As with most species habitat is a critical issue for Whitetail Deer. Habitat is an extremely important key to the survival of wildlife species.  The five main factors of habitat for a species are food, water, cover, space, and arrangement.  Certain aspects of habitat, especially food supplies are the predominant constraint on the numbers of a specie.  Responses of a specie to nutritional conditions have been documented or identified speculatively in many studies.  In general, good nutrition is reflected in animals by (1) good physical condition and above-average body weights; (2) high reproductive rates; (3) high survival rates, especially for newborn; and (4) increasing populations.  Poor nutrition would cause the opposite of these conditions.  Cover, space, and arrangement are also critical to physical and behavioral well-being for most species of wildlife, more so in some than others.

Food Preference and Utilization:

Basic to any appraisal of whitetail habitat is a knowledge of what foods the deer will consume, usually on a seasonal basis. After this has been determined, the biologist or manager can use the abundance or scarcity of these food plants as indices of habitat condition, and attempt to rehabilitate the habitat by increasing the more important plants. The degree to which certain plants are used by whitetails depends on the number of deer per unit of area, condition of the habitat, season, growth stage of available plants, age of stand and variety of plants within the area.

For example, when whitetails are forced to concentrate, as in winter yards, the most desired foods quickly become depleted from overuse, often resulting in starvation. However, this loss of life by overcrowding and starvation is not confined just to winter yards. In the Everglades of Florida,, extended high water levels force deer onto tree islands where they quickly deplete the life sustaining plants. In some habitats in the South, whitetails feed on twig growth primarily during the early spring period. The twig ends are most palatable and nutritionally beneficial at this time.

A standard technique in wildlife management is to determine the preferred browse plants within an area. As a matter of practicality, these plants then are singled out for intensive study. This approach has been particularly useful for categorizing winter deer yards, although plant lists also have been developed for use in studying southern deer habitats. These plant lists can be very misleading, however, if based only on field observation of utilization, since fruits, herbs, mushrooms and woody leaves can be, consumed entirely, leaving no evidence of use. 

The most common techniques used in studying the food preferences of whitetailed deer include rumen analysis, fecal analysis, lead deer studies and field observations of plants utilized. Each has advantages and disadvantages. 

Rumen Analysis:

Use of rumen contents to investigate the foods consumed by whitetailed deer was first reported in the Southeast by Ruff (1938). To identify and measure the foods taken, Ruff collected stomachs from whitetails on the Pisgah National Forest in North Carolina, and calculated the frequency of occurrence and percentage composition by volume of forages found in the stomachs. Harlow and Hooper (1972) obtained a good estimate both of frequency and composition of foods eaten by deer by sifting a composite sample collected from deer stomachs. A 9.51 millimeter (0.37 inch) sieve separated the largest food items immediately. A 5.66 millimeter (0.22 inch) sieve enabled recovery of any given food item that had reached its maximum frequency of occurrence.

Rumen analysis has several advantages. It will reveal deer consumption of forbs and the deciduous leaves of woody plants. Because whitetails consume such items entirely, utilization cannot always be detected by field inspection. Food preferences of deer can be investigated over an entire region or within a specific location in a relatively short time. For example, Puglisi et al. (1978) found that a five man crew could process 80 to 100 one quart rumen samples in eight hours. An obvious disadvantage is that animals have to be sacrificed in order for researchers to obtain an adequate sample. Also, differences in the digestibility of plants make quantification of food items difficult and sometimes unreliable (Norris 1943).

Gray et al. (1980) described and compared three methods commonly used to analyze rumen contents the point frame technique, the gross volumetric technique and the microhistologic technique.

The point frame method of analysis was much faster than gross volumetric and microhistological methods but sampled only 80 percent of the plant species or species groups identified by gross volumetric analysis. There was relatively close agreement between gross and microhistological techniques with the exception that fruits and fungi were estimated incorrectly or undetected microscopically, but were readily identified in gross analysis. Grasses and other herbaceous material, which were not detected or not identifiable with species by gross analysis, were identified more readily microscopically. Analyses of deer rumen contents were found to be more complete if both gross and microhistological techniques were utilized.

