SummaryThe Red-tailed Newtonia Newtonia fanovanae, known from two sites in the eastern rainforests of Madagascar, was found in the Réserve Spéciale d'Ambatovaky in February 1990, when two observations of birds in mixed-species flocks were made in primary lowland forest at 650-700 m. Such habitat may be rare in reserves, recent fieldwork having concentrated on higher-altitude sites. Ambatovaky's faunal richness as a lowland site is emphasised. Some differences in descriptions of the Red-tailed Newtonia exist.Le Newtonie à queue rouge Newtonia fanovanae, antérieurement connu de deux sites dans les forêts tropicales orientales du Madagascar, fût trouvé dans la Réserve Spéciale d'Ambatovaky en février 1990, où deux individus fûrent observés parmi des bandes plurispécifiques d'oiseaux à I'intérieur d'une excellente forêt de plainé à 650-700 m d'altitude. II se peut qu'un tel habitat soit rarement trouvé à I'intérieur de réserves, car les investigations de terrain fûrent récemment concentrées sur des sites en plus haut altitude. La richesse faunistique du site de plaine d'Ambatovaky est mise en évidence. II existe des différences de descriptions du Newtonie à queue rouge.
Abstract
Four hypotheses for the function of the head-down display performed by Brown-headed Cowbirds were tested with observational data from free-ranging and captive cowbirds. Free-ranging cowbirds performed 284 interspecific and four intraspecific displays during 59.2 daylight hours while roosting in mixed-species flocks adjacent to feeding areas. The most common recipients of displays, female Red-winged Blackbirds and House Sparrows, preened cowbirds during 25 displays. Cowbirds that had just been preened displayed more often than those that had not recently been preened. Captive cowbirds displayed intraspecifically 475 times during 13.3 h, and dominant captive birds displayed more often than their subordinates. The following hypothesis was proposed to explain the display's function: the head-down display of Brown-headed Cowbirds is an appeasing agonistic behavior, the displayor is most often dominant to the recipient, and subsequent displaying is stimulated by interspecific preening. The display may function in: (a) obtaining food, (b) minimizing roosting energetics, and/or (c) establishing flock order.
Multicontinental community phylogenetics of avian mixed-species flocks reveal the role of the stability of associations and of kleptoparasitism