Descrição e análise do padrão de nidificação de Leptopogon amaurocephalus Tschudi, 1846 (Aves, Tyrannidae) na Zona da Mata de Minas Gerais

Abstract

Leptopogon amaurocephalus is a small Tyrannidae widely distributed in Central and South America, where it inhabts the lower and middle strata of primary and secondary forests and woods. According to the brief descriptions available, its nest is purse shaped, hanging under natural or artificial cover. Since nest shape has been used as an auxiliary character to solve questions concerning relationships at genus and infra-genus levels in Tyrannidae, as for example the possible monophyletic links amongst Leptopogon, Mionectes, Zimmerius and Phylloscartes, studied L. amaurocephalus nest shape and dimensions to check if they vary according to the different microclimates occuring in Viçosa, MG. Additionally, some data on reproductive biology are also presented. Fifty two active nests were found in three different forest fragments; the supports could be grouped as: a) road banks outside the woods; b) idem, inside the woods; e) natural banks and d) fallen tree trunks, the last two inside the woods. The four supports could be statistically grouped as three different microclimates. It is concluded that L. amaurocephalus nest structure varies only slightly, with thicker nests in the open; that nesting depends on avaliability of shelter against rain, wind and predators; that the species is specialized in nesting, with some plasticity as to microclimates, providing adaptation for environmental problems; that constancy of nest shape and dimensions supports use of nest type as an auxiliary taxonomic character in Tyrannidae; that, in Viçosa, the species is confined to forest fragments, reducing total populations even through the species persists in second growth. Its adaptive fitness, therefore, should not be overestimated.