The Seasons

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Spring is the time of plenty for deer. New succulent plants send out tender shoots every day. Food is abundant even in areas that do not normally provide deer with nutritious food. At this time of year, the woods become a huge salad bar, and deer are able to sample different flowers and plants as they choose. Among the spring favorites in Missouri are wild lettuce, grape vines, trumpet vine, cinquefoil, sweet clover, violets and spring beauty. Most plants offer peak nutrition during spring, and whitetails respond with growth spurts and weight gain. Males channel energy to their antlers and regain the weight lost during last year's breeding activities. Females transfer energy to unborn fawns, which now undergo rapid growth.

Almost all Missouri does 1 1/2 years old or older breed and produce fawns each year. In addition, 30 to 40 percent of fawns that are less than 1/2 years old breed and produce offspring by the time they are 1 year old. The number of fawns that are born and survive annually is dependant upon a number of factors including the age and nutrition of the mother, deer density in the area and winter stress. Birthrates vary from region to region as these factors change.

In Missouri, the pregnancy rate of whitetails was measured by examining the number of fetuses in road-killed does. These data were grouped by natural regions because habitat and nutrition are similar (Figure 5). Pregnancy rates for deer 2 1/2 years old and older and yearling does were nearly equal, but rates for younger deer were markedly lower (Table 2). Adults had more offspring per doe than yearlings, who had more than the youngest group. In Missouri, most adult and yearling does have twins each year. The folk tale that old does tend to be barren is a myth. Researchers documented fetuses in does over 15 years of age. In fact, some researchers suggest that older does are more successful mothers because they are experienced and have the best territories.

Regional Pregnancy Rates
Natural Division	Age of Deer	Number Sampled	Percent Pregnant	Average Number of Offspring
Glaciated Plains	Fawn Yearling Adult	266 161 247	32 93 34	0.43 1.74 1.86
Mississippi Lowlands	Fawn Yearling Adult	6 2 10	50 100 100	0.83 1.50 2.19
Ozark Border	Fawn Yearling Adult	108 69 133	26 94 94	0.34 1.71 1.68
Osage Plains	Fawn Yearling Adult	36 25 50	50 88 94	0.67 1.67 1.68
Ozarks	Fawn Yearling Adult	122 77 219	21 89 94	0.28 1.51 1.78
Statewide	Fawn Yearling Adult	538 337 659	30 90 94	0.40 1.67 1.81

Peak fawning takes place in late May and June and begins when pregnant does isolate themselves and drive other deer from their fawning areas. Adult deer use the same areas each year. The establishment of fawning territories is thought to limit social stress and help distribute populations evenly. Territories also may prevent newborn fawns from imprinting on deer other than their mothers.

Does may give birth while standing but often are bedded during delivery. The actual birthing process lasts 30 to 150 minutes with twins born 15 to 30 minutes apart. After giving birth, the doe consumes placental membranes and afterbirth-probably to reduce scent and recycle nutrients. Mothers also consume their fawn's fecal materials for the first two to three weeks. Fawns, which weigh from four to eight pounds at birth in Missouri, can stand as soon as 30 minutes after being born and usually begin nursing at this time. During these first hours and days, fawns imprint on their mothers or, in some cases, on another deer or animal.

The first weeks of life for newborn fawns are precarious. Young fawns are vulnerable to a variety of predators, diseases, parasites and human-caused mortality. In Missouri, the major natural predators are coyotes, dogs and bobcats. To reduce exposure to predators, fawns spend most of their time bedded and hidden in heavy cover, such as hay fields, grown pastures and old fields. Studies using radio transmitters suggest fawns are active less than one-fifth of a 24-hour day.

Both the doe and its offspring spend most of their time in a 10- to 20-acre area these first weeks. Does visit their fawns two to four times a day to nurse and groom them. Fawns move to a new bed site after each feeding and grooming session, but siblings generally do not bed together. During this time, does sometimes physically defend their offspring from predators. It is also during this period that people find what they believe are "abandoned" fawns. In most cases, its mother is close by. Bedded fawns should be left alone.

Following its first month, the fawn increases nursing and activity periods. After four to six weeks, a doe may visit her fawn as often as five or six times per day. Fawns begin eating vegetation and ruminating at two weeks, although they cannot digest plant nutrients until five weeks. Fawns become more social, are more likely to be seen with their siblings or mother and increase their activity to levels similar to adult does. After 10 weeks, fawns eat grasses and forbs and are functional ruminants.

Young does typically establish fawning territories next to their mother's, but sometimes they disperse and establish in a new area. Missouri deer studies suggest does travel widely during spring then, before giving birth, reduce their movements dramatically.

It is much more common for 1-year-old bucks to disperse. In a northern Missouri study that used radio transmitters, 77 percent of buck fawns roamed more than 8 miles. Dispersal by young bucks and does is especially pronounced in areas with high deer densities. Dispersing deer tend to have higher mortality rates, but this phenomenon is part of deer biology. It helps expand populations and limits inbreeding.

