Measures of body condition, immune function, and hematological health are widely used in
ecological studies of vertebrate populations, predicated on the assumption that these traits …

The evolutionary origin and the maintenance of extra-pair mating in birds has been a major
field of study in the last decades, but no consensus has been reached on the adaptive …

Based on molecular technology, researchers find that extra-pair paternity (EPP) prevails
among socially monogamous bird species. This phenomenon challenges traditional views …

Behavioural syndromes have been identified in a large number of species, yet our
understanding of them in an ecological context remains poor. Specifically, there are few data …

Physically challenging signals are likely to honestly indicate signaler quality. In trilled bird
song two physically challenging parameters are vocal deviation (the speed of sound …

Abstract Models of sexual selection predict that socially monogamous females may gain
direct or indirect (genetic) benefits by mating with multiple males. We addressed current …

The forces driving the evolution of extra-pair reproduction in socially monogamous animals
remain widely debated and unresolved. One key hypothesis is that female extra-pair …

Quality differences between offspring sired by the social and by an extra-pair partner are
usually assumed to have a genetic basis, reflecting genetic benefits of female extra-pair …

Background Maternal antibodies are believed to play an integral role in protecting
immunologically immature wild-passerines from environmental antigens. This study …

The manipulating androgens hypothesis (MAH) proposes that female birds increase the
level of testosterone (T) in their eggs to promote greater offspring begging, and thereby elicit …