Greenfinches – a closer look
Last week I received new rings and dug out my ringing equipment and nets here at the farm in Denmark. The last feathers I felt in my fingers were neo-tropical birds in the lowland jungles of Peru. It was both exciting and refreshing to reacquaint myself with some locals, despite the fact that the spring weather left my fingers more than a little cold and stiff – that didn’t happen in Peru!
One of the first birds I caught was a male greenfinch (Carduelis chloris). I haven’t had much experience with greenfinches, having ringed a total of 4 to date, and I didn’t realise they could present some interesting challenges, especially in spring. Adult birds undergo a complete post-breeding moult in the late summer / early autumn, while first year birds have a partial post-juvenile moult slightly later than the adults, which can be limited or quite extensive, sometimes including primaries as I found out from David Norman’s detailed blog and Stephen Menzie’s blog. However in southern greenfinch populations the post-juvenile moult can also be complete (Harris, 1992).
I decided to review my photos to better understand how to accurately age Greenfinches in spring, for when I (hopefully) come across them again. Firstly the plumage was in superb condition with bright contrasting colours and sharp clean edges on the feathers, with little or no sign of wear. The primaries and secondaries appeared dark, with a pale yellow edge. The tertials were broad, square and grey with dark centers (adult like). I was unable to find a moult limit within the greater coverts, or any contrast in wear between the adjacent carpal covert or alula (adult like) .
The primary coverts were round in shape and had dark centres, with a yellowish green fringe, becoming greyish towards the tip of the feather (adult like). The tail feathers were broad, rounded and also in good condition (adult like). Having a closer look at the wing I spotted a feather which was a little different to the others. The innermost secondary (identified above with red arrow) contrasted with both the tertials and other secondaries as it was more brownish in colour, showing a reasonable amount of wear.
Combining all the information “presented” in the feathers, along with photos and information from various sources, it appears that this bird is an adult (3rd calendar year or older, EURING 6). However it has retained one secondary from the previous years plumage. According to Jenni & Winkler (1994) arrested moult, where a bird retains unmoulted feathers can “accidentally” happen in almost all species. It is more common among birds with that have limited time to moult i.e. long distance migrants, northern populations and late breeders.
As mentioned previously, research has shown that in southern populations (Harris 1992 in south Portugal) first year greenfinches (among other finches) can undergo a complete post-juvenile moult, thus making it difficult to differentiate age groups from late autumn onwards. However as this greenfinch was caught in Denmark, I think there is a very small possibility that it is a juvenile with a very extensive post-juvenile moult, retaining one single secondary. Furthermore I would expect a retained juvenile feather to have far more extensive wear, as the feather quality of juvenile feathers is much poorer than that of adults.
With southern greenfinches in mind I dug out some photos I took while ringing in Aiguamolls National Park in northern Spain in the spring of 2014. It is possible that the female greenfinch below is either an adult (EURING 6) having undergone a complete post-breeding moult, with no retained feathers, or a second year (EURING 5) with a similar complete moult, with no retained juvenile feathers. I’m somewhat glad I’m on the northern edges of the breeding range!
Now all I have to do is catch a few second years to put it all into practice!
First-year Greenfinches with moulted primaries – David Norman Blog
Finchy Fun – Stephen Menzie Blog
Harris, P. (1992) Ageing finches in southern Portugal, Ringing & Migration, 13:3, 175-176
Jenni, L. & Winkler, R. (1994): Moult and Ageing of European Passerines. Academic Press, London, UK