Ornaments, weapons and aggressive behaviours may evolve in female animals by mate
choice and intrasexual competition for mating opportunities—the standard forms of sexual …

The negative co‐variation of life‐history traits such as fecundity and lifespan across species
suggests the existence of ubiquitous trade‐offs. Mechanistically, trade‐offs result from the …

Behavioral Ecology of Tropical Birds, Second Edition provides the most updated and
comprehensive review on the evolution of behavior in tropical landbirds. The book reviews …

The challenge hypothesis (Wingfield et al. 1990, American Naturalist, 136, 829–846)
predicts varying androgen responses to mating, breeding or territorial behaviour in avian …

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 …

When selection on males and females differs, the sexes may diverge in phenotype.
Hormones serve as a proximate regulator of sex differences by mediating sex-biased trait …

In 1849, Berthold demonstrated that testicular secretions are necessary for aggressive
behavior in roosters. Since then, research on the neuroendocrinology of aggression has …

Berthold's classic study of domesticated roosters in 1849 demonstrated that testicular
secretions are necessary for the normal expression of aggressive behaviour. Although this …

Historically, research on the neuroendocrinology of aggression has been dominated by the
paradigm that the brain receives sex steroid hormones, such as testosterone (T), from the …

Traditionally, the production and regulation of steroid hormones has been viewed as a multi-
organ process involving the hypothalamic–pituitary–gonadal (HPG) axis for sex steroids and …