A Happy Ending...Hopefully

The last post was mostly about a redpoll. Between then and now there have been a few developments, so this post is likewise rather redpoll oriented. But first I should set the scene with a brief - and scrupulously accurate - review of redpoll taxonomy...

There is only one species of redpoll. It is called Redpoll. But just one measly species for so many different-looking birds? Well, that will help no one at all to get their list buzzing along rapidly towards 500 or more, so, officially there are actually three species of redpoll. Much more list-friendly. They are called Arctic, Common and Lesser Redpoll. Basically Arctic is white, Lesser is little, and everything else is Common. In the part of England where I live, Lesser is by far the most likely redpoll species to be encountered. Personally I've not seen anything but Lesser Redpolls locally. Arctic Redpoll is stupidly rare here, and Common Redpoll is almost as bad. Any claim of Common Redpoll would need to jump through all kinds of hoops in order to eliminate the possibility of a badly misinterpreted Lesser Redpoll. At this point, enter the Cogden beast...

The Cogden redpoll

As you could probably tell from the previous post, this intriguing little bird got me all fired up and, with basically nothing else of interest around, it has had my undivided attention. And in yesterday afternoon's blasting hoolie I headed out once again to Cogden to see if it was still there. Flooded roads meant I had to walk all the way from Burton Bradstock, but I didn't care...

Rough...but lovely

The redpoll was exactly where it had been the day before, but in the dismal light it seemed a waste of time to take photos at pathetically slow shutter speeds, so after a few pitiful efforts I tried a bit of video...

I was very pleased with the outcome, especially as point-blank range means there is hardly any shake at all. The dreadful background noise is the sea by the way.

Anyway, when I first stumbled across this bird on Saturday, its appearance was so striking that as soon as I'd got a few shots I was straight on the phone to Steve Waite, hoping he might have had experience of a few Lessers in the hand during his ringing exploits. Among other things, we talked about the importance of biometrics (measurements taken when a bird is trapped for ringing) and whether it might be possible to assess the bird's actual size in the field somehow.

At the time I couldn't think of anything, but later that evening had an idea. So. Back to yesterday...

Despite the rubbish light I did take a handful of shots, for a very specific reason. When the bird had moved from its perch, I found a bit of dead unbellifer stalk, propped it up exactly where the bird had been, and took a photo from my original position. It wasn't perfect, but good enough I think. I then carried my precious, flimsily brittle stick the two miles or so back to Cliff Road in Burton Bradstock, trying not to let the wind snatch it from my grasp (or snap it) as I battled along the raging beach. And this evening I did this...

In-the-field biometrics (patent applied for)

Explanation: On the right is my stick, placed where the bird had been. When I got home I found two identifiable spots on the stick, two corresponding spots on the adjacent herbage, and measured the distance between them. I could then take that measurement back to the photo of the bird, and when I'd drawn some lines approximately where the start and finish of a wing-length mearurement would normally be taken, use my stick-gauge distance as a scale. That's where the figure of 76.8mm comes from.

Discussion: Yes, I know. Super-rough. But, I have been reliably informed that an in-the-hand measurement would likely be a few millimetres longer, because the wing is straightened and flattened against a rule. Also, if the bird is actually not 100% side-on to the camera, that wing will be foreshortened, so again, add a millimetre or two.

According to the definitive 2013 British Birds paper on redpolls, Lesser Redpoll wings measured from 62-77mm, with a mean of 69.5. Meanwhile, Common Redpolls of the Greenland variety (the suspected identity of the Cogden bird) measured between 71 and 85mm, with a mean of 78.4. I rest my case.

To be honest, I'd have been a bit stuffed if the measurement hadn't been favourable. But in the event it merely backs up what seems to have been a concensus view from everyone who has kindly thrown in their two-penn'orth on this bird. It appears to be a Common Redpoll of the Greenland type, Acanthis flammea rostrata. I understand this is a first for Dorset.

PS. Just in case anyone missed it, I did not find this bird; I saw it on its second day.

And this is a prime example of what sometimes happens when the birding is very slow. Out of nowhere comes a fascinating little bird which presents a challenging puzzle. And a bit of quality time is nicely repaid with a satisfying conclusion*. Brilliant.

*I hope.