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It is ironic that the genus of New World quails that not only has the greatest collective geographic range (from central Mexico to northeastern Argentina) but also the largest number of species (12 or more, varying with the authority), is one of the least known groups of American gallinaceous birds. This is in large measure the result of the fact that all of the species are forest-adapted, and generally are associated with tropical to sub-tropical communities, where opportunities for easy observation are virtually absent.
Not only is this the largest genus of the subfamily Odontophorinae, but also the species tend to consist of fairly large birds. The Spotted Wood Quail averages about 11-12 ounces in adults, and nearly all of the species are very similar to this in their measurements. Indeed, one of the interesting features of the genus is the fact that the species are all remarkably similar in size and proportion. and almost certainly feed on much the same foods. It is therefore not surprising that the species are geographically well dispersed, and probably no more than two of them are to be found in any single region. In areas where more than one species is present, there seem to be altitudinal differences that reduce inter-species contacts. Thus, from Nicaragua south to Costa Rica the Spotted Wood Quail (O. guttatus) may be in contact with the Rufous-fronted Wood Quail (O. erythrops), but there the former species occurs in cloud forest, while the latter occupies the tropical zone, where guttatus is to be found in Mexico, (Fig. 1). Likewise, in Panama, two species (O. leucolaemus and gujanensis) coexist and respectively occupy intermediate elevations and lowland tropical forests. The region supporting the largest number of species is probably Colombia, which supports five species. This area would appear to be in the centre of ancestral distribution of the genus, which in turn occupies a central position in the subfamily Odontophorinae.