In the Wyoming Range in western Wyoming, mule deer numbers have plummeted by 20,000 animals since the early 90’s. One problem has been the high number of fawns that don’t make it to adulthood. Now, a new study of that herd shows a rare disease called adenovirus may be a culprit.

University of Wyoming professor Kevin Monteith is working closely with the Wyoming Game and Fish Department, the Wyoming Wildlife and Natural Resource Trust and Animal Damage Management Board on the study.

“This is the first study that’s ever been conducted within the state of Wyoming where we’ve captured and monitored neonatal mule deer. So this is really the first opportunity where we’ve been able to confirm what’s killing these animals at such a young age.”

The viral disease causes fawns to lie down and die without an obvious cause. He says tests show they die of fluid build up in the lungs or bleeding in the intestines.

University of Wyoming graduate student Samantha Dwinnel leads the project. She says not much is known about the disease, but they think it’s spread by direct contact.

“Some of the very few things that we could try to do now is minimize areas where there’s artificial feeding, you know, hay piles or watering holes because that just gets animals to aggregate together.”

Dwinnel says they hope to extend the study at least another year to confirm that adenovirus is affecting the herd size there.