The Siberian Chiffchaff is given by authorities as Phylloscopus (collybita) tristis, or Phylloscopus collybita tristis, or Phylloscopus collybita tristis fulvescens, or Phylloscopus tristis fulvescens. Because of the disagreement on its taxonomy and lack of sufficient data for firm taxonomy, it is also known generally by the plain name "Eastern Common Chiffchaff”It is a leaf-warbler which is usually considered a subspecies of the common chiffchaff, but may be a species in its own right.
Siberian chiffchaff breeds in Siberia east of the Pechora River and winters in the lower Himalayas.
It is also regularly recorded in western Europe in winter, and it is likely that the numbers involved have been underestimated due to uncertainties over identification criteria, lack of good data and recording policies (Sweden and Finland only accept trapped birds).
It is a dull bird, grey or brownish above and whitish below, with little yellow in the plumage, and the buff-white supercilium is often longer than in the western subspecies. It has a higher pitched suitsistsuisit song and a short high-pitched cheet call. It is sometimes considered to be a full species due to its distinctive plumage and vocalisations, being similar to P. s. sindianus in these respects.
Common chiffchaffs (of the nominate race) and Siberian chiffchaffs do not recognize each other's songs. Pending resolution of the status of the form fulvescens, which is found where the ranges of common chiffchaff (of the race abietinus) and Siberian chiffchaff connect and may or may not be a hybrid between these, tristis is maintained in P. collybita by most checklists.
Certain Siberian Chiffchaffs seem to differ in appearance in that they display some yellow/green on their face, nape and mantle and/or below. This type of variation has been described by some as ‘fulvescens’. While Vaurie described ‘fulvescens’ as‘relatively ‘grey and white’, Williamson acknowledged variation in the tone of the upperparts of ‘fulvescens’ and noted that some individuals showed yellow streaking below while on others this was absent. He interpreted this variation as arising from secondary inttergradation between tristis and abietinus. It is important to note that both Vaurie and Williamson included in ‘fulvescens’ birds from the region from northeast Iran to southwest Transcaspia. Chiffchaffs breeding in this area are now recognised as belonging to a separate race, menzbieri. Hence, the variation in upperparts colour and yellow streaking below commented upon by Williamson was at least partly influenced by individuals now considered to be from outside the distribution of ‘fulvescens’.
A somewhat different perspective on ‘fulvescens’ is apparent in the paragraphs on ‘Geographical variation’ in BWP. Here, the plumages of tristis are portrayed in two groups. A paler, ‘fulvescens’ type is described as having (inter alia): Upperparts brown to greyish-brown, with distinct olive tinge on rump and uppertail-coverts and sometimes slightly on mantle; underparts whitish, washed buff; tail-feathers, flight-feathers and tertials brown, outer edges olive-green.
A second type, regarded as the ‘classic’ or ‘typical’ tristis, is described thus: Rather darker brown with no or only very slight olive tinge on mantle, rump and uppertail-coverts; underparts with more distinct buff suffusion, appearing less white; edges to tail- and wing-feathers, tertials, and bastard wing more brownish, less greenish.
In this treatment, there is no mention of ‘extraneous’ yellow (i.e. yellow away from the bend of the wing and the underwing). Rather, it suggests a darker and browner ‘classic’ form of tristis, more intensely buff on the breast and flanks, and a rather paler and greyer ‘fulvescens’ form, with brighter olive fringes to feathers of the tail and wings and somewhat whiter on the underparts. While acknowledging that considerable taxonomic confusion exists (see below), both Williamson and BWP advocated that ‘fulvescens’ be included within tristis.
The original designation of ‘fulvescens’ The form ‘fulvescens’ was first described by Severtzov in 1873, based on a ‘type series’ of over 100 migrants taken ‘in Turkestan’. Thus, it was not described from birds on the breeding grounds, which Severtzov supposed to be western Siberia (although, rather confusingly, he adds ‘possibly near Irkutsk’, a locality which is hardly in western Siberia). We have not had the opportunity to examine the type series and it is a matter of assumption that the ‘type series’ actually consists of a single subspecies (see later comments on a ‘variant’ portrayed within the ‘type description’). Birds breeding from the Urals to the Yenisey are now generally equated with ‘fulvescens’.
There appear to be few, if any, detailed accounts in English of Severtzov’s original description. Clearly, the original description based on the ‘type series’ is important in establishing the correct use of the name ‘fulvescens’ and its implications in terms of appearance. Severtzov’s description (kindly provided and translated by Dr Vladimir Loskot, Curator of the Ornithological Department, Zoological Institute, Russian Academy of Sciences, St Petersburg) was as follows:
Ficedula (Phyllopneuste) fulvescens, nob. – (Ph. tristis? Gould). Upperparts, from forehead to uppertailcoverts and small wing-coverts rusty-grey with olive tint, olive-brown in autumn; supercilium and underparts rather pale rufous-yellowish, brighter in autumn; cheeks not pure rusty; wings and tail feathers blackish, with olive fringes which, on coverts, cover blackish middle of feathers; small underwing coverts sulphur yellow; first primary twice as long as its coverts; 3=4=5>6>7>2>8. Male and female do not differ from each other; in juvenile birds, differing in general only in looser texture of feathers, sometimes unclear longitudinal stripes of pale sulphur-yellow colour are present on the breast; in others, the breast stripes are similar but greyish (var. naevia), and then all the plumage is more greyish than usual. Bill and legs black; bill is relatively small even for a leaf warbler, and claws are large, especially on the hind and mid toes.
In comparing the basic description with modern interpretations of tristis, ‘fulvescens’ would appear to have more extensive olive in the upperparts and wing feathers and the presence of yellow in the supercilium and on the underparts. These features would today be regarded by many as indicating ‘intergrade’ characters. Overall, there is little in the basic description to indicate a match with the ‘paleand-grey’ individuals reported in Britain. A variant ‘naevia’ in Severtzov’s diagnosis is described as lacking yellow streaking on the breast, at least in juvenile plumage, and being greyer overall. This perhaps comes closer. However, the location of the type specimen of ‘naevia’ is unknown (Vladimir Loskot in litt.), so its precise characters cannot be confirmed.
Examination of skins confirms that birds from the Urals and the Ob basin are often slightly different from more easterly tristis, being slightly yellow beneath, with thin yellow streaks on the lower throat, and a faint yellow tinge on the fore-supercilium and/or eye-ring. Such yellow tinges are absent on other birds in this area, and on all birds breeding farther east in Siberia. Such individuals with limited yellow have been equated with the form ‘fulvescens’, notwithstanding the inconsistent descriptions in the literature (see above). Following this convention, the term ‘fulvescens’ is used hereafter to signify the yellow-streaked birds breeding in the region from the Urals to the Yenisey.
From Wikipedia, the free encyclopedia
And: http://britishbirds.co.uk/wp-content/uploads/article_files/V98/V98_N08/V98_N08_P396_410_A001.pdf
Photos Achelia 18/11/2015 by George Konstantinou
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