Saturday, 22 February 2014

Finches at Last .........

Getting two weeks of ringing in a row has been difficult in 2014 to date due to the unsettled weather, but this week we managed it!  A light south-westerly wind gradually increased over the morning, but despite this, and bright conditions making the nets more visible, it was a successful session, with 66 birds trapped.

Female goldfinch
The breakdown was as follows: wren 1 (0), blue tit 13 (5), great tit 5 (2), chaffinch 2 (0), greenfinch 17 (2), goldfinch 18 (1), reed bunting 10 (2).  Re-trapped (ringed) birds are indicated by the brackets.

The most welcome aspect of the session was that it was the first time since we started ringing at the site in March 2013 that the catch was dominated by finches.  Despite establishing a winter feeding station in autumn 2013 and keeping this stocked with sunflower hearts, black sunflower and millet at least twice a week, only small numbers of finches had been trapped previously.
Adult male goldfinch
As well as being very attractive, goldfinches are nice birds to catch as they can be aged and sexed (with a degree of caution) throughout the year.  Males tend to show dark nasal hairs, red on the head that extends well behind the eye, relatively extensive red below the bill (8-10mm as opposed to 5-8mm in females), and limited brown in the lesser coverts (this feature is not listed in Svensson).  Male wing lengths are often between 78 and 81mm, with females typically a few milometers shorter.  None of these features is likely to be 100% reliable in isolation, but many birds shows several or all of them.
Ageing goldfinches involves looking for retained feather tracts.  First winter birds sometimes have retained juvenile greater coverts, but more often have abraded, pointed tail feathers, frequently with brown tipping.  Adults, such as the adult male to the right, tend to show more rounded tail feathers.  Of the 18 birds trapped today, 13 were first winters, 4 fledged prior to 2013, and one was of unknown age (it was considered likely to be a first winter bird that had moulted extensively but this conclusion could not be reached with sufficient confidence for it to be aged so specifically).
Other welcome aspects of the session were the continued good numbers of reed buntings and the capture of what may be a 'control' great tit.  A further 8 new reed buntings takes the annual total to 28 (only 36 new birds were trapped in 2013).  'Controls' are birds that are ringed at sites more than 5km distant from where they are recaptured.  Great tits do not often move substantial distances, however, and this may actually point to the presence of a currently unknown local ringer!
Thanks to Heather Coates, Cedwyn Davies and Jessica Whitehead for their help this morning - particularly to Jessica for acting as scribe when we had a couple of relatively large rounds.
Owain Gabb
Reference.  Svensson, L.  (1992).  Identification guide to European passerines.  Privately Published, Stockholm. 

Sunday, 16 February 2014

Oxwich Marsh 16 February 2014

This morning saw the first ringing session at Oxwich Marsh for a month, following a sustained period of unsettled weather.  The rides were (predictably) almost knee-deep in liquid sludge, while an early covering of ice on the surface, made the experience like walking in a half frozen crème brûlée.  And to think I had been missing ringing ........

Male reed bunting
Although the feeders and bird table had been kept topped up, the catch was lower than in January.  The total of 37 birds was made up of the following: wren 1 (1), dunnock 2 (1), robin 1 (1), blue tit 13 (8), great tit 6 (5), chaffinch 1 (0), greenfinch 2 (0), goldfinch 1 (0) and reed bunting 10 (4).  The proportion of re-traps in the total for each species are indicated by the brackets.
The most pleasing element continued to be the numbers of reed bunting trapped.  Reed bunting is an amber-listed species of conservation concern in Wales due to a long term (moderate) decline in the Welsh breeding population.  There is a considerable data set held for the species for Oxwich Marsh.

The six new reed bunting trapped today, and the four re-trapped birds brought the total of new birds to 20 (only 36 new birds were ringed in 2013) and 'unique birds' to 26 in 2014.    As can be seen from the photos above and to the right, most male reed buntings are now starting to come into breeding plumage, with the striking black head feathers wearing through. 
Ageing reed buntings can be difficult, and a proportion should probably always be left un-aged - as educated guesswork just creates data noise.  Ageing is primarily on tail shape and wear, but both adult and juvenile tails can be very worn by February (this makes sense given the habitats they occur in), so tail shape is probably the more useful feature.  The shape of the tip of the fifth tail feather is suggested by Svensson as being the most reliable for separating 1st winter from adult birds (juvenile birds have a more pointed tip to the feather and a different shape to the final centimetre or so). 
Other than the reed buntings, it was good to continue to capture greenfinches, while a goldfinch was the first of the year to date.  Unfortunately, the pictures of the bird, and the features used to age and sex it were absolutely awful!

Thanks to Charlie Sargent for coming along.

Owain Gabb