Tuesday, 29 January 2013

Garden Bird Ringing January 2013

Bird ringing at my usual haunts has been somewhat disappointing of late and so rather than risking another disappointing session, I opted for a bit of garden ringing for this session. On the plus side this would mean that I could fall out of bed and have the nets open within five minutes, but on the negative side it would mean that I would catch loads of blue and great tits, and probably not much else. The day started as expected and before long I had a net full of blue and great tits, which consisted of mainly retraps but also a few new ones. 

Blue Tit Cyanistes caeruleus - one of 23 birds captured during the garden ringing session. of
those captured 15 were retraps, two of which were originally ringed over four years ago,
one on 6th December 2008 and one on 31st December 2008. 

There have been two great spots Dendrocopos major, one male and one female, frequenting the garden and both of them were squabbling over the peanut feeder, before the female ventured into the net. This bird was very easy to age since it had an obvious contrast in the greater coverts, showing  the difference between old juvenile and newer adult type feathers. A retrap dunnock Prunella mondularis was a bird from just over a year ago, and new song thrush Turdus philomelos and blackbird Turdus merula were worthy rewards for my efforts, before two pied wagtails Motacilla alba ssp. yarrellii dropped into the net. 

Pied wagtail - first year bird

Over the last few winters one or two pied wagtails, and the occasional white wagtail Motacilla alba ssp. alba have spent much of the winter in my garden, and as a result I usually end up catching one or two. These two birds, I am presuming they are the same two, had been frequenting the garden all through the recent cold snap and heavy snow, so it was not really a surprise to catch them, but a welcome break from blue tits.

Pied Wagtail - First winter bird - there is an obvious contrast between the outer wing
(primary coverts, primaries, secondaries, alula etc) and the inner wing
(lesser, medium and majority of greater coverts). Note the two outermost greater
coverts, which are retained juvenile feathers. The general coluration of the outer wing is
brown-ish as opposed to dark grey below.

The moult strategy of this species is similar to that of many passerines, in that adult birds undergo a complete moult in the summer, post breeding, whereas juvenile birds only undergo a partial moult. The result of this I have discussed before, but essentially it means that a contrast will be visible between the old juvenile feathers and new adult feathers. Luckily I caught one adult and one first year bird, which was ideal for comparison.

Pied Wagtail - Adult bird - note the general colouration of the wing (dark grey) and the broad
primaries with a pale tip on the outer edge of the feather. In addition, there is no contrast/break
in the greater coverts and the primary coverts are broad and tipped white.

At one point I noticed a male Eurasian Siskin Carduelis spinus on the peanut feeder, a species that was very common in my garden six or seven years ago, but recently I have not recorded them. I watched the bird for a while before it flew off, so I was surprised to find, that not only had it come back but I had caught it.

Eurasian Siskin - male bird - note the black crown, and extensive yellow
 to the sides of the head and breast

Adult siskins undergo a complete moult post breeding, whereas juvenile birds usually undergo a partial moult, and so there will typically be a contrast between juvenile and adult feathers in the greater coverts. In addition the tails feathers on juvenile birds are usually pointed and show a high level of wear. This bird showed no discernible break in the greater coverts and the tails feathers were broad and rounded, with very little wear, therefore this bird was aged as an adult.

By the end of the session I had captured 42 birds of 11 species; more than half of the birds were blue tits, but they still provided some interesting retrap data. The variety of species ringed was unexpected so it was definitely worth the effort.

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