We examined phylogeographic structure in gray fox ( Urocyon cinereoargenteus ) across the United States to identify the location of secondary contact zone(s) between eastern and western lineages and investigate the possibility of additional cryptic intraspecific divergences. We generated and analyzed complete mitochondrial genome sequence data from 75 samples and partial control region mitochondrial DNA sequences from 378 samples to investigate levels of genetic diversity and structure through population- and individual-based analyses including estimates of divergence (F ST and SAMOVA), median joining networks, and phylogenies. We used complete mitochondrial genomes to infer phylogenetic relationships and date divergence times of major lineages of Urocyon in the United States. Despite broad-scale sampling, we did not recover additional major lineages of Urocyon within the United States, but identified a deep east-west split (∼0.8 million years) with secondary contact at the Great Plains Suture Zone and confirmed the Channel Island fox ( Urocyon littoralis ) is nested within U. cinereoargenteus . Genetic diversity declined at northern latitudes in the eastern United States, a pattern concordant with post-glacial recolonization and range expansion. Beyond the east-west divergence, morphologically-based subspecies did not form monophyletic groups, though unique haplotypes were often geographically limited. Gray foxes in the United States displayed a deep, cryptic divergence suggesting taxonomic revision is needed. Secondary contact at a common phylogeographic break, the Great Plains Suture Zone, where environmental variables show a sharp cline, suggests ongoing evolutionary processes may reinforce this divergence. Follow-up study with nuclear markers should investigate whether hybridization is occurring along the suture zone and characterize contemporary population structure to help identify conservation units. Comparative work on other wide-ranging carnivores in the region should test whether similar evolutionary patterns and processes are occurring.
Bears (Ursidae) have extensive home ranges and may move long distances, thereby potentially serving as hosts to, and vectors of, large numbers of ticks. We assessed the composition of the parasitizing tick community on American black bears (Ursus americanus) to discern hard tick species capable of successfully feeding, which is a necessary step for tick reproduction. We counted ticks from free-ranging, live-trapped, or road-killed black bears in southern Missouri, USA, during 2015, and collected a subset of engorged ticks (n = 967). All bears (n = 17) were infected with ticks (n = 6,993), with a mean intensity of 411 ticks/bear, of which 14% were engorged females. The infracommunity size of engorged ticks was 57 ticks/bear. From these engorged ticks, we identified 5 species: Amblyomma americanum, A. maculatum, Dermacentor variabilis, D. albipictus, and Ixodes scapularis. Amblyomma americanum was the most common species, collected on all surveyed bears, and represented 58.2% of engorged ticks, whereas D. albipictus and A. maculatum were the least common species, collected from only 3 and 4 bears, respectively, and representing 4.7% and 2.4% of engorged ticks, respectively. Our data suggest that individual black bears have the potential to host large numbers of ticks to engorgement, and may be important vectors for tick dispersal and for the maintenance of tick populations.
Disentangling the complexities that influence animal space use poses substantial challenges based on decision trade-offs and constraints imposed on animals. Optimal decisions suggest that the spatial complexity of home-range shapes should be inversely related to energy conservation and fitness. Hence, the most beneficial shape should be the circle. We evaluated whether shape complexity (i.e., an index of circularity) of home ranges was influenced by two extrinsic (spatial heterogeneity, preferred habitat [i.e., deciduous forest]), and three intrinsic (sex, season [breeding, non-breeding], intensity of use) factors, with intensity of use indexed as contours containing core and peripheral areas. We estimated utilization distributions of 39 radiomarked adult American black bears (Ursus americanus), a habitat generalist, using fixed-kernel techniques and estimated 50% (core area) and 95% (peripheral area) contours. We fit a set of 47 models using linear modeling and ranked models using small-sample Akaike Information Criterion. Coefficients for the best model were the intrinsic factors intensity of use (reference category = core; 0.118; 95% CL = 0.064-0.173), sex (reference = female; 0.105; 95% CL = 0.043-0.167), and intercept (0.229; 95% CL = 0.186-0.272). Shape complexity was less for core areas than peripheral areas and less for females than males. Considering complex resource selection patterns within a fragmented landscape, both sexes appeared to use energy-maximizing strategies, although the increase in shape complexity for males may be an allometric relationship based on size dimorphism. Our approach supported the phenomenon of optimality as manifested through home-range shape complexity, but we suggest that assessment of this phenomenon for habitat specialists may yield different results, including the potential importance of intrinsic factors based on more restrictive limiting factors. (C) 2016 Gesellschaft fur Okologie. Published by Elsevier GmbH. All rights reserved.
Previously, American black bears (Ursus americanus) were thought to follow the pattern of female philopatry and male-biased dispersal. However, recent studies have identified deviations from this pattern. Such flexibility in dispersal patterns can allow individuals greater ability to acclimate to changing environments. We explored dispersal and spatial genetic relatedness patterns across ten black bear populations—including long established (historic), with known reproduction >50 years ago, and newly established (recent) populations, with reproduction recorded <50 years ago—in the Interior Highlands and Southern Appalachian Mountains, United States. We used spatially explicit, individual-based genetic simulations to model gene flow under scenarios with varying levels of population density, genetic diversity, and female philopatry. Using measures of genetic distance and spatial autocorrelation, we compared metrics between sexes, between population types (historic and recent), and among simulated scenarios which varied in density, genetic diversity, and sex-biased philopatry. In empirical populations, females in recent populations exhibited stronger patterns of isolation-by-distance (IBD) than females and males in historic populations. In simulated populations, low-density populations had a stronger indication of IBD than medium- to high-density populations; however, this effect varied in empirical populations. Condition-dependent dispersal strategies may permit species to cope with novel conditions and rapidly expand populations. Pattern-process modeling can provide qualitative and quantitative means to explore variable dispersal patterns, and could be employed in other species, particularly to anticipate range shifts in response to changing climate and habitat conditions.
The spatial scales at which animals make behavioral trade-offs is assumed to relate to the scales at which factors most limiting resources and increasing mortality risk occur. We used global positioning system collar locations of 29 reproductive-age female black bears (Ursus americanus Pallas, 1780) in three states to assess resource selection relative to bear population-specific density, an index of vegetation productivity, riparian corridors, or two road classes of and within home ranges during spring–summer of 2009–2013. Female resource selection was best explained by functional responses to vegetation productivity across nearly all populations and spatial scales, which appeared to be influenced by variation in bear density (i.e., intraspecific competition). Behavioral trade-offs were greatest at the landscape scale, but except for vegetation productivity, were consistent for populations across spatial scales. Females across populations selected locations nearer to tertiary roads, but females in Michigan and Mississippi selected main roads and avoided riparian corridors, whereas females in Missouri did the opposite, suggesting population-level trade-offs between resource (e.g., food) acquisition and mortality risks (e.g., vehicle collisions). Our study emphasizes that female bear population-level resource selection can be influenced by multiple spatially dependent factors, and that scale-dependent functional behavior should be identified for management of bears across their range.
Abundance and distribution of feral swine (Sus scrofa) in the USA have increased dramatically during the last 30 years. Effective measures are needed to control and eradicate feral swine populations without displacing animals over wider areas. Our objective was to investigate effects of repeated simulated removal activities on feral swine movements and space use. We analyzed location data from 21 feral swine that we fitted with Global Positioning System harnesses in southern MO, USA. Various removal activities were applied over time to eight feral swine before lethal removal, including trapped-and-released, chased with dogs, chased with hunter, and chased with helicopter. We found that core space-use areas were reduced following the first removal activity, whereas overall space-use areas and diurnal movement distances increased following the second removal activity. Mean geographic centroid shifts did not differ between pre- and post-periods for either the first or second removal activities. Our information on feral swine movements and space use precipitated by human removal activities, such as hunting, trapping, and chasing with dogs, helps fill a knowledge void and will aid wildlife managers. Strategies to optimize management are needed to reduce feral swine populations while preventing enlarged home ranges and displacing individuals, which could lead to increased disease transmission risk and human-feral swine conflict in adjacent areas.
