Slaty-backed Gull alongside Great Black-backed Gull

Slaty-backed Gull alongside Great Black-backed Gull

The parade of winter rarities Lake Champlain, this time with a Slaty-backed Gull, a visitor from the northern Pacific Rim. This bird was spotted on Mar. 1 on Mud Island from the public access at Turkey Ln. in Panton by Spencer Hardy, Ian Worley and myself. We had rare gulls on our minds a bit after seeing a huge flock of 2,500+ gulls on the northernmost edge of the ice sheet at Potash Bay earlier that morning. Ian even mentioned while looking at that flock that conditions similar to what we were seeing produced the first ever sighting of a Slaty-backed in Vermont. But even so, Ian and I reacted with a certain level of incredulity when Spencer said he believed he was looking at a Slaty-backed.

When Ian and I got a look at the bird though, there was no question that we were looking at something unusual. Smaller and lighter colored than a Great black-backed Gull, and similarly sized to, but darker than a Herring Gull, we were left with only other rarities to rule out to make the ID. Its pink legs ruled out Lesser Black-backed Gull and the brown streaking on the head ruled out Western Gull. We called for reinforcements and put out the word on the VTBIRD listserv, and soon other birders arrived, including Ted Murin who observed the bird and concurred with our ID. We are in the process of writing up a Rare Species Documentation form to submit to the Vermont Birds Records Committee. If accepted, this would be the the second official record of this species in the State.

The next day birders searched the lake in a attempt to re-find the Gull but came up empty. They did however find two Iceland Gulls, a more common rarity, among the mass of Gulls at Potash bay. Given the large expanse of open water on the lake though, it wouldn’t be surprising for this bird to pop up again soon. Looking at the eBird Range Map, it seems that most years a few of these birds are found in the eastern U.S. so rare as it may be, it is a species anyone should have on their mind when looking at winter gull flocks on Lake Champlain.

– Ron Payne