Influence de la lumière sur le choix de l’habitat et le comportement sexuel des Pipridae (Aves : Passeriformes) en Guyane française

Abstract

The influence of spatial and temporal patterns of illumination on habitat selection and courtship performances of male manakins were studied for 23 months in French Guiana. Seven sympatric species were studied in a pristine lowland rain forest and along forest edges. The relationships between light intensity, structure of the ornamental feathers, location of courtship arenas in « lek » species, and courtship postures, were given particular attention. The courtship arenas of all the species studied were not established at random in the forest. They must meet definite conditions for each species : a certain degree of « openness », the presence of perches of a given diameter and inclination, and a certain level of illumination at set times of the day. The male displays of three lek species Manacus manacus, Pipra erythrocephala and Corapipo gutturalis were shown to coincide in time with definite light intensity levels on their respective arenas. The same is quite likely the case for Pipra pipra. As for the most vividly coloured of the six species, Pipra serena, it does display in more shady habitats, but around forest gaps or in the swamp forest. The males of the non-dimorphic manakins, Schiffornis turdinus and Tyranneutes virescens, do not possess ornamental feathers ; the first do not form « leks », and the latter has a very different kind of display. Among the typical « lek » species, males apparently use their courtship arenas only when these are properly illuminated to enhance the brightness of their own colour markings. When the ornamental feathers are located on the upper parts of the body, the males display on perches in understorey trees or vines ; such is the case for Pipra erythrocephala and P. pipra. When the colour markings are located on the underparts of the body, as in Manacus manacus and Corapipo gutturalis, the males display on cleared courts on the forest floor or on fallen logs. Pipra serena whose feathers colours are due to light diffraction, is the only species to display in the shade of the understorey.