Meeting Abstract
P2.121 Monday, Jan. 5 Surf and turf: foraging choices of an island sparrow population NICHOLS, KS*; ERICKSON, PA; MAUCK, RA; WHEELWRIGHT, NT; Bowdoin College; Kenyon College; Kenyon College; Bowdoin College knichol2@bowdoin.edu
Foraging choices of parents feeding nestlings play an important role in offspring survival and quality. Different prey items can affect nestling growth and development. Savannah Sparrows (Passerculus sandwichensis) breeding on Kent Island, New Brunswick, Canada forage in both terrestrial (field and forest) and intertidal habitats during the breeding season. Analysis of 13C, a stable isotope of carbon, can quantitatively describe differences in foraging choice within and between populations. Differential uptake of 13C between terrestrial and aquatic photosynthesis allows for the determination of the percentage of an organisms diet that comes from terrestrial or aquatic sources. We used stable isotope analysis of blood and feather samples of adults and nestlings, visual observations of nests, and monitoring of nestling weight to determine whether different foraging choices by parents affected offspring growth. We observed 26 nests for an average of 2 hours each during which time identity of parent, direction of approach, food size and type, and habitat where foraging occurred was recorded for each visit to the nest. Preliminary analysis of the observational data suggests that at some nests parents forage preferentially from one direction while other parents forage randomly in relation to direction. Once stable isotope samples are analyzed, we will test how foraging behavior and diet choice influence offspring quality in P. sandwichensis in an island ecosystem.
