Bighorn Sheep Restoration at Big Bend Ranch State Park
Texas is entering a promising new phase of a multi-partner effort begun in 1954 to restore desert bighorn sheep to Far West Texas. In the late 1800s there were perhaps up to 1,500 sheep in the rugged mountains of the Trans-Pecos. However, due mainly to unregulated hunting and diseases from domestic and exotic livestock, bighorn numbers dwindled to about 500 in 1903 and by the 1960s they were gone.
Today bighorns are coming back, thanks to decades of work by Texas Parks and Wildlife Department, wildlife conservation groups, private landowners and others. TPWD biologists in September 2011 reported 1,026 bighorns in Texas, slightly down from the 2010 survey of 1,115 sheep. The decrease is believed to result from population stabilization, with sheep reaching or exceeding carrying capacity in the Beach, Baylor and Sierra Diablo Mountains. This phenomenon provides surplus bighorns for capture and transplant into mountain ranges where bighorns have disappeared.
The latest restoration phase involves releasing sheep in the Bofecillos Mountains of Big Bend Ranch State Park, which contain quality bighorn habitat. As of early 2012 more than 140 sheep have been transplanted to the park from Elephant Mountain WMA and the Beach, Baylor, and Sierra Diablo Mountains.
Establishing sheep at the park will increase numbers and distribution of the bighorn sheep population in Texas, help restore the park’s native wildlife and provide a new visitor wildlife viewing opportunity. (No hunting of bighorns in the park is planned at this time.) By early 2012, state park visitors and staff have already begun to see bighorns in the park’s mountains.
The department is taking various management actions to facilitate survival of the reintroduced bighorn sheep, including mountain lion predation management within specific zones of the park, control of exotic species such as aoudad sheep, and construction and placement of “water guzzlers” to catch and hold rainwater for sheep to drink.
USDA-Wildlife Services is trapping mountain lions in specific zones of the park in collaboration with TPWD. The purpose is to limit sheep predation, not to eradicate lions. Research and management experience from various U.S. states shows that lion predation management is an important element to successfully restore bighorn sheep.
There will be little or no impact to the region’s overall lion population, since management activity targets only lions with territories in bighorn core use areas, comprising less than one fourth the size of the park. Once bighorns are established and have reached or exceeded a viable population, lion management will shift to an adaptive strategy targeting individual lions that are primarily preying on sheep.
TPWD staff will also continue efforts to control aoudad, or Barbary sheep, an exotic from North Africa. Aoudads reproduce and spread quickly, with herds often exceeding 100 individuals. In the Trans-Pecos, they compete with native mule deer and bighorn sheep for space, forage, and water and can be devastating to desert environments. Aoudads may also pose a disease threat to wildlife and livestock.
TPWD biologists recognize that aoudads are almost impossible to eradicate, but reducing their numbers is critical to prevent continued detrimental impacts to the desert environment and native wildlife. This follows longstanding agency practices to control exotic, invasive species.
TPWD policy regarding feral and exotic species also includes the need to remove feral burros from Big Bend Ranch. The burros are damaging limited desert water resources and the native ecosystem, posing threats to a range of native plants and animals.
The department’s Bighorn Sheep Restoration Plan for Big Bend Ranch references scientific findings from other states that show the negative impact burros can have on bighorn sheep. Given the current distribution of burros and sheep in the park, there is little direct competition now, although conflicts are possible as bighorn sheep populations continue to expand. To sum up, burro control is needed to protect the park’s native plants and animals, lands and waters, regardless of the bighorn restoration project.
TPWD continues to explore non-lethal alternatives to manage the feral burro population at Big Bend Ranch, as it has since the early 2000s. The department continues to invite any reasonable and practical offers from groups who wish to offer alternatives, with the understanding that any proposal must include a commitment for adequate and sustained support, and the goal is to remove burros from the park.
The department is discussing an aerial survey to determine burro numbers and locations with the Humane Society of the United States (HSUS), which has offered its resources to assess non-lethal options. TPWD has agreed to cost-share up to $10,000 to help pay for the survey, which should occur this spring.
It is not likely that TPWD will conduct lethal burro control in the near future until it is determined whether non-lethal methods are feasible. However, department policy regarding feral and exotic species has not changed, the need to remove burros from the park remains, and TPWD retains the option to conduct lethal control if non-lethal options are not feasible.