Phenotypic Variation among Thick-billed Murres from Colonies in Hudson Strait

Abstract

Thick-billed Murres (Uria.hvio) breeding in the Canadian Arctic are restricted to a small number of colonies, all comprising more than 10 OOO pairs. Five of these colonies are scattered through HudsonS trait. We collected adultb reeders at three of the colonies - Digges Island, Hantzsch Island, and Akpatok Island- and compared wing and bill measurements and body weights to lookf or intercolonyd ifferences. Significant intercdony differences were present for all measurements and a discriminant function analysis showed that sane individuals fall compleley outside the rangeof variation for the other colonies.. Because of the presence of the Laurentide ice-sheet over Hudson Strait, the present colony sites could not have been occupied for more than 10 OOO years. If the observed differences reflect differences in genotype then their evolutionm ust have occurred over this perid.