Dynamics of a Black Bear Population within a Desert Metapopulation

Understanding metapopulation dynamics in large carnivores with naturally fragmented populations is difficult because of the large temporal and spatial context of such dynamics. We coupled a long-term database of visitor sighting records with an intensive 3-year telemetry study to describe population dynamics of recolonization by black bears (Ursus americanus) of Big Bend National Park in Texas during 1988–2002. This population, which occurs within a metapopulation in western Texas and northern Mexico, increased from a single pair of known breeding-age animals in 1988 to 29 bears (including 6 females of breeding age) in March 2000 (λ = 1.25/year). A migration and dispersal event in August–December 2000 reduced the population to 2 adult females and as few as 5–7 individuals. One-way movement distances from the study area during this event averaged 76 km for females (n = 7) and 92 km for males (n = 4), and 3 animals conducted migrations of at least 154, 178, and 214 km, respectively. Our observations exemplify the importance of stochastic events on demographics of small populations and highlight the potential scale of bear movement among montane islands of southwestern North America. They also provide insight into the use of dispersal data in parameterizing metapopulation models for large carnivores

Is there a single best estimator? Selection of home range estimators using area-under-the-curve

Background: Global positioning system (GPS) technology for monitoring home range and movements of wildlife has resulted in prohibitively large sample sizes of locations for traditional estimators of home range. We used areaunder- the-curve to explore the fit of 8 estimators of home range to data collected with both GPS and concurrent very high frequency (VHF) technology on a terrestrial mammal, the Florida panther Puma concolor coryi, to evaluate recently developed and traditional estimators. Results: Area-under-the-curve was the highest for Florida panthers equipped with Global Positioning System (GPS) technology compared to VHF technology. For our study animal, estimators of home range that incorporated a temporal component to estimation performed better than traditional first- and second-generation estimators. Conclusions: Comparisons of fit of home range contours with locations collected would suggest that use of VHF technology is not as accurate as GPS technology to estimate size of home range for large mammals. Estimators of home range collected with GPS technology performed better than those estimated with VHF technology regardless of estimator used. Furthermore, estimators that incorporate a temporal component (third-generation estimators) appeared to be the most reliable regardless of whether kernel-based or Brownian bridge-based algorithms were used and in comparison to first- and second-generation estimators. We defined third-generation estimators of home range as any estimator that incorporates time, space, animal-specific parameters, and habitat. Such estimators would include movement-based kernel density, Brownian bridge movement models, and dynamic Brownian bridge movement models among others that have yet to be evaluated

Evolutionary and Practical Implications of Pseudo-Estrus Behavior in Florida Panthers (Puma Concolor Coryi)

Estrus behavior by females for reasons other than reproduction (pseudo-estrus) has been reported in species of primates and felids, and alternative hypotheses have been put forth to explain its evolution and function. We observed 3 separate cases of pseudo-estrus behavior by 2 Puma concolor coryi (Florida Panther) females while they were nursing young (old) kittens. We used VHF and GPS telemetry data, genetic pedigree analysis, and visual observations to provide insight into the evolutionary and practical implications of this behavior for Panthers. We suggest that female Panthers likely consort with males while nursing kittens to maintain amicable relations with these males to prevent infanticide. For studies monitoring Puma dens with radio-telemetry, pseudo-estrus events may be confused with litter abandonment, and thus our observations are useful to fi eld biologists who may consider removing kittens from the wild following presumed abandonment events to prevent kitten mortality

Genetic Structure of American Black Bears in the Desert Southwest of North America

Abstract American black bears (Ursus americanus) have recolonized parts of their former range in the Trans-Pecos region of western Texas after a \u3e40-year absence. Assessment of genetic variation, structuring, gene flow, and dispersal among bear populations along the borderlands of Mexico and Texas is important to gain a better understanding of recolonization by large carnivores. We evaluated aspects of genetic diversity and gene flow for 6 sampling areas of black bears in southwestern North America using genotypic data from 7 microsatellite loci. Our results indicated that genetic diversity generally was high in the metapopulation of black bears in northern Mexico and western Texas. The episodic gene flow occurring via desert corridors between populations in northern Mexico and those in western Texas has permitted the establishment of only moderate levels of genetic structuring. Bayesian clustering analyses and assignment testing depicted the presence of 3 subpopulations among our 6 sampling areas and attested to the generally panmictic nature of bear populations in the borderlands region. The potentially ephemeral nature of the small populations in western Texas and genotypic characteristics of bears recolonizing these habitats attest to the importance of linkages along this portion of the borderlands of the United States and Mexico to effectively conserve and manage the species in this part of its range

Habitat Selection by Critically Endangered Florida Panthers across the Diel Period: Implications for Land Management and Conservation

Decisions regarding landscape management, restoration, and land acquisition typically depend on land managers’ interpretation of how wildlife selects habitat. Such assessments are particularly important for umbrella species like the endangered Florida panther (Puma concolor coryi), whose survival requires vast wildlands. Some interpretations of habitat selection by panthers have been criticized for using only morning locations in defining habitat use. We assessed habitat selection using a Euclidean distance analysis (EDA) and location data collected throughout the diel period from GPS collars deployed on 20 independent Florida panthers. We corroborated aspects of earlier analyses by demonstrating selection of forested habitats by panthers. We also confirmed selection of open habitats (i.e., marsh–shrub–swamps, prairie–grasslands), a novel result. Habitat selection did not vary by sex or season but varied by time of day. Panthers were located closer to wetland forests in the daytime and used prairie–grasslands more at night. Our assessment of the effect of patch size on selection of forest habitat revealed that panthers were not solely reliant on large patches (\u3e 500 ha) but utilized patches of all sizes (≤ 1 ha, \u3e 5–10 ha, \u3e 1000 ha, etc.). Our results emphasize the importance of collecting panther location data throughout the diel period when assessing habitat selection. Conservation strategies for panthers should consider a mosaic of habitats, a methodology that will protect other sensitive flora and fauna in South Florida

