Sunday, 16 January 2011

A buzzard's tail

I have been trying to get a photograph of this Common Buzzard's uppertail for quite a few weeks. After having seen an intriguing buzzard at Barn's Ness earlier in the autumn, I thought I would try spend more time studying the plumage of the local birds.

This regular bird in the Hermitage of Braid, Edinburgh, caught my attention with its clean white underwings. This feature, combined with its apparently rufous uppertail, is more typical in eastern forms (vulpinus). Of course the plumage of Common Buzzard is very variable and the compact structure of this individual tells us that it is likely to be a local bird (buteo). That it is not particularly massive suggests that it is possibly a male.

This photo was taken in early December. The pale flight feathers with fine bars may be more typical of vulpinus than buteo, but the dark brown rather than reddish coverts along with the diffuse border of the dark trailing edge of the wing are more typical of buteo. Structurally it appears to be a perfect buteo, with no suggestion of vulpinus. Notice that it has lost the tip of primary 9 on its left wing.

I next managed to see the same bird a month later - its missing primary tip obvious as it passed over. The pale flight feathers were emphasised by the dark trailing edge but the uppertail and upperwing was not visible.
 The following day it drifted past again over a ridge.
 This time I glimpsed some complex upperwing detail.
 Then it lost some height and gave a quick hint of a rufous tail before disappearing behind trees.

The next sighting was earlier this week. The buzzard was the target of this mass mobbing event by 20 Carrion Crows, 6 Rooks and 4 Jackdaws. I left them to it as I felt that the bird already had enough problems without me adding to them.

Finally, today I managed to get a reasonable view of the uppertail as well as a couple of record shots. My suspicion that the bird had some rufous in its tail proved correct.
The shots with the spread tail show that the outer web of each feather has darker pigmentation, whereas each inner web is reduced in dark pigment and appears whiter and allows the underlying rufous colouration to show through. This, I think, is a fairly common tail pattern in buteo. Nevertheless, this tail, when combined with strong pale bases of the primaries made for a surprisingly contrasty upperpart colouration - well worth the patient stalk in my opinion.

No comments: