Mule deer nutrition and reproduction studied
PULLMAN — Is poor nutrition contributing to a decrease in the number of mule deer in the Pacific Northwest? That is a question researchers at Washington State University are working to answer using deer hand-raised on the Pullman campus.
Lisa Shipley, associate professor in natural resources and a scientist in the WSU Agricultural Research Center, is part of a team led by wildlife biologist Woody Myers of the Washington Department of Fish and Wildlife working to determine why the number of mule deer in the state has steadily declined over the past 20 years. She says the captive herd makes it easier to determine exactly what’s going on in the wild.
“There are too many variables in the field,” she said. “The importance of captive animals is that you can isolate and remove different variables to determine exactly how nutrition affects reproduction.”
Shipley, along with graduate student Troy Tollefson, have hand-raised approximately 30 mule deer does, two bucks and numerous fawns, so they are able to work with the animals more easily. They feed each doe one of three diets – high, medium or low nutrition – based on fiber and protein content.
“We try to mimic the conditions in the field as closely as possible,” said Shipley. “Some years in some locations, there is plenty of water and lots of yummy vegetation for the deer to eat. In other years – drought years – there isn’t as much.”
The research team carefully monitors the differences in the does. They measure body weight and devised a way to measure body fat as well. They take milk samples and study nursing patterns. They also keep track of the size and growth of the fawns.
While still in the process of analyzing the data gathered over the past three years, Shipley says nutrition does appear to play a pivotal role in the number of fawns born.
“It looks like we’ve got fewer twins among the does on the lowest nutrition diet,” she said. “And the thinnest does haven’t given birth yet, and may not at all. Although, it also appears that even at about 5 percent body fat they can still reproduce.”