Wed December 12, 2012

Scientists Trying To Solve Case of the Disappearing Mule Deer

Scientists throughout the West are trying to solve the mystery of the disappearing mule deer. Since the 1970s, biologists in Colorado, Wyoming and Utah have seen deer populations drop by 50 percent.

Theories as to why they’re vanishing vary. Oil and gas drilling and a growth in coyote populations top the list.

Aspen Public Radio's Luke Runyon reports on the declining number of mule deer in Colorado.

About a dozen men and women stand on a flat ridge as the sun peeks over a nearby hill. These biologists and veterinarians clutch coffee cups, trying to keep away shivers from chilly morning air.

They’re standing in the middle of the Piceance Basin, about 40 minutes outside Meeker, and they're trying to find out how mule deer are handling the rapid growth of oil and gas drilling. The Piceance Basin means a lot to both mule deer and humans.

“Well it’s the largest migratory deer herd in the state. And it’s also one of the largest energy reserves in the state,” says state wildlife researcher Chuck Anderson.

Anderson leads this particular study, which is trying to find the best way for oil and gas operators and mule deer to live in such close proximity. Scientists with Colorado Parks and Wildlife are herding up mule deer to study why they’re disappearing so quickly, and what role drilling plays.

“Mule deer throughout the range have declined since the late 70s, early 80s. We’re probably at about 50 percent of the numbers we had back then. And there’s a lot of factors contributing to that,” Anderson says.

Those factors fit into two camps. One school of thought says coyote and mountain lion populations have gone unchecked and the predators are killing off mule deer in greater numbers. The other says human encroachment, in the form of oil and gas development and road-building, has fractured the deer’s habitat and diminished the sage-brush mule deer forage on.

At this capture in the Piceance Basin, a small blue and yellow helicopter drops does off at a field station. The buzz of the helicopter blades is a constant.

"Mule deer throughout the range have declined since the late 70s, early 80s. We're probably at about 50 percent of the numbers we had back then. And there's a lot of factors contributing to that." - Chuck Anderson

The team rushes to the deer that’s just been dropped off. They place her on a stretcher, weigh her, and take her to a tent. There she’s measured and given an ultrasound. While the deer is lying on the table, sedated and blindfolded, the team attempts to calm her.

“I’m just rinsing her mouth out. Just giving her a drink of water, making her feel a little better,” says Lisa Wolfe, a veterinarian with the state. She pets the doe’s neck before taking any more measurements.

“Now I’m giving her some oxygen so she can catch her breath.”

The whole process is stressful for the deer. But Wolfe says it’s essential to solving this mystery. One thing is certain; the Piceance Basin has seen dramatic changes over the past twenty years. Wolfe mentions the road-building and habitat split because of rapidly growing oil and gas operations over the past decade. That’s been a major shift for these generations of mule deer. The contrast, she says, is stark.

“Especially at night, because everything lights up and you’re so used to being out in the middle of nowhere and then now it’s all lit up it’s like, whoa, where am I?” Wolfe says.

This ten-year study is just one of many going on right now in the West. In Utah researchers are focusing on how coyotes play into the mix. Some states have been proactive, paying out more money for dead coyotes.

Here in Colorado, oil and gas development isn’t expected to disappear anytime soon. So this study will be used to figure out better ways for the two populations, mule deer and humans, to coexist.