INTERCOLONY DIFFERENCES IN THE SUMMER DIET OF THICK-BILLED MURRES IN THE EASTERN CANADIAN ARCTIC

The diet of Thick-billed Murres collected near six colonies in the eas tern Canadian Arctic comprised invertebrates (84% of 23 462 items) and fish (16%). Adult diets differed significantly among colonies, both w ithin the Low Arctic (Hudson Strait), between Low and High Arctic (Lan caster Sound - Baffin Bay). and between Low-Arctic colonies and a colo ny close to the High/Low Arctic boundary (Davis Strait). Murres from t he High Arctic took more invertebrates, fewer fish, and a smaller numb er 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 o ne another than was true for other colonies. Differences among Low-Arc tic colonies suggest variation in the relative abundance of different nekton components within Hudson Strait.