Meeting Abstract

56.1  Saturday, Jan. 5  Effects of pre-breeding food supplementation and group size on growth and survival of nestlings in the cooperatively breeding Florida Scrub-Jay (Aphelocoma coerulescens) RENSEL, M.A.*; SCHOECH, S.J.; Univ. Memphis; Univ. Memphis mrensel@gmail.com

Conditions during development may play an important part in the realization of an individual�s lifetime fitness. Many factors can influence the growth and survival of young birds during development, including parental condition. During brooding, parents in poor body condition will be less likely to feed nestlings and may spend more time away from the nest, increasing the probability of offspring mortality. The presence or absence of helpers at the nest may also affect development and survival of nestlings to fledging. The objective of this study was to investigate the effects of pre-breeding food supplementation and group size on the physiology and survival of Florida Scrub-Jay (Aphelocoma coerulescens) nestlings. To determine the effects of parental body condition on nestling condition, we supplemented territories during the pre-breeding season in 2006 and 2007. Nests in supplemented and un-supplemented territories were monitored through egg-laying, incubation, and brooding. We took morphological measurements from each nestling on the date of hatching, five days post-hatching, and at eleven days post-hatching. In addition, blood samples were taken from each individual on day 11 to assess baseline circulating levels of the stress hormone corticosterone. Subsequent survival to fledging, independence, and over-winter were recorded. Survival and growth of nestlings were then related to breeder condition and number of helpers in each territory.