Recovery potential of understory bird communities in Amazonian rainforest fragments

Abstract

Understory bird communities have been studied in a series of Amazonian rainforest fragments near Manaus, Brazil for about 20 years. Previous analysis of standardized mist-net samples revealed considerable temporal dynamism in capture rates, with communities in fragments responding to growth or cutting of the second growth matrix. This pattern was superimposed on expected fragment size effects among the 1-, 10-, and 100-ha fragments. Here we extend our earlier analysis of landscape effects by separately considering 1- and 10-ha fragments, with the goal of describing the recovery of bird communities in fragments surrounded by abandoned second growth. Most guilds, with the exception of terrestrial insectivores, appear to be on a trajectory to return to pre-isolation abundance in 10-ha fragments within about 40 years. Although some guilds showed similar recovery in 1-ha fragments, these were mostly species also common in second growth. Our results suggest that matrix development can allow bird communities to approach pre-isolation structure in fragments of at least 10 ha, but we emphasize that this conclusion represents a best-case scenario facilitated by the proximity to primary forest of the fragments we studied.