Is there a single best estimator? Selection of home range estimators using area-under-the-curve

Background: Global positioning system (GPS) technology for monitoring home range and movements of wildlife has resulted in prohibitively large sample sizes of locations for traditional estimators of home range. We used areaunder- the-curve to explore the fit of 8 estimators of home range to data collected with both GPS and concurrent very high frequency (VHF) technology on a terrestrial mammal, the Florida panther Puma concolor coryi, to evaluate recently developed and traditional estimators. Results: Area-under-the-curve was the highest for Florida panthers equipped with Global Positioning System (GPS) technology compared to VHF technology. For our study animal, estimators of home range that incorporated a temporal component to estimation performed better than traditional first- and second-generation estimators. Conclusions: Comparisons of fit of home range contours with locations collected would suggest that use of VHF technology is not as accurate as GPS technology to estimate size of home range for large mammals. Estimators of home range collected with GPS technology performed better than those estimated with VHF technology regardless of estimator used. Furthermore, estimators that incorporate a temporal component (third-generation estimators) appeared to be the most reliable regardless of whether kernel-based or Brownian bridge-based algorithms were used and in comparison to first- and second-generation estimators. We defined third-generation estimators of home range as any estimator that incorporates time, space, animal-specific parameters, and habitat. Such estimators would include movement-based kernel density, Brownian bridge movement models, and dynamic Brownian bridge movement models among others that have yet to be evaluated

Evolutionary and Practical Implications of Pseudo-Estrus Behavior in Florida Panthers (Puma Concolor Coryi)

Estrus behavior by females for reasons other than reproduction (pseudo-estrus) has been reported in species of primates and felids, and alternative hypotheses have been put forth to explain its evolution and function. We observed 3 separate cases of pseudo-estrus behavior by 2 Puma concolor coryi (Florida Panther) females while they were nursing young (old) kittens. We used VHF and GPS telemetry data, genetic pedigree analysis, and visual observations to provide insight into the evolutionary and practical implications of this behavior for Panthers. We suggest that female Panthers likely consort with males while nursing kittens to maintain amicable relations with these males to prevent infanticide. For studies monitoring Puma dens with radio-telemetry, pseudo-estrus events may be confused with litter abandonment, and thus our observations are useful to fi eld biologists who may consider removing kittens from the wild following presumed abandonment events to prevent kitten mortality

Strategically Locating Wildlife Crossing Structures for Florida Panthers Using Maximal Covering Approaches

Crossing structures are an effective method for mitigating habitat fragmentation and reducing wildlife-vehicle collisions, although high construction costs limit the number that can be implemented in practice. Therefore, optimizing the placement of crossing structures in road networks is suggested as a strategic conservation planning method. This research explores two approaches for using the maximal covering location problem (MCLP) to determine optimal sites to install new wildlife crossing structures. The first approach is based on records of traffic mortality, while the second uses animal tracking data for the species of interest. The objective of the first is to cover the maximum number of collision sites, given a specified number of proposed structures to build, while the second covers as many animal tracking locations as possible under a similar scenario. These two approaches were used to locate potential wildlife crossing structures for endangered Florida panthers (Puma concolor coryi) in Collier, Lee, and Hendry Counties, Florida, a population whose survival is threatened by excessive traffic mortality. Historical traffic mortality records and an extensive radio-tracking dataset were used in the analyses. Although the two approaches largely select different sites for crossing structures, both models highlight key locations in the landscape where these structures can remedy traffic mortality and habitat fragmentation. These applications demonstrate how the MCLP can serve as a useful conservation planning tool when traffic mortality or animal tracking data are available to researchers

Accuracy of Home Range Estimators for Homogeneous and Inhomogeneous Point Patterns

The only assumption of kernel density estimation, the most popular method of animal home range delineation, is that sample points used to approximate the utilization distribution are independent and identically distributed (i.i.d.), or what is termed ‘homogeneous’ or ‘stationary’. This research evaluated the accuracy of several home range estimators for both homogeneous and inhomogeneous point patterns of animal tracking data. A novel technique was developed to simulate home ranges from an extensive database of observed Florida panther (Puma concolor coryi) locations. Thirty-five homogeneous and inhomogeneous point distributions, each, were generated and used to delineate known home ranges for individual animals. Random samples of 100, 250, 500, and 1000 points from each simulated distribution were used to evaluate the accuracy of fixed and adaptive kernel density estimation (KDE), local nearest neighbor convex hull (k-LoCoH), and characteristic hull polygon (CHP) methods for delineating home ranges. Both fixed and adaptive KDE overestimated home ranges by up to 30% for homogeneous samples and underestimated areas by about 50% for inhomogeneous ones. The k-LoCoH method performed relatively better than KDE, tending to produce slight underestimates of home range sizes, but its performance was widely affected by both homogeneity and sample size. The CHP method produced relatively unbiased estimates of home range sizes for both types of samples, with results fairly robust to sample size. These findings demonstrate the influence of inhomogeneity or nonstationarity in animal locational data on the accuracy of home range estimation methods and suggest that ecologists should consider multiple underlying statistical assumptions when selecting a home range estimator