In late December 2002, I spent a few hours at the wonderful Merced NWR east of San Francisco in northern California. Whilst sifting through a large flock of Ross's Geese looking for birds with neck collars (there were several with blue or yellow collars present) I found one non-white phase bird. The pattering of the plumage seems consistent with a Lesser Snow Goose, although the shape and detail of the bill makes me think it might be a hybrid. Comments please!
Fig. 1. A lone blue-phase goose stands with Ross's Geese in a farm field adjacent to the Merced National Wildlife Refuge in California's Central Valley.
Fig. 2. Closer view of the same bird. The bill does not show a prominent grin patch.
Fig. 4. Slightly overexposed shot showing the head at a slightly different angle.
Fig. 5. Here is a shot of some different birds from the same flock. What is the bird just right of center? A male Ross's, Lesser Snow or hybrid?
Fig. 6. I think this is a blue-phase Greater Snow Goose. Note the similarity in plumage to the Californian bird, although of course the bill is larger with an obvious grin patch.The gra rather than blackish tone may be a product of the heavily overcast conditions. I think most of the Snow Geese at Jamaica Bay are Greaters, even though blue birds are regular and sometimes multiple individuals are present at once. Indeed there was a neck collared individual from Bylot Island, Canada just to the left of this bird. This bird was as large as the white phase birds around it.
Some nice photos of blue-phase
Lesser Snows taken in North Carolina here. For a nice discussion of the
problem take a look at the editorial in the Winter
Season: December 2001-February 2002 Seasonal highlights (North American
Birds, Vol 56: No 2).