It is that time of year at my ringing sites, where the summer migrants have yet to arrive and the winter visitors have all but gone, but despite that it has been a steady weekends ringing which included a nice couple of surprises. With some interesting bits to write about I have decided to spread things out over several posts, rather than cram it all into one, so here goes with the first.
This weekends ringing started with a couple of hours in the garden on Saturday afternoon, a couple of Great and Blue Tits got things going, and then I caught a retrap Eurasian Robin, nothing unusual about that, but this bird had a fully formed brood patch. I have been watching a pair of Robins, and Blackbirds, in the garden for a few weeks now, but wasn't sure whether they had started nesting yet....but I guess this confirms it. After release this bird flew straight down to the end of the garden and jumped into the open fronted box on the rear fence, so I now know where she is nesting too!
After a couple more Great Tits the next bird captured was a male Greenfinch, which was quickly followed by two more, giving me the ideal opportunity to compare the features of the different ages.
Adult Greenfinch's undergo a complete moult post breeding, whereas juveniles undergo a partial post juvenile moult...usually, sometimes they also have a complete post juvenile moult. Therefore, it should be possible to age birds due to the presence of a moult limit in the greater coverts, and also due to the shape and colouration of the primary coverts, and other feathers.
|First year male Greenfinch. Note retained outer two greater coverts|
and colouration and pointed shape of primary coverts.
The first bird captured was an obvious juvenile since it had two retained greater coverts, very pointed and brownish primary coverts and abraded primary tips. In addition the tail feathers were very pointed and abraded. So no doubt with this one.
|First year male Greenfinch. Note pointed and abraded tips|
to tail feathers.
In stark contrast the next bird was a full adult. Its primary coverts were broad, rounded and tipped grey.
|Adult male Greenfinch. Note steely grey colouration and |
rounded tips to primary coverts
In addition, the primaries themselves were broad very dark with a grey tip and showed very little wear.
|Adult male Greenfinch. Note broad and rounded primary feathers|
and lack of abrasion to tips.
The tail feathers were also very dark centred, broad, rounded and tipped grey, and as with the primaries they showed very little wear....so no doubting this one either.
|Adult male Greenfinch. Note broad, rounded and dark centred |
tail feathers, also lack of abrasion and grey tips..
The third bird was a little more interesting. Looking at the primary coverts this bird was a first year, since the outer three and the alula were narrow and pointed, whereas the inner primary coverts were more rounded with a slight grey tip.
|First year male Greenfinch. Note colouration and|
shape of primary tips.
The primaries themselves were also indicative of a first year bird, since the were more pointed and abraded than those of the adult, yet not as worn and darker that those of the first bird.
|First year male Greenfinch. Note shape, colouration and|
abrasion to the tips of the primaries.
The tail though was more indicative of an adult bird; broad and rounded although there was a more pointed and worn feather on one side (tail feather five on the birds left side).
|First year male Greenfnch tail. Interesting one this, the feathers|
are generally broad, rounded and dark centred, except that is for
tail feather five on the birds left (lower) side.
The presence of juvenile primary coverts, and the shape of the primaries, clearly ages this third bird as a first year, but it was interesting to see the variation between the three birds.