Birds of brushy areas and the desert

Birds of brushy areas

Some birds make their home in and around brushy areas, which are covered by bushes and low scrubby trees. Such areas commonly occur on the edges of forests and woodlands, between woodlands and grasslands, and in abandoned fields that are developing into woodlands. Brushy areas exist throughout the United States and southern Canada. Many of the birds that live in these habitats are also wide ranging. They include the eastern towhee, gray catbird, loggerhead shrike, rufous-sided towhee, and yellow-breasted chat. Other birds of brushy habitats have a more limited range. The bobwhite and Carolina wren are permanent residents in the southeastern United States and in Mexico. The painted bunting nests chiefly in the southeastern half of the United States but migrates to Mexico in winter.





Birds of the desert

Many birds that live in the deserts of the southwestern United States nest in saguaros and other large cactuses. The cactus wren builds its nest among cactus spines. Gila woodpeckers and gilded flickers nest in holes that they make in cactus stems. Elf owls, the smallest owls in the world, nest in holes that the woodpeckers abandon. A large percentage of desert birds chiefly eat animal flesh or insects. The deserts are dry, and such a diet provides more moisture than a diet of seeds. Meat-eating birds, including the golden eagle, roadrunner, and various species of owls, rank among the most common desert birds. Most of the cactus dwellers mainly eat insects. Gambel's quail and several species of sparrows are among the few ground-nesting, seed- eating birds of the North American deserts.

The Distribution of Birds

Every species of bird has its own range-that is, a particular part of the world in which all the members of the species normally live. Some birds have a broad range. The osprey and common barn owl, for example, live on every continent except Antarctica. However, no species of bird is found in every part of the world, and many species have an extremely limited range. For example, a species called the Whitehead's broadbill lives only in a small, mountainous area of northern Borneo.

Oceans and continents strongly influence the distribution of various species of birds. Most birds cannot make long ocean flights. Widely separated continents, such as Africa and North America, therefore have different kinds of birds. However, people have transported many species overseas, and some of these birds have become adapted to their new environment.

Climate also influences a bird's range. Most birds would starve during a long cold spell. For this reason, few birds live all year in regions with severe winters. However, many birds nest in such regions in summer and migrate to warmer climates for the winter. Birds that migrate have two ranges-a summer one and a winter one. They are summer residents in their summer range and winter residents in their winter one. Along their migration route, they are transients (temporary visitors). Birds that do not migrate are permanent residents.

More kinds of birds live in the tropics than anywhere else in the world. Tropical rain forests have more kinds of birds than any other habitat. Most birds of the tropics are permanent residents. However, some parts of the tropics have an annual dry season, and many of the birds migrate to moister parts of the tropics to avoid it. The tropics also have many winter residents that migrate from cool or cold climates. The temperate zones-that is, the parts of the world between the tropics and the polar regions-have fewer permanent residents than do the tropics. In the parts of the temperate zones nearest the polar regions, most of the birds are summer residents only. Few birds live all year in the polar regions. However, both the Arctic and the Antarctic have many residents during the summer.

The ranges of birds are further determined by the kinds of food and nesting places that are available. For example, fish-eating birds must live near bodies of water. Birds that nest in trees normally live only in wooded areas. Thus, most birds live not only in a particular region of the world but also in a particular type of environment, or habitat, within that region.