Fecal Analysis:In the United States, Dusi (1949) was the first to study the food habits of herbivorous mammals by histological analysis of feces. Currently, however, the most widely used techniques for preparing reference slides and fecal samples are those of Baumgartner and Martin (1939). Sparks and Malechek (1968) used the Baumgartner/Martin method for preparing samples, and then developed the method commonly used today for estimating weight percentage of a plant in the diet from plant fragment density in feces.

When using the fecal analysis technique, Ward (1970) emphasized that only fresh droppings should be used, and that samples should be placed in plastic bags to prevent drying and then stored by refrigeration, or in any preservative. Also, a good plant reference collection is essential.

The principal advantages of fecal analysis over rumen analysis are that (1) animals do not have to be sacrificed, (2) adequate samples are relatively easy to obtain, and (3) a more extensive listing of plants can be obtained in the same amount of time it takes to analyze rumen samples (Anthony and Smith 1974, Mengak 1982). Disadvantages include the amount of time involved in the preparation of reference material, cost of equipment and difficulty of interpreting data quantitatively. This method has not been widely used on whitetailed deer probably because it requires a more sophisticated analysis than for rumen contents. However, it was used to determine the food habits of Key deer in Florida (Dickson 1955) and on whitetails in Mississippi (Mitchell 1980) and in the Coastal Plain of South Carolina (Mengak 1982).

Lead Deer Studies:

Wallmo and Neff (1970) credited McMahan (1964) as first in the United States to observe specially trained wild ruminants to determine the kinds and amounts of forage taken on rangelands. Watts (1964) used specially raised whitetails to determine forage consumption in relation to seasonal availability of plant foods in hardwood forests in Pennsylvania. Healy (1967) also used tame whitetails to continue this work in other areas of Pennsylvania. Whelan et al. (1971) used three tame deer to determine food selectivity during early spring in western Virginia. They allowed the deer to feed for approximately one hour per day for the first week in order to familiarize them with the area. Then, during a 10 - day data - gathering period, observers noted the number of times the deer selected a particular plant species and its parts.

Lead deer are domestically reared semi tame animals. While being observed, the deer is kept under control by the scientist using a harness and a leash of about 6 meters (20 feet) in length (Healy 1967). Information is collected on the Plant species and plant parts taken and the time it takes the deer to chew and swallow the item.

Lead deer studies enable researchers to collect data on feeding habits at close range during any time of the year. Also, rough quantification of foods taken can be made, since differential digestibility of foods will not be a factor not as in rumen analysis. Disadvantages include the time and expense involved in raising deer and trying to keep them tame. Furthermore, controlling deer in the field is difficult. Finally, the sample size with this method is comparatively small, and the researcher cannot be entirely certain that the diet of the tamed deer would be that of a free-roaming whitetail under similar time and space conditions and minus an observer.

Field Observations of Plants:

Possibly, the first studies of deer feeding habits were accomplished through observation of browsed plants. It probably is safe to say that deer utilize most the plants they like best, and in field observations, wildlife researchers are inclined to consider those plants utilized most as the ones most preferred. However, such observations may be misleading because of the effect of seasonal influence on plant abundance and palatability, and on the stage of succession of the habitat regarding availability of certain plants (Harlow 1979). For example, some of the less preferred plants may receive heavy utilization on overstocked range (Latham 1950, Goodrum and Reid 1962, Gill 1957b, Jenkins and Bartlett 1959). In other cases, preferred plants may have grown out of reach of deer or have been eliminated (Swift 1946).

