Article

Habitat Use by Adult Red Wolves, Canis rufus , in an Agricultural Landscape, North Carolina, USA

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

We used a species distribution model to characterize habitat use by red wolves, Canis rufus, on the Albemarle Peninsula of North Carolina, USA. Using more than 4,000 VHF telemetry locations of 178 individual animals from 1999–2008, we quantified habitat use and modeled potential habitat suitability of red wolves. Areas of agriculture where secondary road density was high (up to 1 km/km2) and human population density was low (less than 1.67 individuals/km2) were most suitable. Our study supports the baseline knowledge of red wolf suitable habitat, and shows that red wolves will use habitats altered by humans and occupied by humans at low densities. This research represents the use of the most comprehensive red wolf VHF telemetry dataset for habitat suitability modeling to date, and the results should contribute to the growing knowledge of suitable red wolf habitat. This knowledge is critical to identifying future reintroduction sites and protecting the future of this species.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Although the North Carolina reintroduction continues, reintroduction to the Great Smoky Mountains National Park was terminated after 6 years because red wolves were unable to maintain territories within park boundaries while the population experienced low pup survival [25][26]. Likewise, red wolves in eastern North Carolina reside proximate to agricultural habitats on private and federal lands over large, contiguous forested habitats available on USFWS national wildlife refuges [27][28][29][30]. Consequently, the USFWS Red Wolf Recovery Program (hereafter Recovery Program) faced potential issues with predicting how the red wolf population would distribute itself on the landscape as it expanded, anticipating logistic and social constraints (i.e., conflict with landowners and hunters), and understanding interactions between red wolves and coyotes. ...
... Previous studies of red wolf space use and habitat selection reported home ranges that varied between 10-150 km 2 , comprising mostly agricultural habitats [27][28][29][30]. However, past studies only focused on space use patterns of resident red wolves, did not analyze space use and habitat selection together, and suffered from small sample sizes. ...
... For instance, Hinton and Chamberlain [27] only assessed home-range sizes and habitat use by 2 red wolf packs during pup rearing, whereas Chadwick et al. [28] observed yearly home ranges of 4 male wolves. Moreover, Dellinger et al. [29] only measured habitat selection by resident red wolves and Karlin et al. [30] measured habitat selection using data obtained from VHF radio-collars collected during diurnal (0900-1200 hours) telemetry flights. Understanding space use and habitat selection patterns of resident red wolves is important because residents comprise the reproductive portion of the population. ...
Article
Full-text available
Recovery of large carnivores remains a challenge because complex spatial dynamics that facilitate population persistence are poorly understood. In particular, recovery of the critically endangered red wolf (Canis rufus) has been challenging because of its vulnerability to extinction via human-caused mortality and hybridization with coyotes (Canis latrans). Therefore, understanding red wolf space use and habitat selection is important to assist recovery because key aspects of wolf ecology such as interspecific competition, foraging, and habitat selection are well-known to influence population dynamics and persistence. During 2009–2011, we used global positioning system (GPS) radio-telemetry to quantify space use and 3rd-order habitat selection for resident and transient red wolves on the Albemarle Peninsula of eastern North Carolina. The Albemarle Peninsula was a predominantly agricultural landscape in which red wolves maintained spatially stable home ranges that varied between 25 km2 and 190 km2. Conversely, transient red wolves did not maintain home ranges and traversed areas between 122 km2 and 681 km2. Space use by transient red wolves was not spatially stable and exhibited shifting patterns until residency was achieved by individual wolves. Habitat selection was similar between resident and transient red wolves in which agricultural habitats were selected over forested habitats. However, transients showed stronger selection for edges and roads than resident red wolves. Behaviors of transient wolves are rarely reported in studies of space use and habitat selection because of technological limitations to observed extensive space use and because they do not contribute reproductively to populations. Transients in our study comprised displaced red wolves and younger dispersers that competed for limited space and mating opportunities. Therefore, our results suggest that transiency is likely an important life-history strategy for red wolves that facilitates metapopulation dynamics through short- and long-distance movements and eventual replacement of breeding residents lost to mortality.
... Although the North Carolina reintroduction continues, reintroduction to the Great Smoky Mountains National Park was terminated after 6 years because red wolves were unable to maintain territories within park boundaries while the population experienced low pup survival [25][26]. Likewise, red wolves in eastern North Carolina reside proximate to agricultural habitats on private and federal lands over large, contiguous forested habitats available on USFWS national wildlife refuges [27][28][29][30]. Consequently, the USFWS Red Wolf Recovery Program (hereafter Recovery Program) faced potential issues with predicting how the red wolf population would distribute itself on the landscape as it expanded, anticipating logistic and social constraints (i.e., conflict with landowners and hunters), and understanding interactions between red wolves and coyotes. ...
... Previous studies of red wolf space use and habitat selection reported home ranges that varied between 10-150 km 2 , comprising mostly agricultural habitats [27][28][29][30]. However, past studies only focused on space use patterns of resident red wolves, did not analyze space use and habitat selection together, and suffered from small sample sizes. ...
... For instance, Hinton and Chamberlain [27] only assessed home-range sizes and habitat use by 2 red wolf packs during pup rearing, whereas Chadwick et al. [28] observed yearly home ranges of 4 male wolves. Moreover, Dellinger et al. [29] only measured habitat selection by resident red wolves and Karlin et al. [30] measured habitat selection using data obtained from VHF radio-collars collected during diurnal (0900-1200 hours) telemetry flights. Understanding space use and habitat selection patterns of resident red wolves is important because residents comprise the reproductive portion of the population. ...
