Monday, 15 February 2016

Oxwich Marsh 14 February: an influx of finches

The first ringing session in a while, following a couple of weeks of rain and wind.  Over the past few days the wind had swung to the east, and although it was not as light as forecast, we were able to get a session in.  It was a cold, relatively bright morning with a light to moderate south-easterly breeze.

The catch of 70 birds was as follows:

Species
Ringed
Recaptured
Total
Dunnock
0
1
1
Blackbird
0
1
1
Blue Tit
2
2
4
Great Tit
3
4
7
Chaffinch
3
1
4
Greenfinch
2
1
3
Goldfinch
20
8
28
Siskin
17
4
21
Reed Bunting
1
0
1
Total:
48
22
70

The features of the catch were 21 siskin and 28 goldfinches, most of which were newly-ringed.  All of the birds were captured in a single 60-foot net.  It was nice to see a number of returning siskins from 2015, including the male (below).  We aged this bird as a 6 (hatched before last calendar year but exact year of fledging unknown) based on the criteria listed in Svensson (1992), some of which are illustrated in the photographs below.  IPMR Data later revealed that the bird was initially ringed as a 5 (a first winter / second calendar year) when first captured in the late winter of 2014/15.  

Siskin (male)
Siskin (male) showing relatively broad and largely unworn tail feathers typical of an adult as opposed to a juvenile.  The tertial tips are also visible at the top of the photo. In first winter birds the tertials are often unmoulted, and do not show the smart broad white fringes visible here.
Close up of the greater covers showing the uniformity in colouration across them
Most first winter goldfinches can be aged on evidence of moult limits in the wing (with the most straightforward to age having retained greater coverts), and the shape of / wear in the tail feathers. Some are challenging, however, such as the goldfinch shown in the following pictures.  This bird had moulted its tail completely, and showed rounded, unworn feather tips.  However, close inspection of the wing suggested that the alula feathers and primary coverts had been retained.  The bird had also moulted most of its primaries and secondaries, and moult of these feathers is more typical of adult than juvenile birds. However the three outer primaries had not been moulted (as is clear from the photo below); they were markedly shorter, bleached and also showed different tipping:

Goldfinch wing showing three retained primary feathers.  The bird also appeared to have unmoulted alula feathers and primary coverts.
Tail of goldfinch (no juvenile feathers present).
We concluded that this bird was aged 5 (a first winter bird), but had undergone an extensive post juvenile moult including some of the primaries and secondaries, but would be happy to hear any thoughts.  

Thanks to the team of Heather Coats, Wayne Morris, Emma Cole and Val Wilson for company and assistance yesterday.

Owain Gabb
15/02/2016

2 comments:

  1. I can see where all my garden goldfinches have gone now...

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  2. There are at least 80 goldfinch and probably 50 siskin present there at the moment Alun - albeit it is very difficult to get any accurate estimates with flocks constantly milling, coming and going.

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