Wildlife biologists have conducted aerial and ground surveys to find and map deer wintering areas since the 1950s.
In Maine, deer select winter habitats that offer protection from the wind, lighter snow cover, and food. These winter habitats, commonly referred to as deer yards or deer wintering areas, typically contain varying amounts of mature coniferous forest stands (shelter), which are interspersed with other forest types and openings that provide forage. Deer wintering areas are essential for the survival of deer in Maine, as deer are at the northern limit of their range in Maine.
Deer use of deer wintering areas -- mature stands of balsam fir, spruce, cedar, hemlock, and pine that may span entire watersheds -- is traditional. Specific sites may receive annual use by successive generations of deer. In some instances, continuous use of specific areas has been documented for 50-100 years. The size of the deer wintering area and the portion occupied by deer varies with the severity of the winter. When the winter is severe and deer mobility is poor, deer occupy a small portion of their winter range and are largely confined to the shelter portion of the wintering area. Under less severe conditions, deer may travel widely, even far beyond the normal boundaries of the wintering area. As winter weather is highly dynamic over time, so too is the area that deer occupy within and beyond the wintering area in response to changes in snow cover, sinking depth, and temperature.
Potentially, 10 -30 % of the deer population may die during any Maine winter, depending on its severity. We have experienced more snowfall this past winter, particularly in southern Maine, compared to the past several years. Later this spring, wildlife biologists will calculate the statewide winter severity for 2004-2005 by evaluating a variety of measurements including weekly snow depths, the depth that the deer sink in the snow as they are walking, and minimum and maximum daily temperatures at weather stations scattered throughout Maine's deer wintering areas.
The harvesting of trees for lumber and paper may compete with the ability of the forest to sustain different species of wildlife. In particular, the size and health of the deer population depends upon a diversity of habitats that must include an interspersion of food and cover. Dense evergreen stands provide winter cover, while open areas, where new growth occurs, are necessary for food production. Thus, timber harvesting can contribute to the health of the deer herd by making food available and regenerating softwood cover; however, excessive harvesting in deer wintering areas can contribute to deer mortality.
Consequently, the Land Use Regulation Commission (LURC) created the Fisheries and Wildlife Protection (P-FW) zone in which critical portions of documented deer wintering areas were to be protected in Maine's unorganized towns while allowing timber harvesting and other traditional economic uses that were not destructive to the habitat. In particular, the Commission sought to protect deer wintering areas by administering a balanced zoning program that considered the management needs of landowners and the economic constraints on them. LURC has zoned deer wintering areas since 1975. Currently, LURC and the Department have zoned almost 200,000 acres of the most critical deer wintering areas in Maine's unorganized towns.
The Department's long-term strategy to minimize deer mortality during the winter is to improve the availability of good wintering habitat by working with landowners, especially large paper and forestry companies. Trees may be cut in these deer wintering areas but a proportion of the area must provide adequate winter cover. Over the years, the Department has found that the zoned deer wintering areas represent only a fraction of the winter cover needed. More recently, it has developed cooperative agreements with a number of large landowners to provide for a reliable supply of wintering shelter within the constraints of a working forest. In essence, each agreement outlines the strategy by which a continuous supply of pulp and lumber will be available for the landowner, while maintaining winter shelter for deer. This is achieved by ensuring that approximately 50% of the deer wintering area is composed of mature, closed-canopy softwood stands that provide cover. The remainder of the deer wintering area is composed of young, growing coniferous stands of several ages that provide browse -- and future shelter. When necessary, the agreements delineate "travel corridors," bands of softwood shelter that allow deer to pass freely throughout the wintering area and its patchwork of young softwood stands. The agreements may also contain specific management guidelines for road construction, herbicide application, sand and gravel extraction, and the leasing of recreational property (i.e., camps) within the deer wintering area.
The cooperative agreements, because they cover larger areas over many years, have several benefits over zoned deer wintering areas (P-FWs): greater flexibility in selecting timber management options; greater certainty and predictability regarding future land management, timber productivity, and economic return; and with a larger area managed as winter habitat, the Department can more fully achieve its deer management goals and objectives, with benefits accruing to other wildlife as well. There are approximately 140,000 acres of deer wintering habitat conserved under cooperative agreements.