Helpers at the nest in the cooperative breeding system of long-tailed tits Aegithalos caudatus exhibit kin preference in their helping behavior. The aim of this study was to use multivariate analyses to investigate whether helpers accrue indirect fitness benefits through their cooperation by...

Paired male and female eastern whipbirds, Psophodes olivaceus, sing precisely coordinated, male-led duets. Four broad explanations have been proposed for the function of duets: 1) cooperative resource defense, 2) prevention of partner usurpation, 3) defense of an individual's own position within...

Life-history theory suggests that offspring desertion can be an adaptive reproductive strategy, in which parents forgo the costly care of an unprofitable current brood to save resources for future reproduction. In the burying beetle, Nicrophorus vespilloides, parents commonly abandon their...

Nestling brood parasites vary in the harm that they do to their companions in the nest. Here we use a game-theoretical model to attempt to account for this variation. Our model considers hosts that might routinely abandon single nestlings, regardless of whether they are host young or brood...

Female superb fairy-wrens Malurus cyaneus initiate extragroup fertilizations by forays to the territory of preferred males, just before sunrise, 2--4 days before egg laying. Over a prolonged breeding season, males advertise their availability to foraying females by singing during the dawn...

An overabundance of hypotheses have been proposed to account for reversed sexual size dimorphism (RSD; females the larger sex) in raptors. Previous research principally focused on examining interspecific patterns of RSD, rarely testing predictions of various hypotheses within populations. To...

Fisher's theory predicts equal sex ratios at the end of parental care if the costs and benefits associated with raising each sex of offspring are equal. In raptors, which display various degrees of reversed sexual size dimorphism (RSD; females the larger sex), sex ratios biased in favor of...

The growing importance of multilateral diplomacy is a phenomenon of the 21st century. This is in part because the 21st century has thrown up problems which are universal in nature, such as human rights, the international control of disease, the international flow of capital and information,...