Sunday, 31 July 2011

Bullfinch Bonanza at Botley Wood

An early morning ringing session on 29th July, did not produce the same number of birds as would be expected at Titchfield Haven, but the aim of the session was to try to catch any remaining Common Nightingales before they departed. Well, I failed on that count but still managed a total of 27 birds of 9 species. The species captured included 5 Robins, 2 Blackcaps, both juveniles, 3 Goldcrests, 2 Chiffchaff and a Nuthatch, but the most numerous was the Bullfinch, with 8 different birds captured. I have never had a ringing session where bullfinch was the most numerous species, and to make it even more interesting, the haul included a range of different ages and both sexes.

Male birds are stunning, with their bright pinkish-red underparts and their glossy black primaries, crown and tail. The mantle and back is ash grey, and the rump is white and is most obviously visible in flight.

Male Bullfinch

Females have the same glossy black primaries, crown and tail, but lack the pinkish-red underparts, instead they are brownish in colouration.

Female Bullfinch

Juveniles on the other hand lack the black crown, until they have undergone their post juvenile moult, which is usually completed by September/October.

Juvenile Bullfinch

The moult strategy for Bullfinch's is fairly straight forward, with adults undergoing a complete moult of all their feathers, whereas juveniles have a partial moult and therefore do not replace their wing and tail feathers. In the image below, all of the feathers are of the same generation, with no retained juvenile feathers visible.

Adult Bullfinch Wing

In the image below, a retained juvenile carpel covert and the alula covert can be seen to have a brownish fringe. I have inset a close up of these to feathers in the top right corner for ease of viewing. This bird would have been hatched in the summer of 2010, and is showing retained juvenile feathers, these will be moulted out following completion of its post nuptial moult in the next few months.

Second Calendar Year Bullfinch

The image below is a fully juvenile wing, prior to the start of its post juvenile moult. The brownish colouration to the tips of the greater coverts is clearly visible, in contrast to the greyish tone in the image above.

Juvenile Bullfinch

One of the male birds captured was a re-trap, which was originally captured on 6th June 2010 at the same site. This bird was originally aged as a second calendar year bird, which would have originally been hatched in the summer of 2009. 

All in all a good mornings ringing and I suspect that it will be a while before I catch 8 Bullfinch's in a single session again.

2 comments:

  1. Can't dispute your synopsis Trev. Well done!

    ReplyDelete

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