Sunday, 19 January 2014

Oxwich Marsh 19 Jan 2014

The second session of 2014 coincided with a relatively hard frost that froze the padlock to the gate of the site (which needed some warming up prior to working).  The weather was otherwise pretty good for ringing, however, with a gentle south-westerly breeze and relatively open skies.  Recent rain had left several inches of standing water in most of the net rides, and the area had also been churned up by Highland cattle (which are used to seasonally graze the marsh), resulting in a muddy soup.  Hopefully the combination of flooding, trampling and grazing will deter / supress bramble regrowth in the spring ......

Male Chaffinch
We had the nets up by dawn, by which time there were already reed buntings and chaffinches feeding in the rides.  By the time we took the nets down, at around 11:40, we had captured 66 birds of 8 species.  The catch was made up of the following (recaptures are indicated in brackets): great spotted woodpecker 1 (1), dunnock 1 (1), robin 2 (2), blue tit 39 (19), great tit 3 (1), chaffinch 4 (1), greenfinch 3 (0), reed bunting 10 (3).


Blue wearing through on head of chaffinch












An increase in reed bunting numbers was readily apparent in the marsh, with an estimated 20-25 birds foraging around the feeding station.  Capturing 10 of these was a relatively good return, and brings the annual total to 19 unique birds for 2014.  In 2013 36 new reed buntings were ringed.  With 14 new birds already in 2014, it is looking like last years' total will be exceeded.


Of the 38 chaffinches that had been ringed at the marsh since March 2013, only one had been recovered prior to the session this morning.  It was therefore initially hoped that a ringed bird would prove to be a control.  This didn't prove to be the case, but the bird did show a good range of adult features and was aged correctly (a subsequent check showed that the bird had been ringed as an adult male in March 2013 so it was likely to have been at least 18 months old when re-trapped today). 

Some of the key features used for ageing chaffinches can be seen in the two photographs above.  The shape of the tail feathers of 1st winter male chaffinches is typically rather pointed, whereas in adults (like this one) the tail feathers are rounded and broad (see photo above left).  There is also some green edging to the central tail feathers that is visible here - this feature is listed in Svensson (1992) as being typical of adults.   The photo of the wing (above right) shows that there are no retained greater coverts, and little contrast between the alula feathers / primary coverts and the greater coverts (retained greater coverts or clear contrast would both be indicative of a first winter bird - as they would indicate a moult limit).

Hopefully next week will bring good weather, better diversity and a higher proportion of finches in the catch.

Many thanks to Charlie Sargent and Aaron Davies for coming along this morning.

Owain Gabb
19/01/2014

Reference.  Svensson, L.  (1992).  Identification guide to European passerines.  Privately Published, Stockholm. 

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