Natal dispersal is what happens when young animals leave home to make a life for themselves. Birds leave the nest. Mammals leave their home territories.
Scientists think there are a number of reasons why young animals leave home. By doing so, they avoid competing with their relatives for resources. They avoid competing with each other for mates. They also avoid inbreeding which can lead to less healthy offspring.
Not all animals disperse in this way, however.
Of those animals that do disperse, though, bears are a good example.
Sceintists kept track of bear dispersal in several parts of the world. Most bears left their mother's territory before they reached sexual maturity at age five. In Scandinavia, 94 percent of brown bear males and 41 percent of femals left their natal territory.
In Canada, grizzly bear males and females left their mother's territory, but males left in greater numbers and traveled farther than females. In Virginia, black bear mothers encouraged their young to move away at one year of age, and males even swam across rivers to find a new home.
Sources and Further Reading
- Croteau, E. K. (2010). Causes and Consequences of Dispersal in Plants and Animals. Nature.com.
- Zedrosser, A., et al. (2007). Should I stay or should I go? Natal dispersal in the brown bear. Animal Behaviour. 74 (3), 369-376.
