Female Common Terns Sterna hirundo start autumn migration earlier than males

Abstract

We used geolocators to track Common Terns Sterna hirundo from a breeding colony in the northeastern USA. Seven females started autumn migration between 1 and 22 August (mean 9 August), whereas four males started between 12 August and 5 October (mean 6 September). Common Terns have prolonged post-fledging care and our findings support earlier inferences that males perform more of this care than females. This would result in higher costs for males.