Avian duetting is an unusual but taxonomically widespread phenomenon, occurring in over
400 species, representing 40% of bird families. Duets vary in form from loosely overlapping …

The bi-directional links between hormones and behavior have been a rich area of research
for decades. Theory on the evolution of testosterone (T) was greatly advanced by the …

In spite of recent interest in sexual selection in females, debate exists over whether traits that
influence female–female competition are sexually selected. This review uses female–female …

Steroid hormones have similar functions across vertebrates, but circulating concentrations
can vary dramatically among species. We examined the hypothesis that variation in titres of …

Hormones coordinate the co-expression of behavioral, physiological, and morphological
traits, giving rise to correlations among traits and organisms whose parts work well together …

While much research has focused on the evolution of conspicuous male displays,
ornaments and behaviours, less is understood about the evolution of similar traits in …

Testosterone is a key hormone for the development of secondary sexual characters and
dimorphisms in behavior and morphology of male vertebrates. Because females often …

The evolution of sexually monomorphic (ie mutual) ornamentation has attracted growing
attention as a 'blind‐spot'in evolutionary biology. The popular consensus is that female …

Female–female aggression often functions in competition over reproductive or social
benefits, but the proximate mechanisms of this apparently adaptive behaviour are not well …

Blood sampling is often critical for answering a variety of questions about wild birds.
However, it is important to assess the impacts, if any, of blood collection on wild birds. Here …