Breeding seasonality in central Amazonian rainforest birds

Abstract

ABSTRACT. Although it has long been recognized that many tropical birds do not share the same narrow breeding periods as temperate birds, conventional thinking considers tropical breeding seasons to be discrete periods generally governed by rainfall seasonality. We used a database of >31,000 captures of 104 species collected over 17 years in rainforest near Manaus, Brazil (2.5'S), to examine timing of breeding. The proportion of individuals with active incubation patches peaked at 7% in the dry season, from October through December. The peak was about twice as high as the lowest rate, in the late wet season (April—June). From 9 to 15 families and >20 species bred in every month. Many taxa did not conform to the general pattern, instead peaking in the wet season (e.g., Galbulidae, Sclerurinae, Grallariidae, and Formicariidae). Most well-sampled species, even those with strong seasonal peaks, bred at almost any time of year, a pattern also shown by some individual birds that were captured multiple times in ...