ABSTRACT The use of baits often increases success for many wildlife management activities, including wildlife capture for research, harvest by hunters and trappers during regulated activities, and lethal and nonlethal control for damage management. However, some baits have unintended toxicity to wildlife, including theobromine and caffeine found in chocolate when used in sufficient quantities by hunters to bait bears. Recent examples have occurred in Michigan and New Hampshire, USA, and regulatory adjustments to prohibit use of chocolate (and other processed food products) as bait for bears have been proposed with varying degrees of success. To account for the potential lethal effects to both target and nontarget animal species, agencies charged with managing wildlife species should consider regulations or educational efforts to eliminate or minimize use of chocolate products for recreational feeding or baiting to attract wildlife species for capture, harvest, or observation. © 2016 The Wildlife Society.
Mobile computing and big data analytics have great potential for improving efficiency, productivity, and knowledge discovery in conservation tasks. This paper presents some recent development of mobile computing and data analysis systems for the Missouri Department of Conservation (MDC), including a mobile data collection system, an improved bear tracking website, and new analytics results obtained from real Missouri bear and deer GPS trajectories. The mobile data collection system using Android tablets is developed for surveying the usage and status of conservation areas. The new bear tracking website is developed to be mobile friendly and can dynamically present information of tracked bears. Lastly, for analyzing real GPS trajectories obtained from Missouri bears and deer, a density-based spatial and temporal clustering method is developed for identifying stay regions in trajectories of low sampling rate GPS points. Using real world data, interesting movement patterns of a large number of bears and white-tailed deer have been obtained, therefore advancing a step in achieving a better understanding of the behaviors of various types of animals in their natural environments.
American black bears are closely associated with forest habitat. They were nearly extirpated from the Central Interior Highlands, United States, in the early twentieth century, but have recolonized this part of the range since the 1960s. Due to lower population densities (as a result of recent recolonization), we hypothesized that bears in this region would show strong associations with forest habitat at both the home range and landscape scale. To test this, we analyzed hair snare and GPS telemetry data from five sampling grids with a combined spatial capture-recapture and resource selection function model to investigate individual space use within home ranges and landscape scale variation in density of black bears in the southern Missouri part of the Interior Highlands. We performed a linear discriminant analysis to identify habitat correlates of black bear density. We found that at the home range level, bears selected for more forested habitat and steeper slopes. Black bear density varied among sampling grids from 0.842 to 10.248 individuals/100 km(2) which is at the low end of the spectrum of reported black bear densities. There were no clear habitat correlates for among-grid variation in density, but in the three higher-density grids, density declined with increasing forest cover and increasing distance from human settlements. This suggests that the bear populations benefited from more heterogeneous habitat and that rural settlements may represent food resources. Exploiting these anthropogenic resources could be facilitated by the fact that bears in our study were not hunted and were viewed as a novelty rather than a nuisance, which may lead to low perceived risk from anthropogenic sources. Our results highlight the need to interpret habitat associations of American black bears not only at local scales but also in the landscape context.
Reintroduction is an effective tool for restoring endangered populations. There is increasing concern, however, that demographic restoration may not equate with genetic restoration. We examine the demographic-genetic contrast in the context of one of the world's most successful carnivore population restorations. Beginning in 1982, a total of 835 river otters Lontra canadensis were reintroduced to Missouri, USA, more than 50 years after extirpation. Most otters were translocated from Louisiana, USA, and released at 43 sites across the state. An estimated population of 11000-18000 otters existed by 2000, and density estimates for Missouri otters are now similar to those reported for populations across the continent, indicating demographic recovery. We used microsatellite genotyping and mitochondrial sequence analysis of DNA extracted from fecal samples from eight southern Missouri rivers, in conjunction with mitochondrial DNA (mtDNA) analyses from several native Louisiana otter populations, to evaluate the genetic diversity and population structure of otters within Missouri as compared with Louisiana. The Missouri population showed moderate to high heterozygosity and allelic diversity, similar to that of the source populations, but low mtDNA haplotype diversity. We detected five distinct genetic clusters distributed throughout the eight rivers, with no evidence of isolation by distance. These data collectively suggest that 30 years after restoration efforts commenced, Missouri river otters have retained genetic diversity levels similar to those of the source populations, but that genetic structure has not reached an equilibrium between migration and genetic drift. Thus, the Missouri otter population has made a robust recovery despite retaining the genetic signature of the reintroduction.
