and camera traps installed within the middle of two reference land‐bridges that lacked glide poles failed to detect crossings by gliding mammals despite their presence in adjacent forest. These observations suggest that glide poles can facilitate road crossing and thereby restore habitat connectivity for gliding mammals. This lends support to the notion that glide poles have the potential to mitigate road‐induced habitat fragmentation for gliding mammals worldwide.
After 15 years, it is timely to review the 4-year bachelor degree in forestry offered by Southern Cross University (SCU), now the only remaining
such 4-year degree in Australia. The SCU program is characterised by innovative teaching, a strong fieldwork component, emphasis on
research, and strong links with local interest groups (both environmental and industrial). The progressive introduction of two-site delivery and
on-line lectures has maintained the viability of the course despite modest student demand.
Roads can disrupt the population processes of vertebrate wildlife species through habitat fragmentation and vehicle collision. The aims of this review were to synthesise the recent literature on road impacts on wildlife, to identify gaps in our understanding of this topic and to guide future research and management in Australia. We reviewed 244 published studies from the last decade on road and vehicle impacts on wildlife conducted worldwide. A geographic bias was evident among the studies, with 51% conducted in North America, 25% in Europe, 17% in Australia and 7% across several other countries. A taxonomic bias was evident towards mammals (53%), with far fewer studies on birds (10%), amphibians (9%) and reptiles (8%), and some (20%) included multiple taxonomic groups. Although this bias is partly explained by large insurance and medical costs associated with collisions involving large mammals, it is also evident in Australia and signals that large components of biodiversity are being neglected. Despite a prevalence of studies on wildlife road mortality (34%), population impacts are poorly described, although negative impacts are implicated for many species. Barrier effects of roads were examined in 44 studies, with behavioural aversion leading to adverse genetic consequences identified for some species. The installation of road-crossing structures for wildlife has become commonplace worldwide, but has largely outpaced an understanding of any population benefits. Road underpasses appear to be an important generic mitigation tool because a wide range of taxa use them. This knowledge can guide management until further information becomes available. Global concern about the decline of amphibians should lead to a greater focus on road impacts on this group. Priorities for research in Australia include (1) genetic studies on a range of taxa to provide an understanding of life-history traits that predispose species to barrier effects from roads, (2) studies that examine whether crossing structures alleviate population impacts from roads and (3) studies that describe the behavioural response of frogs to crossing structures and that identify factors that may promote the use of suitable structures. A national strategy to mitigate the impacts of roads on wildlife populations is long overdue and must ensure that research on this topic is adequately funded. © 2010 CSIRO
An extensive fauna survey of forest habitats in the Murwillumbah Forestry
Management Area of north-eastern New South Wales allowed us to examine and
compare the use of Elliott traps, wire cage traps, soil plots, hair tubes,
spotlighting, dry pitfall traps, sightings and vocalisations as methods to
determine the identity, distribution and abundance of ground-dwelling and
arboreal mammals. Transects were established in 10 areas in six State Forests
and one National Park.
The aim of this study was to examine each method to satisfy three criteria and
to determine the most efficient and effective method or combination of methods
to survey arboreal and ground-dwelling mammals in forests. The three criteria
were to identify the species present, to determine their distribution and to
establish an index of their abundance. In all, 35 species were identified by
the seven methods. However, the species recorded, and the usefulness of the
method to provide their distribution and/or an index of abundance,
differed markedly according to the method used.
Stratified sampling with Elliott traps for small mammals, spotlights for
arboreal mammals and soil plots for medium-sized and large ground-dwelling
mammals was the most labour-efficient and productive combination for recording
species present and their status comprehensively. If needed, other methods
such as hair tubes or cage traps may be used locally and intensively to assist
in the identification of species. Moreover, randomly gathered sight and
vocalisation records accumulated during the survey were found to be very
useful in corroborating species present and in helping to identify the tracks
recorded to genus or family by the soil-plot method.
A total of 127 road-kills of the swamp wallaby, Wallabia bicolor, on North Stradbroke Island in
south-east Queensland was recorded between May 1981 and April 1982. The majority of kills were
of adults. Road-kills occurred mainly at night, suggesting that W. bicolor is nocturnal, and were
significantly correlated with the number of vehicles brought onto the island by ferries. Faecal pellet
counts were made in classified habitats along the road in order to determine the relationship between
the population density and road-kills of W. bicolor. Road-kills were significantly correlated with the
faecal pellet counts in the Disturbed Ares (narrow, artificially cleared areas adjacent to the road)
but not with the counts in the Native Area (i.e. native forest). This indicates that the wallabies were
attracted to the disturbed area and became more susceptible to being killed by vehicles. There was no
significant variation in the number of road-kills between lunar phases.
