A Snow Bunting performs

19th January 2015 - Powderham

Here are a few shots of the very obliging Snow Bunting which has taken up residence on the cycle track near Powderham. Snow Buntings are often tame but this one seems to want to be photographed - to be honest I almost stepped on it, it was so close I had to move back to get it in focus.

Snow Bunting - 19/1/2015 Powderham

Snow Bunting - 19/1/2015 Powderham

When disturbed by passing walkers it just flew on to the wall or over to the rocks on the estuary side, always returning to feed in the shaded side of the path - maybe it was too hot in the sun?

Snow Bunting - 19/1/2015 Powderham

Snow Bunting - 19/1/2015 Powderham

So, a nice accommodating bird but, as ever, I can't resist digging a bit deeper to see if any more can be deduced - what age is it? Male or female? And, if possible, what subspecies? Apart from the obvious Svensson (1992) and, as it's a Bunting, Byers et al (1995), I also found Rae & Marquiss (1989) and Winters (2013) extremely useful.

The sex is the easiest to determine, the sharply pointed black centres to the scapulars indicate that it's a female (on a male they would be much more rounded). The underside of the primaries is also a safe character though often hard to see in the field, luckily it gave me a handy view as it preened. It showed a white underwing shading diffusely into darker grey primaries, this would be blacker and more sharply defined in a male.

Snow Bunting - 19/1/2015 Powderham

Its age is rather more difficult to decide. The shape of the tail feathers can be useful - pointed in 1cy, more rounded in adults - but this is hard to assess accurately, at times they looked pointed, at other times more rounded. The degree of wear on the tertials and greater coverts is also a guide - 1cy birds should look more worn than the more recently moulted adults. Again this is hard to judge but this next shot does show what look to be fairly worn inner GC's. However, the longest tertial doesn't look particularly worn so perhaps it's best left unaged.

Snow Bunting - 19/1/2015 Powderham

If ageing it is tricky maybe I shouldn't even think about subspecies but, fools rush and all that...

I can't help thinking that there's a degree of contrast between the pale and fairly cold fringes to the mantle feathers and the slightly warmer toned scapulars. Also the underparts are very white with only a hint of colour on the flanks. I would suggest, tentatively, that this points towards it being nominate nivalis since insulae (the commonest in winter in Britain) should look darker and warmer brown above and more saturated below. A diagnostic character is the amount of white on P2 (numbered descendantly); ≥ 60% = nivalis, ≤ 40% = insulae. I tried but I couldn't get it to fully spread a wing, or even fly much at all.

Nominate nivalis (coming from as near as Scandinavia) isn't all that rare in Britain (not sure about Devon) but it's believed to be less frequent than insularis (from Iceland and Scotland). Anyone got any opinions on this one?

References

 

Byers, C., Olsson, U., & Curson, J. 1995. Buntings and Sparrows. Robertsbridge.

 

Rae, R., & Marquiss, M., 1989. Ageing and sexing of Snow Buntings wintering on the Aberdeenshire coast, their biometrics and sex ratios. Ringing and Migration 10: 133-140.

Svensson, L. 1992. Identification Guide to European Passerines.
Fourth edition. Stockholm.

Winters, R., 2013. Snow Bunting: sexing, ageing and subspecies. Dutch Birding 35: 7-14.