Five-year Study of Mammals in Big Bend National Park Contributes to Park Biodiversity Data

Between 2014 and 2019, BRI placed game cameras in Big Bend National Park to get a better understanding of mammal distribution, activity, habitat use and co-occurrence. Pictured here is a coyote.

On the northeastern range of the Chihuahuan Desert along the US-Mexico border, Big Bend National Park (BBNP) is a place of magnificent scenery and nearly unparalleled biodiversity. The over 800,000 acre park boasts a diversity of ecosystems and hosts a variety of plant and animal species. BBNP was established in 1944 in part to preserve these species, and it is the largest protected area of the Chihuahuan Desert in the United States.(1)

Given the importance of BBNP for biodiversity and habitat protection in the Trans-Pecos ecoregion, the distribution of species in the park has been well-studied. However, it is also important to monitor changes in the distribution of species over time and to gauge what factors within the park may contribute to change, such as increased visitation use and climate change.

Carmen Mountains white-tailed deer in Big Bend National Park.

The Borderlands Research Institute conducted a study on the mammals of BBNP to understand their distribution, activity, habitat use, and co-occurrence patterns. We surveyed specifically for carnivores and ungulates due to the higher detection rate of large-bodied animals as well as their importance to ecosystem functions and human interests. Fifty-eight motion-triggered camera traps were placed within and surrounding the Chisos Basin between 2014–2019.

A variety of mammals were documented in BBNP, including the two large carnivores of the park, mountain lions and black bears, as well as mesocarnivores such as bobcats, badgers, coyotes, kit foxes, gray foxes, raccoons, ringtails, long-tailed weasels, hooded skunks, hog-nosed skunks, striped skunks, and spotted skunks. Ungulates in the park include the Carmen Mountains white-tailed deer, mule deer, and javelina, and the invasive feral hog and aoudad.

We identified potential niche partitioning between white-tailed deer and mule deer, with white-tailed deer mostly occurring in higher elevations and mule deer in lower elevations. There was evidence of bobcat and coyote coexistence due to their similar temporal and spatial patterns.

Bobcat in Big Bend National Park.

Exotic species of aoudad were present and identified as habitat generalists, raising the concern of potential competition with native desert bighorn sheep, which are repopulating the park and are currently found along the eastern boundary near Black Gap Wildlife Management Area. We found that mountain lions and black bears overlapped with all mammal species within the park, indicating large carnivores can influence species diversity and distribution. However, there was a weak correlation for spatial and temporal overlap between these two apex predators. Black bears and mountain lions also differed in their use of areas near human infrastructure, with black bears
detected more often and closer to human use areas.

This study occurred over a 5-year period and can help park biologists identify potential areas of species interactions and human-wildlife conflict in order to make habitat management decisions.