Several investigators have used subjective methods to classify the extent of browse utilization by deer. Cole (1959) used three categories: (1) no browsing to light browsing (unaltered to slightly altered plants); (2) moderate (second-year growth somewhat lengthened and only moderately altered); and (3) severe (second-year growth relatively short and drastically altered from normal growth). Aldous (1944) used -H- to designate heavy browsing (50-100 percent of a plant showing evidence of utilization), -M- for moderate (10-50 percent of plant utilized) and "L" for light (trace-10 percent of a plant utilized).

Subjective measurement data of whitetail utilization and food preference can be gathered rather quickly, so large areas often can be sampled in a relatively short time. One subjective habitat evaluation technique based on available forage, described by Williamson et al. (1978), provided a useful index to forage abundance and required about 20 percent of the time required for analogous vegetative sampling techniques. A big drawback is the potential degree of human error. Even experienced field workers find their estimates often vary widely.

Twig count and twig length are two direct methods of measuring whitetail utilization and preference in the field. In the twig-count method, browsed and unbrowsed twigs on each sampled plant are counted and their ratio expressed as a percentage (Bramble and Goddard 1953, Stiteler and Shaw 1966, Moore and Johnson 1967). The investigators used variable-sized plots (1-2 milacres to 0.0025 acre), some of which were shaped as transects, often permanently installed and systematically established to represent the important habitats. The twig-length method determines the average normal length of twigs and the average length after browsing. Deer use is expressed as a percentage of normal twig length. These lengths may be measured or estimated. Hormay (1943) used the twig-length method to estimate the amount of current twig growth grazed on bitterbrush. He established plots 50.8 centimeters (20 inches) wide and 40 or 60 meters (131-197 feet) long, which included 20 to 25 average-sized plants per plot. Hubbard and Dunaway (1958) found that a random sample of 19 to 39 leaders from each of five bitterbrush plants were required for estimating the true mean length within 10 percent of the actual value. Cole (1959) expressed plant leader use estimates as an average based on the percentage of total available leaders showing use. He recommended sampling about 25 browse plants within each sampling unit.

Exclosures have been used in many areas to study the effects of browsing on plants and to determine plant preference by whitetailed deer. In Pennsylvania, Grisez (1959) used a deer exclosure to demonstrate the effect of deer browsing on planted red pines and native woody plants. Shafer used deer exclosures to demonstrate how deer browsing affects natural tree seedling and sprout reproduction in northeastern Pennsylvania. In the Southern Appalachian Mountains, Harlow and Downing (1970) used exclosures to determine the effect of deer browsing on the height growth of important timber species.

For management purposes, it is important to know the extent to which preferred plants can sustain browsing. For example, Brown (1954) cited as an example the permissible use of antelope bitterbrush in California, which had been worked out to 60 percent of current twig growth. The remaining 40 percent must be left on the plant to maintain its vigor and ensure seed production. Krefting et al. (1966) found that mountain maple survived even though 100 percent of each year's current annual growth was clipped for nine consecutive years. Harlow and Halls (1972) found that dogwood seedlings in Texas were affected drastically when clipping intensities during summer reached 90 to 100 percent of annual growth. The investigators noticed that mortality of yellow poplar in North Carolina may be 40 percent or more if terminal twigs are removed. 

Senses and Whitetail Feeding Habits:

Whitetails are sensitive to sound and smell. Their large ears are constantly at the alert, and they depend on their acute sense of hearing to monitor the whereabouts and behavior of other animals, including predators. Their sense of smell also helps deer to identify individuals. Individual recognition occurs in large part through scents produced as tarsal pheromones. Smell attracts whitetails to food. If food smells nd unbrowsed twigs on each sampled plant are counted and their ratio expressed as a percentage (Bramble and Goddard 1953, Stiteler and Shaw 1966, Moore and Johnson 1967). The investigators used variable-sized plots (1-2 milacres to 0.0025 acre), some of which were shaped as transects, often permanently installed and systematically established to represent the important habitats. The twig-length method determines the average normal length of twigs and the average length after browsing. Deer use is expressed as a percentage of normal twig length. These lengths may be measured or estimated. Hormay (1943) used the twig-length method to estimate the amount of current twig growth grazed on bitterbrush. He established plots 50.8 centimeters (20 inches) wide and 40 or 60 meters (131-197 feet) long, which included 20 to 25 average-sized plants per plot. Hubbard and Dunaway (1958) found that a random sample of 19 to 39 leaders from each of five bitterbrush plants were required for estimating the true mean length within 10 percent of the actual value. Cole (1959) expressed plant leader use estimates as an average based on the percentage of total available leaders showing use. He recommended sampling about 25 browse plants within each sampling unit.

