Saturday, 8 April 2017

The astonishing tail of the blue rock thrush!

When a blue rock thrush turned up in somebodys back garden in Stow-in-the-Wold in Gloucestershire in late December last year there was mixed reaction. Although some people embraced the bird and dashed off to see it, others were more cautious and questioned its credentials as a wild bird. Even I waited until the beginning of January to go.

How could this be? A bird which in Europe is unapproachable was overwintering and showing well in back gardens and on the roofs of a housing estate in leafy Gloucestershire. Not just for a day, but for 3 months! Then the analysis of its plumage began. It's wing was a little droopy, it's bill didn't look quite right and it permanently looked like it was trying to cough something up. Possible signs of captivity? Many thought so, but others weren't convinced. Interestingly, it also had a an unusually short and distinctive central tail feather, which at the time didn't seem important either way, but ultimately was to prove a decisive feature.

However when photographs appeared, showing what looked like a gossamer thin strand of thread around its leg, the birds fate seemed sealed. But was that a man made thread? It was incredibly thin and couldn't be seen on any of the early pictures of the bird, and it was not seen on later pictures. Perhaps it was just something it had accidently picked up in its wanderings around suburbia?

Rumours began to spread. Some bloke in Kent claimed it was his. There was talk of a car crash, a damaged aviary, an escape, a night flight to freedom. It seemed that anything was possible with this bird.

Eventually the bird obliged by leaving some DNA which was collected and whisked off to the Doc in Aberdeen. Analysis of the DNA proved that the blue rock thrush was of the sedentary south west European race rather than of the migratory eastern race, further strengthening the belief that it was an escape. Still a few of us clung onto the hope that it was wild, but how could it ever be proven either way? It looked as though it was just one of those birds which would never get accepted as wild by either the British Birds Rarities Committee (BBRC) or the wider birding community. Yes it's your list, tick it if you like, but don't be surprised if we all snigger behind your back!

Everything changed on the 7th April though, when a blue rock thrush was found at Beachy Head in Sussex, 150 miles south east of Stow and at a classic migration point. I jokingly tweeted that it was the Stow bird moving south east back to its breeding grounds in Europe, but in truth I didn't really believe it. However somebody then noticed that the Beachy Head bird also had a droopy wing and a slightly odd bill. What's more it had a short central tail feather. This could only mean one thing. It was indeed the Stow bird!

Still questions persisted. Why did it stop at Beachy Head and not continue on to France under the clear skies? The droopy wing might offer a clue to this, suggesting that it's not as strong a flier as it should be. Perhaps it bottled it at the sight of the Channel and was waiting for another day. Who knows? We held our breath.... would it do the decent thing and be gone in the morning, further enhancing its credentials as a wild bird, or would it spoil things by staying 6 months at Beachy Head? The following day we had our answer, it was gone, and at the time of writing there have been no further reports. Hopefully it is now on it's breeding grounds in south west Europe.

Of course even this remarkable relocation doesn't prove that this is a wild bird, since captive birds are sometimes known to attempt to migrate, but surely now it's as good as it gets, beyond reasonable doubt? No doubt here will always be people who question it's credentials, especially amongst those who didn't go to see it because they were so convinced it was an escape from the beginning, and to be honest I'd more or less written it off myself. I'd reached the stage of half heartedly joking about it being on my list whatever the BBRC decided. But if we're still going to persist in calling this a likely escape, then to be consistant we'll have to qualify a large proportion of other birds we see as possible escapes, even the likes of a golden eagle in the highlands could be an escape. Blue rock thrush is definately on my UK list now.

To be honest, even if it is utlimately proven to be an escape, it's been great fun and well worth seeing and being part of. Much better than sitting at home and slagging it off.

Blue rock thrush..... it went from joke plastic tick to Bird of the Year so far in a few short hours! I hope that you got to see it. It was there for 3 months after all!

Update August 2017: Blue rock thrush accepted as a wild bird by BBRC.

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