Sex differences in feeding visit rates in Northern Wheatears Oenanthe oenanthe

Abstract: AbstractThe Northern Wheatear (Oenanthe oenanthe) is a small insectivorous passerine bird living in open landscapes. Both parents feed the brood of approximately five chicks, but little is known about how each sex allocates their feeding effort. In this study I investigate feeding nest visit differences between male and female Northern Wheatears relative to the age of the chicks, the number of chicks and the quality of the territory for 17 pairs from 2008-2010. Data were collected using automated data loggers to record nest visitation rates during chick feeding, and the sex was determined from nest video cameras. I also examine if the parents’ rate of feeding visits changes over the nestling period. The predictions were that: (1) the male would visit relatively more when the chicks were young compared to the female, and that these roles would reverse (i.e. the female would become the parent with most feeding visits) when the chicks grew older; (2) any differences between the feeding rates of parents would be smaller for larger broods; (3) any differences between the feeding rates of parents would be relatively small when the quality of the territory was low; and (4) parents would increase their rate of feeding visits as the chicks grew. The predictions are based on the theory of resource limitation.I found some support for differences in feeding nest visits between the sexes. The male had a greater share of feeding visits when the chicks were young and a smaller share when the chicks were older. There was no difference between the male and the female in their feeding visit rates with varying numbers of young. The quality of the territory had a small effect on the sexes’ feeding visits, but only when the age of the chicks was added to the analysis. The rate of feeding visits was higher when the chicks were older.This study is the first to provide information on wheatear behaviour in the nest relative to its sex and should outline the basis of future research on sex differences in the Northern Wheatear.