11 March 2013

Northern Chiffchaffs

Siberian Chiffchaff (Phylloscopus collybita tristis) is, to my mind, a superb bird with an appearance and call redolent of autumn migration. It breeds in coniferous taiga forest  from the Ural region eastwards and is regular in Britain in autumn, usually late autumn and sometimes wintering here.  Identification has gradually developed over the years and had seemed pretty secure regardless of the counter-intuitive nature of the grey and white Chiffchaff problem. There have, however, been recent developments in the process and therefore a lot of further comment regarding the identification of Siberian Chiffchaff. Martin Garner on his 'Birding Frontiers' site has worked through the visual features using photos and the audio  features including sonagrams. There has also been related material in 'British Birds'.

What are the features of 'tristis'?

  • The standard features of Siberian Chiffchaff remain in place. Briefly these are: a basically brown and buff bird with weak olive tones confined to wings, rump and tail. The head pattern is important, having a thick buffy supercilium and tobacco tinged ear coverts. Bill and legs are clearly black.
  • The soft, even monosyllabic note with a sad tone (as suggested by the name 'tristis') remains pretty conclusive, if somewhat subjective without a recording.

The problem of grey and white individuals.

  • Martin Garner suggests that descriptions of grey plumage tones or brown/buff plumage tones may often be affected by light and posture variations, both in the field and in photographs. It may be that what is considered grey and what brown or buff is variable and extremely subjective and should not rule out 'tristis'. 'Grey and white' birds have generally been considered 'abietinus' or just 'unknown'.
  • Some birds are very grey (cf a bird on St Agnes in October 2011 - photo and comment from Alan Deans in a recent edition of  British Birds). These seem to be rare and are, as yet, something of an enigma.
  • 'abietinus' often looks very like 'collybita' but the plumage demarcation of this race appears to be very poorly known.
Previously presumed 'abietinus' 2012
St Davids Hd  (Mark Hipkin)

The variety of calls.

  • Martin Garner has suggested that various calls are possible for 'tristis' not only the well known call already mentioned. It has been suggested that 'tristis' may use a range of calls other than the characteristic calls of'tristis'.
  • 'tristis' can call with a higher pitched 'happier' tone or with a 'collybita' type call.
  • However presumably all races can give eccentric or unusual calls.

This is a very brief note  but the 'Birding Frontiers' posts and the papers in British Birds and elsewhere on these topics are thorough and fascinating. They deserve to be read in full by anyone interested in the topic.

Where have all the 'abietinus' gone?

One of the catalysts for the current discussion is a study from The Netherlands. Between 2009 and 2011, 41 samples from birds identified as 'abietinus' or 'tristis' when trapped were sent for mitochondrial DNA analysis. The results were startling, all were 'tristis' (though obviously these results have to be tested and more tests done). So where are the 'abietinus' birds? Two independent studies in The Netherlands and Britain have found no evidence of 'abietinus' DNA in autumn and wintering Chiffchaffs.  Maybe they are the real rarity, perhaps because they have a north-west to south-east migration pattern as with Baltic Gull? Could it be that the 'washed out' autumn Chiffchaffs recorded fairly routinely as 'abietinus' in Britain (including by me and noted elsewhwere on this blog) aren't 'abietinus' at all? Clearly this is all speculation but it does seem that answers may be on the way in the near future.

'Northern Chiffchaff' originally presumed 'abietinus'
Porth Clais October 2011

 Siberian Chiffchaffs in Pembrokeshire

The Pembrokeshire Report has occasionally mentioned 'Northern Chiffchaffs'  ('abietinus' and 'tristis')  but not with much conviction and I don't notice any requirement for descriptions. I don't know if this means there are no descriptions extant, if not it may be difficult to revisit previous records (a good reason for descriptions and initials with records in my view). Other 'tristis' records have not been submitted (including by me). It seems to me that full descriptions of possible 'tristis' should be required by the Bird Recorders, preferably with photos and, where the characteristic 'tristis' call is absent, also with sound recordings? Perhaps it would be best if all Pembs birders sent them in anyway.

The following individual was seen but not heard by Adrian Rogers and Steve Berry at Goodwick Moor in 2008, it would likely have gone down as 'abietinus' but what is it now?

Pale Chiffchaff Goodwick Moor 2008
Photo Adrian Rogers

The same individual

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