What's for dinner mom? Selective provisioning in southern rockhopper penguins (Eudyptes chrysocome)

摘要

Breeding seabirds must balance self-care and reproduction, especially once offspring have hatched and have to be fed regularly. Seabirds may selectively provision chicks with higher quality food than they consume themselves. In contrast, adults may prioritize their survival rather than their progeny by feeding chicks with lower quality prey items than they feed themselves. We examined the parental provisioning strategies of southern rockhopper penguins at Isla de los Estados in 2012 using nitrogen (delta N-15) and carbon (delta C-13) stable isotope analysis to determine if selective provisioning and foraging habitat differences exist between parents and their offspring. We found that chicks had higher delta N-15 values compared to both male and female penguins, and female had slightly higher delta N-15 values compared to male penguins. There was also a strong positive relationship in delta N-15 values between female penguins and their offspring, indicating that chicks' diet resembles the female parent more than the male parent. Our results support the hypothesis of selective provisioning of chicks with higher trophic level (i.e., delta N-15 value) prey and the observation that females exclusively feed chicks during the guard stage. We did not find differences in delta C-13 values between adult and chicks suggesting no differences in the areas or habitats used to forage for self-provisioning and chick-provisioning. These findings likely have broader significance as provisioning rates and quality of food consumed by chicks is often strongly related to chick growth and survival.