Following functional extirpation in Missouri, American black bear (Ursus americanus) populations in this state have been increasing in recent years through recolonization from re-established populations in northern Arkansas. To increase our understanding of resource selection by recolonizing black bears in the Ozark Highlands of the United States, we attached Global Positioning System (GPS) transmitters to 54 black bears during May August 2010 2013, and used location data based on biological seasons. We constructed models with anthropogenic (distance to nearest development, distance to nearest road), biological (sex, age class, season), and environmental (distance to nearest water, land cover) categories. We used infinitely weighted logistic regression to approximate the inhomogeneous Poisson point process model for presence-only (i.e., GPS locations) data to fit models. We used Bayesian Information Criterion and found that the best-performing model in the set of 81 models included all independent variables except sex and all combinations of 2-way interactions except those between biological covariates. Forested areas generally were more strongly selected than non-forested areas and bears generally selected areas distant from roads and other human development. However, selection for areas proximate to roads in the composite cover type (e.g., shrub scrub, woody wetlands) occurred, where roads may have been used as travel corridors in unsuitable cover during the breeding season (ad) or dispersal (subad), or alternatively as a potential barrier, depending on road type and traffic volume. Use of apparent lower quality non-forested areas by bears suggests that the current level of human development in southern Missouri is unlikely to halt their recolonization.
Accounting for low and heterogeneous detection probabilities in large mammal capture–recapture sampling designs is a persistent challenge. Our objective was to improve understanding of ecological and biological factors driving detection using multiple data sources from an American black bear (Ursus americanus) DNA hair trap study in south-central Missouri. We used Global Positioning System telemetry and remote camera data to examine how a bear's distance to traps, probability of space use, sex-specific behavior, and temporal sampling frame affect detection probability and number of hair samples collected at hair traps. Regression analysis suggested that bear distance to nearest hair trap was the best predictor of detection probability and indicated that detection probability at encounter was 0.15 and declined to < 0.05 at nearest distances > 330 m from hair traps. From remote camera data, number of hair samples increased with number of visits, but the proportion of hair samples from known visits declined 39% from early June to early August. Bears appeared attracted to lured hair traps from close distances and we recommend a hair trap density of 1 trap/2.6 km2 with spatial coverage that encompasses potentially large male home ranges. We recommend sampling during the late spring and early summer molting period to increase hair deposition rates.
The distribution of animals is influenced by numerous factors including spatial distribution and temporal availability of resources. We tested the spatial resource variability hypothesis (increasing landscape heterogeneity results in increasing amount of space use) and the temporal resource variability hypothesis (temporal variation in resources reduces amount of space use) using location data from radiomarked American black bears Ursus americanus in Missouri and Arkansas, USA. We used 95% utilization distributions (UDs) to define individual seasonal space use and constructed 22 models using covariates that described composition, spatial arrangement and diversity of land cover types (an index of heterogeneity or patchiness); seasonal hard mast production; and seasonal use of land cover to test our hypotheses using linear modeling and small-sample Akaike information criterion (AIC(c)) model selection approaches. The AIC(c) best performing model supported the spatial resource variability hypothesis and included Shannon diversity index [95% confidence limit (CL) of coefficient=1.56-2.42] and sex (male; 95% CL of coefficient=0.05-0.49) as covariates that explained variation in transformed values of UD size. Predicted and observed values during model evaluation were highly correlated (r=0.90). As land cover heterogeneity increased, UD size increased, likely a consequence of bears responding to greater patchiness to maintain sufficient resources. Further, the Shannon diversity index was greater for males than females , suggesting larger bodied males used larger areas to meet their higher energetic costs due to landscape fragmentation. Studies of resource hypotheses in solitary species should consider intraspecific allometric relationships such as sexual size dimorphism as has been addressed using group size in social species.
