Helping western pronghorns: Study hopes to shed light on decreasing herd

Last winter, Colorado Division of Parks and Wildlife biologists and wildlife managers, concerned about unexplained decreases in a herd of about 100 pronghorns living in the harsh desert between Delta and Grand Junction, began a multiyear study to determine why the herd was not adding to its numbers.

What the biologists weren’t able to control was the weather, specifically the drought that continues in western Colorado.

According to the Division of Parks and Wildlife, the pronghorns are descendants of animals transplanted to the area in the 1970s. During the past 10 years, it’s been noticed that individual groups of the animals are getting smaller and the overall size of the herd is declining.

“Very few fawns are surviving, and we don’t know why,” said Brad Banulis, terrestrial biologist for the Montrose area. “We hope that this study will help us figure out what’s going on in this herd.”

Fast forward to midsummer 2012, and things haven’t improved for the pronghorns. If anything, the drought-like conditions gripping Colorado and the West have kept a thumb firmly on these prairie ghosts, said Banulis.

“We’ve been trying to get out and look for fawns with recently captured and transplanted does, but we haven’t been seeing much yet,” Banulis said. “It could be related to our timing, but drought conditions there look pretty bad.”

The conditions include lack of forage and hard-to-find water sources.

The project began in mid-February, when Division of Parks and Wildlife captured 19 pronghorns from the existing herd and placed radio collars on 10 of them and neck bands and ear tags on the rest to let biologists and managers track their movements. A few weeks later, 24 pronghorn were captured from a herd south of Limon in eastern Colorado and released near the Delta-Mesa county line. Nine were fitted with radio collars and the others received ear tags and neck bands.

The pronghorns also were vaccinated against viruses responsible for fatal hemorrhagic diseases in deer and pronghorns.

It was expected the transplanted pronghorns would join the existing herd, Banulis explained. By tracking the animals, biologist hoped to determine the habitat the pronghorn are utilizing, learn whether they’re having young and learn whether fawns are surviving.

But the effects of the drought have made it difficult for biologists to see any early improvement in herd numbers.

“We should have a better idea at least by August, if not sooner, how our pronghorn fawn crop will look,” Banulis said.

Because of the concern about the pronghorn numbers, there is no pronghorn hunting this year in Units 41, 411 and 62.