Saturday, 12 October 2013

Saturday 12/10/13

Redwings were dropping into the garden and taking a few Rowan berries from the trees early doors. None of the flocks stayed long and it was difficult to gauge numbers but many hundreds moved through or passed overhead during the day.

The wind was quite gusty but kept falling light in the relative shelter of the garden and I erected an 18ft net towards midday. A few hours later I had caught 42 birds including 33 new Goldfinches which was far more than expected.

The plumage characteristics of the Goldfinches caught provided some interest and I photographed quite a few to show the variation between adults and juveniles and between males and females. I was prompted to do this having seen a new Goldfinch ageing and sexing guide recently published on the BTO website and I felt I could contribute some additional material and knowledge.

I won't bore you with the feather by feather detail but my initial comments have been emailed to those involved with this new initiative. Some Goldfinches can be difficult to age and a fair proportion can be even trickier to sex with any certainty.

Juvenile Goldfinch with white sub-terminal patches to outer 3 tail feathers.
Some ageing guides say that birds with 3 white sub-terminal patches are
adult but this is not the case. I have caught quite a number of juveniles with
tails like the one above over the years including several today.

Juvenile Goldfinch with white sub-terminal patches to outer 3 tail feathers.

I also retrapped an adult Goldcrest in the garden which was unusual in the extreme. This was the first known age adult I have ever caught in getting on for 40 years of ringing. The tail shape wasn't quite as rounded as expected or as illustrated in the Svennson guide and goes to show how difficult it can be to age this species. I have caught a few Goldcrests with adult type tails over the years but this was the first with the age being confirmed by the ringing details.

Adult male Goldcrest.
Adult male Goldcrest tail.
Ringed as a juvenile male 27/09/12 and retrapped today.

In the late afternoon I wandered up to Longshaw and put a net up there for a couple of hours to see what was about. I only caught 8 birds with a Blackcap being the best of the bunch.

Ringing totals for 12/10/13 with retraps in brackets:
Goldfinch 33 (3)
Chaffinch 5
House Sparrow 1
Linnet 1
Great Tit 1
Blue Tit 1
Collared Dove 1
Dunnock 1
Goldcrest 1 (1)
Blackcap 1
Total 46 (4)

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