Altitudinal distribution of birds in a mountainous region in southeastern Brazil

We studied the altitudinal distribution of 426 bird species in the Serra dos Orgaos, a mountainous region in southeastern Brazil. Thirty-four localities were visited between 1991 and 2009. Our study revealed a decline in bird species richness with elevation, although a smaller number of species was recorded at lower altitudes (below 300 m) possibly due to local extinctionscaused by the intense human occupation of the region. A less diverse avifauna was found above 2,000 m, with only one species ( Caprimulgus longirostris) recorded exclusively in this altitudinal range. Most endemicspecies were found between 300 and 1,200 m, but the endemismwas more significant at higher altitudes. Nearly half of the birds found above 1,400 m were endemicspecies. Most of the threatened speciesfrom the state of Rio de Janeiro recorded in our study were found below 1,200 m, but no significant difference was found between the proportions of threatened speciesamong different altitudinal ranges. Species of seventeen genera have exhibited some replacement (sometimes with partial overlap) along altitudinal gradients.