Kangaroo–vehicle collisions are frequent on Australian highways. Despite high economic costs, detrimental effects on animal welfare, and potential impacts on population viability, little research has been done to investigate the impact of road mortality on kangaroo populations, where and why accidents occur, and how the collisions can be mitigated. We therefore collected data on species (Macropus rufus, M. giganteus, M. fuliginosus, M. robustus), sex and age of kangaroos killed on a 21.2-km bitumenised section of outback highway over 6 months in far western New South Wales, Australia. The spatial and temporal distribution of road-killed kangaroos was investigated in relation to the cover and quality of road-side vegetation, road characteristics, the density of kangaroos along the road, climatic variables and traffic volume. A total of 125 kangaroos were found killed on the road at a rate of 0.03 deaths km–1 day–1. Grey kangaroos of two species (M. giganteus, M. fuliginosus) were under-represented in the road-kill sample in comparison with their proportion in the source population estimated during the day. No bias towards either sex was found. The age structure of road-killed kangaroos was similar to age structures typical of source kangaroo populations. Road-kills mainly occurred in open plains country. In road sections with curves or stock races, road-kill frequencies were higher than expected. Greater cover and greenness of roadside vegetation at the verge probably attracted kangaroos to the road and variation in this vegetation affected the spatial distribution of road-kills. The temporal distribution of road-kills was positively correlated with the volume of night-time traffic. The probability of a kangaroo–vehicle collision increased exponentially with traffic volume. Results are discussed in relation to the potential for mitigation of kangaroo–vehicle collisions.
The eVects of roads on the natural environment is of growing concern world-wide and foremost amongst these eVects are the fatalities of wildlife killed in collisions with vehicles. Aside from animal welfare and human safety considerations, fatalities may have signiWcant impacts on the population dynamics of species living adjacent to roads and thus can adversely aVect the viability of local populations. As such, the need to quantify and mitigate road-based fatalities is paramount. With a vast expanse of roads it is imper-ative to identify where animals are most likely to be killed (i.e. hotspots) and what are the contributing factors. In order to identify hotspots, we develop a modelling approach for both presence and presence/absence data. We use data collected from the Snowy Mountain Highway in southern New South Wales, Australia, to compare the eVectiveness of this approach for Wve species/groups of species. We observed that models of species killed in a clumped fashion were eVective at identifying hotspots, while for species where fatalities were distributed evenly along the road the models were less eVective. We recommend that where actual presence data exists spatial clustering is the preferred method of hotspot identiWcation. Predictive models of presence/absence date should be constructed if the intention is to extrapolate to additional areas. The added beneWt of predictive models are that they enable the identiWcation of explanatory factors and this knowledge enables species-speciWc management strategies to be developed and implemented at hotspot locations.
An obvious sign of potential human impact on animal populations is roadkill. In Tasmania, this impact is perceived as relatively greater than in other Australian states, and is often noted by visitors and locals alike, such that calls for management action are common in the popular press. The goal of this three-year study was to assess the frequency and distribution of species killed on Tasmanian roads. Seasonal surveys were completed along five major routes, for a total of 154 trips. Over 15 000 km of road were surveyed and 5691 individuals in 54 taxa were recorded for an average roadkill density of 0.372 km À1 . Over 50% of encountered roadkill could be identified to species, with common brushtail possums (Trichosurus vulpecula) and Tasmanian pademelon (Thylogale billardierii) the most common species identified, both in overall numbers and frequency of trips encountered. The 10 most common taxa accounted for 99% of the items observed. The seasonal occurrence, relationship with vehicle speed, and clustering in local hotspots for particular taxa all suggest that mitigation measures, such as vehicle speed reduction in specific areas, may be effective in reducing the number of animals killed. Mitigation measures, however, will not apply equally to all species and, in particular, success will depend on changing human behaviours.
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.
A number of studies have proposed that wildlife passages beneath roads and railway lines might be exploited by mammalian predators as ‘prey-traps’ with prey-species being effectively funnelled into areas of high concentration. This proposition has raised the possibility that use of passages by predators may reduce the effectiveness of passages in conserving other forms of wildlife. We review the literature and conclude that evidence for the existence of prey-traps is scant, largely anecdotal and tends to indicate infrequent opportunism rather than the establishment of patterns of recurring predation. Most passage studies record no evidence of predation in or around passages. Conversely, there is some evidence that predator species use different passages than their prey.