Exclosures have been used in many areas to study the effects of browsing on plants and to determine plant preference by whitetailed deer. In Pennsylvania, Grisez (1959) used a deer exclosure to demonstrate the effect of deer browsing on planted red pines and native woody plants. Shafer used deer exclosures to demonstrate how deer browsing affects natural tree seedling and sprout reproduction in northeastern Pennsylvania. In the Southern Appalachian Mountains, Harlow and Downing (1970) used exclosures to determine the effect of deer browsing on the height growth of important timber species.

For management purposes, it is important to know the extent to which preferred plants can sustain browsing. For example, Brown (1954) cited as an example the permissible use of antelope bitterbrush in California, which had been worked out to 60 percent of current twig growth. The remaining 40 percent must be left on the plant to maintain its vigor and ensure seed production. Krefting et al. (1966) found that mountain maple survived even though 100 percent of each year's current annual growth was clipped for nine consecutive years. Harlow and Halls (1972) found that dogwood seedlings in Texas were affected drastically when clipping intensities during summer reached 90 to 100 percent of annual growth. The investigators noticed that mortality of yellow poplar in North Carolina may be 40 percent or more if terminal twigs are removed. 

Palatability:

Characteristics that stimulate the selection of certain plants are referred to as "palatability factors" (Heady 1964). They may be chemical or physical, but chemical composition seems to be of major importance, even though the effective constituents are not well defined. Chemoreceptors in the nose and tongue respond to compounds that encourage or discourage consumption of potential foods.

The sense of taste in deer may be different from that in humans, who respond to substances that are sweet or sour, salty or bitter. However, blacktailed deer showed a pronounced preference for water solutions of sucrose and a moderate preference for acetic acid, while sodium chloride or quinine solutions were not preferred over plain water (Crawford and Church 1971). Whether these preferences can be related to natural foods has not been established. An association between essential oil composition and palatability of certain plants has been reported (Oh et al. 1968), and chlorogenic-acid concentrations have been associated with the susceptibility of Douglas-fir clones to browsing by blacktailed deer (Radwan 1972). No obvious preference was found among whitetailed deer for protein-energy supplement blocks treated with extracts of white Cedar fronds, cloves, wintergreen or a commercial "attractant," in comparison with that of untreated blocks (Ullrey et al. 1975b). 

The sense of smell has not been studied separately from the sense of taste in deer. However sheep deprived of the smell sense did not at flowering heads of grasses while normal Sheep did (Arnold 1966b). When the sense of touch also was impaired, the consumption of lowering heads was reduced less than by impairment of smell alone. Impairment of taste alone or touch alone resulted in increased intake of some plants and reduced intake of others.

The importance of sight in deer has not been studied objectively, although fawns tend to mimic the food choices of their mothers -- a behavior that depends on sight. Obscured vision in sheep resulted in greater consumption of tall grass and less clover, but sight was most important for space orientation (Arnold 1966).

It is unlikely that deer possess nutritional wisdom, but their survival under a variety of unfavorable circumstances suggests that their food choices generally are beneficial, regardless of the basis for these choices. In any case, survival is not exclusively dependent on the successful acquisition of nutrients, but on avoidance of toxins as well. Blacktailed deer strongly reject poisonous tansy ragwort and have a high tolerance for its toxin (Dean and Winward 1974).

