It is important to recognize that seasonal migration to DWAs is different than dispersal movements. Migration occurs during most or all years by animals across all age classes, and it is a seasonal movement in the North to enhance winter survival.
Migration occurs during late fall or early winter when snow depths reach 10 to 12 inches and temperatures drop below freezing. Occasionally, extremely low temperatures (below zero) will cause deer to yard even in the absence of snow.
Older deer teach migration routes to younger animals, and animals return to their spring ranges when the snow subsides. Deer average 135 days in DWAs in northern Maine and nearly 100 days in southern Maine.
Dispersal movement also occurs annually, but it is predominantly by 12- to 18-month-old bucks. About 25 percent of dispersal occurs during spring and the rest in the fall. This activity is believed to occur to reduce inbreeding within a population. Yearling bucks disperse an average of 1 to 5 miles, but distances over 30 miles have been documented. Dispersal occurs across all habitat types and in all deer herds, North and South, as long as the population isn't enclosed.
Unfortunately, DWAs are disappearing at an alarming rate due to development, logging operations, and infestations of spruce budworm and woolly adelgid. According to John Ozoga, the Michigan wintering area mentioned earlier that supported 43,000 deer in the late 1980s only supports about half that many deer today due to poor forest management. In recent years, the deer herd in Michigan's Upper Peninsula has dropped due to loss of winter habitat and increased winter mortality.
To maintain adequate winter habitat, many states and provinces have regulations governing the harvest of softwood species. Some jurisdictions even monitor these habitats. New Brunswick, for example, maintains 862 DWAs encompassing nearly 700,000 acres on public lands and nearly 115,000 acres on private lands. These wintering areas range from less than 20 acres to more than 22,000 acres. The average DWA is 934 acres.
So what does this mean to deer managers in the North? Support of local landowners is critical to provide good winter habitat. If you are in a region where deer migrate to DWAs, it is crucial to recognize the importance of this habitat type since biologists consider quality winter shelter the major limiting factor in sustaining deer populations at the northern limits of their range. If you manage land containing an active DWA, you should have a forest management plan designed to maximize the quality of the habitat.
Most state and provincial wildlife agencies have guidelines for forest management practices in or adjacent to DWAs. If you manage land that doesn't contain an active wintering area, you can enhance the habitat through forest management practices to create one. Managers should contact their state wildlife agency, Cooperative Extension Forester or consulting forester for assistance in assessing these habitats and especially before cutting any trees.
If you are involved in a QDM Cooperative in the North--a group of neighboring landowners who cooperate to meet QDM goals across large areas--then protecting or enhancing DWAs in the Cooperative is extremely important. When northern deer have access to high-quality DWAs, they are healthier and fewer succumb to malnutrition and predation. This also minimizes the subsequent fawn losses resulting from does in poor condition the following spring.
Kip Adams is a wildlife biologist and director of outreach and education in the northern U.S. for the Quality Deer Management Association (QDMA). This article was originally published in Quality Whitetails, the membership journal of the QDMA.
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