The impact of roads on local biodiversity is a major issue associated with urbanisation. A major arterial road in the southern suburbs of Brisbane, south-east Queensland, was upgraded in 2004–05 from two to four lanes. In an attempt to minimise the impact of the larger road on local wildlife populations, a range of fauna crossing structures were constructed at the site. Monitoring of road-kill was undertaken for 4 months before construction and after the completion of construction. Assessment of the use of two underpasses and a large overpass ('land-bridge') started 6 months after construction using sand tracking in underpasses and scat sampling on the land-bridge. An initial 26-week period of intensive monitoring was undertaken from August 2005 to February 2006 followed by monthly monitoring from June 2006 to June 2007. On average, 1–5 tracks per day were detected in the underpasses at the start of the survey, increasing steadily to ~42 tracks per day by February 2006. The monthly survey showed regular use of the underpasses by a wide range of species and species-groups, the most abundant being 'rodents', most likely Rattus species, both native and introduced. The land-bridge was also used continuously by three species of macropod (red-necked wallaby, Macropus rufogriseus; swamp wallaby, Wallabia bicolor; and eastern grey kangaroo, Macropus giganteus) with brown hare (Lepus capensis) becoming increasingly common in summer 2006. The exclusion fencing was extremely effective in preventing most road-kill, at least of larger species, except following human-related breaches in the fence. Yes Yes
An eight-month survey of the terrestrial vertebrate fauna of coastal Byron Shim produced records of 15 species of amphibians, 19 species of reptiles, 182 species of birds and 23 species of mammals. These results, together with records from other sources, show the area has a rich and diverse vertebrate fauna with only reptiles not well represented Vertebrate communities were characterized by species typical of low, dense vegetation formations The area's richness is partly the result of its position at the centre of the Macleay-McPherson overlap zone where the Torresian and Bassian faunas meet Did differences were established between the vertebrate communities of vegetation growing on the low-lying, low-nutrient sands of the coastal plain (Wallum) and those of vegetation on elevated, higher nutrient meta-sediments. Past intensive land use in the south of the survey area may have caused the local extinction of one native rodent and its niche appears to have been partly filled by two other native species. No ...
From July 1970 to June 1972 1,675 animals of eighty-seven species killed by traffic were found by monthly counts along 301 kilometres or road between Canberra, ACT and Lake Cowal, NSW. The incidents involved birds (65.9%), mammals (29.1%), reptiles (4.9%) and amphibia (0.1%). One bird was found every thirteen kilometres, one mammal every thirty kilometres and one reptile every 176 kilometres. Black-backed Magpies accounted for 37 per cent of the birds. rabbits for 40 per cent of the mammals, and Common Bearded Dragons for 55 per cent of the reptiles.Most birds were killed during the spring and summer and were mainly young. The highest numbers of animals killed per kilometre were on bitumen roads running through savanna woodland.
Potorous longipes, sp. nov., is described from east Gippsland, Vic. It is distinguished from P. tridactylus on the basis of cranial and pedal morphology, the presence of 24 chromosomes in both sexes (cf. P. tridactylus, 12 males, 13 females ) and electrophoretic differences in blood proteins. Descriptions of its open forest habitat are provided and its distribution relative to P. tridactylus in eastern Victoria is mapped. Brief notes on maintenance of the species in captivity are given.
A 20-km section of highway near Heathcote in Central Victoria was surveyed for road-killed macropods
over 5 years. Road-kills of seven swamp wallabies, Wallabia bicolor, and 37 eastern grey kangaroos,
Macropus giganteus, were recorded. Kills of grey kangaroos peaked in the autumn of two years. The
majority of kills were of adult males, indicating that motor vehicles act as a selective mortality factor.
Most road-kills also occurred around the time of full moon, suggesting that kangaroos are more mobile
during that phase. The highest incidence of kills per kilometre was recorded between an area of woodland
on one side of the road and farmland on the other. Kangaroo warning signs were erected during
the study, but were not effective in reducing the incidence of road-kills.
The value of road-kill counts in monitoring changes in numbers of the eastern
barred bandicoot, Perameles gunnii, was investigated in
the Huon Valley, south-eastern Tasmania, by comparing population trends on two
trapping grids with trends in road-kills on adjacent segments of highway.
Between 1992 and 1996, both the number of P. gunnii on
the trapping grids and the number of road-kills on the adjacent highway
underwent a significant decline. While our data are preliminary, we suggest
that road-kills may provide a useful index of gross, long-term trends in
numbers of P. gunni. Such an index could be used to
track long-term trends in local populations adjacent to a segment of highway,
as in the present study. Alternatively, by considering a highway as a
continuous ‘chain’ of such segments, road-kills may provide an
index of trends over a larger (i.e. regional) scale.
