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Posts tagged “Odocoileus virginianus

White-tailed Deer Scent-Marking

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Scent-marking plays an important communication role in the animal world. A variety of species use glandular secretions to convey (for some distance) messages. From beavers spreading castoreum on scent mounds to fishers leaving their scent every time their hind feet touch the ground, the woods are alive with messages often undetected by most humans. Some of these are left by White-tailed Deer, which have two primary scent-marking behaviors: antler rubbing and scrapes.

One used to associate an antler rub with the act of a buck removing drying velvet from its antlers. However, it turns out that very few rubs are made by deer removing antler velvet, a process that’s normally completed within 24 hours. Instead, most rubs are made by relatively few dominant bucks to signal their readiness to breed and to mark their territory.

All White-tailed Deer possess specialized forehead glands that become increasingly active in autumn, particularly in adult males. All bucks spread their scent by rubbing their foreheads (which contain specialized scent glands) against trees and shrubs that have smooth bark, few, if any, lower limbs and are ½” to 4” in diameter. (Older bucks also will rub trees six or more inches in diameter.) In the Northeast, Trembling Aspen, Staghorn Sumac, Red Maple, and willows are often used for this purpose.

Mature, socially high-ranking bucks exude greater amounts of the glandular secretion than do younger males or females. They begin marking their territory soon after losing velvet and continue marking until they cast their antlers in December or January. The chemical signals left at a rub site tend to suppress the aggressiveness and sex drive of young males. However, those same signals stimulate females. The amount of rubbing an individual buck does depends on the level of testosterone in his blood, which in turn is largely determined by the animal’s age and dominance status.

We may not be able to detect the chemicals on a rub, but it’s hard to miss the sight of the light-colored blazes that magically appear in the woods at this time of year. (Photo: White-tailed Deer rub on Staghorn Sumac. Thanks to Chiho Kaneko and Jeffrey Hamelman for photo op.)

 

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Three-month-old Fawns Soon To Lose Spots

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By the end of August, White-tailed Deer fawns are about three months old. Their mother weans them between two and four months of age and during this time they molt, losing their white spots. A new gray-brown winter coat replaces the coat they were born with.

 


Coyotes and White-tailed Deer

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Coyotes will eat just about anything they come across – rodents, rabbits and hares, beavers, muskrats, birds, even garbage. Whatever is available and whatever they can catch they will consume. Very often you find white-tailed deer hair in their scat (see photo), and while a majority of the time it comes from deer carcasses that they have come across, there are two times of year when they are known to hunt deer. One is in the spring, when fawns are vulnerable, and the other is during the winter, when one of two conditions are present that favor coyotes: when the snow is deep and deer have to struggle to move faster than coyotes, and when there are crusty conditions, when coyotes are held up on top of the crust, but deer break through, often cutting and exhausting themselves.

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White-tailed Bucks Shedding Antlers

1-2-16-antler-049a2440Antlers, the fastest growing mammal tissue on earth, are grown by male White-tailed Deer (and very occasionally females) every year and shed every year. They begin growing in the spring, usually April, and complete their growth in August or September. During this period they are covered with “velvet,” a soft skin containing blood vessels and nervous tissue that supply oxygen and nutrients to the antler. Once growth ceases, the velvet dries up and falls off or is inadvertently rubbed off. The mating season of White-tailed Deer, or rut, during which time their antlers are instrumental in establishing hierarchy and securing a mate, peaks in mid-November. Once mating is over, the disadvantages of antlers (cumbersome shape for traveling through woods, and the energy required to carry them) promote the shedding of these bony structures. Specialized cells (osteoclasts) destroy the bone tissue between the antlers and the skull and antlers are shed sometime between the end of December and the beginning of February.

Most sources state that antlers just fall off or that the buck knocks them off by striking them against a tree. My personal observation of a buck in captivity clarified the way antlers are dropped, at least in this one instance. The buck put his head down, quickly jerked it up and to one side, and the antler went flying.

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White-tailed Deer Winter Diet

1-4-16-fungus-eaten-by-deerimg_0948The diet of White-tailed Deer varies with the seasons, but in general deer require a high-quality diet and tend to choose the most nutritious options available. In addition to mast (fruit, acorns, beechnuts) and browse, herbaceous plants and fungi make up the greatest portion of their food. However, their foraging choices are extensive. White-tailed Deer have been known to consume the washed-up carcasses of alewives after they (the alewives) have spawned as well as insects, mice and the nestlings of ground-nesting songbirds.

Microorganisms inside a deer’s four-chambered stomach enable cellulose in the plant material consumed to be digested. In winter, the microorganisms within the deer stomach are different from the microorganisms in spring, summer, and fall. This change allows deer to digest a diet of woody browse during winter months and turn the high-fiber diet into proteins through intricate physiological processes. Offering food items during this period other than woody browse (such as hay) is detrimental to deer, as it requires different microorganisms in the stomach in order to be digested. Thus, even though a deer’s stomach might be full (of hay, for instance), it may starve due to the inability to digest it.   (Photo: shelf fungus eaten by White-tailed Deer, showing lower jaw incisor grooves)

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White-tailed Deer Diet In Transition

10-25-16-deer-scat-20161017_5319Even if you didn’t know that a white-tailed deer’s diet changes in the fall, their scat would be a dead giveaway. Its texture and formation are excellent indicators of what a deer has been eating. During the summer, individual pellets are often lumped together due to the moisture content of their summer diet (grasses, clover, alfalfa, apples and other herbaceous food). As winter approaches, deer transition to a diet of twigs, leaves and acorns which results in the formation of individual, dry pellets. At this time of year, it is possible to find both forms of deer scat.

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White-tailed Deer’s Diet Changing With The Season

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Being ruminants, white-tailed deer have a four-chambered stomach which allows them to digest a wide variety of food, including leaves, twigs, fruits and nuts, grass, corn, alfalfa, and even lichens and fungi.  Their stomach hosts a complex set of microbes – organisms such as bacteria, which are too small to be seen with the naked eye – that change as the deer’s diet changes through the seasons.

In general, the green leaves of growing plants are consumed in the spring and summer, while fruits and seeds are eaten as they become available. Hard mast foods, such as hickory nuts and acorns, are an extremely important component of fall and early winter diets when deer need to establish fat reserves. The buds and twigs of woody plants are a mainstay of their diet in winter.

At this time of year it is not unusual to see deer grazing in fields that are just starting to have a touch of green. Grass is a welcome change from their winter woody diet, but it only comprises a very small (less than 8%) of a deer’s overall diet, due to its low crude protein and digestibility. Because their rumen (the stomach chamber where most microbial fermentation takes place) is small relative to their body size, a white-tailed deer’s diet must be high in nutritive value and capable of being rapidly degraded in the rumen.  Therefore, white-tailed deer rely primarily on alfalfa, clover, beans and other legumes, additional herbaceous flowering plants, and browse, all of which have more protein and are more easily digested than grasses.

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