Tracking Deer Providing Valuable CWD Information

When deadly Chronic Wasting Disease was found in southeastern Minnesota’s Fillmore County in 2016, state wildlife officials saw a need to study the possible role of wild deer dispersal in CWD’s spatial spread. As of Oct. 31, 19 whitetails in Deer Permit Area 603 had tested positive for the disease.

A multi-year study that began last March involves using nets fired from helicopters to capture deer, fit them with GPS collars and release them back into the wild. Researchers then track the movements of each deer by satellite.

The study began with netting, collaring and releasing 109 deer. According to Dr. Chris Jennelle, research scientist for the Department of Natural Resources, early data have shown interesting dispersal — especially among “juvenile females” (doe fawns). In fact, to date the two widest roamers have been doe fawns; one moved approximately 77 miles (straight line) from her winter range, while the other traveled 40 miles.

“The average spring dispersal distance of juvenile females thus far has been 19 miles,” Dr. Jennelle notes. “But excluding the two outliers, the average falls to six miles. Juvenile males dispersed an average of nine miles, with one traveling 23 miles.”

The extreme travelers in each group skewed the data, due to the low number of deer being tracked, Still, 40 percent of doe fawns moved in excess of three miles from their winter range, while 28 percent of buck fawns did so.  

“Preliminary analysis suggests juvenile does disperse at similar rates to juvenile bucks in spring,” the researcher says. “Some (doe fawn) dispersal may be due to high densities and the influence of matriarchal does.”

At last report, 48 deer that were fawns when captured — 19 does and 29 bucks — still had functioning GPS collars. Dr. Jennelle says plans to continue collaring and tracking another 65 or so deer (roughly equal numbers of each sex) will add to confidence in the data set. The next captures are scheduled to occur in January.

More Information

This study received start-up funding from the Environment and Natural Resources Trust Fund, overseen by the Legislative-Citizen Commission on Minnesota Resources. For more on the research, visit: dnr.state.mn.us and search for “deer movement study."