1. Counts of road traffic casualties (RTCs) have been proposed as one potential method of monitoring changes in the abundance of several mammal species in Britain. However, before such schemes are implemented, it is vital that the relationship between animal density and RTCs is verified and quantified. In this paper, we analyse data collected as part of a long-term study of red foxes Vulpes vulpes in Bristol, UK to determine whether RTCs reflected changes in fox numbers.
2. Associations between fox density and RTC counts were examined using data collected from throughout Bristol during 1978–84 (spatial model) and from an intensive longitudinal study in the north-west of the city during 1990–94 (temporal model). For both sets of data, there was a significant relationship between fox density and RTCs; in the case of the temporal model, this was only evident after the data had been manipulated by calculating running means across seasons. These regression models only explained 58% and 43% of the variance observed in the data, respectively.
3. In both analyses, there was a significant difference between the distribution of casualties and the availability of different road types; more foxes were killed on major category roads (e.g. motorways, A-roads). Incorporating the length of each road category in each region in the spatial model improved the variance explained to 81%. This level of precision would be sufficient for a national monitoring programme. However, we were able to minimize or eliminate a number of factors that could potentially confound the use of RTCs for a national monitoring programme; these factors are discussed in detail. At present, we conclude that further investigation into the validity and precision of this technique is required for a range of mammal species before it could be used in a national monitoring programme.
Summary Four large underpasses, specifically designed for movements by fauna, form part of a major road upgrade project on the Atherton Tablelands in northeast Queensland, Australia. We describe the design and rationale of a project to test their effectiveness in restoring habitat continuity for tropical rainforest fauna. The large blocks of upland rainforest divided by the road are recognized for their high faunal conservation significance, forming habitat for many rare or threatened species. Ecologists, road engineers and the Atherton Tablelands conservation community have united with a common conservation goal: to design the ‘furniture’ within the underpasses and accomplish rainforest revegetation to provide protective cover and attract fauna to underpass entrances. Prior to construction, small mammals were trapped weekly for several months in habitats close to the road upgrade. The small mammal community comprised grassland species in abandoned pasture and differed significantly from the rainforest specialists found in three closed canopy habitats: rainforest edge, rainforest interior and Lantana shrubland. Rainforest restoration works designed to restore connectivity for rainforest fauna across this abandoned pastureland (via the underpasses to major rainforest blocks to the north and south of the road) are currently in progress. Monitoring of the effectiveness of the underpasses in allowing faunal movements will involve the use of infra-red-triggered cameras within the underpasses and near underpass entrances, and a survey of road-killed fauna both prior to and postconstruction. Further examination of small mammal community structure and movements, with respect to both the new road and the underpasses, will be undertaken once rainforest plantings have become established. This evaluation should provide insights for further road-associated restoration projects in rainforest regions.
Roads affect animal populations in three adverse ways. They act as barriers to movement, enhance mortality due to collisions with vehicles, and reduce the amount and quality of habitat. Putting fences along roads removes the problem of road mortality but increases the barrier effect. We studied this trade-off through a stochastic, spatially explicit, individual-based model of population dynamics. We investigated the conditions under which fences reduce the impact of roads on population persistence. Our results showed that a fence may or may not reduce the effect of the road on population persistence, depending on the degree of road avoidance by the animal and the probability that an animal that enters the road is killed by a vehicle. Our model predicted a lower value of traffic mortality below which a fence was always harmful and an upper value of traffic mortality above which a fence was always beneficial. Between these two values the suitability offences depended on the degree of road avoidance. Fences were more likely to be beneficial the lower the degree of road avoidance and the higher the probability of an animal being killed on the road. We recommend the use offences when traffic is so high that animals almost never succeed in their attempts to cross the road or the population of the species of concern is declining and high traffic mortality is known to contribute to the decline. We discourage the use offences when population size is stable or increasing or if the animals need access to resources on both sides of the road, unless fences are used in combination with wildlife crossing structures. In many cases, the use offences may be beneficial as an interim measure until more permanent measures are implemented.
The number of families in the urban fox population of Sapporo, Japan, was estimated from two sets of data reported by the
public to government: records of road-killed foxes (information-A) and records of complaints about foxes (information-B).
