SHERIDAN — Cheyenne Stewart, senior wildlife biologist with the Wyoming Game and Fish Department in Buffalo, presented an update of a regional study of mule deer that began in 2018 at the Mars Agriculture Center Wednesday.
The mule deer initiative is still in phase one of research but biologists are already seeing some unexpected results, Stewart said.
From 1985 to 2018, biologists have seen a decreasing trend of mule deer populations, well below population objectives, Stewart said. The mule deer population in the Upper Powder River Basin area hasn’t met objectives since 1999.
Stewart said the initiative began as a way to analyze what was causing the unit to decline, rather than lowering objectives arbitrarily.
The study was prefaced by analyzing population impacts and existing management actions. For predation, WGFD has a liberal mountain lion and bear harvest season, Stewart said.
For concerns of over-harvesting, there are limits or complete bans on doe mule deer harvesting. Rapid habitat assessments and treatments address habitat quality and quantity issues.
For competition with other wildlife, WGFD has a substantial elk and white-tailed deer harvest season, Stewart said. She also monitors fawn survival annually.
Biologists are closely monitoring the deer for chronic wasting disease, she said. Of the 70 adult, female mule deer who were initially collared as part of the initiative in 2018, 12% tested positive for CWD.
Research goals for the study include life history strategies, nutritional status coming into and out of winter, survival, CWD dynamics, fawn recruitment and habitat preferences.
The collars collect a deer’s GPS location every six hours, information that is sent to Stewart directly. GPS data collected every two hours is stored on collars until they are recollected. The collars are intended to last for all three years of the study. Collars from deer who die during the study will be replaced on new deer, she said.
The majority of deer Stewart is studying are considered residents — they have a relatively consistent and consolidated home range. A small group are “short-distance migrants” and an even smaller number travel long distances up to 30 miles over the research area.
Stewart said she looks forward to comparing the deer’s subcutaneous fat levels with the results from last year, which showed the deer were in poor nutritional condition. They were in the same lean condition going into the winter season that they should have been after a winter season with poor foraging.
So far, 18 of the collared deer have died; eight from CWD, five unknown, three from coyotes, two from mountain lions and one from trauma. Phase Two of the study will continue with annual captures every December to test for CWD and gather other data.
Stewart said it is crucial to use the data gathered from the study for education. She has been working with students in fifth-grade classrooms to develop their interest and research skills and get them excited about wildlife in their own backyards, she said.
The presentation was part of Sheridan College’s Science Museum Fall 2019 lecture series. The next lecture will take place Nov. 13 with paleontologist Georgia Knauss, “Shoebox Collections: Small Vertebrate Fossil Collection with Assistance from Tiny Harvesters.”