Food availability influences relative preference. During periods of scarcity, any kind of available food, palatable or not, may be consumed out of necessity. This situation prevails regularly in northern climates where winter foods are restricted largely to woody browse.

Previous experience also seems to influence food selection. Young deer raised in captivity on formulated diets frequently prefer food items different from those consumed readily by wild deer. Preferences may be transmitted from one generation to the next through imitations of a doe's food selection by her fawns.

Appetite:

Assuming acceptable foods are available, the amount of food consumed per unit of time is a function of appetite. Food intake is physiologically regulated over both the long term and short term, otherwise starvation or obesity would be more common. Hunger and satiety centers have been identified in the hypothalamus, and lesions of these centers may induce under eating or overeating. In monogastrics, blood glucose levels stimulate these centers. In ruminants, very little blood glucose is derived directly from the diet, and volatile fatty acids from microbial fermentation in the rumen-reticulum are major energy sources. Intraruminal infusions of acetate, propionate or butyrate (or mixtures of these acids) depress food intake (Baile and Mayer). However, this effect may not be due to direct action on the hypothalamic appetite-control centers, since intravenous infusion produces less depression in food intake. Perhaps other appetite-control centers exist, or other metabolites are more important in regulating hypothalamic function.

Physical limitations of the digestive tract very likely limit the intake of coarse foods. Foods difficult to digest are retained longer in the rumen-reticulum than are easily digested foods, restricting the amount of food consumed per unit of time. Montgomery and Baumgardt have shown that in the lower ranges of dietary nutritive value, physical factors such as bulkiness (large volume per unit of mass) may be most important in limiting dry-matter intake, and digestible energy intakes may never reach need. In the upper range, chemostatic or thermostatic mechanisms such as rumen or blood volatile fatty-acid levels or the body-heat load may regulate intake such that energy consumption corresponds to need, while dry-matter intake declines with increasing nutritive value.

Whitetailed deer fawns consume dry matter in conformity with the Figure 38 model, at least in winter (Ammann et al. 1973). When digestible energy density of an artificial diet was increased from 1.9 to 3.5 kilocalories per gram of dry diet, dry-matter intake in grams per kilogram of body weight O.75 increased to a dietary-digestible energy density of 2.2 kilocalories per gram, then declined. Dry-matter consumption at a digestible energy density of 2.2 kilocalories per gram was sufficient to meet energy needs for maintenance of body weights in winter in a northern United States environment (Croyle 1969). This digestible-energy density is equivalent to a dry-matter digestibility of about 50 percent. When whitetails are fed diets of less than 50-percent digestibility, physical limitations of the digestive tract will limit dry-matter intake to less than maintenance requirements, and fawns will lose weight. Environmental factors, animal individuality and other characteristics of the food (such as nutrient content) may alter this 50-percent digestibility limit.

When adult whitetailed does were fed northern white cedar fronds with a dry-matter digestibility of 60 percent, dry-matter consumption in a Michigan winter was 0.58 kilogram (1.28 pounds) per day, and the does lost weight (Ullrey et al. 1972). Greater weight loss was experienced when the deer were fed bigtooth aspen shoots with a dry-matter digestibility of 49 percent. Dry-matter intake was only 0. 17 kilogram (0.37 pound) per day. Since daily energy intake must balance daily energy loss if weight is to be maintained, any factor that results in very low intakes of food, regardless of digestible-energy density, will be detrimental.

