Deer Biology

General Biology

Reproduction

White-tailed deer breed from October to January, depending on latitude. Peak activity for breeding is in November. Does are in heat for 24 hours every 28 days for 2 or 3 consecutive cycles. One buck may inseminate several does, and no pair bonding takes place. Most does breed during their second fall, although in good habitat, up to 30% of doe fawns (6 months old) will breed. Gestation is about 202 days. Fawns usually are born in May or June. Most reproducing fawns give birth to a single fawn, but adult does typically bear twins. Reproductive potential is sensitive to nutrition. Fawns weigh 7 to 8 pounds at birth and increase in weight for 5 to 6 years. 

Loafing Cover

Bedding areas vary, depending on time of year and location. Beds may be found in woodland, grassland, and agricultural fields.  

Behavior

In northern areas, deer gather or “yard up” in dense cover for the winter. They may move up to 100 miles from a summer range to a winter yard. They have a home range of several hundred acres that varies with season, sex, and habitat quality. Life expectancy depends on pressure from hunting and winter snowfall. Records show deer can live for up to 20 years, although 10 years is above average in the wild.  

Habitat

Ideal habitat for deer is forest edge rather than dense, old-growth forest. They thrive in agricultural areas interspersed with woodlots and riparian habitat. Deer favor early successional habitats where brush and saplings are within reach (typically 6 feet tall or less). Many populations of deer flourish in urban areas. 

Food Habits

Deer browse on leaves, stems, and buds of woody plants all year long. Preferred species of plants vary considerably in quality and regional availability. Forbs are eaten in spring and summer, when available. Fruits and nuts, especially acorns, are seasonally important, and grasses are relatively unimportant in the diet. Agricultural crops such as corn, soybeans, grains, alfalfa, vegetables, and fruit trees are eaten readily. Local food habit studies are available in most states. Consult your state’s wildlife agency for more information.  

Nutrient requirements and the amount of food consumed vary with age of the deer, season, and reproductive cycle. Daily consumption of dry matter averages 2% to 4% of live body weight. For adult bucks, daily consumption is greatest in spring and averages 4.4 to 6.4 pounds of food per day. Consumption drops by half during winter.