Article
Full-text available
Little information exists on coyote (Canis latrans) space use and habitat selection in the southeastern United States and most studies conducted in the Southeast have been carried out within small study areas (e.g., ≤1,000 km2). Therefore, studying the placement, size, and habitat composition of coyote home ranges over broad geographic areas could provide relevant insights regarding how coyote populations adjust to regionally varying ecological conditions. Despite an increasing number of studies of coyote ecology, few studies have assessed the role of transiency as a life-history strategy among coyotes. During 2009-2011, we used GPS radio-telemetry to study coyote space use and habitat selection on the Albemarle Peninsula of northeastern North Carolina. We quantified space use and 2nd- and 3rd-order habitat selection for resident and transient coyotes to describe space use patterns in a predominantly agricultural landscape. The upper limit of coyote home-range size was approximately 47 km2 and coyotes exhibiting shifting patterns of space use of areas >65 km2 were transients. Transients exhibited localized space use patterns for short durations prior to establishing home ranges, which we defined as "biding" areas. Resident and transient coyotes demonstrated similar habitat selection, notably selection of agricultural over forested habitats. However, transients exhibited stronger selection for roads than resident coyotes. Although transient coyotes are less likely to contribute reproductively to their population, transiency may be an important life history trait that facilitates metapopulation dynamics through dispersal and the eventual replacement of breeding residents lost to mortality.
... First, red wolves could not be included in this analysis because melanistic individuals were absent in the extant wolf population. Additionally, estimates of wolf space use and habitat selection have been reported [65,75,80]. Second, we excluded coyotes and hybrids in the NC Recovery Area who were fitted with VHF radio-collars because they were not monitored intensively to have achieved sufficient numbers of locations (e.g., ≥30) required for reliable estimates of home range size and habitat selection [81]. ...
Article
Full-text available
Background Gloger’s rule postulates that animals should be darker colored in warm and humid regions where dense vegetation and dark environments are common. Although rare in Canis populations, melanism in wolves is more common in North America than other regions globally and is believed to follow Gloger’s rule. In the temperate forests of the southeastern United States, historical records of red wolf (Canis rufus) and coyote (Canis latrans) populations document a consistent presence of melanism. Today, the melanistic phenotype is extinct in red wolves while occurring in coyotes and red wolf-coyote hybrids who occupy the red wolf's historical range. To assess if Gloger’s rule could explain the occurrence and maintenance of melanistic phenotypes in Canis taxa, we investigated differences in morphology, habitat selection, and survival associated with pelage color using body measurements, GPS tracking data, and long-term capture-mark-recapture and radio-telemetry data collected on coyotes and hybrids across the southeastern United States. Results We found no correlation between morphometrics and pelage color for Canis taxa. However, we observed that melanistic coyotes and hybrids experienced greater annual survival than did their gray conspecifics. Furthermore, we observed that melanistic coyotes maintained larger home ranges and exhibited greater selection for areas with dense canopy cover and wetlands than did gray coyotes. Conclusions In the southeastern United States, pelage color influenced habitat selection by coyotes and annual survival of coyotes and hybrids providing evidence that Gloger’s rule is applicable to canids inhabiting regions with dense canopy cover and wetlands. Greater annual survival rates observed in melanistic Canis may be attributed to better concealment in areas with dense canopy cover such as coastal bottomland forests. We suggest that the larger home range sizes of melanistic coyotes may reflect the trade-off of reduced foraging efficiency in lower quality wetland habitat for improved survival. Larger home ranges and differential use of land cover by melanistic coyotes may facilitate weak assortative mating in eastern coyote populations, in which melanistic animals may have lower success of finding compatible mates in comparison to gray conspecifics. We offer that our observations provide a partial explanation for why melanism is relatively low (< 10%) but consistent within coyote populations throughout southeastern parts of their range.
Article
Full-text available
Reintroducing species into landscapes with persistent threats is a conservation challenge. Although historic threats may not be eliminated, they should be understood in the context of contemporary landscapes. Regenerating landscapes often contain newly emergent habitat, creating opportunities for reintroductions. The Endangered St Croix ground lizard Pholidoscelis polops was extirpated from the main island of St Croix, U.S. Virgin Islands, as a result of habitat conversion to agriculture and predation by the small Indian mongoose Herpestes auropunctatus . The species survived on two small cays and was later translocated to two islands. Since the 1950s, new land-cover types have emerged on St Croix, creating a matrix of suitable habitat throughout the island. Here we examined whether the new habitat is sufficient for a successful reintroduction of the St Croix ground lizard, utilizing three complementary approaches. Firstly, we compared a map from 1750 to the current landscape of St Croix and found statistical similarity of land-cover types. Secondly, we determined habitat suitability based on a binomial mixture population model developed as part of the programme monitoring the largest extant population of the St Croix ground lizard. We estimated the habitat to be sufficient for > 142,000 lizards to inhabit St Croix. Thirdly, we prioritized potential reintroduction sites and planned for reintroductions to take place during 2020–2023. Our case study demonstrates how changing landscapes alter the spatial configuration of threats to species, which can create opportunities for reintroduction. Presuming that areas of degraded habitat may never again be habitable could fail to consider how regenerating landscapes can support species recovery. When contemporary landscapes are taken into account, opportunities for reintroducing threatened species can emerge.
