Tuesday, October 18, 2016

MA - Greater White-fronted Geese

Greater White-fronted Geese (two adults) - Turner's Falls, Franklin Co., MA. October 18th, 2016. 

This evening I finally managed to get decent views of the two Greater White-fronted Geese present in the Turner's Falls area since October 10th. The birds were calm resting amid some 1200 Canada Geese on a lovely, warm autumnal evening. These were also the first really large numbers of Canada Geese that I've seen this autumn.

I've been naturally reluctant to attempt assigning the white-fronts to sub-species without having extended views in good conditions. However, since one bird had already been seen to have a bright orange bill and dark, almost 'oily' brown plumage, I'd assumed that both would prove to be the Greenland form 'flavirostris', a scarce but now expected migrant through our region.

Since both birds were close together throughout the observation, differences in bill color as well as overall color, size and structure became apparent leading me to believe that perhaps two distinct sub-species had to be involved. One bird, the larger of the two, appeared to be a pretty good a example of 'flavirostris' with a bright orange bill closely matching the orange leg color, along with dark, 'oily' brown plumage and an obvious but somewhat restricted white 'blaze' around the base of the bill. The other bird looked consistently smaller, stockier and grayer (especially on the breast) with a  much more striking white blaze around the bill riding higher on the forehead. The difference in the distribution of white around the bill was obvious on both birds at all angles. Above all, the smaller bird had a distinctly pinkish rather than bright orange bill, again obvious at all angles even in low afternoon light. The differences were subtle but distinct enough to follow and sort out both birds with ease as they mingled among the Canada Geese.

So, what to make of the smaller, pink-billed, grayer-breasted bird? Well, background reading should offer some insight but at the moment the features seem to be most suggestive of the 'Tundra' form 'gambelli/frontalis' or possibly, though obviously rather less likely, the European/Siberian form 'albifrons'. 

Greater White-fronted Geese (two adults) - Turner's Falls, Franklin Co., MA. October 18th, 2016. 

Greater White-fronted Goose (adult, Greenland form flavirostris) - Turner's Falls, Franklin Co., MA. October 18th, 2016. 

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