Breeding synchrony and EPF rates: the key to a can of worms?

Abstract

Given that roughly 95% of bird species are classified as ‘monogamous’1, some might claim that the class Aves is short on mating system diversity. Whatever the group might lack in this respect, however, is offset by rather impressive species differences in the prevalence of covert matings by females. By a recent count2, extra-pair fertilization (EPF) rates range from 0 to 76% across avian species, with the mean for all species at about 13%.