Article
Full-text available
Little information exists on coyote (Canis latrans) space use and habitat selection in the southeastern United States and most studies conducted in the Southeast have been carried out within small study areas (e.g., ≤1,000 km2). Therefore, studying the placement, size, and habitat composition of coyote home ranges over broad geographic areas could provide relevant insights regarding how coyote populations adjust to regionally varying ecological conditions. Despite an increasing number of studies of coyote ecology, few studies have assessed the role of transiency as a life-history strategy among coyotes. During 2009-2011, we used GPS radio-telemetry to study coyote space use and habitat selection on the Albemarle Peninsula of northeastern North Carolina. We quantified space use and 2nd- and 3rd-order habitat selection for resident and transient coyotes to describe space use patterns in a predominantly agricultural landscape. The upper limit of coyote home-range size was approximately 47 km2 and coyotes exhibiting shifting patterns of space use of areas >65 km2 were transients. Transients exhibited localized space use patterns for short durations prior to establishing home ranges, which we defined as "biding" areas. Resident and transient coyotes demonstrated similar habitat selection, notably selection of agricultural over forested habitats. However, transients exhibited stronger selection for roads than resident coyotes. Although transient coyotes are less likely to contribute reproductively to their population, transiency may be an important life history trait that facilitates metapopulation dynamics through dispersal and the eventual replacement of breeding residents lost to mortality.
Article
Full-text available
The recent co-occurrence of red wolves (Canis rufus) and coyotes (Canis latrans) in eastern North Carolina provides a unique opportunity to study prey partitioning by sympatric canids. We collected scats from this region and examined them for prey contents. We used fecal DNA analysis to identify which taxa deposited each scat and multinomial modeling designed for mark-recapture data to investigate diets of sympatric red wolves and coyotes. Diets of red wolves and coyotes did not differ, but the proportion of small rodents in the composite scats of both canids was greater in the spring than in the summer. White-tailed deer (Odocoileus virginianus), rabbits (Sylvilagus spp.), and small rodents were the most common diet items in canid scats. The similarity of diet between red wolves and coyotes suggests that these 2 species may be affecting prey populations similarly.
Article
Full-text available
We tested the reliability and predictive capabilities of the activity meter in the new Wildlink Data Acquisition and Recapture System by comparing activity counts with concurrent observations of captive wolf (Canis lupus) and free-ranging white-tailed deer (Odocoileus virginianus) activity. The Wildlink system stores activity data in a computer within a radio collar with which a biologist can communicate. Three levels of activity could be detected. The Wildlink system provided greater activity discrimination and was more reliable, adaptable, and efficient and was easier to use than conventional telemetry activity systems. The Wildlink system could be highly useful for determining wildlife energy budgets.
Article
Full-text available
Telemetry triangulation is commonly used for obtaining location estimates of animals in the field. Although this technique provides only an estimate of the animal true position, most authors do not report the error associated with the radio-telemetry location. We show the results of estimating error in a radio-telemetry study of roe deer in a hilly environment in central Italy. Ten VHF radio-collars were hidden in the study area by an external field operator and five field workers involved in the collection of the data were asked to locate the transmitters. The position of the radio-collars was changed three times, thus generating thirty different locations. Radio-locations were obtained using standard triangulation from settled receiving stations. We estimated linear and angular errors associated with the radio-telemetry technique, we tested the experience effect of the filed workers and the topography effect of the study area on linear and angular errors. Furthermore, we quantified the proportion of estimated locations not correctly associated with the habitat types. The mean linear and angular errors were respectively 42.9 m and 12.6°. For both linear and angular errors, no differences were detected among field operators and between the expert and not expert field operators. The linear error was strongly related to the angular error and to the mean distance between the transmitter and the receiving stations. The angular error was negatively related to the slope of transmitters. The assignation of an erroneous habitat occurred on 22.7% of the times. This study is aimed to emphasize the importance of reporting radio-telemetry error in studies were triangulation technique is used.
Article
Full-text available
Transforming the results of species distribution modelling from probabilities of or suitabilities for species occurrence to presences/absences needs a specific threshold. Even though there are many approaches to determining thresholds, there is no comparative study. In this paper, twelve approaches were compared using two species in Europe and artificial neural networks, and the modelling results were assessed using four indices: sensitivity, specificity, overall prediction success and Cohen's kappa statistic. The results show that prevalence approach, average predicted probability/suitability approach, and three sensitivity-specificity-combined approaches, including sensitivity-specificity sum maximization approach, sensitivity-specificity equality approach and the approach based on the shortest distance to the top-left corner (0,1) in ROC plot, are the good ones. The commonly used kappa maximization approach is not as good as the afore-mentioned ones, and the fixed threshold approach is the worst one. We also recommend using datasets with prevalence of 50% to build models if possible since most optimization criteria might be satisfied or nearly satisfied at the same time, and therefore it's easier to find optimal thresholds in this situation.
