White-tailed Deer Biology

 

White-tailed deer (Odocoileus virginianus) hold strong social, ecological and economic importance in Ontario. White-tailed deer are an integral part of Ontario's biodiversity and generate millions of dollars in economic activity through hunting, viewing and tourism each year. White-tailed deer have great social and cultural importance to many communities and are the smallest of Ontario’s four cervid species (deer, caribou, elk, moose).

 

White-tailed Deer: Some Interesting Facts

 

Buck in Snow
  • White-tailed deer are the most common and widely distributed large mammal in North America. They range from the southern tip of the continent northward into Canada's boreal forest.
  • Ontario's white-tailed deer population is estimated to be approximately 400,000 deer.
  • White-tailed deer are herbivores, which means they feed on plants and plant material.
  • White-tailed deer antlers grow each year beginning in the spring and then fall off in the early or mid-winter. Typically, only male white-tailed deer grow antlers.
  • The name white-tailed refers to the white underside of which it commonly displays when running.
  • Most white-tailed deer will not live beyond six years in the wild. Although rare, some deer live 10 years or longer.

 

 

Range and Habitat
 

Distribution of White-Tailed Deer in Ontario
Distribution of white-tailed deer in Ontario.

White-tailed deer are well adapted to a wide range of environmental conditions and can tolerate the presence of people very well. White-tailed deer can currently be found in Ontario from the boreal forest to the most southern extent of the province. The northern limit of white-tailed deer range can naturally fluctuate over time according to winter severity (i.e., snow depth, temperature and length of winter season) and food availability.
 

Healthy white-tailed deer populations require habitat that provides a good mix of food, water and cover. White-tailed deer thrive in young forests where food is abundant, and often benefit from recent disturbances in the forest, such as wildfire or forestry operations. These types of disturbances open up the forest and allow light to penetrate to the forest floor. Light promotes the growth of young trees and shrubs that are primary foods for white-tailed deer.
 

In Ontario, white-tailed deer prefer young conifer (e.g., cedar, hemlock) habitat during the winter, particularly when snow deepens and temperatures drop. These young conifer tree stands are important to deer because they provide cover from falling snow and help to moderate extreme temperatures.

 

 

Good Habitat for Deer Illustration Showing Conifer Swamp
  Diagram courtesy of Michigan Department of Conservation

Habits  

Deer food
Some common foods of white-tailed deer, top to bottom: white cedar, acorns, mountain ash, chokecherry.

White-tailed deer habits and diet are heavily influenced by the time of year. These seasonal habits are associated with finding the best food and cover available, as well as mating and birth in the fall and spring, respectively.

The general area where a deer lives is called its "home range". The size of a deer's home range will vary depending on a number of factors, including age, sex, population density, time of the year, habitat, social interactions, weather, etc.
 

White-tailed deer can be active at any time, but they tend to be most active at dawn and dusk.
 

Spring
In the spring, female deer (called "does"), that were bred the previous fall give birth. The gestation period for a doe is about six and a half months and fawns are usually born in May or June. Fawns will normally stay with their mother for their first year.
 

During the spring, deer will eagerly seek high energy foods including grasses, clovers and other new growing plants following the winter months.

 

Summer
In the summer, white-tailed deer will spend more time feeding in order to gain weight for the coming fall and winter months. Deer will eat up to 4 kg of green plant material each day. Although there is an abundance of green food during the summer, deer become extremely selective, choosing high protein, high energy, and highly digestible foods (e.g., newly growing shoots, tips and buds of plants, flowers).
 

During the summer months, the white-tailed deer's coat is a light reddish-brown and is made up of short, rather stiff and wiry hair.

 

 

Fall

Illustration of Scent Glands in White-tailed Deer

 

SCENT GLANDS IN WHITE-TAILED DEER

White-tailed deer have a number of external scent glands that are used primarily for communication with other deer. Gland secretions can describe a deer’s social status, breeding condition, health and warn other deer of potential danger.

In the fall, adult white-tailed deer breed. This period is called "the rut". During the rut, male deer (called "bucks") spend the majority of their time pursuing does. Bucks will create "scrapes" on the ground and "rubs" on trees or shrubs to attract female deer and warn other bucks to stay away. Bucks also become more aggressive and use their antlers to fight with other bucks for potential mates and territories.

 

White-tailed deer will continue to seek out high energy and high carbohydrate food sources during the fall to help build fat reserves for the coming winter. Available grasses, clovers, buds, and acorns/nuts are common food items during the fall in Ontario.

 

Deer begin to develop a thicker, greyish-brown coat in the early fall. This coat is made up of longer, thicker and hollow hair, which provides insulation for the coming winter. This coat has an under layer of soft, downy hair.

 

Winter
During the winter months, deer tend to live on a diet of low quality food. The major natural food at this time of year is browse which is comprised of the woody plants and twigs, and the leaves of conifers such as cedar and hemlock.
 

As snow deepens, white-tailed deer will move into winter deer yards. These areas concentrate deer during the winter because they provide food and shelter from weather and predators. Deer will sometimes travel significant distances to these wintering yards. Once there, white-tailed deer become less active in order to conserve their energy during the winter.
 

White-tailed deer may have difficulty surviving the winter, particularly if snow becomes too deep or if there is too much competition for limited food sources. Deer must find a delicate balance between consuming enough food and not expending too much energy during snowy winter months. If food is scarce and fat stores become used up, then the chances of survival to the spring are reduced.
 

For most of the year bucks and does generally stay in separate groups, but during the winter larger groups of deer gather together in winter deer yards. This helps to conserve energy by keeping winter trails cleared for easy movement and offers protection from predators.

 

Life Cycle
 

White-tail doe and fawn at water's edge
White-tailed deer doe and fawn.

White-tailed deer populations have the potential for relatively quick growth when good food and habitat conditions exist. In Ontario, a female white-tailed deer will typically give birth to one or two fawns each year. A comparison of the reproductive potential for moose, deer and black bear can be viewed here.
 

Fawns
At birth, fawns usually weigh between 2 and 4 kilograms (4-9 lbs.). Their coat is spotted for the first 3 – 4 months, which provides a natural camouflage and helps them blend in with the forest. This spotted coat is lost when their first winter coat comes in. Fawns are weaned at about 4 to 6 weeks, sometimes later. They will grow quickly over the summer months, reaching 25-40 kilograms (55-85 lbs.) by fall. The birth of twin fawns is quite common in areas where high quality habitat is available.
 

Yearlings (Juveniles)
These are deer in their second year of life, but they look almost full grown. Bucks often have spikes or small forks for antlers when they are 1½ years old.  
 

Adults
Male white-tailed deer are generally larger than females and usually range from 45 to 136 kilograms (100-300 lbs.), while female deer usually range from 39 to 60 kilograms (85-130 lbs.). White-tailed deer usually stand about 0.9 to 1.1 metres (3-3.5 feet) high at the shoulders. Bucks have antlers, which are dropped in the winter and are re-grown again during the following spring and summer. Does do not generally grow antlers. Antler size is an important factor in determining the dominance of bucks during breeding time each fall.

 

 

 

 

• In Ontario, forests on Crown land are managed on an ecosystem basis to provide sufficient natural habitat for all wildlife species – including deer.

 

• White-tailed deer are excellent runners and jumpers – they can reach speeds of up to 50 km/h and can jump over two metres high.

 

• Female white-tailed deer will often leave their fawn(s) unattended for hours at a time. Fawns have very little scent and their spotted coat provide natural camouflage, which keeps them relatively safe from predators. The doe returns periodically to feed the fawn.