DALLAS Researchers studying what has caused pronghorn in West Texas to die off will wait until at least next year to relocate more of the animals to the area because of the ongoing drought.

Last spring, researchers had moved about 200 of the animals from the Panhandle — where there's a thriving population. They'd hoped that in addition to bolstering the population, studying them would offer some clues to the decline.

But a year of harsh conditions including freezes, drought, extreme heat and wildfires took a toll.

Officials at Sul Ross State University in Alpine and the Texas Parks and Wildlife Department have been studying the decline.

The area had about 17,000 pronghorn in the mid-1980s. Last year the population hit a 30-year low with 3,745 animals.