The differential allocation hypothesis predicts that females invest more resources into reproduction when mating with attractive males. In oviparous animals this can include prefertilization decisions such as the production of larger eggs and the deposition of hormones, such as the steroid...

Stress may have consequences for the evolution of condition-dependent sexual traits. For example, stress may be related to sexual traits through immune function, and sexual traits can reflect how individuals bear the costs of stress-mediated immunosuppression. However, male traits may be...

Investigations of avian influenza have so far focused on the global circulation and conversion of virus strains and showed that wild waterfowl and especially ducks represent the reservoir and source of virus strains that can become highly pathogenic in domestic species. Information is largely...

Bird song is usually regarded as an attribute of males. However, in some species, females may also produce songs even with comparable complexity to that of males. It has been suggested that female song may evolve due to similar selection pressures acting on males, but no study has yet...

Neural correlates of bird song involve the volume of particular song nuclei in the brain that govern song development, production, and perception. Intra- and interspecific variation in the volume of these song nuclei are associated with overall brain size, suggesting that the integration of...

Bird song is usually considered to have evolved in the context of sexual selection. Because extrapair paternity is a major component of sexual selection, mating advantages at the social level for males that produce songs of high quality may be transformed into higher success in extrapair...

Although heterospecific vocal imitation is well documented in passerines, the evolutionary correlates of this phenomenon are poorly known. Here, we studied interspecific variation in vocal mimicry in a comparative study of 241 European songbirds. We tested whether vocal mimicry is a mode of...

Recent developments in ecological statistics have reached behavioral ecology, and an increasing number of studies now apply analytical tools that incorporate alternatives to the conventional null hypothesis testing based on significance levels. However, these approaches continue to receive mixed...

Most studies of the evolution of sexual ornamentation have dealt with plumage attributes. White plumage patches are widespread in birds, the disproportionate role of wearing costs makes their evolutionary trajectories unique, and their visual assessment is less biased than that of other color...