What?s for dinner mom? Selective provisioning in Southern Rockhopper penguins (Eudyptes chrysocome).

ROSCIANO N; M POLITO; A RAYA REY

Congreso; 9 International Penguin Congress; 2016

Seabirds overcome several constrains while brooding, especially once chicks have hatched and have to be fed regularly. As such, during foraging trips adult seabirds need to balance self-provisioning and chick-provisioning. Some species of seabirds exhibit selective provisioning of chicks, with higher quality food; while others feed the chicks with lower quality prey items than they feed themselves, probably prioritizing their survival rather than their progeny. We examined the parental provisioning strategies of Southern Rockhopper penguins (SR) penguins using stable isotope analysis of parents and chicks to determine if there is selective provisioning and differing foraging habitats at sea where parents feed for themselves vs. for their chicks. We took whole blood samples from 12 SR penguin family groups (male, female and chick) at the crèche stage (Late December 2012) for stable nitrogen (δ15N) and carbon (δ13C) isotopic signatures. Preliminary results showed that chicks had higher δ15N values compared to both male and female SR penguins, and female had slightly higher δ15N values compared to male SR penguins. Also, there was a strong positive relationship in δ15N values between female SR penguins and their chicks, indicating that chicks? diet resembles the females? more than the males?. This is in line with the idea that female SR penguins exclusively feed chicks during the guard stage. These results also confirm the hypothesis of selective provisioning of chicks with higher trophic level as inferred by δ15N values, and thus higher quality, prey in SR penguins. We did not find differences among members of family groups in δ13C values. Therefore there is likely no differences in the areas or habitats used to forage for adult self-provisioning and chick-provisioning or between sexes in SR penguins. 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. (303)