Student Scholars Day

Sex Differences in Parental Anti-Predator Responses During the Nestling Period in Tree Swallows

Henry Hall Atrium 66

Parental effort influences the survival of nestling birds. We examined sex differences in Tree Swallow parental responses to a potential human predator in 2009, and to a mounted raccoon model in 2010. Parents treated the human and model raccoon predator the same. Brood size, weather conditions, and time of day did not influence attack rates. There was no significant difference in the number of attacks made by males and females. Both sexes attacked more frequently during the second half of the nestling period. Females attacked consistently across the 5 min observation period, males did not. Females that attacked often during the first half of the nestling period also did so in the second half. Males did not show this pattern. Parental nest defense efforts were not coordinated. Male defense efforts may be related to male physical quality. Individual attack rates were not repeatable between years. Parents increased defense as nestlings got older, but male and female patterns differed.