Article
Full-text available
Recovery of populations of wolves (Canis lupus) and other large, wide-ranging carnivores challenges conservation biologists and resource managers because these species are not highly habitat specific, move long distances, and require large home ranges to establish populations successfully. Often, it will be necessary to maintain viable populations of these species within mixed-use landscapes; even the largest parks and reserves are inadequate in area. Spatially delineating suitable habitat for large carnivores within mixed, managed landscapes is beneficial to assessing recovery potentials and managing animals to minimize human conflicts. Here, we test a predictive spatial model of gray wolf habitat suitability. The model is based on logistic regression analysis of regional landscape variables in the upper Midwest, United States, using radiotelemetry data collected on recolonizing wolves in northern Wisconsin since 1979. The model was originally derived from wolf packs radio-collared from 1979 to 1992
Article
Full-text available
Over the past 15 years the endangered eastern timber wolf (Canis lupus lycaon) has been slowly recolonizing northern Wisconsin and, more recently, upper Michigan, largely by dispersing from Minnesota (where it is listed as threatened). We have used geographic information systems (GISs) and spatial radiocollar data on recolonizing wolves in northern Wisconsin to assess the importance of landscape-scale factors in defining favorable wolf habitat. We built a multiple logistic regression model applied to the northern Great Lakes states to estimate the amount and spatial distribution of favorable wolf habitat at the regional landscape scale. Our results suggest that areas with high probability of favorable habitat are more extensive than previously estimated in the northern Great Lake States. Several variables were significant in comparing new pack areas in Wisconsin to nonpack areas, including land ownership class, land cover type, road density, human population, and spatial landscape indices such as f
Article
Full-text available
Surveys of recent (1973 to 1986) intentional releases of native birds and mammals to the wild in Australia, Canada, Hawaii, New Zealand, and the United States were conducted to document current activities, identify factors associated with success, and suggest guidelines for enhancing future work. Nearly 700 translocations were conducted each year. Native game species constituted 90 percent of translocations and were more successful (86 percent) than were translocations of threatened, endangered, or sensitive species (46 percent). Knowledge of habitat quality, location of release area within the species range, number of animals released, program length, and reproductive traits allowed correct classification of 81 percent of observed translocations as successful or not.
Article
"WOLFERS" IN NORTHEASTERN North Carolina were busy on February 5, 1768. Records from the Tyrrell County courthouse read: “Giles Long and Thomas Wllkinson awarded one pound for a certified wolf scalp; Jeremiah Norman awarded two pounds for certified wolf and wild-cat scalps; Davenport Smithwick awarded one pound for a certified wolf-scalp. Such was the nature of the war on the wolf: people killed them for money. The belief of the time held that the war was necessary because it was humankind's manifest destiny to tame the wilderness. And for the wilderness to be tame, the wolf had to be exterminated. The wolf was resourceful and hardy, but the wolfers persisted with increasingly sophisticated methods of killing. The war lasted 200 years, and the wolf lost.”
Article
Canis rufus (Red Wolf) is critically endangered, with the only wild population consisting of <150 individuals. Currently, little is known about the food habits of this population. Such information may be vital to managing for the population's long-term persistence. We collected scats of Red Wolves for two consecutive pup-rearing seasons from six packs, classified contents into prey categories, and assessed diet composition for each pack. Five of the six packs studied consumed only mammalian prey items. Adult Odocoileus virginianus (White-tailed Deer) and White-tailed Deer fawns accounted for 37–66% of diet of Red Wolves depending on the metric of diet composition. Adult White-tailed Deer and White-tailed Deer fawns accounted for 21–83% of the diet of individual packs of Red Wolves according to biomass consumed. Two packs regularly consumed foods associated with humans. Generalized linear modeling indicated that diet varied between packs and was not influenced by reproductive status, nor did diet vary between years.
Article
The MaxEnt software package is one of the most popular tools for species distribution and environmental niche modeling, with over 1000 published applications since 2006. Its popularity is likely for two reasons: 1) MaxEnt typically outperforms other methods based on predictive accuracy and 2) the software is particularly easy to use. MaxEnt users must make a number of decisions about how they should select their input data and choose from a wide variety of settings in the software package to build models from these data. The underlying basis for making these decisions is unclear in many studies, and default settings are apparently chosen, even though alternative settings are often more appropriate. In this paper, we provide a detailed explanation of how MaxEnt works and a prospectus on modeling options to enable users to make informed decisions when preparing data, choosing settings and interpreting output. We explain how the choice of background samples reflects prior assumptions, how nonlinear functions of environmental variables (features) are created and selected, how to account for environmentally biased sampling, the interpretation of the various types of model output and the challenges for model evaluation. We demonstrate MaxEnt’s calculations using both simplified simulated data and occurrence data from South Africa on species of the flowering plant family Proteaceae. Throughout, we show how MaxEnt’s outputs vary in response to different settings to highlight the need for making biologically motivated modeling decisions.
Article
We analyzed natal dispersal characteristics for 79 red wolves in the first long‐term dispersal analysis for this species. Variables analyzed included straight‐line dispersal distance, duration, timing, age, direction, and evidence of natal habitat preference induction of dispersers. We compared these values during a time when the population was increasing (1990–1998) to a period when the numbers had leveled off (1999–2007) and stabilized. We found no difference in average dispersal distance, duration or age between the two periods, and no gender bias in these characteristics. Yearlings/adults dispersed shorter distances (29.5 km) than pups (42.5 km) from 1999 to 2007 and decreased their dispersal distances during this period. After 1999, dispersals occurred 11 months of the year (compared with 7 months in 1990–1998), and the peak in pup dispersal timing shifted from December to January. The peak in dispersal timing was also significantly later for pups than yearlings/adults in 1999–2007. Dispersal direction was not random and there was a preference for a westward dispersal direction, attributed to the avoidance of water and a preference for agriculture. Natal habitat preference induction was also evident in dispersers during both time periods.