During summer, does and bucks are segregated, sedentary and spend most of their active time eating. Does and fawns travel and feed together throughout the summer. Sometimes fawns from the previous year travel with this year's doe/fawn groups. Does with fawns may spend 70 percent of their time eating to meet their high nutritional requirements. They often seek shrubby, thick cover because it offers better hiding and higher quality forage.

Bucks often congregate in bachelor groups composed of neighboring bucks. Males typically use open habitats, such as mature hardwoods, fields and poorly stocked forests. Thus, they often are found in different habitats than family groups of does and fawns. Some deer researchers suggest males prefer open areas so that they can keep track of their position in the social hierarchy and to keep from damaging their antlers while feeding. Others theorize that the males' nutritional requirements are lower per pound of body weight or that their large rumens allow them to consume more food and gather sufficient nutrition from poorer ranges.

Activity levels in deer are proportional to their nutritional needs. Larger bucks are reported to be more active than smaller bucks during summer. Females are more active than males. Nonetheless, both sexes tend to have smaller home ranges during summer and use wooded cover during daytime periods and open areas at night.

Fall and Winter

Fall is a frenzied time of year for whitetails. Does and fawns continue to travel in groups, but now fawns are totally weaned and does feed aggressively to recover from the stresses associated with raising them. During fall, deer eat items rich in starch and carbohydrates. In oak-hickory forests, this means acorns and soft mast, such as persimmons. Deer also graze on cool season grasses and legumes, which are undergoing a resurgence of growth with cooler fall temperatures and rain.

Yearling bucks that have not dispersed the previous spring do so in fall and winter. According to studies, this group represents less than 20 percent of yearling bucks in Missouri. Adult and yearling buck bachelor groups break up, and bucks begin to shed their antler velvet and rub trees. An increased production of testosterone, triggered by decreasing day length, brings on the changes in buck behavior and the hardening of antlers. Rutting behavior and activity varies with the age and experience of the bucks and the sex and age ratios of the local deer herd.

Sparring matches are common prior to the break up of bachelor groups, especially among younger animals. Yearling (1 1/2-year-old) and 2 1/2-year-old bucks spar to size each other up without injuring themselves. Older bucks with previously established dominance tend not to participate in much pre-rut sparring.

Through sparring and visual posturing, fraternal groups of whitetails establish a social hierarchy. This limits energy expenditures on unnecessary fighting. Bucks establish a dominance ranking that tends to hold year round, but a dominant animal may temporarily lose rank if it casts its antlers sooner than the others. Occasionally, two evenly matched individuals meet, and the resulting battle for dominance is quite serious. Adult bucks can injure or kill one another. Sometimes antlers become locked, and both animals perish.

About the time bucks decrease their sparring activities, they increase their antler rubbing. Most rubs are thought to be signposts made by bucks to advertise their presence. Rubs provide visual cues and scents that inform other deer about the rub maker. Although no one knows for sure, these rubs probably relay information about social status. The number of rubs a deer makes seems to vary among individuals, but studies of penned deer have shown that adults rub more often than yearlings.

The pattern and frequency of buck sign in an area often reflect the age structure and sex ratios of the resident deer herd. Areas with mature adult bucks have more buck sign, and these areas show signs of rubbing and scraping activities earlier than areas with predominantly yearling bucks.

Scrapes also are signposts made by bucks. They probably are used to attract or keep track of breeding females and to advertise the presence of the maker. When making a scrape, a deer paws the ground and urinates on the disturbed soil. Most scrapes are made near deer travel routes under low tree branches that typically are nibbled on and marked with a scent gland from the deer's forehead. Adult bucks make about twice as many scrapes as yearlings. Although not common, buck fawns and does have been observed freshening scrapes.

Testosterone levels increase as the rut progresses, and bucks become driven to find estrous does-those that are ready to breed. The period just prior to peak breeding probably offers bow hunters the best hunting of the season because bucks constantly move and search for does in heat. Rutting bucks spend more time searching for and tending to does than eating during breeding season and sometimes lose considerable weight. Bucks typically visit the various doe family units in their home range checking for estrous does.

Prior to breeding, does also increase activity levels, thus increasing the likelihood of finding a buck and being bred. Does allow a buck to breed only during the 24-hour-period when they are in peak estrous. Does that are not bred cycle again about 28 days later and may be bred in subsequent cycles. In Missouri, most adult does are bred the second and third weeks of November. Doe fawns are bred about a month later because they cycle later than adults. Some hunters and biologists have voiced concerns that not all does are bred in populations with heavily exploited bucks. This may not be the case for yearling and adult does in Missouri. During a Conservation Department reproductive study, more than 90 percent of examined does were pregnant.

During the whitetail's courtship, bucks trail and chase does to test their receptivity to breeding. Does aid this process by urinating frequently, which allows trailing bucks to determine their stage of estrous by smelling and tasting the urine. When a buck finds a receptive doe, he remains close by, and the two mate several times. Using radio telemetry during deer studies in north Missouri, researchers determined that mating pairs spent more than 12 hours together in some cases.

