Deer are herbivore mammals found in many ecosystems. An adaptable nature enables them to live almost anywhere, from arid shrublands and mountains to grasslands, wetlands, and deciduous or rain forests. There are over 40 deer species out there, and you may wonder whether those living in temperate and cold climate areas hibernate or migrate.
Do Deer Hibernate?
Deer do not hibernate. Deer species living in temperate and cold climate areas are adapted to surviving harsh winters. Some types of deer migrate from summer to winter habitats, while others live in the same territory all year long. Whether or not they migrate, all deer grow thicker winter coats and change their behavior to survive cold weather.
Like all animals that have to survive cold temperatures, deer have two primary concerns during winter: warmth and sustenance.
Unlike carnivores that can still find a variety of prey during winter, deer can only rely on whatever vegetation is available. In most cases, the ungulates will search for food above the snow, eating berries, twigs, and, occasionally, fir needles. Digging for food in the snow is also common; however, digging requires more energy, and most deer will avoid it if possible.
In areas with little snowfall or in warmer periods when the snow and ice thaw, deer also eat grasses and mushrooms, if available.
When possible, they also supplement their diets with higher-calorie foods, including seeds and nuts.
On the coldest days, deer also minimize their activity to preserve as much energy as possible. They usually find a warmer place where they can rest and can spend days sleeping.
However, deer do not go into torpor or hibernation. They remain active and keep their guard up at all times, majorly because they are the preferred winter prey of many carnivores, including wolves, coyotes, and even bears.
Deer Mating Season
For most deer species, winter is also the breeding season. However, the actual mating season peak can vary depending on habitat.
Deer living in temperate climates, for instance, generally breed between October and December. In warmer climates, the mating season peaks in January or February. At the opposite end are the deer living in cold and arctic climates, which usually breed in late August or early September.
Very few deer species mate in summer or fall. Roe deer is one of these species. These deer live in Scotland, other areas of the UK, and Europe. Their mating season occurs from mid-July to mid-August. However, the fertilized egg will only begin to develop at the end of December or in early January.
Fallow deer, also found in Europe but also in North America and parts of Asia, breed from September to November. However, this species has a longer gestation period compared to other deer (about 7.5 months vs. 6.5 months in most other species).
Fawns are born in late spring or early summer, when there is an abundance of food and the rich vegetation can hide them from predators. The young will stay with their mothers for about one year.
Most deer are polygamous, and males play no role in raising fawns. Roe deer are monogamous, and while the bucks are not involved in raising the young, the family generally stays together during winter.
Do Deer Migrate?
Not all deer species migrate, but some do. Those that do generally migrate so that they can avoid deep snow and other harsh conditions during winter. Deer may also migrate to areas where winter foraging is easier.
From all deer species, the vast majority are non-migratory or migrate over short or medium distances to summer or winter ranges, respectively.
In some species, migration may or may not occur, depending on where they live. The white-tailed deer, for instance, generally migrates over short distances, but white-tailed deer living in warmer climate areas display a non-migratory behavior.
Roe deer is a species of non-migratory deer. However, roe deer living in alpine areas may migrate to lower altitudes in winter. This is only a partial migration, not a complete change of habitat.
Mule deer is one of the few deer species that migrate over long distances, traveling up to 500 miles from the summer to the winter range.
The table below highlights the habitat and migration behavior of the most common deer species:
|Deer species||Habitat||Migration pattern|
|White-tailed deer||North America||Seasonal short to mid-distance migration|
|Black-tailed deer||North America||Non-migratory|
|Mule deer||North America||Seasonal mid- to long-distance migration|
|Elk||North America||Seasonal short to mid-distance migration|
|Moose||Arctic & Subarctic regions||Seasonal short to mid-distance migration|
|Sika deer||East Asia, Japan, America||Seasonal short-distance migration|
|Red deer||Great Britain||Seasonal short to mid-distance migration|
|Roe deer||Great Britain, Europe||Partial migration in alpine areas|
|Reindeer||Arctic & Subarctic regions||Seasonal long-distance migration|
|Indian muntjac deer||Asia||Non-migratory|
|Sambar deer||Asia||Partial migration in alpine areas|
|Taruca deer||South America||Seasonal short-distance migration|
|Marsh deer||South America||Non-migratory|
|Pudù deer||South America||Partial migration in alpine areas|
How Do Deer Survive Cold Winters?
Deer do not hibernate. Some deer species migrate, but in cold climate regions, the winter ranges are still cold. So, how do deer stay warm? No matter what species they are, deer survive winter through:
Undeniably, adaptation plays the most important role in a deer’s chances of survival during winter.
Like most mammals in temperate and cold climate areas, deer prepare for winter by shedding their summer coats and growing thicker coats for winter. The winter coats have a dual layer with dense underfur and hollow hair shafts for the top layer.
The top layer is impermeable, preventing moisture from soaking into the underfur. At the same time, the fluffy underfur traps residual air, creating a warm air chamber around the deer’s skin.
In addition to a thicker coat, deer also have special skin muscles that allow them to adjust the top layer hair shaft angle. It is a mechanism working more or less as the human skin muscles that raise the hair on our bodies when we are cold, resulting in goosebumps.
By adjusting the hair shaft angle, deer can adjust the level of insulation and minimize thermal loss.
Another way deer stay warm in winter is by building up sufficient fat during late summer and fall.
In fact, most deer change their diets in late summer, from grass and green twigs to berries, fruit, mushrooms, and other, more caloric foods, including nuts and seeds. They will continue eating the same foods throughout the winter if they are available. Alternatively, a deer’s winter diet will mostly consist of twigs, pine or fir needles, and berries.
Whether or not they’re getting enough food, deer also survive winter by reducing their metabolic rate.
Another strategy deer use to minimize heat loss and survive winter is by limiting their movement, especially when the snow is too deep or the temperature is too cold.
When the temperatures get really cold, deer can sit and sleep for days at a time. This behavior is specific to hibernating animals, with the difference that deer do not fall into a deep slumber and remain alert the whole time.
Finding adequate shelter during winter is crucial, not only to survive harsh temperatures but also to stay out of the sight of predators.
Generally, deer search for places where they are protected from cold winds and are sheltered from above to block falling snow and rain. This could be under a pine tree or other type of coniferous. Deer rarely sleep in caves to avoid being trapped inside by predators.
Lastly, some deer survive winter by changing their social behavior. Most deer species are considered solitary during summer. Some deer may be observed grazing together in herds; however, the common social structure is a doe with her fawns.
This behavior changes in winter when deer gather together in herds. Small herds consist of three to five animals, generally of the same gender. Larger herds can count a dozen or more deer of both genders. Throughout the winter, deer herds move together to foraging sites and sleep in the same area.
Sticking together provides protection from predators, especially wolves and coyotes who attack in packs, but also mountain lions and, occasionally, bears.
Deer are the most widespread ungulates. They live all over the world, in climates varying from subtropical to arctic. No matter where they live, deer do not hibernate. However, some species migrate from summer to winter ranges to avoid deep snow and to have easier access to food. In addition to remaining active all year round, winter is also important for deer because it’s their breeding season.
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