Article
This study describes circadian and social movement patterns of 9 wolves and illustrates capabilities and limitations of Global Positioning System (GPS) telemetry for analysis of animal activity patterns. Wolves were studied at the Camp Ripley National Guard Training Site in Little Falls, Minnesota, and were captured via helicopter net-gunning. All study wolves showed nocturnal movement patterns regardless of time of year. One wolf's movement pattern switched to diurnal when he conducted an extraterritorial foray from his natal territory. All data sets with GPS intervals ≤1 hour (n=4) showed crepuscular movement peaks. We identified patterns of den visitation and attendance, estimated minimum distances traveled and minimum rates of movement, and observed that GPS location intervals may affect perceived rates of wolf travel. Global Positioning System telemetry was useful in determining when pack members were traveling together or apart and how long a breeding female wolf spent near her pups (e.g., 10-month-old pups were left unattended by their mother for as long as 17 days).
Article
In 1993 we conducted a follow-up study of the 1987 survey by Griffith et al. (1989) of 421 avian and mammalian translocation programs in North America, Australia, and New Zealand to reassess the programs’ status and the biological and methodological factors associated with success. Our survey response rate was 81%. Approximately 38% of usable programs in 1993 reported a change in outcome from 1987 (e.g., a translocated population was “declining” but now is “self-sustaining”), but the difference between the overall success rates was not statistically significant (66% in 1987 and 67% in 1993). Since 1987, an increase was observed in the median number of animals translocated per program (31.5 to 50.5), median duration of releases (2 to 3 years), and proportion of programs releasing more than 30 animals (46% to 68%). Multiple logistic regression analyses indicated that release into the core of the historical range, good-to-excellent habitat quality, native game species, greater numbers of released animals, and an omnivorous diet were positively associated with translocation success. Moreover, our results indicate that translocated birds were less successful at establishing self-sustaining populations than translocated mammals. Our findings, using comparable logistic analyses, generally corroborate the results of Grifftth et al. (1989). Variables not found to be significantly correlated with translocation success include species’ reproductive potential (number of offspring and first age of reproduction), number and duration of the releases, and source of the translocated animals (wild-caught versus captive-reared).
Article
We modeled populations of lynx (Lynx canadensis) and snowshoe hares (Lepus americanus) to determine prey densities required for persistence of lynx translocated to the southern portion of the species' range. The models suggested that a density of 1.1–1.8 hares/h is required for lynx persistence; these densities are higher than those reported for most hare populations across the USA. We found that lynx dispersal and density-independent mortality substantially increased the hare density required for lynx persistence. Reintroduction success was associated with number of release events, total number of animals released, and timing of release relative to the phase of the hare population cycle. However, no release protocol could override the negative effects of low prey density or high population losses. We conclude that successful lynx reintroduction requires high hare densities and minimal anthropogenic disturbance; few areas in the contiguous USA currently posses such qualities.
Article
Gray wolf (Canis lupus) populations have persisted and expanded in northwest Montana since 1986, while reintroduction efforts in Idaho and Yellowstone have further bolstered the regional population. However, rigorous analysis of either the availability of wolf habitat in the entire region, or the specific habitat requirements of local wolves, has yet to be conducted. We examined wolf-habitat relationships in the northern Rocky Mountains of the U.S. by relating landscape/habitat features found within wolf pack home ranges (n = 56) to those found in adjacent non-occupied areas (n = 56). Logistic regression revealed that increased forest cover, lower human population density, higher elk density, and lower sheep density were the primary factors related to wolf occupation. Similar factors promoted wolf pack persistence. Further, our analysis indicated that relatively large tracts of suitable habitat remain unoccupied in the Rocky Mountains, suggesting that wolf populations likely will continue to increase in the region. Analysis of the habitat linkage between the 3 main wolf recovery areas indicates that populations in central Idaho and northwest Montana have higher connectivity than either of the 2 recovery areas to the Greater Yellowstone recovery area. Thus, for the northern Rocky Mountains to function as a metapopulation for wolves, it will be necessary that dispersal corridors to the Yellowstone ecosystem be established and conserved.
Article
Four adult male Canis lupus rufus (Red Wolf) were monitored with GPS collars in 2006–2008 on the Albemarle peninsula of North Carolina in the first high temporal resolution (4 locations/day) study of this endangered species in the wild. The Wolves occupied home ranges during 11–18 month observation periods, and the GPS data were divided into 30-day subsets to evaluate changes in the spatial characteristics of the home ranges over time. The subset location data were then combined with land-cover maps derived from Landsat satellite imagery. Proportions of different land-cover types occupied by the Wolves were seasonally cyclic, with increased use of agricultural areas when tall row crops were available from summer to autumn and increased use of adj acent grass, brush, and forest areas from winter to late spring when tall crops were absent. The spatial extents of home ranges (95% fixed-kernel probability areas) were also seasonally variable, reaching maximum sizes (73–121 km2) in early autumn to winter and contracting by 40% to 63% during whelping and pup-rearing in the spring. Our study shows the potential for GPS collars to provide useful information about space and habitat use by Red Wolves, and that at least a full year of observation may be required to fully determine the variability of home-range characteristics.
