Tinamous

Tinamous are about 45-50 species of ground-dwelling birds that comprise the family Tinamidae, the only member of the order Tinamiformes. Tinamous have a plump, partridge-like body, but they are not related to the "true" partridges, which are species in the pheasant family (Phasianidae). The evolutionary relationships of tinamous are not well understood, but their closest living relatives may be the rheas, which are large, flightless birds of South America that make up the order Rheiformes.

Tinamous occur from Mexico in Central America, to Patagonia in South America. Species of tinamous breed in a wide range of habitats, from lush tropical rain-forest, to savannah, grassland, and alpine tundra. Tinamous are resident in their habitats—they do not migrate.

Tinamous range in body length from 8–20 in (20–53 cm). These birds have a stout body, short, rounded wings, and a short tail. The legs of tinamous are short but robust, and the strong feet have three or four toes. The sternum, or breastbone, is strongly keeled for the attachment of the large flight muscles. The small head is placed at the end of a rather long neck, and the beak is downward-curved, hooked at the end, and generally fowl-like in appearance.

Tinamous are brown colored, with streaky, barred, or mottled patterns. This coloration is highly cryptic, and helps tinamous to blend in well with their surroundings, thereby avoiding predators to some degree. The sexes are colored alike, but females of some species are slightly larger than males.

Tinamous are running, terrestrial birds. They have sonorous, whistling calls, which may function to proclaim their territory. Tinamous can fly rapidly, but they tire quickly and can only fly over a short distance. Tinamous often prostrate themselves in thick vegetation to hide from predators. Tinamous eat roots, seeds, fruits, buds, and other plant materials, and insects when available.

The eggs of tinamous are brightly colored in glossy, solid hues, and are considered to be among the most beautiful of all birds' eggs. Depending on the species, the egg color can be brown, purple, black, gray, olive, or green. The clutch size is highly variable among species, ranging from 1-12, although the larger numbers may represent the output of several females.

Tinamous nest on the ground. Only the male incubates the eggs, and only he cares for the brood of young birds. This is, of course, a reversal of the usual role of the sexes in most groups of birds, in which females play a more prominent role. Newly hatched tinamous are highly precocious, and can leave the nest and run well within a few days of hatching. Soon after birth, the chicks follow their male parent about, feeding themselves.

Tinamous are obviously different from all other living birds, and this is the reason why they are assigned to their own order, the Tinamiformes. Although some avian systematists believe the Tinamiformes is most closely related to the order Rheiformes, there are important differences between these groups, especially the presence of a keeled sternum in tinamous. Rheas and other ratites, such as ostriches, emus, and cassowaries, are characterized by a nonkeeled sternum and are incapable of flight.

While they may be different from all other birds, the various species of tinamous are all rather similar to each other in their color, size, and shape. The entire group is believed to be composed of rather closely related taxa, and consequently, the taxonomy of tinamous is not well established. Although 45-50 species are named, further study may result in some of these taxa being joined together as subspecies of the same bird, while other species may be split into several.

Two of the more common species are the variegated tinamou (Crypturellus variegatus) and the Martineta or crested tinamou (Eudromia elegans). Both of these are birds of open grasslands of South America, known as pampas. The Martineta tinamou is one of the few social tinamous, occurring in flocks with as many as one-hundred individuals.

The rufescent tinamou (Nothocercus julius) occurs in Venezuela, Ecuador, and Columbia. The thicket tinamou (Crypturellus cinnamomeus) breeds in brushy habitats from Mexico to Columbia and Venezuela.

The Chilean tinamou (Nothoprocta perdicaria) is native to tundra-like habitats of southern South America. This species was introduced to Easter Island in the South Pacific in the late nineteenth century, and it still breeds there.

Wherever they are abundant, tinamous are hunted as a source of wild meat, or for sport. Excessive hunting, coupled with habitat loss, has resulted in numerous species being threatened with extinction. The World Conservation Union has listed 14 species of tinamous as being endangered.