We analyzed the occurrence of molt and brood patches in resident passerines from four localities in south-central Brazil. The annual patterns of molt and reproductive activity were very similar among the sites. Brood patches first appeared in August, but were most common between October and January, with a peak in November, early in the rainy season. Molt started in October but was most widespread from the middle to the end of the rainy season, between December and April with a peak in February. Timing of the appearance of brood patches was not related to trophic guild (insectivores, frugivores, omnivores). Molt of flight feathers started at the end of the reproductive period, which varied slightly among trophic guilds. Molt and brood patch overlap occurred in little more than 4% of individual birds, or in less than 2% considering just those molting flight feathers. This overlap occurred mostly between November and February. Regional environmental factors, instead of local factors, seem to be responsible for the annual breeding and molt patterns of the considered species.
Padrões Anuais de Muda e Atividade Reprodutiva de Passeriformes na Região Centro-Sul do Brasil
Resumo. Este estudo analisa a ocorrência de muda de penas e reprodução em Passeriformes residentes em quatro localidades na região centro-sul do Brasil. A atividade reprodutiva foi inferida a partir da presença de placas de incubação ativas. Os padrões anuais de muda e reprodução apresentaram-se bastante similares entre as regiões estudadas. Placas de incubação começaram a ser detectadas em agosto, sendo mais comuns entre outubro e janeiro, com um pico em novembro, no início da estação chuvosa. O principal período de mudas começou em outubro, sendo mais intensas nos dois terços finais da estação chuvosa, entre dezembro e abril, com um pico em fevereiro. Os padrões de ocorrência de reprodução e mudas apresentaram pequenas diferenças entre diferentes guildas alimentares, e, de modo geral, o início do período de mudas esteve relacionado ao fim do período reprodutivo. Sobreposição entre mudas e placas de incubação foi detectada em pouco mais de 4% do total de indivíduos analisados, ou em menos de 2%, quando apenas indivíduos mudando penas de vôo foram considerados. Esta sobreposição ocorreu principalmente entre novembro e fevereiro. Os padrões ambientais regionais, mais que os locais, parecem influenciar os ciclos anuais das espécies analisadas.
We analyzed patterns of species richness, size, structure, and composition of mixed-species flocks in relation to forest fragment size and forest successional stage during dry and rainy seasons, at the state of Minas Gerais, southeastern Brazil. Three forest fragments (1.7, 50, and 200 ha) were used for fragment size analysis, and two fragments (200 and 300 ha) were used for successional stage analysis. Fragment size and season affected flock richness, size, stability, and composition. In the 1.7-ha fragment, flock species richness, size, and stability were significantly different only during the rainy season. Fragment successional stage also influenced flock richness and size, although season did not. Flock composition also had changes related to fragment successional stage. Fragment geometry seems to be an important factor influencing flock structure and composition.
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