Be careful. More Questions still.
It’s become something of an enigma. Routinely recorded in old bird reports as abietinus (Scandinavian Chiffchaff), or sometimes ‘Eastern Chiffchaff’ as a catch-all for those uncertain tristis/abietinus. Birders are increasingly more savy and better informed. Siberian Chiffchaffs (tristis) are identifiable most of the time. And they are probably better classified as a full species…
We do still get birds with characters of more obvious abietinus and usually in conditions bringing other Scandinavian migrants (two memorable birds in mid October at Flamborough this year). Yet early studies showed all birds trapped in late autumn/ winter in the Netherlands and Britain and thought to be abietinus or tristis.…were all tristis.
Blessed with frustratingly good skills in photography and prose, Anthony McGeehan took these highly instructive comparative images of a stick-on Siberian and seeming Scandinavian Chiffchaffs on his haven on Inishbofin on Ireland’s west coast, in late October.
Do notice the differences- especially in ear coverts pattern and distribution of plumage tones.
The read on Siberian Chiffs is excellent- more on Anthony’s Facebook page is well worth a visit.
Topmost bird – a Common Chiffchaff with plumage tones typical of some (more obvious) Scandinavian ‘abietinus’. Many abietinus are indistinguishable form typical collybita (Magnus Hellström).
Lower 3 birds – All of the same Siberian Chiffchaff (tristis)
All photographs- Inishbofin, October 2014 by Anthony McGeehan