Seasonal factors, and related physiological cycles, also influence dry-matter intake. Young deer fed a pelleted diet with a dry-matter digestibility of 65 percent showed a marked decline in food consumption and weight in midwinter in New Hampshire (Holter et al. 1977). Food intake by free-roaming adult mule deer in Colorado showed a similar pattern, being greatest in summer; however, food intake by sub adults showed little fluctuation (Alldredge et al. 1974). In the South (Short et al. 1969a), captive yearling whitetails increased food consumption from lows in November and December to highs in spring. Food consumption generally decreased during the hot, humid southern summer, but increased slightly in August for bucks and gradually increased from July to October for does. It then fell rapidly to lows in late autumn and early winter. In a northern Michigan winter study, activity and browse consumption by fawns and adult does was high during December-January and in late March (Ozoga and Verme 1970). Activity and food consumption were reduced in the interim. Peaks of activity were noted at four- to six-hour intervals-sunrise, midday, sunset and twice during the night. As winter progressed, nocturnal and early morning movements were reduced, and food consumption was concentrated during the warmer part of the day. Such behavior represents an attempt to maximize energy conservation when food is scarce or of limited nutritive value.

Whitetail Deer Nutrient Requirements:

Although not experimentally established in every case, qualitative nutrient requirements of the adult deer probably include water, energy, nitrogen, essential fatty acids, calcium, phosphorus, magnesium, sodium, chlorine, potassium, sulfur, iron, copper, iodine, cobalt, manganese, selenium, chromium, fluorine, nickel, silicon, vanadium, tin, arsenic, molybdenum, vitamin A, vitamin D and vitamin E.

In addition, some indigestible fiber must be present in the diet to support normal digestive tract function. Nursing fawns require the aforementioned nutrients plus vitamin K, thiamin, riboflavin, niacin, pantothenic acid, vitamin B6, folic acid, biotin and cobalamin. Essential amino acids for the young fawn probably include arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.

Quantitative nutrient requirements have been established in only a few instances. Water requirements vary with climatic conditions, type of food, physiological state (growth, maintenance, lactation) and amount of activity. In 2 temperate environment, captive pregnant whitetailed deer typically consume two to three times is much water as dry matter. The amount of liquid water consumed is inversely proportional to the concentration of water in food. Snow may be consumed when liquid water is unavailable.

The daily digestible energy requirement for maintenance of pregnant does in a Michigan winter was determined to be 155 to 160 kilocalories per unit of metabolic size (kilograms of body weight 0.75) (Ullrey et al. 1969, 1970). Croyle found that male and female fawns required 168 and 155 kilocalories of digestible energy per kilogram of body weight O.75 , respectively, for maintenance in a temperate environment. Thompson et al. (1973) found that fawns required 199 kilocalories of digestible energy per kilogram of body weight O.71 daily for growth during their first summer, and 144 kilocalories of digestible energy per kilogram of body weight 0.75 for maintenance during their first winter. Free-ranging deer will undoubtedly have higher energy requirements due to the additional costs of foraging for food. Movement in snow greatly increases energy expenditure, with highest values occurring when deer sink to depths of 25 to 30 centimeters (10-12 inches) or more (Mattfeld 1974). Energy costs of maintaining body temperature are related to heat loss as influenced by exposure to cold and wind, and the insulative properties of subcutaneous fat and body hair. By lying in a curled position underneath evergreens, a deer can minimize heat loss to the immediate environment and the cold winter sky. Energy costs for reproduction are barely discernible from those for maintenance except during the last third of pregnancy and during lactation, when energy requirements are related to milk production.

Protein requirements for growth of fawns after weaning were estimated to be 14 to 22 percent (dry-matter basis), with males having higher requirements than did females (Ullrey et al. 1967b). S. H. Smith et al. (1975) proposed that approximately 24 percent protein (dry-matter basis) was required for maximum tissue nitrogen balance by weaned fawns, but as Hegsted (1964) pointed out, an animal may be in nitrogen equilibrium over a wide range of dietary nitrogen intakes. Nitrogen intakes required to maintain or build labile protein reserves are higher than those required to support minimal requirements. Holter et al. (1977, 1979) suggested that about 1 percent protein (dry-matter basis) is adequate for yearling deer. Protein requirements for maintenance of adults may be as low as 6 to 10 percent (dry basis) (French et al. 1956, McEwen et al. 1957). Protein requirements for gestation and antler development are probably intermediate - between those for growth and maintenance, while lactation requirements likely approximate those for growth.

