Jo. Leafloor et Dh. Rusch, CLINAL SIZE VARIATION IN CANADA GEESE AFFECTS MORPHOMETRIC DISCRIMINATION TECHNIQUES, The Journal of wildlife management, 61(1), 1997, pp. 183-190
We evaluated morphometric discrimination models designed to use skull
length to differentiate between giant Canada geese (Branta canadensis
maxima) and interior Canada geese (B. c. interior). We found significa
nt differences in mean skull lengths of interior Canada geese from 3 a
reas in James Bay (Duncan's multiple range test, P < 0.05). Geese decr
eased in size with increasing latitude, but those from Akimiski Island
did not Bt this pattern, and were smaller than those from the adjacen
t mainland. Morphometric discrimination techniques appeared to work ad
equately in northwest James Bay and on Akimiski Island, but were less
reliable in southern James Bay, where the largest interior Canada gees
e were found. Molt migrant giant Canada geese were apparent in all are
as, but most were distinguishable by morphometric methods from interio
rs at all sites except southern James Bay. Detailed knowledge of geogr
aphic variation in body size will improve the usefulness of morphometr
ic discrimination techniques for Canada goose research and management.
We recommend the skull length models developed by Moser and Rolley (1
990) for use in differentiating giant from interior Canada geese in mu
ch of the Mississippi Flyway, except where southern James Bay mainland
geese occur.