MORPHOLOGICAL DIFFERENCES IN PACIFIC COAST POPULATIONS OF GREATER WHITE-FRONTED GEESE

We examined morphological relationships of three Pacific coast populat ions of Greater White-fronted Geese (Anser albifrons). Adult geese wer e captured and measured at three breeding areas in Alaska and two wint ering areas in California, 1980-1991. A two-step discriminant function analysis examined morphological differences among the three populatio ns. Stepwise discriminant function procedures created the simplest mea surement models. Each sex was analyzed separately since multivariate a nalysis of variance indicated that males were significantly larger tha n females for all three populations. Tule Greater White-fronted Geese (A. a. gambelli) were significantly larger than Pacific Greater White- fronted Geese (A. a. frontalis), hereafter Pacific Geese. The first st ep of discriminant function analysis created models to differentiate T ule Geese from the Pacific Geese. Bivariate stepwise discriminant func tion models consisting of only two measurements correctly classified 9 2% of males (bill height, bill width) and 96% of females (bill height, culmen) of these subspecies. The second step of discriminant function analysis compared a small population of Pacific Geese from the Bristo l Bay Lowlands (BBL) of southwestern Alaska with the large population of Pacific Geese that breed on the Yukon-Kuskokwim River Delta (YKD) o f westcentral Alaska. We developed models with three (culmen, diagonal tarsus, midtoe) and five (culmen, diagonal tarsus, midtoe, total tars us, bill height) measurements from stepwise discriminant function anal yses to correctly classify 72% of males and 74% of females of these po pulations. Thus, morphology of Tule Geese differed highly significantl y from Pacific Geese, as expected, but differences between populations from the BBL and YKD areas were also significant. Morphometric analys es as these provided supporting evidence for clinal variation in popul ations of Greater White-fronted Geese. They also underscore a need for further studies of differences among North American populations of Gr eater White-fronted Geese to resolve classification and to allow formu lation of subpopulation/subspecies management strategies.