28 February 2015

February 2015 Quiz

Pointed primary tips with relatively crisp and checkered upperwing coverts readily age this bird as a first cycle. It's obviously bigger than the medium sized Ring-billeds in the background, so the default large white-headed gull to begin with would be American Herring. This taxon has a range that's more widespread than any other North American gull. It would behoove anyone with a serious interest in gull identification to become intimately familiar with Herrings.

The majority of participants nailed this month's quiz, but a fair number of participants - perhaps unsurprisingly - answered Thayer's Gull. The overall pale and uniform coffee-color to the upperparts, and pale-tipped primaries do bear a superficial resemblence to Thayer's.

It's not, however, uncommon for 1st cycle Herrings to show pale chevrons on the tips of the outer primaries. When Herrings do show this pattern, the pale color is typically restricted to the very tips of the primaries and not as encompassing as in Thayer's (which shows pale edges coming up towards the sides of the primaries - here's an example).

Other features that favor a 1st cycle Herring Gull is the paling bill base and smokey gray upper mantle. Although this aspect isn't unheard of with Thayer's, it's much more common with Herrings.