Home range

The fourth requirement for wildlife habitat is having adequate “space,” also known as the home range of an animal. The home range is defined as the space necessary to move about, locate food, water, or cover, avoid predators, find a mate, rest, or feel comfortable.

As you would expect, larger animals need more space than smaller animals and carnivores (meat eaters) need more space to find prey than herbivores (plant eaters). Some animals like the wolverine lead a solitary existence and don’t do well in crowded conditions while others like the barren ground caribou may be found in large herds.


Credit: nwf.org

The availability of the other habitat elements may also dictate how large an animal’s home range extends. A large carnivore like a polar bear may have to travel hundreds of miles in search of food in the vast Arctic region while a deer that has its entire habitat requirements close by may not travel very far at all.

Most year-round resident animals spend most of their life within about one half-mile from where they are born; the home range of these animals could be contained on a 160 – 320 acre parcel of land as long as this land contains adequate food, shelter, and water.

Preferred habitats vary from one species to the next. A generalist like a deer may be found in fields, the forest, a wetland area or most places in between, while a forest interior dweller like a wood thrush needs a deep unbroken forest to feel comfortable. The plant composition and canopy layers in a forest play an important role in the amount and kinds of animals that would be found there.

A forest with a number of understory layers normally contains more animals than a forest that contains the main canopy and not much else. Most woodland dwelling wildlife have preferred canopy layers, so a forest that has low ground cover, medium-sized trees and shrubs and a main canopy supplies numerous habitats for animals to exploit.

The kind of vegetation present also plays an important role in the home range of animals because it corresponds with food availability. Certain species, such as cardinals, prefer a number of plant communities, and they tend to be found where these communities overlap. These overlapping areas are sometimes referred to as edge. Other animals like deep woods and avoid edge. Parasitic edge species such as the cowbird deposit their eggs in the nest of smaller birds such as the red eyed vireo. The young cowbirds will outcompete the young of vireo; the adult vireo ends up raising clutch of cowbirds. On the other hand a vireo nest in a deep woods area would be less likely to be invaded by cowbirds. Some animals with large home ranges include wolverine, which needs 40 to 400 square miles, snow leopard, which needs 40 to 2,000 square miles and the granddaddy of them all, the polar bear, which needs 4,000 to 50,000 square miles, depending on the availability of food and ice melt.

Article by FCFCDB

Nature Note for 2/16/2014