The breeding behavior of yearling bucks seems to be more haphazard and frantic. Yearlings probably don't do much of the breeding if there are an appreciable number of adult bucks in the area. Never the-less, yearlings are capable of breeding and may do most of the breeding in heavily exploited populations.

As breeding activities wind down, testosterone production decreases in males, and they, in turn, begin to shed their antlers. Some studies suggest that antler shedding also is tied to nutrition because deer living on better ranges tend to carry antlers longer than those on poorer ranges. Young deer typically shed antlers earlier than adults. The older deer, who are actively breeding, shed their antlers after there are no longer does coming into estrous.

During the rut, bucks are struck by vehicles more frequently than at other times of the year and are more vulnerable to hunting. In areas with large predators, such as wolves or mountain lions, rutting bucks are preyed on because they are less wary and perhaps weakened by intensive breeding activities. The rut leaves most bucks in poor physical condition. Besides weight losses of up to 20 percent, bucks also may suffer from battle scars and exhaustion. They often enter winter in poorer condition than the rest of the herd.

Winter can be a very difficult time of year for deer, especially in the north. Cold weather and reduced food availability force deer to change their habits in order to conserve energy and survive. Although Missouri winters are not severe, our whitetails display some of the same behaviors as their northern counterparts. These northern deer spend the winter in a sheltered area, sometimes referred to as a deer yard, then return to their summer range the following spring. A number of radio-tagged deer in Missouri made movements of up to 10 miles each winter then moved back to their summer ranges each spring.

Extended family members often reunite during winter. Most family units winter in the same areas each year, but deer concentrate in new areas if food is abundant. Typically, bucks and does are still segregated. Does and their offspring from several generations often form large groups while males reunite with members of their bachelor group or travel alone.

Deer reduce activity during the winter months. Studies have documented activity changes of up to 50 percent. One study found deer were active 68 percent of the time in October but only 37 percent of the time in February. Their metabolic rate slows down as their activity rate declines, and they require less energy to live. In Missouri, researchers noticed this reduced metabolic rate while tranquilizing deer to draw blood or affix ear tags. Deer trapped during the winter months required less tranquilizer than those captured during fall and spring months because the higher metabolism burned up the drug faster.

During the winter months, deer readily eat foods that are rich in carbohydrates, such as acorns and waste grain. Deer also browse on young trees and shrubs-staple foods for deer in areas lacking agricultural crops and a supplement for all deer during the winter months.

The degree to which deer browse certain shrub and tree species sometimes is used as an indicator of deer population levels and winter severity. Some species of sumac and dogwood, for example, are readily consumed by deer. Red cedar and hickory are considered starvation foods and are only eaten when populations are high.

Browse surveys that reveal high use of starvation foods generally are interpreted to mean deer populations are surpassing the carrying capacity of the habitat. Deer weight, growth and nutrition are linked closely to available foods. Population reduction and, in some cases, habitat management are prescribed to alleviate overpopulation problems.

Diet

Because whitetails are ruminants, they are able to use a wide variety of foods. Their four-part compound stomach enables them to break down woody browse and herbage, but they cannot digest low quality forage, such as grass and woody browse, as efficiently as cattle and goats.

Deer are selective feeders and seek out preferred plant species. They seem to possess an ability to select those plants that offer the most nutrition during that particular time of year, such as when the plants are flowering, producing fruit or undergoing rapid growth.

Deer have been documented eating more than 600 different types of plants. Deer in the Ozark region of Missouri live in chiefly wooded areas and rely on natural forage, such as grape vines, green briar, Virginia creeper, oak leaves, pussy toes, clovers and prickly lettuce. During spring and summer, deer eat perennial plants more than annuals.

Studies in agricultural areas of Missouri, Iowa and Ohio indicate cultivated crops comprised 41 percent, 56 percent and 48 percent respectively of deer diet by volume. Most researchers found wild browse, fruits and seeds also are major food items. Deer prefer corn, soybeans and hay from the variety of agricultural crops. Listed below are the agricultural crops used by deer:

• Soybeans: Green leaves are eaten from germination to yellowing. Beans are eaten throughout winter if left unharvested.
• Corn: Silk is eaten in June and July. Dented corn is used from September through winter.
• Milo: Milo is eaten from dough stage (70 days) through spring.
• Wheat: Wheat is used from germination in September until snow covered or several hard freezes and then again in spring.
• Alfalfa and Clover: Alfalfa and clover are used after germination until hard frost.
• Sunflowers: Sunflowers are eaten from germination to maturation.

Oak mast and leaves, corralberry and various forbs are important wild browse food for deer in agricultural areas. These differences in plant use and regional food habit studies are likely a reflection of plant availability. Agricultural crops may be preferred when they are available, but deer still rely on early successional plants and oak mast. Ask your local conservation agent for details on which species to plant or encourage to attract deer to your land.

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