Selectively learning from specific types of individuals may be adaptive if demonstrator characteristics can used to identify more beneficial sources social information. Such “social biases” have been experimentally demonstrated in a number species, but these experiments generally involve restricted laboratory conditions using limited potential demonstrators and tend consider only the rather tha...

Adaptive immunity, when vertically transmitted from mother to offspring, creates an essential advantage for the fitness of a species. The transfer of maternal antibodies provides a considerable degree of protection to the offspring from birth on, especially against virulent pathogens (Powell, 1987). Although it has been known since long time that birds are able to accumulate a considerable amou...

Recently it has been recognized that reproduction itself, or the regulatory processes controlling reproduction, might contribute to physiological costs of reproduction. Reproductive anemia, a decrease in hematocrit and hemoglobin concentration, might provide one such mechanism underlying the costs of egg production in birds. In this study, we investigated the effect of repeated cycles of egg pr...

The relationship between sperm energetics and sperm function is poorly known, but is central to our understanding of the evolution of sperm traits. The aim of this study was to examine how sperm morphology and ATP content affect sperm swimming velocity in the zebra finch Taeniopygia guttata We exploited the high inter-male variation in this species and created extra experimental power by increa...