Temporal niche of acoustic activity in anurans: interspecific and seasonal variation in a neotropical assemblage from south-eastern Brazil

Abstract

AbstractSympatric anuran species tend to differ in their temporal niche breadth and may also have considerable seasonal variation in diel activity patterns. We studied the temporal niche breadths of six anuran species during 24 consecutive months in an area of secondary forest at the Brazilian Atlantic Rainforest. Along hourly intervals, at each of three observation points along a stream, the number of calling males of Adenomera marmorata, Eleutherodactylus parvus, Physalaemus signifer, Aplastodiscus eugenioi, Scinax hayii and S. trapicheiroi was recorded. The influence of rainfall, air humidity and temperature on the variation in the niche breadth of each species was analysed. Mean niche breadth differed for all species. Scinax trapicheiroi had the broadest niche and S. hayii had the smallest. Temporal niche breadth varied seasonally for all species. Two species (E. parvus and S. hayii) showed strong variation in the temporal niche when compared to the other species. Eleutherodactylus parvus, A. eugenioi and S. hayii were significantly affected by rainfall, air humidity and temperature. Niche overlap among species pairs also varied annually with mean temporal niche overlap being greater during the rainy season than during the dry season.