CONSERVATION BIOLOGY RESEARCH
ESTIMATING BLACK BEAR POPULATION DENSITY AND DISTRIBUTION
Matt Hewitt, Nicole Dickan, Amanda Veals Dutt, Justin French, Dana Karelus (TPWD), Warren Conway (Texas Tech University), and Louis Harveson
Black bears are native to the Texas mammalian community, and after a roughly 50-year absence, they are once again reestablishing themselves among the mountains and basins of the arid West Texas landscapes. This natural recolonization of black bears in the state is a testament to their resilience and adaptability. While their recolonization is exciting, bears come with their own set of challenges for coexisting with humans.
Due to a half-century hiatus from the region, the residents and wildlife managers of West Texas are having to readjust to their presence on the landscape. However, the general lack of knowledge of how bears use the West Teas landscape hinders human-bear coexistence. Managers rely on a robust understanding of the natural history, ecology, and preferences of a species when making management actions or recommendations, and the black bear is one such species where we are lacking this information.
Over the next couple years, our goal is to study black bears in this novel landscape to bring to light some of these unknowns. Specifically, we want to estimate the density of bears on the landscape, which in the sense of this study, is the number of bears per unit area, for example; one bear per square mile. We also want to understand what environmental factors may influence that estimate, and use information from the resulting model to estimate where bears are now and how they may continue to recolonize places in the future.
To do this we will use genetics to determine individuality from hair samples collected on a spatial grid across the landscape. This will give us the information needed to use a model that ties each individual bear to specific spots at specific times, known as a spatially-explicit capture-recapture model, to estimate species density and how things like elevation, slope, vegetation community, and other environmental factors may influence it. This spatially-explicit capture-recapture model will provide us with a foundation from which we can draw conclusions about where the recolonizing population currently is, and what paths are most likely to serve as travel corridors within the existing population and to habitats beyond the current extent.
The second component of our project will focus on unique behaviors surrounding winter denning given the hot, arid climate of the Chihuahuan desert within the Trans-Pecos. We aim to 1) locate, classify, and measure dens, 2) record timing of denning, and 3) classify fine-scale habitat characteristics surrounding den sites. Den sites are crucial for bear survival and reproduction. Information on winter behavior is crucial for bear population management, particularly for this newly recolonizing population.
This research will help inform management of black bears by the Texas Parks and Wildlife Department and ultimately assist these bears on their journey toward a successful recolonization and subsequent coexistence with humans.