Blagdon Lake Birds

Common Chiffchaff Phylloscopus collybita (Vieillot, 1817)

Siberian Chiffchaff Phylloscopus c. tristis Blyth, 1843.

1.  Two, 29th Nov. 1992 to 13th Feb. 1993 (A.H. Davis, R.M. Andrews et al.). Heard calling.
2.  One, 24th Mar. 1996 (A.H. Davis)
3.  One, 20th Jan.-1st Feb. 2023 (N.R. Milbourne, R. Mielcarek et al.). Record subject to acceptance by the Local Recorders Committee.

The latest v.13.1 of the IOC World Bird List has marked the Common Chiffchaff sub-species P.c. tristis as a proposed split which, if made, would accord it species level recognition. Therefore, I have pulled together the following notes of recent deliberations relating to the proposed split. As a result of those deliberations we have currently arrived at a position where birds that originate from east of the Yenisey River can be reliably identified in the field given a good enough description, photos and, where possible, a sound recording. With this in mind, I have decided to put together this page for birders at the lake who may come across a candidate Siberian Chiffchaff in future. Currently accepted field identification criteria are as follows:

• Absence of olive in the crown and mantle
• Absence of yellow away from the underwing
• Presence of a grey-brown or pale brown hue in the upperparts
• Presence of warm buff in the supercilium and ear-coverts
• Presence of buff at the breast-sides/flanks
• Very black-looking bill and legs
• A thin, piping near-monosyllabic Bullfinch-like or Dunnock-like call
• A song markedly different from western Chiffchaff's

There is a very valuable contribution from the Sound Approach team on vocalizations of Chiffchaffs including Siberian Chiffchaff. It is well worth reading and listening to the various sound recordings. You can click on the link below in the Bibliography.

In 2005 Dean, A.R. & Svensson, L. penned an article 'Siberian Chiffchaff' revisited (see link below), and wrote "the Common Chiffchaff Phylloscopus collybita has a broad distribution across Europe and east to Siberia, with six sub-species currently recognised by most authorities. Broadly speaking, the nominate form collybita of western Europe is replaced by abietinus in eastern Europe and by tristis in Siberia. From further south in Europe, in Turkey and in Central Asia, brevirostris, caucasicus and menzbieri have been described. The ‘chiffchaff complex’ is completed by three further closely related species of southerly distribution: Iberian Chiffchaff Ph. ibericus, Canary Islands Chiffchaff Ph. canariensis and Mountain Chiffchaff Ph. sindianus. The taxonomy and identification of the ‘chiffchaff complex’ was discussed by Clement et al. (1998)." The authors, based on the information presented, considered the provenance and appearance of the pale, ‘grey-and-white’ tristis-like chiffchaffs reported in Britain.

In 2007 Andy Stoddart, on behalf of the British Birds Rarities Committee (BBRC), wrote "Establishing the status in Britain of 'Siberian Chiffchaff' Phylloscopus (collybita) tristis has long been problematic. Key to this problem is the correct identification of the form - the difficulties of separating true Siberian tristis (largely from east of the Yenisey) and 'fulvescens' (on the West Siberian Plain) from abietinus (from Scandinavia and western Russia west of the Urals) continue to plague both observers and records committees." Following the establishment of several key identification criteria outlined in the paper (see link below), it was decided that "2008 has been designated as a 'trial year' in order to try and gain a deeper understanding of the British status of tristis." The BBRC set up a 'tristis panel to consider the records submitted in 2008 with a view to making "recommendations on how the occurrence of this form might best be documented now and in future." Avon Bird Recorder, John P. Martin, was co-opted onto the BBRC 'tristis panel' and penned an article entitled 'Sorting out 'Eastern Chiffchaffs' in the Avon area' (Avon Bird Report, 2007).

The paper resulting from the BBRC deliberations was published in British Birds in 2010 (see link below) and concluded, among other things, that "Currently, the numbers of Siberian Chiffchaffs reaching Britain in autumn are comparable with those of Pallas’s Leaf Warblers but significantly less than those of Yellow-browed Warblers. However, Siberian Chiffchaffs are considerably more frequent than these two species during the winter months, December to February." The authors concluded that Siberian Chiffchaffs are a scarce migrant to the UK.

Previous documented records of 'Eastern Chiffchaffs' were reviewed by the Avon Recorders Committee, and the results were published in the 2015 Avon Bird Report. Grey-looking individuals, formerly thought to have been Scandanavian Chiffchaffs Phylloscopus collybita abietinus, have now been accepted as Siberian Chiffchaffs in the light of recent findings.  For details of the deliberations about previous records see the systematic list on pps. 115-116, which resulted in 48 previous records being accepted in the Avon area and a further 7 accepted in 2015. This resulted in the first two records for Blagdon Lake being established as shown above.

Bibliography (sources of information):

1.  Rose, Dr H.E. (ed.). Avon Bird Report, 2007. Avon Ornithological Group.
2.  Rose, Dr H.E. (ed.). Avon Bird Report, 2015. Avon Ornithological Group.
3.  'Siberian Chiffchaff' revisited, British Birds 98 • August 2005 • 396-410
4.  British Birds: 'Siberian Chiffchaff' in Britain. Birdguides, 2007.
5.  The Status in Britain of 'Siberian Chiffchaff'. British Birds 103, June 2010, 320–338.
6.  Sound Approach Chapter 16: Drab