Intercolony differences in the summer diet of Thick-billed Murres in the eastern Canadian Arctic

Abstract

The diet of Thick-billed Murres collected near six colonies in the eastern Canadian Arctic comprised invertebrates (84% of 23 462 items) and fish (16%). Adult diets differed significantly among colonies, both within the Low Arctic (Hudson Strait), between Low and High Arctic (Lancaster Sound – Baffin Bay), and between Low-Arctic colonies and a colony close to the High/Low Arctic boundary (Davis Strait). Murres from the High Arctic took more invertebrates, fewer fish, and a smaller number of species overall than those from the Low Arctic. Diets were more diverse in the Low Arctic than in the High Arctic, in keeping with the greater number of prey taxa available at lower latitudes. Similarity indices show that diets at High-Arctic colonies were more similar to one another than was true for other colonies. Differences among Low-Arctic colonies suggest variation in the relative abundance of different nekton components within Hudson Strait.