Discrimination of Ross's and Lesser Snow Goose eggs

Our objective was to assess whether egg measurements could be used to discr iminate accurately eggs of Ross's (Chen rossii) and Lesser Snow Geese (Chen caerulescens caerulescens). We used lengths and widths of eggs found in ne sts of known species at Arlone Lake in 1963 and Karrak Lake, Northwest Terr itories, in 1968, 1976, 1988, and 1991-1996. Although accuracy of classific ation varied slightly among years, discriminant function analyses were 89-1 00% successful in identifying species based on dimensions of individual egg s and clutch means. Bias in estimates of species ratios, which reflects com bined effects of misclassifications in both species, was only 2% in favor o f Ross's Geese when all years were pooled. Sir, conclude that classificatio n equations, derived from discriminant function analyses using known-specie s eggs, are reliable and objective techniques for determining species of eg gs and nests of unknown origin at Ross's and Snow Goose colonies.