Perching Birds: Passeriformes

Because of their leg, foot, and toe arrangement, passerines are able to sleep while perched when special features in the foot automatically grip a perch. Being songbirds, passerines are very vocal birds with highly developed vocal chords. In fact, the birds are some of the most complex and rich singers in the bird world. They sometimes copy the songs and calls of other birds, especially the songs of competing males within their own species. Some species even copy the sounds of insects, frogs, and (even) mechanical sounds heard in their environment. Many passerines migrate from their nesting grounds to warmer regions, or from southern temperate regions north to the tropics. Predators (animals that hunt other animals for food) of passerines include raccoons, feral (wild) cats, and snakes.

There are many different ways that passerines build nests and many different materials that are used to construct nests. Generally, nests are made out of sticks or grass on the ground, in trees, and even sometimes in the banks of fast-flowing rivers. Nests are often camouflaged (KAM-uh-flajd; designed to hide by matching the colors and textures of the surrounding environment) in order to conceal them from predators. Although nests range from being built very simply to very elaborately, they can be classified as being constructed in three different ways: built out of a hole, built so the opening is from above, and built with a dome or roof.

Parental care by both sexes is common in passerines, although females sometimes are left with all of the duties. Cooperative breeding, in which young birds delay breeding and assist other individuals (often their parents) in raising young and defending the territory, is common in several passerine groups. Female passerines lay small eggs that are usually colored or marked in some manner. Clutch size (group of eggs hatched together) varies greatly from one to sixteen eggs. Passerines are born blind, naked, and completely helpless. The incubation period (the time that it takes to sit on eggs before they hatch) is around fourteen days but can last up to twenty-eight days in large species and fifty days in lyrebirds. Some females are able to replace eggs that have been lost or destroyed. The fledgling period (the time necessary for young birds to grow feathers necessary to fly) is eight to forty-five days.