Dispersal of Animals

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Dispersal of Animals

 

the gradual expansion of the region inhabited by certain animal species. The dispersal of animals is usually linked with a change in abiotic and biotic environmental conditions and in the population size of the animals. The state of a population of a given species, for example, an increase in number that causes greater population density, stimulates the dispersal of the animals. Hence, the general warming trend in Eurasia in the 20th century has influenced the northerly shift in the northern boundary of distribution for a number of animal species.

Dispersal can be either active (running, swimming, or flying) or passive (carried by rivers, ocean currents, objects floating in the ocean, or wind). Passive dispersal mainly characterizes such small animals as marine plankton and insects, but sometimes it is significant for larger animals as well. For example, a flock of white herons was transported by a storm from Africa to America, where the birds then settled. Small reptiles, such as snakes and geckos, sometimes are dispersed on floating tree trunks. Some small animals are dispersed by larger ones; thus, birds transport not only parasites but sometimes also mollusks and the eggs of freshwater animals.

REFERENCE

Geptner, V. G. Obshvhaia zoogeografiia. Moscow-Leningrad, 1936.

V. G. GEPTNER

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
In other words, it provides perches for raptor species, thereby increasing the risk of predation, and especially it acts as a barrier to the movement and dispersal of animals (Wisdom et al.
Range expansion of the EFS over the 100-year period occurred through natural dispersal of animals and through human activity.