Spatial capture-recapture (SCR) models have advanced our ability to estimate population density for wide ranging animals by explicitly incorporating individual movement. Though these models are more robust to various spatial sampling designs, few studies have empirically tested different large-scale trap configurations using SCR models. We investigated how extent of trap coverage and trap spacing affects precision and accuracy of SCR parameters, implementing models using the R package secr. We tested two trapping scenarios, one spatially extensive and one intensive, using black bear (Ursus americanus) DNA data from hair snare arrays in south-central Missouri, USA. We also examined the influence that adding a second, lower barbed-wire strand to snares had on quantity and spatial distribution of detections. We simulated trapping data to test bias in density estimates of each configuration under a range of density and detection parameter values. Field data showed that using multiple arrays with intensive snare coverage produced more detections of more individuals than extensive coverage. Consequently, density and detection parameters were more precise for the intensive design. Density was estimated as 1.7 bears per 100 km(2) and was 5.5 times greater than that under extensive sampling. Abundance was 279 (95% CI = 193-406) bears in the 16,812 km(2) study area. Excluding detections from the lower strand resulted in the loss of 35 detections, 14 unique bears, and the largest recorded movement between snares. All simulations showed low bias for density under both configurations. Results demonstrated that in low density populations with non-uniform distribution of population density, optimizing the tradeoff among snare spacing, coverage, and sample size is of critical importance to estimating parameters with high precision and accuracy. With limited resources, allocating available traps to multiple arrays with intensive trap spacing increased the amount of information needed to inform parameters with high precision.
American black bears (Ursus americanus) were nearly extirpated from Missouri (USA) by the early 1900s and began re-colonizing apparent suitable habitat in southern Missouri following reintroduction efforts in Arkansas (USA) during the 1960s. We used anecdotal occurrence data from 1989 to 2010 and forest cover to describe broad patterns of black bear re-colonization, human bear incidents, and bear mortality reports in Missouri. Overall, 1,114 black bear occurrences (including 118 with dependent young) were reported, with 95% occurring within the Ozark Highlands ecological region. We created evidentiary standards to increase reliability of reports, resulting in exclusion of 21% of all occurrences and 13% of dependent young. Human bear incidents comprised 5% of total occurrences, with 86% involving bears eating anthropogenic foods. We found support for a northward trend in latitudinal extent of total occurrences over time, but not for reported incidents. We found a positive correlation between the distribution of bear occurrences and incidents. Twenty bear mortalities were reported, with 60% caused by vehicle collisions. Black bear occurrences have been reported throughout most of Missouri's forested areas, although most reports of reproduction occur in the southern and eastern Ozark Highlands. Though occurrence data are often suspect, the distribution of reliable reports supports our understanding of black bear ecology in Missouri and reveals basic, but important, large-scale patterns important for establishing management and research plans.
