02 February 2016

Appledore Gulls - Herring x Lesser Black-backed Hybrids

Appledore Gull is the title I've suggested for putative American Herring x Lesser Black-backed hybrids. They appear to be increasing with rapidity and it seems every week I'm being sent photos or someone is posting good candidates of this combination.

There are two individuals that have provided us with some insight: "Green F07" and "Green F02", the offpring of an American Herring and Lesser Black-backed Gull (Green F05) from Appledore Island in Maine.

(Click on each)

Green F07
This is the most well-documented hybrid available to us in North America. Interestingly, this bird has kept mostly yellow legs in 4th basic. It's easy, then, to discredit the notion that adult F1 hybrids should have a blend of dull pink and yellow legs.

Green F02
This bird has been missing in action since 2nd basic. It looks much more like a 2nd cycle Lesser than a Herring (or an intermediate bird for that matter). Both size and the gray upperparts don't scream Herring Gull to my eyes.


Green F05. Banded on Appledore Island after found hybridizing with American Herring Gull.
This individual, known as Pierre, has been documented up and down the Atlantic, spending most of
its winters in the Daytona Beach Shores area. More here.


While in Florida a couple of weeks ago, I found two examples of adults that I feel make good candidates of this hybrid combination. Let's start with the more obvious individual.

BIRD #1











BIRD #2







I base my identifications of these two birds primarily on two points: intermediate upperparts and corrupted leg color. P-molt is better for a LBBG at this time of year. The head/bill on both birds look more like Herring Gull, to me.  

The continuing barrier of little data and few known-age, known-provenance birds makes our identifications tentative. There is no known "hybrid zone" where we can openly observe this mix, and so the range of features in these hybrids is reduced to guesswork and imagination. This presents several critical identification problems for North American observers: 1) Identifying Yellow-legged Gulls with confidence, 2) Confusion with dark-backed "Herrings" and pale-backed "graellsii".

4 comments:

  1. Christopher GeorgeFebruary 3, 2016 at 3:53 PM

    That HERGxLBBG leg color is so distinctive...like someone tried blending yellow and pink play-doh and gave up halfway through.

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    1. You'd hope, ideally, that a hybrid would show this blended leg color. Green F07 didn't play by the rules, however.

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  2. Christopher GeorgeFebruary 3, 2016 at 6:48 PM

    I thought the two listed at the beginning were the individuals in the pics, didn't realize they were links to other birds...it is kind of alarming how yellow Green F07's legs turned out...they almost have a greenish tinge.

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    1. Yes, Green FO7 is not exactly intermediate is it? Lots to be learned, Christopher. And then the horror of thinking about F2 and F3, etc, hybrids...fun stuff!

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