Proof! Photographic evidence of the validity of conflicting waterfowl reports in Tompkins Co., New York, October 2000.


These pictures were taken with an Olympus D-450 digital camera through a Swarovski HD80 spotting scope.

All photographs 2000 Kevin J. McGowan.


While looking for the Sabine's Gull on 7 October 2000 at Stewart Park, Ithaca, NY, at the south end of Cayuga Lake, a number of us saw a single adult male White-winged Scoter (Melanitta fusca) swimming with two scaup. We were not paying much attention to the ducks because of the gull excitement, but it turned out that several people reported the scaup as Lesser Scaup (Aythya affinis) and others as Greater Scaup (Aythya marila). Which were they? Only two scaup were apparent off the park, so people must have been looking at the same ducks. Everyone probably assumed they were both of the same species, identified one, and considered the other identified by association.

I propose that the two scaup were in fact of different species, and I took photographs that support this idea.

Here is the Lesser Scaup with the scoter. Note the bump on the back of the head, and how the peak in the head curve is rather far back on the head.

Contrast that with this photo taken a few minutes later:

Note the rounded head shape, how the peak is farther forward on the head, and especially how the white in the wing stripe extends out into the primaries, all making this a Greater Scaup.

Conclusion: Everybody was correct! (I actually saw the wing stripes on both ducks to verify that they were, in fact, of different species.)


On the morning of 10 October 2000, I reported an all dark White-winged Scoter hanging out with two Greater Scaup at Dryden Lake, Tompkins Co., NY. Only slightly later that morning Ken Rosenberg reported an adult male Surf Scoter (Melanitta perspicillata) on the lake, hanging out with two Greater Scaup. Seems odd that we each saw only one scoter, and that it was hanging out with the scaup. But, mine was seen well and was all dark, and Ken's was a full adult male with orange bill and big white patches.

What gives? Did either of us screw up?

No. We both saw what we reported, and here is the proof:

Here is the bird I saw on that foggy morning. Note that although the white face of the scaup is readily apparent, no white of any kind is visible on the scoter. I had tentatively identified it by head shape, but had to watch it for several minutes before it preened and showed me the white wing patch.

Compare the head shape of this bird to the male from Stewart Park on 7 Oct. Notice the "stair-stepped" effect typical of the species.


In the evening after work I went back to Dryden Lake and looked for Ken's bird. Sure enough, there was a male Surf Scoter:

It was too distant to get a clear photo (and it was sleeping nearly all of the time I was there), but obviously it's a Surf Scoter.

Conclusion: We were both correct. My bird must have left shortly after I saw it, and Ken's must have arrived about the same time.

When identifications conflict, we always want to claim that two birds were involved. Some times we just make mistakes on a single bird (everyone does!), and some times there really ARE two birds.


All photos Kevin J. McGowan

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Revised: October 01, 2001.