DESERT BIGHORN SHEEP RESEARCH
Recent Bighorn Restoration: Big Bend Ranch State Park
In 2010 and 2011, 141 sheep were captured and transplanted to the Big Bend Ranch State Park (46 from the Elephant Mountain Wildlife Management Area and 95 from the Beach, Baylor and Sierra Diablo mountain ranges). This past effort marks the biggest bighorn translocation effort in Texas history.
Research plays an important role in recent restoration efforts. Information gathered from satellite and GPS technology help quantify movements, survival, and habits of restored populations. This information is then used to better our management practices for bighorn sheep in Texas.
The translocation had two purposes. Foremost, the translocation was to restore desert bighorn sheep to historic habitat of the Bofecillos Mountains. Second, the effort help alleviate pressure of burgeoning populations. Population growth rates coupled with browse evaluations suggested bighorn populations were at or near carrying capacity in the Beach, Baylor and Sierra Diablo mountain ranges.
Of the 141 sheep transplanted to BBRSP, 78 of them were radio-collared for research analysis. These collars collect and save location points every 3-5 hrs for up to 2 years. This information will allow us to see the sheep’s movements without having to visually spot or track each individual sheep on a daily basis.
With this information, we will compare movements, home ranges, and core areas between: rams and ewes, diurnal and nocturnal locations, and behaviors of initial and supplemental sheep. We also plan on analyzing topographical tendencies (slope, elevation, aspect, etc.); this may help us delineate preferred travel corridors, thus bettering our knowledge for future restoration efforts.
Out of the 78 collared sheep, 15 of the sheep have died. Based on carcass investigations, we determined >7 of the sheep were killed by mountain lions. Evidence at the mortality sites did not allow us to determine cause of death for 8 bighorns. With the collected GPS data to date, the farthest recorded sheep we know of has traveled >25 miles from the release site. We have also documented sheep crossing back and forth into Mexico. This reiterates the need for international conservation efforts for desert bighorn sheep in Texas and Mexico.