MEPS 461:233-243 (2012)  -  DOI: https://doi.org/10.3354/meps09835

ABSTRACT: Stable isotope analysis of tissues of seabirds and their prey has proven to be an extremely useful tool in seabird dietary studies in general and in the potential use of seabirds as ecological indicators in particular. The measurement of stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope values is important since they provide information on source of feeding and trophic position, respectively. However, the stable isotope approach provides information on spatial and trophic ecology of seabirds during a window of temporal integration that depends on the elemental turnover rate in the tissue being measured. Most researchers have relied on only 1 or 2 tissue types to study seabird diets and foraging ecology. Here, the potential for modeling trophic position and habitat use by seabirds over the annual cycle is demonstrated by using multiple tissues from the same individual. Isotopic measurements of bone collagen provide information integrated over the lifetime of the individual and those of feathers during the post-breeding molt period. Analysis of liver provides information integrated over the previous week and that of muscle integrated over a few months. We developed multi-tissue trophic models for thick-billed murre Uria lomvia, dovekie Alle alle, black guillemot Cepphus grylle, glaucous gull Larus hyperboreus, northern fulmar Fulmarus glacialis, black-legged kittiwake Rissa tridactyla, and ivory gull Pagophila eburnea using the Northwater Polynya in Northern Baffin Bay, 1998 to 1999. The careful application of stable isotope methods to a spectrum of tissue types represents a powerful means of extending our ability to investigate diet and potentially to use seabirds as ecological indicators.

KEY WORDS: Stable isotopes · Carbon-13 · Nitrogen-15 · Seabirds · Temporal integration