I have a proposal. An adult Thayer’s Gull is only a Thayer’s Gull if it has the following: An all dark eye, the correct primary pattern p10 to p5, no break on the p6 strap, the primaries must appear near black and not gray. It needs a darker mantle than Kumlien’s, a pale, two-tone bill, and a rusty shawl in winter along with pink legs. Everything else is Kumlien’s, even if it upsets the Californians – agreed, we ignore anything ‘Thayer’s like’ until maturity, good.
The reasons for lumping Thayer’s is, in part, because of so many in-betweeners, but I would ask, do birds with the full suite of requirements, as stated in the first paragraph, interbreed with those that do not, if not then sorted, the problem is that nobody really knows because it is not something that grabs much attention. Virtually all the Thayer’s types we get here Nova Scotia are in-betweeners, but we have had a couple of pure looking Thayer’s including the one found by Alix and Paul on January 8th, 2017. By keeping it this simple, we are doing the gulling and listing world a favour and the Californians benefit too if they think about it, they all tick Iceland Gull easily and spend less time messing about with possibles.
The thing is, the tick doesn’t matter, the species does. Thayer’s isn’t a form of Herring nor Iceland it is just at that tricky, teen time in its evolution where it wants to be different, and it will be eventually. I have long thought that birders following the current system are severely restrained by it, it doesn’t apply to everything, it is like pushing your feet into shoes two sizes too small, uncomfortable. Gulls especially need a little latitude, even eBird can’t deal with them, Juvenal, Immature and Adult nowhere near covers it when entering a bird’s age.
As birders we have two pieces of equipment that help us considerably when it comes to identifying birds, eyes and ears. You might argue brain too but not all are born equal, else how do you explain 52,000,000 Americans and 51% of the British? So we use the equipment we have to sort out the tricky things, conversation, avoiding obstacles and, of course, word puzzles. When we apply these senses to birds, we split them up by how they look and or sound. We, again as birders and not Ornithologists, have nothing else at our disposal, we can’t record the DNA in the field and nor do we need to, the birds themselves are quite aware of their relationships and what constitutes a good mate. Sometimes though, like those awful people on daytime TV, they get it wrong and mate with something else.
All this brings me to the news that I finally got to 300 species seen in Nova Scotia and that the 300th species was the Thayer’s Gull at Dennis Point (great name!), Lower West Pubnico on January 15th 2017. I know that, at some point, the species will lose its status and I will lose it off my unofficial list, the one in eBird. It will stay on my official list, the one I keep for myself as it should. Thanks to Alix and Paul for finding the bird in the first place and Alix for re-finding it on the day. It has all the qualities a Thayer’s Gull should have, there is nothing in-between about it at all. I recommend anyone who can, getting over to see it although it can be inconsistent in its appearances, like all vagrant gulls.
Just to save you from another gull post. The Herring Gull below was at Pubnico the same evening as the Thayer’s. It is very different from the other Herring Gulls. The wing pattern differs too, I place it here for you to enjoy, not to suggest that it is anything else although my mind, such as it is, is cast back to days in the 1980s when we would watch UK gull roosts and, infrequently, see gulls that looked so different from the Herring Gulls alongside. They became Caspian Gulls, is it too left-field to wonder whether the evolution of Caspian Gull in Europe, from European Herring Gulls, might also have happened in North America from American Herring Gulls? Just a thought.
The left bird is the odd one, the right a regular Herring Gull.