A rare blue morph of the Ross’s goose (Chen rossii) exists. The origin of this blue morph is uncertain. It might be due to hybridization with the snow goose blue morph (Chen caerulescens) or recurrent mutations of Ross’s goose genes controlling feather color.
The Ross’s blue morph has a dark body with white wing coverts. The face is white while the hind crown, nape and neck are dark. There is some white on the lower breast and belly.
Ross’s geese mate for life and choose as a partner the same color morph (blue or white) as their parents were. The dark color is controlled by a single gene. The dark color is partially dominant. Thus a mating of two dark or “blue” Ross’s geese produces mostly dark offspring, but there are occasionally some white young from this cross. These white geese would choose a dark mate.
Leonard and I always considered blue morph Ross’s geese to be extremely rare, an opinion supported by the literature. In February we attended a lecture on white geese (snow and Ross’s) by Kelly Hazen at Winter Wings in Klamath Falls OR. Kelly’s hobby is searching for collared white geese so she observes thousands of white geese. She believes that in a mixed feeding flock there is about one blue morph (snow or Ross’s) in approximately 1,000 birds.
After Kelly’s program, Leonard and I began to search in earnest for a blue morph. We assumed we would find the more common snow goose blue morph. However, much to our delight, the single blue morph we found after about a week of searching was a Ross’s in the flooded wild rice fields near Glenburn CA (Shasta County).
The next quest: a blue morph snow goose.