Article
Aim The assumption of equilibrium between organisms and their environment is a standard working postulate in species distribution models (SDMs). However, this assumption is typically violated in models of biological invasions where range expansions are highly constrained by dispersal and colonization processes. Here, we examined how stage of invasion affects the extent to which occurrence data represent the ecological niche of organisms and, in turn, influences spatial prediction of species’ potential distributions. Location Six ecoregions in western Oregon, USA. Methods We compiled occurrence data from 697 field plots collected over a 9-year period (2001–09) of monitoring the spread of invasive forest pathogen Phytophthora ramorum. Using these data, we applied ecological-niche factor analysis to calibrate models of potential distribution across different years of colonization. We accounted for natural variation and uncertainties in model evaluation by further investigating three hypothetical scenarios of varying equilibrium in a simulated virtual species, for which the ‘true’ potential distribution was known. Results We confirm our hypothesis that SDMs calibrated in early stages of invasion are less accurate than models calibrated under scenarios closer to equilibrium. SDMs that are developed in early stages of invasion tend to underpredict the potential range compared to models that are built in later stages of invasion. Main conclusions A full environmental niche of invasive species cannot be effectively captured with data from a realized distribution that is restricted by processes preventing full occupancy of suitable habitats. If SDMs are to be used effectively in conservation and management, stage of invasion needs to be considered to avoid underestimation of habitats at risk of invasion.
Article
Global Positioning System (GPS) and very high frequency (VHF) telemetry data redefined the examination of wildlife resource use. Researchers collar animals, relocate those animals over time, and utilize the estimated locations to infer resource use and build predictive models. Precision of these estimated wildlife locations, however, influences the reliability of point-based models with accuracy depending on the interaction between mean telemetry error and how habitat characteristics are mapped (categorical raster resolution and patch size). Telemetry data often foster the assumption that locational error can be ignored without biasing study results. We evaluated the effects of mean telemetry error and categorical raster resolution on the correct characterization of patch use when locational error is ignored. We found that our ability to accurately attribute patch type to an estimated telemetry location improved nonlinearly as patch size increased and mean telemetry error decreased. Furthermore, the exact shape of these relationships was directly influenced by categorical raster resolution. Accuracy ranged from 100% (200-ha patch size, 1- to 5-m telemetry error) to 46% (0.5-ha patch size, 56- to 60-m telemetry error) for 10 m resolution rasters. Accuracy ranged from 99% (200-ha patch size, 1- to 5-m telemetry error) to 57% (0.5-ha patch size, 56- to 60-m telemetry error) for 30-m resolution rasters. When covariate rasters were less resolute (30 m vs. 10 m) estimates for the ignore technique were more accurate at smaller patch sizes. Hence, both fine resolution (10 m) covariate rasters and small patch sizes increased probability of patch misidentification. Our results help frame the scope of ecological inference made from point-based wildlife resource use models. For instance, to make ecological inferences with 90% accuracy at small patch sizes (≤5 ha) mean telemetry error ≤5 m is required for 10-m resolution categorical rasters. To achieve the same inference on 30-m resolution categorical rasters, mean telemetry error ≤10 m is required. We encourage wildlife professionals creating point-based models to assess whether reasonable estimates of resource use can be expected given their telemetry error, covariate raster resolution, and range of patch sizes. © 2011 The Wildlife Society.
Article
Summary 1. After an absence of almost 100 years, the Eurasian lynx Lynx lynx is slowly recover- ing in Germany along the German-Czech border. Additionally, many reintroduction schemes have been discussed, albeit controversially, for various locations. We present a habitat suitability model for lynx in Germany as a basis for further management and conservation efforts aimed at recolonization and population development. 2. We developed a statistical habitat model using logistic regression to quantify the factors that describe lynx home ranges in a fragmented landscape. As no data were available for lynx distribution in Germany, we used data from the Swiss Jura Mountains for model development and validated the habitat model with telemetry data from the Czech Republic and Slovenia. We derived several variables describing land use and fragmentation, also introducing variables that described the connectivity of forested and non-forested semi-natural areas on a larger scale than the map resolution. 3. We obtained a model with only one significant variable that described the connec- tivity of forested and non-forested semi-natural areas on a scale of about 80 km 2 . This result is biologically meaningful, reflecting the absence of intensive human land use on the scale of an average female lynx home range. Model testing at a cut-off level of P > 0·5 correctly classified more than 80% of the Czech and Slovenian telemetry location data of resident lynx. Application of the model to Germany showed that the most suitable habitats for lynx were large-forested low mountain ranges and the large forests in east Germany. 4. Our approach illustrates how information on habitat fragmentation on a large scale can be linked with local data to the potential benefit of lynx conservation in central Europe. Spatially explicit models like ours can form the basis for further assessing the population viability of species of conservation concern in suitable patches.