Neither quantitative nor qualitative fatty-acid requirements for deer have been published. An unpublished study (Ullrey et al. 1972) of the effects of low-fat and low-linoleic-acid diets on gestation and lactation in whitetailed deer revealed no deficiency signs, nor any reproductive response to linoleic-acid supplementation.

Calcium requirements (dry-matter basis) to support growth, skeletal development and antler development of weaned fawns are about 0.45 percent (Ullrey et al. 1973). Phosphorus requirements (dry-matter basis) do not exceed 0.28 percent and may be lower (Ullrey et al. 1975a).

 Other elements that sometimes may be deficient in natural ecosystems (because of the geological origin of the soil and particular climatic conditions) are sodium, cobalt, iodine and selenium. Terrestrial browse species may contain sodium concentrations appreciably lower than those considered necessary for domestic ruminants. Whitetailed deer may adapt by using sodium-containing mineral licks (Weeks and Kirpatrick 1976, Weeks 1978). Cobalt deficiencies have been described in domestic ruminants in New York, but whitetailed deer in that region did not seem limited by a shortage of this element (Smith et al. 1963).

Iodine concentrations in deer foods in Michigan range from 0.008 to 3.1 parts per million (dry basis), with the minimum value far below the requirements for domestic livestock species (Watkins 1980). Selective foraging presumably helps deer meet their iodine needs. Watkins (1980) established that a diet containing 0.26 parts per million of iodine (dry basis) is adequate for maintenance and reproduction in captive whitetailed deer.

Selenium-deficient areas are widespread in the United States, with an apparent relationship existing between browse-selenium concentrations and those in the muscle tissue of free-ranging deer (Ullrey et al. 1981). Based on a number of parameters, dietary selenium concentrations of 0.2 parts per million probably are adequate for deer, but freedom from deficiency lesions also is dependent on dietary supplies of vitamin E and the degree of stress to which deer may be exposed (Brady et al. 1978).

Very little research has been conducted on the vitamin requirements of deer. Based on comparisons of liver vitamin-A concentrations in deer with those in domestic ruminants, incipient vitamin-A deficiency was suspected in 2 to 3 percent of vehicle-killed deer at the end of winter in Michigan (Youatt et al. 1976). Vitamin-D requirements presumably are met by exposure to sunlight and conversion of 7-dehydrocholesterol to cholecalciferol (D3) in the skin, or else by consumption of ultraviolet-irradiated dead-plant material (irradiation resulting in conversion of ergosterol to ergocalciferol [D2]). Vitamin-E requirements probably do not exceed 45 International Units per kilogram of dry diet when deer consume 0.2 parts per million of selenium and are not excessively stressed (Brady et al. 1978). However, it may be necessary for the diet to contain 80 or more International Units per kilogram to protect against peroxidative lesions in muscle of deer subjected to severe physical exertion. The need for vitamin K and B-vitamins in the diets of fawns before active rumen fermentation begins has not been explored.

Feeding Patterns:

Deer spend more time feeding than in carrying on any other activity (Michael 1970). When traveling to and from feeding areas whitetails often move in single file at a fairly steady walk along well-established trails, occasionally stopping to take a few bites of food. Once in the feeding area they usually separate and move about, rarely stopping long enough to consume a food source completely.

The lead deer or the lead group usually determines the direction of travel (Michael 1970). It may be a yearling or an adult, a male or a female. An adult doe customarily assumes leadership in small groups of three to five. Individual deer do not maintain any particular place within the group. Leadership is most evident when one or two adult does are grouped with yearlings and fawns. When groups of bucks feed and bed together, it is difficult to identify a leader.

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