Habitat-Distribution Modeling of a Recolonizing Black Bear, <em>Ursus americanus</em>, Population in the Trans-Pecos Region of Texas

Abstract

Black Bears (Ursus americanus) were once widespread across Texas, but their numbers were reduced in the early 1900s. Recolonization of the Trans-Pecos region of Texas has occurred via bears migrating northward from Mexico. Recent bear sightings have increased in this area. This could be an indication that the population in Texas is beginning to recover, but the population will continue to expand only if there is suitable habitat to occupy. To help identify suitable habitat and restoration areas, we developed a predictive habitat-distribution model by using records of Black Bear sightings from 1996 to 2003 to map the species' distribution. Using Bayesian statistics, we modeled the probability of occurrence of Black Bears in the Trans-Pecos region based on sighting locations. We used GIS layers for land use/landcover, elevation, water sources, and road networks to obtain covariates in our modeling. We used a 10-fold cross-validation to test the effectiveness of using sighting data. Our results indicated a negative association with bare areas, agriculture, and grassland landcovers. In addition, southern aspect, elevation, distance to water, slope, and western aspect also influenced suitable habitat. Both the original and validation datasets correctly classified bear sightings 93.9% and 93.7% of the time, respectively. Our model can be used to target restoration efforts to enhance the ability of the Black Bear to expand in the Trans-Pecos region. It can also identify private landowners most likely to be affected by the expansion of Black Bears for education and cooperative efforts.

Potential distribution of Ursus americanus in Mexico and its persistence: Implications for conservation

“…Our results indicate that black bear is a highly marginal species that prefers sites with coniferous forest vegetation cover, which is consistent with previous studies (Baldwin & Bender 2008;Delfín-Alfonso et al, 2012;Herrera, 2003;Martínez-Muñoz, 2001;Onorato et al, 2003;Rogers, 1991;Rice et al, 2009;Sierra et al, 2005;Tankersley, 1996;Verdugo, 2005). The importance of the coniferous forest is related to the availability and quality of food.…”

“…In addition, the region of Serranías del Burro, Coahuila, México is identified as suitable. In this region, Doan-Crider and Hellgren (1996) reported the highest population density in Mexico, which has served as a reservoir for the reproduction of the black bear as well as for dispersion and recolonization into Texas (Onorato, Hellgren, & Doan-Crider, 2004;Rice et al, 2009). Likewise it has been reported the migration and dispersal of individuals towards areas of the State of Chihuahua (Hellgren, Onorato, & Skiles, 2005).…”

“…We considered environmental and anthropogenic variables related to the presence of black bear: vegetation cover; elevation; slope; distance to water bodies and, human population density (Baldwin & Bender, 2008;Delfín-Alfonso et al, 2012;Herrera, 2003;Martínez-Muñoz, 2001;Onorato, Hellgren, Mitchell, & Skiles Jr., 2003;Rogers, 1991;Rice, Ballard, Fish, McIntyre, & Holdermenn, 2009;Sierra et al, 2005;Tankersley, 1996;Verdugo, 2005). All variables were processed to a resolution of 1 km 2 and the correlation between them was analyzed in Biomapper 4.0 software to verify that the correlation coefficients were low (<0.5, de Pando and Peña , Merow, Smith, & Silander, 2013.…”

Activity and resource selection of a threatened carnivore: the case of black bears in northwestern Mexico

“…Additionally, PD negatively affected resource selection, and black bears preferred remote areas with higher plant productivity and avoided anthropogenic environments (Rudis and Tansey , Rice et al. , Duquette et al. ).…”

Evaluating population expansion of black bears using spatial capture‐recapture

“…Furthermore, characteristics of the landscape into which individuals expand, such as topography or barriers to movement, can produce complex demographic and population genetic patterns (Bowler and Benton , Holt et al , Wegmann et al ). Estimating and understanding how populations change in size and distribution is important for effective management that anticipates future changes (Fortin et al , Rice et al , Frary et al ).…”