The forecast for the day of our latest scheduled ringing session was for strong winds and rain showers so at very short notice we brought it forward a day and fortunately five members were able to make it. Wind was forecast to be light but picked up a little as we were setting up, so nets were restricted to the sheltered spots in and around the scrub at the top of Colyford Common.
|Ringing base at Colyford Common|
Ten birds were processed with some showing clear signs that the breeding season is well underway. Two male Dunnocks showed typically pronounced cloacae and a female Song Thrush a well defined brood patch (BP2).
|One of the Goldfinches had an unusually speckled head. |
The AERG only rings about ten House Sparrows on the Axe estuary each year. House Sparrows belong to a small group, which includes Long-tailed Tits, Larks, Starlings and Corn Buntings, that undergo a complete post juvenile moult in the autumn rather than the more usual partial moult.
|Male House Sparrow|
So when we caught a bird at this session we automatically aged it as a 4, i.e. a bird that could have hatched last year or earlier. Both adults and juvenile Sparrows would have carried out a complete moult after the breeding season and an immature House Sparrow would not have retained any juvenile wing feathers which, in other birds, are a leading ageing criteria used to identify immature birds.
As we are always trying to hone our skills, we looked in Laurent Demongin's 2016 Identification Guide to Birds in the Hand, where we were surprised to learn that more than 80% of male birds can be aged. According to Demongin, the median coverts (MCs) in the immature male show "proximal half MC1-MC8 black, distal half white with shaft +/- black" whereas in the adult they are "virtually all white, distal part of shaft without black". Also the immature bird shows a "narrow brown edge on alula 2" whereas the adult shows "a broad rufous edge".
The wing of this bird shows black on the MCs and a narrow brown edge on alula 2, so according to Demongin, we think it's probably a bird hatched last year, i.e. age code of 5. From now on we'll be looking more closely at every male Sparrow we catch to see if this identification feature works.
|Features which suggest this House Sparrow could have been hatched last year. |
We packed up early as conditions deteriorated a little and were joined by two more members to carry out the long awaited group activity, the sorting of nets and labelling of the new net bags.
|Net details being ironed onto new bags, colour-coded for length.|
| A long overdue job well underway....although not quite completed. |