“Blue” Snow Goose

It was darkly overcast, snowy and windy today when Leonard spotted a blue goose (Chen caerulescens) amid a flock of snow geese feeding in a field near the Modoc/Lassen California County Line on Modoc County Road 91. We see blue geese so infrequently I had to try for a picture, even though conditions were very poor.

Snow geese have two morphs or color phases, “white” and “blue”. Snow geese usually appear completely white while blue geese are dark except for white on the head, tail and possibly the belly. White and blue snow geese interbreed and range together so they are considered the same species.

The dark color is controlled by a single, partially dominant gene while the light morph gene is homozygous recessive. If a dark goose mates with a white goose, all the offspring will be dark. A mating between two white geese results in all white offspring. A dark by dark breeding produces mostly dark morphs.

Snow geese most often choose a mate that resembles the color of the parents. If the parents were a mixed-color pair, the goose will choose a mate of either color.

If the gene for the dark morph is dominant, why do we not see more blue snow geese?

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