Biology Reference
In-Depth Information
termine whether a winter-killed deer died of malnutrition and its associated effects or from some oth-
er cause. A biologist simply breaks open the femur (thigh bone), and inspects the marrow within. If
the deer was well nourished when it died, the marrow will be white and fatty, almost like suet. If the
deer was moderately malnourished, the marrow will have a pinkish tinge and will be somewhat less
solid and fatty. But if the deer was badly malnourished, the marrow, lacking any fat, will be thin and
red—almost the color and consistency of red jello. In fact, the marrow of a deer in the final stages of
malnutrition is so thin that it can be spread on a printed page and the print read right through it!
A deer's second defense against bitter cold is its winter coat. Twice each year—once in the spring
and again in the fall—whitetails molt, much as birds do. That is, they gradually shed one coat and re-
place it with a different one. During the spring molt, in particular, the winter coat comes off unevenly,
while the summer coat is replacing it.
The result is that whitetails in late spring or early summer often have a very mangy, moth-eaten look.
This passes quickly, though, and the deer are soon sleek and resplendent in a glossy, reddish summer
coat. This consists of only a single layer of fine, solid hairs that shows its owner off to great advantage.
When autumn arrives, the process is reversed: off comes the summer coat, replaced by winter garb.
This winter coat is a marvel of efficient heat retention. A thick, soft undercoat holds in body heat, and
what heat escapes that layer is retained by the outer coat. The latter consists of longer hairs, each one
of which is hollow—an air trap that provides outstanding insulation. In addition, the winter coat is a
grayish brown, much more suited to the somber color of the fall and winter woods than the red summer
coat.
The third winter defensive strategy is to move into winter quarters. These are popularly called “deer
yards,” which is something of an unfortunate misnomer, since it gives people the impression of deer
crowded into a little area much like a sylvan barnyard.
This misunderstanding manifests itself in a variety of ways. As a classic example, Walter D. Ed-
monds, in his 1936 novel,
Drums Along the Mohawk,
an otherwise well-researched topic, described a
scene in which the settlers went to a deer yard and, when the deer stopped against the far wall, used
them for target practice. This description belies reality, which is entirely different.
Biologists much prefer the term “deer wintering area” to “deer yard,” because it's far more descript-
ive of actual conditions. Even in deep snow, a deer wintering area has packed paths or trails scattered
through it, and it's often possible to wander around in one of these areas for hours and catch little more
than a fleeting glimpse of a deer. There are such things as very small wintering areas, where it's likely
one will get a better look at the inhabitants, but a wintering area that small will normally contain only a
handful of deer. In any event, so-called deer yards don't have “walls” of snow, or anything else.
Deer have very specific requirements for wintering areas, and if the winter habitat is destroyed—by
clearcutting or a housing development, for example—the deer can't simply go and find a replacement.
The first requirement in areas of severe winters and heavy snowfall is low-elevation, mature softwood
growth, usually at least forty years old. The thick, interlocking canopies of mature cedar, spruce, bal-
sam, pine, or hemlock trap much of the snow as it descends; subsequently some of this snow evapor-
