Sex discrimination and measurement bias in Northern Fulmars Fulmarus glacialis from the Canadian Arctic

The Northern Fulmar Fulmarus glacialis is a seabird in which both sexes have similar plumage, but sexual dimorphism in body size is apparent. We used data from 63 Northern Fulmars collected at Cape Vera, Nunavut, Canada, to develop a discriminant function to predict sex that is based on key morphometric variables. The sex of Northern Fulmars from Cape Vera can be ascertained accurately using a combination of four body characters, and using either a site-specific or generalized discriminant function model. Some differences between variables entering in the model for Cape Vera compared to models developed elsewhere for North Atlantic Northern Fulmars may reflect local population differences in typical morphometry, notably in head and bill measures. Discriminant functions developed to identify male and female Northern Fulmars appear to be robust enough to accommodate bias introduced from measurements by different biologists.

Mallory M.L. & Forbes M.R. 2005, Ardea 93(1): 25-36