Long-term Studies of the Green-rumped Parrotlet (forpus Passerinus) in Venezuela: Hatching Asynchrony, Social System and Population Structure

– Few Neotropical birds have been the subject of long-term ecological and behavioral research. I present highlights from 19 years of studies on the Green-rumped Parrotlet (Forpus passerinus) in the llanos of Venezuela, based on marking and resighting over 7500 individuals and monitoring of 2500 nesting attempts in two populations breeding in nest boxes. Initial work focused on the causes and consequences of the extreme hatching asynchrony exhibited by parrotlets. Examining an exhaustive set of fitness correlates at experimentally synchronized or asynchronized nests found no evidence that asynchrony benefited