Intro to post by Martin G.
This little Goldcrest with ‘extra grey’ began a journey of questioning. The joy of others birders and learning from one another kicked in to play. Getting the privilege of being out with octogenarian Peter Colston, famed as the skin man at the Natural History Museum for many years- TRING! He flagged up ‘Eastern Goldcrest as we birded together watching this bird:
extra grey Goldcrest, Geosetter Burn, Shetland. October 2015. Peter Colston
Peter spoke. I had NEVER heard of eastern taxa. Just not come onto my plate. Two subspecies are flagged up here, now. The taxa coatsi and japonensis
Given the distance that Yellow- browed Warblers and Hume’s Warblers come from… reaching my garden at Flamborough- well :
How far do some late autumn the Goldcrests come from?
Do I know we get coatsi for sure? No idea. Can you identify them really? I don’t know. This might be hugely revealing or a flght of fancy. It doesn’t matter. It’s how we discover and I love exploring.
Spurn and Falsterbo (and Cape May)
and meanwhile… I get to champion the wonderful new partnerships. Falsterbo Bird Observatory and Cape May Bird Observatory are forming dynamic partnerships with Spurn Bird Observatory. So I am chuffed to have Stephen bring data from Falsterbo… and thinking of all those Goldcrest and the awesome ringing programme going on work at Spurn Bird Obs. These are wonderful heady days.
Goldcrests from further east?
Map of Goldcrest range from Wikipedia
Autumn 2014 saw exceptional number of Goldcrests ringed at Falsterbo Bird Observatory, Sweden – 11,581 to be precise, a record total and well above the 1980–2013 average of around 2,500 per autumn. The two biggest days came on 11th October (1,853) and 21st October (2,027). Most of the birds we caught were a bit greyer around the head than birds I’m used to seeing in Britain, although some – like the one below – probably wouldn’t be detected amongst British birds.
Above: regulus type ?
Most, however, looked like the bird below:
Above: ‘Continental type’?
It was difficult to know exactly where these birds were coming from. Recoveries gave us a clue as to where they had passed through: (elsewhere in) Sweden, Poland, Kaliningrad (Russia), and a few from Norway. The bird above, in fact, is a control from Kaliningrad. There was perhaps a tendency for eastern-ringed birds to arrive on average a tad later than Swedish/Norwegian ringed birds but I’m quite sure the whole movement was part of one single mass emigration. It’s my gut feeling that many of the Swedish-ringed birds were simply caught on their way through as they headed west in a broad front across northern Europe before filtering down through Falsterbo.
As the season went on, from about mid October, there was an increasing proportion of birds on which the head got greyer, the underparts got less saturated, and the mantle got greener. Some, like the bird below, were striking.
Above: coatsi type?
Side-by-side with a typical (“Continental-type”) bird
, the differences are even more apparent. The grey of the head is purer and more extensive – though we didn’t catch any birds with the grey extending down as far onto the mantle as the bird in this previous post (go HERE! )
– and the mantle is a purer green with a well-defined limit between the two. The buff tones on the underparts were greatly reduced. We also got the feeling that these birds looked consistently more “bull necked”, at least in the hand.
Above: coatsi type?
Some of the more extreme birds we were catching were almost approaching japonensis in appearance (see e.g. HERE)
I would be surprised if we were catching japonensis but I started to wonder how extreme coatsi could get. Spp japonensis is genetically quite distinct from the western group (nominate and the Macaronesian forms), though I’m not aware of any studies that have included coatsi. Nevertheless, we managed to catch a dislodged feather from one bird (not one of the extreme grey-headed birds, but noticeably grey-headed nonetheless – phenotypically somewhere between the two birds in the above photo) and we are awaiting analysis. My worry is that coatsi and regulus are just one big cline and a genetic sample isn’t going to tell us a great deal. Still, it’s worth a try.
These grey-headed green-mantled birds are probably regular visitors, perhaps occurring under irruptions conditions rather than as true migrants.
Indeed, I have photos of one from Falsterbo from mid-October 2012 (an autumn when 4,600 Goldcrests were ringed) but I didn’t note any during autumn 2013 (when just 1,100 Goldcrests were ringed). Sadly I haven’t spent any length of time at Falsterbo this autumn so I can’t comment on the situation there, other than the fact that – contra might what be expected given the arrival of birds on the east coast of Britain – the Goldcrest total stands at a distinctly average 1,850.
There’s still plenty to discover about these autumn-ariving birds and it feels like my brief look into the species has barely scratched the surface. Certainly, if the genetics do show the Falsterbo bird to be coatsi, there’s absolutely no reason to think the taxa isn’t reaching the UK too.