Presentation on theme: "White-Tailed Deer and How they survive in winter BY: Lindsey Keiser and Kimberly Berger."— Presentation transcript:
White-Tailed Deer and How they survive in winter BY: Lindsey Keiser and Kimberly Berger
Body & Behavioral Adaptations to Winter Climate Deer Yards Winter Food Threats to Survival Conclusion
Their coat changes from their summer coat of a reddish color to their winter coat that is a darker brown This process is called Photoperiodism This starts to occur in late August early September Once their winter coat is fully grown they must constantly shake to rid themselves of the water that has soaked in.
Most deer go into winter with some fat on their bodies. Amount is determined by the quality and quantity of food available. They build up the fat reserves in September and October. The way that they achieve this is by searching out food with the most nutrition. Examples are apple orchards, hay, and cornfields.
Basic Metabolism- measure of energy requirements. Heat production must equal heat loss. Deer to not respond to cold in this manner. Their metabolic rate drops instead of speeding up when the temperature gets below freezing. This rate requires a minimum calorie count of 1,140 cal. Per 100 lbs. of body weight. With this low metabolism rate, deer will lose 12-15 % of their body weight.
The parts of the endocrine system that are effected are: Adrenals, pituitary, and the thyroid glands. They are at there smallest and inactive during Jan. and Feb., the period of the coldest weather. If the Temp. drop is slow and steady, the deer can adjust to the slowing down of their endocrine system more easily. If the temp. drop is fast and severe they may go into shock and die.
During winter deer scrape away the snow to lie on the leaves underneath, creating a bed, this is counter productive. They burn more cal. Scraping the snow away, when the snow would be more effective if it enveloped the body like a blanket, creating heat. They spend 90% of their time in winter bedded down, and do little to no activities to conserve energy Deer use these beds over and over again, and will even become territorial about their beds. During a heavy snow fall they will lie down & not move unless disturbed. Literally they are buried in snow
Deer Yards- are usually in dense evergreen swamps, draws, gulleys, or along brushy waterways. White tails travel no more than 2-3 miles to yard up The max. distance they will travel is 15 miles. Main Objective-to get out of the wind. Also in deer yards the snow depth is less because the snow gets caught on trees. Also these spots are warmer then the outside climate due to the fact the trees holding the snow act as a insulator. Not only is there a food shortage & physical stress, the deer yards have a tendency to become over crowded. Whitetails are not herd animals by nature, they gather into herds only when forced to.
Aggression is very common among deer in the yards. Examples of aggression are the bucks turning on the does and the does turning on the fawns. They turn on each other because of food shortage. Dominance is always in a state of flux. This is due to it always having to be reestablished at every contact because of the need for food. Bucks are usually dominate because they are bigger and stronger then does Because Bucks lose their antlers prior or during winter, they fight by kicking out at each other.
The growth of summer vegetation gives false impression that their food is plentiful. It is important but the critical vegetation is that which is available during winter Most deer revert almost entirely to brows because they are forced to. Most herbaceous food is not available. They mostly search out small, nutritious twigs The protein level of the plants drops as the plants begin to dry up. Can drop as much as 25-40% Their digestibility also lessens In spring they can digest 70% of plants consumed, in winter it drops as low as 12%
Deer are selective feeders. They instinctively look for the food with the highest protein. Deer need a mixture of forage types. The very best food will only sustain them for 2 wks. White tailed deer love to eat acorns, oak leaves, whatever corn that has been lost to the picker, and rye grass. Deer also get nutrition from the bark that they eat & not from the cellulose of the wood.
Two main threats to the survival of deer: Starvation & Snow depth’s effect on their movement. Starvation is a major cause of white tail deaths during the winter season. When easily reached food is gone, deer will stand on their hind legs to reach food on upper branches. A 7-mon. fawn can reach about 5 ft., an adult doe can reach 6 ft., while an adult buck can reach 7 ft. Naturally, this causes the fawn to get less food. The 7-ft height is called the “brows line”. When food is gone from here it really means starvation
Deer prefer brows no thicker then a wooden matchstick. When hunger is severe they will eat brows up to the size of a wooden pencil. When the deer eat the browse of a larger diameter, it is a losing battle. The older bark of the larger twigs has less protein, and is less digestible. Also larger twigs have less bark in proportion to their volume. This means that when they eat the larger twigs they are getting less than half of the nutrients. There is one last problem, and this sometimes pushes the deer over the edge of starvation. When they eat brows in winter, it must produce extra body heat to thaw out the frozen twigs in its paunch before they can be utilized.
A deer can lose 30% of it body weight and survive. The critical point lies between 30-33% A loss of a full third is always fatal As temp. drops this is when the fat deposits are used. The fat surrounding the back and hams is first to go, and then that of the abdominal cavity. Then the fat in the bone marrow will be used. A deer in good condition contains 95% fat. As starvation cont. the liver is also effected. Ordinarily the liver produces glycogen from glucose and proteins and stores it to be released to the muscles as energy. Without glucose, the deer develops hyperglycemia. Hyperglycemia-low level of blood sugar.
The legs of a average deer are 18-22 inches long. Fawn legs are 16-18 inches Deer can walk around in 15 inches of snow but can’t in 24 inches. In deep snow deer must bound instead of walking. This is very hard for fawns, and this leads to a high number of fawn deaths in winter.