Article
MaxEnt is a program for modelling species distributions from presence-only species records. This paper is written for ecologists and describes the MaxEnt model from a statistical perspective, making explicit links between the structure of the model, decisions required in producing a modelled distribution, and knowledge about the species and the data that might affect those decisions. To begin we discuss the characteristics of presence-only data, highlighting implications for modelling distributions. We particularly focus on the problems of sample bias and lack of information on species prevalence. The keystone of the paper is a new statistical explanation of MaxEnt which shows that the model minimizes the relative entropy between two probability densities (one estimated from the presence data and one, from the landscape) defined in covariate space. For many users, this viewpoint is likely to be a more accessible way to understand the model than previous ones that rely on machine learning concepts. We then step through a detailed explanation of MaxEnt describing key components (e.g. covariates and features, and definition of the landscape extent), the mechanics of model fitting (e.g. feature selection, constraints and regularization) and outputs. Using case studies for a Banksia species native to south-west Australia and a riverine fish, we fit models and interpret them, exploring why certain choices affect the result and what this means. The fish example illustrates use of the model with vector data for linear river segments rather than raster (gridded) data. Appropriate treatments for survey bias, unprojected data, locally restricted species, and predicting to environments outside the range of the training data are demonstrated, and new capabilities discussed. Online appendices include additional details of the model and the mathematical links between previous explanations and this one, example code and data, and further information on the case studies.
Article
Accurate modeling of geographic distributions of species is crucial to various applications in ecology and conservation. The best performing techniques often require some parameter tuning, which may be prohibitively time-consuming to do separately for each species, or unreliable for small or biased datasets. Additionally, even with the abundance of good quality data, users interested in the application of species models need not have the statistical knowledge required for detailed tuning. In such cases, it is desirable to use ‘‘default settings’’, tuned and validated on diverse datasets. Maxent is a recently introduced modeling technique, achieving high predictive accuracy and enjoying several additional attractive properties. The performance of Maxent is influenced by a moderate number of parameters. The first contribution of this paper is the empirical tuning of these parameters. Since many datasets lack information about species absence, we present a tuning method that uses presence-only data. We evaluate our method on independently collected high-quality presenceabsence data. In addition to tuning, we introduce several concepts that improve the predictive accuracy and running time of Maxent. We introduce ‘‘hinge features’ ’ that model more complex relationships in the training data; we describe a new logistic output format that gives an estimate of probability of presence; finally we explore ‘‘background sampling’’ strategies that cope with sample selection bias and decrease model-building time. Our evaluation, based on a diverse dataset of 226 species from 6 regions, shows: 1) default settings tuned on presence-only data achieve performance which is almost as good as if they had been tuned on the evaluation data itself; 2) hinge features substantially improve model
Article
Species distribution models (SDMs) based on statistical relationships between occurrence data and underlying environmental conditions are increasingly used to predict spatial patterns of biological invasions and prioritize locations for early detection and control of invasion outbreaks. However, invasive species distribution models (iSDMs) face special challenges because (i) they typically violate SDM's assumption that the organism is in equilibrium with its environment, and (ii) species absence data are often unavailable or believed to be too difficult to interpret. This often leads researchers to generate pseudo-absences for model training or utilize presence-only methods, and to confuse the distinction between predictions of potential vs. actual distribution. We examined the hypothesis that true-absence data, when accompanied by dispersal constraints, improve prediction accuracy and ecological understanding of iSDMs that aim to predict the actual distribution of biological invasions. We evaluated the impact of presence-only, true-absence and pseudo-absence data on model accuracy using an extensive dataset on the distribution of the invasive forest pathogen Phytophthora ramorum in California. Two traditional presence/absence models (generalized linear model and classification trees) and two alternative presence-only models (ecological niche factor analysis and maximum entropy) were developed based on 890 field plots of pathogen occurrence and several climatic, topographic, host vegetation and dispersal variables. The effects of all three possible types of occurrence data on model performance were evaluated with receiver operating characteristic (ROC) and omission/commission error rates. Results show that prediction of actual distribution was less accurate when we ignored true-absences and dispersal constraints. Presence-only models and models without dispersal information tended to over-predict the actual range of invasions. Models based on pseudo-absence data exhibited similar accuracies as presence-only models but produced spatially less feasible predictions. We suggest that true-absence data are a critical ingredient not only for accurate calibration but also for ecologically meaningful assessment of iSDMs that focus on predictions of actual distributions.
Article
Eurasian lynx are slowly recovering in Germany after an absence of about 100 years, and additional reintroduction programs have been launched. However, suitable habitat is patchily distributed in Germany, and whether patches could host a viable population or contribute to the potential spread of lynx is uncertain. We combined demographic scenarios with a spatially explicit population simulation model to evaluate the viability and colonization success of lynx in the different patches, the aim being to conclude guidelines for reintroductions. The spatial basis of our model is a validated habitat model for the lynx in Germany. The dispersal module stems from a calibrated dispersal model, while the demographic module uses plausible published information on the lynx’ life history. The results indicate that (1) a viable population is possible, but that (2) source patches are not interconnected except along the German–Czech border, and that (3) from a demographic viewpoint at least 10 females and 5 males are required for a start that will develop into a viable population with an extinction probability of less than 5% in 50 years. The survival rate of resident adults was the most sensitive parameter, and the best management strategy for the success of reintroduction would be to reduce the mortality of residents in the source patches. Nevertheless, the extremely low probability of connectivity between suitable patches makes most of the reintroduction plans isolated efforts, and they are therefore questionable in the long run. With such a model, the suitability of the single habitat patches can be assessed and the most appropriate management scheme applied. This study shows that simulation models are useful tools for establishing the comparative effectiveness of reintroduction plans aimed at increasing the viability of the species.
