What will the fall of 2014 deer harvest be like after a record-breaking harsh winter? This is the question on the minds of most of Wisconsin’s 600,000 deer hunters.
of the car-killed deer assessments conducted by Department of Natural Resources wildlife officials. This finding is in line with field observations from DNR wildlife biologists throughout the state and reports from the public.
This spring, 522 deer were sampled statewide during a period when fat reserves were at their lowest point of the year. Local wildlife biologists inspected and gathered data from deer that were killed in vehicular collisions to evaluate pregnancy rate and fat stores at various points within the deer carcass, including the rump, around the heart and kidneys and in the bone marrow.
Dan Storm, a DNR research ecologist-
“Last January, we heard a lot of concerns about the potential winter impacts on the deer herd. From our radio-collared deer studies, we’ve learned a lot about how winter impacts our northern deer, but we didn’t have similar projects in the southern half of the state. Our research and wildlife staff quickly put a plan in place to look at car-killed deer. This was a very inexpensive and informative way for us to monitor winter impacts on deer throughout the state.”
Fat stores are a key indicator of nutritional condition as deer rely on these reserves, accumulated during summer and fall, to survive winter. Fatter does are able to provide better care to their newborns, which increases survival and is important to herd growth rates – fawn survival is closely linked to doe nutritional condition.
According to the WDNR findings:
In the southern portion of the state, 40 percent of adult deer sampled had rump fat, while rump fat was present in only 14 percent of adult deer sampled in the north. A greater proportion of deer in the north had little or no organ fat, as opposed to deer in the south. Similarly, bone marrow condition was better in the south than the north, and adults were more likely to have fatty marrow than juveniles in both the north and south.
Regardless of where in the state deer in the study were collected, the evaluations revealed that nearly all adult does were pregnant.
“Pregnancy rates among adult does were greater than 90 percent across the state, even in the northern forest, We wouldn’t expect the severe winter to impact this year’s pregnancy rates, because the deer became pregnant before winter began.”
While adult pregnancy rates did not differ between regions of the state, pregnancy rates of juvenile deer approaching their first birthday and the average number of fawns being carried were found to be quite different from north to south and between major habitat types throughout the state.
“The rate of adults carrying twins exceeded 60 percent in both the central and southern farmland zones, while the rate of single fawns for these zones was approximately 9 percent. In contrast, fewer does in the northern forest zone were pregnant with twins and many were carrying a single fawn.”
Juvenile does (under one year old) exhibited much lower pregnancy rates than adult does. Less than 10 percent of juveniles in the northern forest and nearly 20 percent in the central farmland zone were pregnant. Differences in litter size between the farmland and forest zones likely reflected differences in habitat productivity and the late spring experienced in 2013 in the Northern Forest Zone. A late spring limits the food supply available to deer, which in turn limits the amount of resources deer can use to create offspring.