animals that are adapted to life in forests. The greatest number of species inhabit the tropical rain forests, where conditions are optimal for several groups of animals; however, the population of each species is small.
In several major taxa of animals (mammals and birds, up to and including the orders), species associated with the forest predominate. Most of them are well adapted to climbing and are arboreal, spending most of their time in the tree crowns. Among the arboreal mammals are sloths, monkeys, a number of rodents (common squirrels, flying squirrels, scaly-tailed squirrels, and porcupines), insectivores, and predators. Birds that are primarily arboreal include parrots, woodpeckers, toucans, and hoatzins. Among the amphibians that inhabit the forest are frogs of several families. The forest insect fauna is extremely diverse. A narrow food specialization is characteristic of some of them, as well as of some of the birds.
There are few terrestrial species in wet tropical forests because of the sparse undergrowth and grass cover. Most of the principal areas where wet tropical forests developed (northern South America, West Africa, and Southeast Asia) still look like Tertiary forests, and in some places ancient relict forms, such as the okapi, chevrotain, pygmy hippopotamus, giant panda, and African peacock, have survived.
There are fewer species in the deciduous forests of the temperate zones, but some of them have a large population (sometimes found en masse). The taiga fauna is even poorer in number of species and in species population than the temperate deciduous forest fauna. The number of specialized, arboreal species decreases as one goes from the region of the wet tropical forests to the taiga. Thus, although there are several dozen species of tree frogs and toads, only one species of each is found in the deciduous forests of Europe and the Far East. Of the many dozen species of common and flying squirrels characteristic of the tropical forests of South Asia, only one species of each inhabits the Siberian taiga. However, owing to the abundance of light and the presence of undergrowth and grass, there are more terrestrial animals in the taiga and deciduous forests than in the wet tropical forests. Typical taiga animals include the elk, musk deer, Eurasian brown bear, wolverine, sable, Siberian weasel, and blue, or mountain, hare.
The rapid destruction of forests and their changing character are substantially altering both the distribution and composition of the forest fauna. Some species—primarily those that inhabit the treetops (sloths, monkeys, and toucans, for example)—are becoming extinct. On the other hand, the cutting of forests and the replacement of coniferous by deciduous forests favor the development of terrestrial species. For example, the increase in the number of elk in the USSR in recent years is primarily due to the replacement of large areas of coniferous stands with aspen forests and luxuriant coniferous undergrowth. Many forest animals, especially birds that help to clean the forest (woodpeckers, for example), should be protected.
V. G. GEPTNER