Article
This paper presents an on-line unsupervised learning mechanism for unlabeled data that are polluted by noise. Using a similarity threshold-based and a local error-based insertion criterion, the system is able to grow incrementally and to accommodate input patterns of on-line non-stationary data distribution. A definition of a utility parameter, the error-radius, allows this system to learn the number of nodes needed to solve a task. The use of a new technique for removing nodes in low probability density regions can separate clusters with low-density overlaps and dynamically eliminate noise in the input data. The design of two-layer neural network enables this system to represent the topological structure of unsupervised on-line data, report the reasonable number of clusters, and give typical prototype patterns of every cluster without prior conditions such as a suitable number of nodes or a good initial codebook.
Restoration of the red wolf Wolves: Behavior, Ecology and Conservation
  • M Phillips
  • V Henry
  • B Kelly
Phillips, M., Henry, V. and Kelly, B. 2003. Restoration of the red wolf. In (Mech, D. and Boitani, L., eds). Wolves: Behavior, Ecology and Conservation, pp. 272–288. Chicago, Illinois, USA.
Red Wolf Recovery Plan. United States Fish and Wildlife Service
  • Usfws
USFWS. 1989. Red Wolf Recovery Plan. United States Fish and Wildlife Service, Atlanta, Georgia, USA, 115 pp. Available at http://ecos.fws.gov/docs/recovery_plan/901026.pdf (Accessed 5 December 2007).
Notice of Termination of the Red Wolf Reintroduction Project in the Great Smoky Mountains National Park
  • V Henry
Henry, V. 1998. Notice of Termination of the Red Wolf Reintroduction Project in the Great Smoky Mountains National Park. Federal Register 63(195): 54151-54153. Available at http://www.fws.gov/ redwolf/Reviewdocuments/1998_FR%2863%2954151-54153. pdf (Accessed 10 October 2007).
Maximum entropy modeling of species geographic distributions
  • S Phillips
  • R Anderson
  • R Schapire
Phillips, S., Anderson, R. and Schapire, R. 2006. Maximum entropy modeling of species geographic distributions. Ecological Modelling 190: 231-259.
Population and Habitat Viability Assessment Workshop for Red Wolf (Canis rufus)
  • B Kelly
  • P Miller
  • U Seal
Kelly, B., Miller, P. and Seal, U. 1999. Population and Habitat Viability Assessment Workshop for Red Wolf (Canis rufus). Conservation Breeding Specialist Group (SSC/IUCN), Apple Valley, Minnesota, 93 pp.
A Comprehensive Review and Evaluation of the Red Wolf (Canis rufus) Recovery Program Wildlife Management Institute, Inc. Available at http://www. fws.gov/redwolf
  • Wildlife Management Institute
  • Inc
Wildlife Management Institute, Inc. 2014. A Comprehensive Review and Evaluation of the Red Wolf (Canis rufus) Recovery Program. Wildlife Management Institute, Inc. Available at http://www. fws.gov/redwolf/reviewdocuments/WMI-Red-Wolf-Review- FINAL -11142014.pdf (Accessed 15 December 2014).
Statewide Primary and Secondary Road Routes. North Carolina Department of Transportation
  • Ncdot
NCDOT. 2010. Statewide Primary and Secondary Road Routes. North Carolina Department of Transportation, Raleigh, NC. Available at http://www.ncdot.org/it/gis/DataDistribution/DOTData/default. html (Accessed 15 July 2011).
Habitat selection by recolonizing wolves in the northern rocky mountains of the United States
  • J Oakleaf
  • D Murray
  • J Oaklead
  • E Bangs
  • C Mack
  • D Smith
  • J Fontaine
  • M Jimenez
  • T Meier
  • C Niemeyer
Oakleaf, J., Murray, D., Oaklead, J., Bangs, E., Mack, C., Smith, D., Fontaine, J., Jimenez, M., Meier, T. and Niemeyer, C. 2006. Habitat selection by recolonizing wolves in the northern rocky mountains of the United States. The Journal of Wildlife Management 70: 554-563.
Assessing the suitability of Central European landscapes for the reintroduction of Eurasian Lynx
  • S Schadt
  • E Revilla
  • T Wiegand
  • F Knauer
  • P Kaczensky
  • U Breitenmoser
  • L Bufka
  • J Erveny
  • P Koubek
  • T Huber
  • C Stanisa
  • L Trepl
Schadt, S., Revilla, E., Wiegand, T., Knauer, F., Kaczensky, P., Breitenmoser, U., Bufka, L., Erveny, J., Koubek, P., Huber, T., Stanisa, C. and Trepl, L. 2002. Assessing the suitability of Central European landscapes for the reintroduction of Eurasian Lynx. The Journal of Applied Ecology 39: 189-203.
Red Wolf (Canis rufus) 5-year Status Review: Summary and Evaluation. United States Fish and Wildlife Service
  • Usfws
USFWS. 2007. Red Wolf (Canis rufus) 5-year Status Review: Summary and Evaluation. United States Fish and Wildlife Service, Manteo, North Carolina, USA, 58 pp. Available at http://ecos.fws. gov/docs/five_year_review/doc3991.pdf (Accessed 10 September 2008).