Years ago, Lesser Black-backed Gulls were rare in Virginia and now they are quite regular throughout the year. In eBird there is now even a pull-down menu choice for the hybrid Herring Gull X Lesser Black-backed Gull, as that interbreeding is known to occur. The two species are commonly found together. While it would take DNA analysis for actual proof, providing eBird records for this and other suspected hybrid types does help to increase our awareness and understanding of interbreeding among species.
In the above photos, the 3rd bird from the right in front is a suspected Herring X Lesser because the mantle color is clearly intermediate between Herring and Lesser. It stands out as markedly different. It's head is tucked and legs are hidden, but there is so much variability in those features, that if shown, it wouldn't really add much. What's very lucky here is to have the various species side-by-side, because, as we know, lighting and angles can distort colors. A bird like this all by itself would be nearly impossible to judge.
The top shot shows part of a group of 22 Lessers and dozens of Herrings I saw together in southeastern Virginia in late February. There are few Virginia records in eBird for this suspected hybrid, some without photos or details, though birders should be aware of such possibilities and document as much as possible, to add to our knowledge.
Brian Taber
