More evidence has emerged on the Stow BRT and the Richmond and Dungeness Stonechats, thanks to Martin Collinson of Aberdeen University running DNA checks on material collected from all three birds.
Blue Rock Thrush
The bird would appear to be from the Western Europe/North African populations, making its credentials much better for natural vagrancy. Apparently, most (but not all) captive birds could be of the eastern populations, where of course, there is more trapping and a bigger cagebird trade. Whilst there weren’t many other notable rarities from that area in the autumn of 2016, there was a Western Orphean Warbler in Shetland, so the Rock Thrush wasn’t alone.
With regard to the bill, there is still mixed opinion on this, and I didn’t notice anything untoward in the field (but wasn’t really looking that closely, as it was only on photo’s afterwards I noticed anything odd), I have since looked at a lot of photographs, and there doesn’t actually seem to be anything wrong with it. On some photo’s, the bill is fractionally open, and this combined with the angle, makes the tip look odd.
Steve Gantlett posted some pictures on his website that apparently showed some kind of fine thread around one leg, but it was very difficult to make out, and even if it was there and not a photographic artefact, it didn’t look like anything that was – or would have been – put there by humans.
As for the drooping wing, it still has that, and although it seemed to add to the suspicion on the wildness of the bird, it is hard to decide whether that is significant. People also mentioned gapeworm, and I’m not sure exactly what that is or how you tell a bird has it – or what significance it might have.
The only other factor against it as a wild vagrant is its age, and it has to be said, that is still the biggest problem for me – when added to its location and time of year.
Given there will not be any proof either way, everyone has their own opinion, and every pro and con can be argued strongly either way, I guess the best way forward is to have an amnesty on this bird and let it on.
On one condition: the same applies to other birds with equal measures of doubt. In this I would include from the top of my head: Demoiselle Crane, 1993, Booted Eagle, 1999, Falcated Duck, 1987, Dalmatian Pelican 2016. There really does have to be an “all or nothing” approach – balanced with pragmatism of course. A Budgie in the next garden in Stow would have a different level of probability!
At the end of the day, what is the difference between this bird and the wintering Rock Thrush in Kent in 1983, the Baltimore Orioles wintering in Gardens in 1989 and 2003, etc etc etc?
The initial DNA result from the Dungeness bird proved to be erroneous as a result of a lab error. A mix-up of samples meant the wrong bird was assigned to Stejneger’s. That sample was from another bird, at Spurn, and the Dungeness one was re-tested and proven to be a Common Stonechat. It matched the Richmond one in appearance, and the DNA on that bird also proved to be the same. This is good news in a way, as it means the field features for identifying these birds are upheld strongly, giving birders peace of mind that if there is no DNA, at least they should still be identifiable.
Stejneger’s is due to be countable as a British tick when the IOC taxonomy is adopted by the BOURC on 1st January 2018, so another one to go for in the future.