Distribution

Tapaculos are distributed from Costa Rica through South America to Tierra del Fuego. The large majority of species are montane or live in temperate regions. Only one tapaculo, Liosceles, inhabits the Amazonian lowlands. Six species of Scytalopus and Merulaxis, and the peculiar Psilorhamphus, are confined to southeastern Brazil, some of them also occurring in adjacent parts of Argentina and Paraguay. Two of the four species of Melanopareia are found in the arid lowlands of northwestern Peru and southwestern Ecuador, the other two in the arid parts of Brazil, Paraguay, Bolivia and northern Argentina. Teledromas occurs in desert scrub in western Argentina; Rhinocrypta in the chaco and drier part of the pampas.

In the Andes the most widespread genus, Scytalopus, reaches its greatest diversity. Up to five species may occur on a single slope, some showing strikingly sharp altitudinal replacements. In Central America and north-east of the "Tachira Gap" in the Andes near the border of Colombia and Venezuela, the diversity is smaller. In the coastal mountains of Venezuela only a single Scytalopus species is found, none on the Tepuis or in the Guianas. Only two genera, Myornis and Acropternis are endemic to the northern Andes. Three genera, Pteroptochos, Scelorchilus, and Eugralla are endemic to the southern Andes.

Melanopareia and Teledromas the humerus is distinctly curved. Melanopareia (and possibly Teledromas) also differ by the shape of the stapes, a small bone in the inner ear. Most tapaculos have disproportionally strong feet and large claws. Acropternis has a very long hind claw, the function of which has been disputed.

The feather tract of the flank is fused with that of the back except in Melanopareia and Teledromas. The body is densely feathered, particularly on the rump, and the feathers fall off easily, probably to confuse predators. The feathers of the lores are stiff and erect in many tapaculos, protecting the eyes from dirt and ants. These feathers are most evolved in Merulaxis, where they are greatly elongated and allow the bird to see while boring its head into litter.

Tapaculos are nearly flightless. Their wings are short and rounded with ten primary flight feathers. The tail, usually carried half-cocked, is composed of a variable number of feathers ranging from eight to 14, the number varying even within the same population. The more or less graduated tail is decidedly short in many species, but medium long in some forms. The sexes are fairly similar in most species, with females appearing somewhat smaller and duller. In Merulaxis, however, the sexes are distinctly differently colored. Plumage colors are generally dull, grayish or brown, and without marked pattern, but Melanopareia exhibits some

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