We assumed that fox populations consist of families that have exclusive home ranges, i.e., territories, during the period
between gestation and dispersal. The urban area was then divided into hexagons that correspond to the territories. The locations
from the two sets of records during the territorial period were plotted on the map. The number of fox families for which information-A
and/or B was reported was estimated by counting the number of hexagons that include the record. The total number of families
was estimated by using a double-observation method. We adopted Chapman’s unbiased estimator which is based on the hypergeometric
distribution that corresponds to the conditional likelihood. We demonstrated the possibility of estimating the abundance of
animals from government data such as road kill and complaints if the animals have territories.
The movement of vertebrates through 17 culverts under roads and railways in Central Spain was analysed over the course of an annual cycle. Passage was detected for amphibians, lizards, snakes, small mammals, rats, hedgehogs, rabbits and several species of carnivorous mammals, including Felis sylvestris and Genetta genetta. The intensity of animal movement, which varied considerably among the groups, was influenced by various factors such as the culvert dimensions, road width, height of boundary fence, the complexity of the vegetation along the route, and the presence of detritus pits at the entrance of culverts. It is concluded that adequately designed culverts can aid the conservation of vertebrate populations.
Road impacts on Australian frogs are poorly documented. This limits our ability to predict which species may be vulnerable to impacts and to develop strategies for mitigating impacts. We conducted foot-based surveys for road-killed frogs along two 100-m sections of a road that traverses known frog habitat near Lennox Head, in north-eastern New South Wales. More than 1000 dead frogs were counted over 13 mornings.Two threatened species, the Wallum Sedge Frog Litoria olongburensis and the Wallum Froglet Crinia tinnulo, accounted for at least 60% of these roadkills. It is estimated that in an average summer period, there would be >40,000 frogs killed on the 4-km span of road through the heathland habitat.That is, > 10,000 road-kills of each of the Wallum Sedge Frog and Wallum Froglet. Research is needed to ascertain how severe this impact is on these isolated populations and to determine how road mortality of frogs can be minimized.
Culverts have been used for a number of decades in Europe and the USA to reduce wildlife road-kills. In Australia, culverts have been employed by road authorities only relatively recently. This study used sand-strip surveys to investigate wildlife usage of nine purpose-built culverts along a 1.4-km section of the Pacific Highway at Brunswick Heads, north-east New South Wales. Surveys during two eight-day periods in spring and summer 2000 found 1202 traverses by wildlife through the culverts. Frequent culvert users were bandicoots (25% of traverses), rats (25%), wallabies (13%) and cane toads (14%). All culverts were used by these species, suggesting that at least several individuals of each species were involved. Infrequent users (each <2% of crossings) were possums, echidnas, lizards, birds and introduced carnivores. A koala was recorded crossing on two occasions. The long-nosed potoroo was observed in the surrounding habitat but was not confirmed traversing the culverts. Surveys for road-kills on this road section suggest that the exclusion fence bordering the highway prevented mammal road-kills and channeled mammals to the culverts. A single survey on a wet night found many frogs crossing the road surface and many were killed. This study confirms that culverts and exclusion fencing facilitate safe passage across a road for a range of wildlife species. This suggests that this form of management response to extensive road mortality of wildlife is appropriate and should be adopted more widely. However, this form of mitigation is not effective for frogs. Yes Yes
Although vehicle-induced mortality of wildlife is well known on roads throughout Australia, few empirical studies describe the extent of this mortality or assess the potential effects on wildlife populations. We recorded 529 roadkills of 53 vertebrate species along a 100-km circuit of three major roads during 20 weekly surveys across winter, spring and summer. This equates to 0.3 road-kills km–1 week–1 or one road-kill every 3.8 km week–1. The most frequently killed native species were the northern brown bandicoot (4 per week), the mountain brushtail possum (2 per week) and the Australian magpie (2 per week). These values are underestimates because our survey technique could not detect all road-kills and ~40% of those left on the roadside disappeared within 7 days. Detailed study of the local population of the brown bandicoot is needed to determine whether such a level of road mortality is sustainable. A logistic regression analysis was used to determine whether any of 10 road and landscape attributes were closely associated with the presence of specific groups of road-kills. Bandicoots were not associated with any measured attributes. Possums were more likely to occur along roads on mid-slopes and ridge-tops. Magpies were associated with roads on ridge-tops. Canopy-dwelling birds were more likely to be killed on 3-lane roads surrounded by dense vegetation. Road-kill surveys such as this are needed to identify species for which road mortality is unsustainable, to determine the influence on threatened species, and to identify important crossing points where road-kills are high. The frequency of road-kill of many ground-dwelling or arboreal mammal species in this study highlights the importance of impact mitigation by road authorities. Yes Yes
- Spellerberg