Bottlenecks, founder events, and genetic drift often result in decreased genetic diversity and increased population differentiation. These events may follow abundance declines due to natural or anthropogenic perturbations, where translocations may be an effective conservation strategy to increase population size. American black bears (Ursus americanus) were nearly extirpated from the Central Interior Highlands, USA by 1920. In an effort to restore bears, 254 individuals were translocated from Minnesota, USA, and Manitoba, Canada, into the Ouachita and Ozark Mountains from 1958 to 1968. Using 15 microsatellites and mitochondrial haplotypes, we observed contemporary genetic diversity and differentiation between the source and supplemented populations. We inferred four genetic clusters: Source, Ouachitas, Ozarks, and a cluster in Missouri where no individuals were translocated. Coalescent models using approximate Bayesian computation identified an admixture model as having the highest posterior probability (0.942) over models where the translocation was unsuccessful or acted as a founder event. Nuclear genetic diversity was highest in the source (A(R)=9.11) and significantly lower in the translocated populations (A(R)=7.07-7.34; P=0.004). The Missouri cluster had the lowest genetic diversity (A(R)=5.48) and served as a natural experiment showing the utility of translocations to increase genetic diversity following demographic bottlenecks. Differentiation was greater between the two admixed populations than either compared to the source, suggesting that genetic drift acted strongly over the eight generations since the translocation. The Ouachitas and Missouri were previously hypothesized to be remnant lineages. We observed a pretranslocation remnant signature in Missouri but not in the Ouachitas.
Although black bears (Ursus americanus) were believed to be extirpated from the Interior Highlands of North America by the early 1900s, populations have recently recovered, aided in part by reintroductions in Arkansas. Today black bears can be found in the Ozark and Ouachita National Forests of northern and western Arkansas, the White River National Wildlife Refuge in eastern Arkansas, and the Ozark region of southern Missouri. Previous genetic studies have investigated the effects of translocating black bears from Minnesota and Manitoba, Canada, into the Ozark and Ouachita National Forests between 1958 and 1968, with differing results. We used nuclear microsatellite loci to infer the genetic structure of black bears across the Interior Highlands and to investigate the sources of bears found today in southern Missouri. Our results suggest that the Ozark population was strongly influenced by the reintroductions, whereas the Ouachita population was influenced to a lesser degree. Although the majority of bears in the Ozark region of Arkansas and Missouri represent a single genetic unit, bears in Webster County, Missouri, may represent a remnant of the historical population of the region. Our results confirm that the bear population in the White River National Wildlife Refuge is strongly differentiated genetically from other Arkansas populations and support previous reports that the Ouachita bear population may have resulted from an admixture of a remnant population and reintroduced bears.
Abstract Postrelease movements can determine the success of wildlife translocations. We monitored movements of 36 captive-reared Ozark Hellbenders (Cryptobranchus alleganiensis bishopi) released to augment wild populations at two sites on the North Fork of the White River (Missouri, USA). We used radiotelemetry to collect 3610 Hellbender locations from May 2008 to August 2009. We quantified movements at multiple spatio-temporal scales and made comparisons between two seasons of monitoring (1 = release–December 2008; 2 = January 2009–August 2009). At the finest (daily) scale, most Hellbenders (90%–94% per season) were highly sedentary (≥50% of observations indicated no movement). Typical distances between daily locations when Hellbenders moved were <5 m in Season 1 (median = 3.08 m, n = 331; range = 0.19–903.00) and <2 m in Season 2 (median = 1.80 m; n = 161; range = 0.21–34.00). During the study Hellbenders rarely (35 of 492 movements) travelled >20 m between daily locations, and virtually all (34 of 35) such movements occurred in Season 1. At a broader scale, home ranges of Hellbenders varied widely in Season 1 (range = 0.66–986.92 m2, n = 26), but in Season 2 averaged only 31.33 m2 (± 11.81 SE, n = 8) and 11.08 m2 (± 3.25 SE, n = 7) at respective sites. Among Hellbenders monitored long enough to exhibit settlement (estimation of a home range) 69% (18 of 26) dispersed ≤50 m from the point of release. We only noted mortality associated with dispersals >50 m at one site, when it coincided with abandonment of core habitat that was one-third as large as at the other site. At the broadest scale, 68% and 86% of Hellbenders settled in core habitat of respective release sites, and most had settled within 21 d postrelease (range = 0–49 d). Collectively, Hellbender movements indicated a short period of exploration followed by more permanent settlement and high site fidelity typical of wild conspecifics. Captive-reared juvenile Hellbenders may be well suited for translocation; however, the quality of habitat at fine scale (10–30 m2) and the extent of suitable habitat within release sites are important considerations.