Do Redpolls have split personalities?

 So Redpolls are now all one species, according to the latest IOC list. The photos below would indicate otherwise to any self-respecting birder. To me they indicate a lack of consensus as to what constitutes a species, but nowadays it is probably an insurmountable problem. I, for one, only make changes to my list if common sense prevails. If birds look different, then that should be recognised in some way, whatever scientists theorise, because as sure as eggs are eggs, they will be split again when someone needs a thesis for their PhD. I've mentioned this before, so 'nuff said, but recent changes resulting in a couple of new species are interesting, to me at least.

 The first is Mongolian Gull, split from Vega Gull, which was originally a Herring Gull. Although breeding closer to Western Europe than Vega Gull, because it's confined to Mongolia and winters in South China I would think it less likely to take the route across the Arctic Circle which has probably resulted in Vega Gull records. I had only seen one "Mongolian Gull",  in Hong Kong many years ago, and of course then the identification wasn't certain. It was thought to possibly be a race of Herring Gull, taimyrensis, which is no longer recognised by the IOC, or race mongolicus of Caspian Gull, which was then a Herring Gull. the taxon taimyrensis is now thought to be a hybrid Vega/Heuglin's Gull. According to the IOC Heuglin's Gull is a race of Lesser Black-backed now, although several authors do split it. The general concensus among the resident gull experts then at Mai Po was mongolicus, which of course is the recently split Mongolian Gull Larus mongolicus. If that hasn't confused you, it has me, and I must concede that I have not seen a Mongolian Gull. I have re-visited the photo and it is either a Heuglin's Gull or a hybrid. I had been able, since 1995, to say I have seen all the world's gulls, now I cannot. Worry not on my behalf (not that you would) as I had, before the split was announced, booked a trip to Mongolia next year. I think that's serendipity, but I've never really understood the word. My reason for the trip was to see three Category A species that I haven't seen anywhere, Amur Falcon, Red-throated Thrush and Pallas' Reed Bunting. The last is another potential split, but we should see both subspecies involved. So, it's a win-win for me. I think I'm "future-proofed" from further gull splits, having seen most subspecies, but several are potential splits, so I may enjoy a few armchair ticks .

 

The other split concerns Brown Booby, a recent addition to the UK list as ocean currents become warmer and more seabirds wander north.  The subspecies brewsteri has been split as Cocos Booby. Presumably the name Brewster's Booby, by which it has been known for years, is considered inappropriate, being an eponym, although Brewster, a Californian ornithologist, did nothing to offend anyone. Although the bird is found on the western littoral of Mexico and Central America, it is not inconceivable that it could cross in to the Atlantic and muddy the waters of Booby identification in the Western Palearctic. Adults are easily distinguished but juveniles until they begin to develop bill colours are not. An unlikely scenario however. Rather more likely to occur is a proposed potential split, that of Arabian Tropicbird, from Red-billed, proposed by Steve Howell and Kirk Zufelt in their book, Oceanic Birds of the World.  I have seen this (sub)species in Jordan, and whilst records of Red-billed Tropicbirds off Cornwall are likely to be the nominate form or mesonauta which breeds on Cape Verde, what is to stop birds from the Red and Arabian seas traversing the Mediterranean. So if you find one on the east coast??? There is a record from Landguard in Suffolk, found dead and thought to have been ship assisted, but I don't think the ship's route is known.

I have no further thoughts about Redpolls, they've been split and lumped so often. It is likely that they are part-way to full speciation, and there is still some hybridisation, but the birds introduced to New Zealand could become a full species first since they are geographically isolated. I probably won't be around when the matter is finally resolved (and neither will most of you), so you pay your money (to twitch a hornemanni) and take your choice.