Saturday, April 05, 2008

I've found a Siberian Chiffchaff (Phylloscopus collybita tristis) on a small wooden hill in my district (southern Budapest). The first thing I've noted was its non-Chiffchaff like contact call (later realized that it's really Nightingale like as it's said). When I've located the bird, immediately noticed how brown it was, and luckily he started to be singing immediately, making the whole thing suspicious enough to rush for my brothers (in fact we live very close to this patch, this was the practiceing ground for us as teenage birdwatchers. eg. I've seen my very first Blue Tits here).
In the following days we could make detalied observations of the bird, took hundreds of digital photographs, and recorded his calls (contact calls, song, and other). Here I attatch some of my photos with notes on the plumage of the bird.
My very best photo of it, of course with the head turned away. Please note that teh colour of the photos are quite variable, making the judgement of the bird's exact colour not totally reliable. In the field we noticed that there was no yellwo in the plumage (except for the inner wing coverts) and we couldn't notice any greenish hue neither.
On this photo you can discern a faint greyish wingbar. Please note that not only the tips of the coverts are paler, but also a part of the side.

The flanks were greyish-brown, paler than the back, isolating a relatively small white belly patch. Note the dark legs, and the lack of a small yellow patch at the bend of the wing (which I find quite characteristic of the Chiffchaffs breeding here).

Again note the white belly-patch, restricted to the area between the legs. In fact this character was the best separating this bird from the common Chiffchaffs when not calling.

After finding the bird we played tristis song to him, and he reactd quite uniquely. He sat quite patiently near the of bushes, in the open, and was trembling his wings in a manner quite similar to a Starling, giving soft, very Greenfinch-like calls. The yellow innerwing made us uncertain about the identity, but I've found information on the internet that tristis has yellow there (and Hungarian ringers visiting Mongolia also noted that all the tristis they caugth had yellow innerwing). Note the white feather shafts on the breast and the head. Can they be growing feathers?

Again we found the dark flanks a very unique feature compared to the other Chiffchaffs:

Here you can see the isolated white belly patch. Note that the supercilium has no yellow in it (again a usual character of the local Chiffchaffs).

In sunlight the bird appeared more cold greyishbrown, while in overcast light he became more warmer brownish.

The bill was very dark, when seen from below we could see that the inner part of the lower mandible was a bit paler. Diffuse supercilium with no yellow in it, even with some reddish hue in the part in front of the eye.

The bird could be located quite easily when calling. The Nightingale-like contact call was quite different from the call of the common Chiffchaffs (direct comparison was possible as the hill was full of migrating and resident Chiffchaffs).
The song was also very different from the Chiffchaff song, with rarely a clear 'chiffchaff' note. When I first heard it my impression was that it's a mixture of the song of Chiffchaff and Willow Warbler. Our bird was actively singing in the mornings, and rarely in the afternoons.
There was a series of other calls we noted from the bird (I think also recorded), that I don't remember I've ever heard from Chiffchaffs. Most noteably the above mentioned soft, Greenfinch-like calls. I've videoed this call with the Starling-like behaviour (if it's interesting I can post this video also in my blog).
The bird was still present this morning, so I'll go out again tomorrow, at last trying to make some colour sketches.


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