Tuesday, December 6, 2016

Snow Goose

Yesterday, 5 December, Erika and I found two Snow Geese at the Jefferson Parkway Wetlands in eastern Northfield. These birds were first reported by Gerry Hoekstra on 29 November, but had not been seen since. Gerry returned later in the day and found a third, young Snow Goose.

White and “blue” Snow Geese are color morphs of a single species. Only in 1983 did ornithologists figure out this situation. One gene controls this color difference. The dark gene is incompletely dominant over the white one.  The dark gene is unequally distributed across the Snow Goose’s range. Most dark-morph geese breed and winter in central areas of North America. Finally, ornithologists discovered that the two morphs’ ranges did not overlap until about 70 years ago (Mobray et al. 2000).

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