Identification of male Ehrenberg's Redstart

Cover Photo: Ehrenberg's Redstart from the Surfbirds galleries © Nik Borrow

By Brian J Small

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I saw my first male [Ehrenberg’s] Common Redstart Phoenicurus phoenicurus of the form samamisicus in Cyprus, and was as struck then, as I am now, at how stunning they are.
Brian J Small

The following is a much abridged version of an article published in British Birds vol. 102, Feb 2009.  Anyone wishing to get a copy can order a copy from British Birds here 

I saw my first male [Ehrenberg’s] Common Redstart Phoenicurus phoenicurus of the form samamisicus in Cyprus, and was as struck then, as I am now, at how stunning they are. Though they breed in the mountains of central Turkey and the Caucasus region, they pass through the Middle East in spring and it was such a bird that I saw c.20 years ago.  This identification paper was largely catalysed by claims of samamisicus in Britain, assessed during my time on the British Birds Records Committee (BBRC).  As part of the assessment process, it became apparent that our lack of understanding of the appearance of samamisicus was preventing accurate record assessment. So, with a view to establishing criteria by which samamisicus could be separated from the nominate form, hereafter referred to as phoenicurus, the BBRC carried out a detailed investigation to establish whether samamisicus is diagnosable, and also to what extent the appearance of phoenicurus can vary and overlap with samamisicus.

Early on it was felt that female samamisicus is extremely similar in appearance to female phoenicurus, and they are not safely separable based upon current knowledge. However, I feel confident that adult males in particular have well-defined characters and are easily distinguished, whilst some first-winter males may be identifiable with care.

Ageing and identifying males

Adult Common Redstarts undergo a complete post-breeding moult prior to autumn migration, while first-winter birds have a partial post-juvenile moult that includes replacement of the body contour plumage and a variable number of greater and median coverts. Most frequently, all the median coverts and two or three inner greater coverts are replaced but the first generation remiges, rectrices and tertials are retained until the following summer. On the rare occasion, some or all of the tertials may be moulted and very rarely an inner secondary.  This results in adult males appearing very fresh by early autumn, while the tertials, greater coverts and wings of the majority of first-winter males may be up to three months older than those of adults and appear less pristine. 

In the autumn, correctly ageing a redstart is fundamental to the process of identifying samamisicus, with two key areas needing examination:

·     The presence or absence of pale fringing across the lores, but also chin, throat and sides to the head 

·     The presence of any ‘moult contrasts’ in the upperwing coverts and tertials

In autumn males, it is important to carefully examine the extent and colour of pale feather tips obscuring the black facial mask; i.e. the forehead, lores, chin, throat and sides to the head. On adult males of both phoenicurus and samamisicus, the loral and chin feathers lack pale fringes, leaving these areas solidly black. Note, however, that the pale tips to the throat feathering, particularly on nominate phoenicurus, can be broad and extensive. On some individuals this creates the appearance of a white bib along the lower throat that separates the solid black throat and mask from the orange breast. First-winter birds differ from adults in having pale fringes to the loral and chin feathering. These fringes are dull grey-brown or creamy buff rather than the white tips shown by some adults along the lower throat, so the appearance of the entire mask is uniformly drab rather than crisp and blackish.

http://www.flickr.com/photos/36546142@N05/3372563824/sizes/o/in/photostream/

ad male phoenicurus, Spain, October 2008, note the all black lores but also the white edges to the secondaies (discussion of this bird appears below).

http://www.flickr.com/photos/rashed11112/2901526851/sizes/o/ - first-summer male Kuwait, March.  It is not possible to tell from this image, but you can age it due to the pale fringing across the lores.

Of equal importance to correct ageing are the greater coverts, which should be examined for both colour and moult contrast. Any difference in the appearance of the replaced feathers, and the extent of moult contrast in the wing coverts is significant as these can be seen in the field and provide strong supportive evidence when establishing the correct age of a particular individual.

White wing panel

In autumn and spring, the most conspicuous feature of adult male samamisicus is white edges to the remiges. What may not be widely appreciated, however, is that freshly moulted adult male phoenicurus in autumn can also show a surprisingly obvious, but restricted, pale panel in the closed wing. As a consequence, there have been a number of claims of apparent samamisicus showing a pale wing panel that have actually proven on closer examination to be phoenicurus. Therefore, the presence of pale edges to the tertials and secondaries, in itself, is not diagnostic of samamisicus, and very careful attention must be paid to the precise extent and shape of the white. Detailed examination of specimens and photographs of adult phoenicurus have shown that these fringes, if present and contrasting, don’t appear quite as white and are never as extensive (especially aross the primaries) as on adult samamisicus.

Adult

The most obvious feature that separates adult male samamisicus from phoenicurus is the white wing patches. In adult male samamisicus in autumn, the panel in the closed wing is brilliant white, extending from the edges of the outer two tertials, across the outer edges of the secondaries, decreasing from 4mm to 2mm in width, and onto the fringes of the primaries; when fresh this includes p3–p10, but from September onwards, wear may reduce this to p5/6–p10 (primaries numbered ascendantly). Importantly, there is never any hint of a buff tone to this panel, and there is never a pure white fringe to the inner tertial. By the spring, the wings of adult males should be worn and faded, but the wing panel is no less obvious in samamisicus, and can appear as a solid white block across the secondaries but a little less obvious on the primaries. In addition, the white notches at the base of the tertials can sometimes be seen. The extent and brilliance of the wing panel is immediately obvious in the field, and in extending across the secondaries and inner primaries at least, is far more extensive and contrasting than that on adult male Black Redstart P. ochrurus.  

http://www.flickr.com/photos/rashed11112/3316817558/sizes/o/ - Kuwait, January 2000

http://www.flickr.com/photos/rashed11112/2305257523/sizes/o/

http://www.flickr.com/photos/rashed11112/2340648377/sizes/o/

http://www.flickr.com/photos/rashed11112/3366687066/sizes/o/ - ad males March 2008, Kuwait

http://www.pbase.com/image/81558205 - ad male, Israel, March 2005

http://www.pbase.com/image/110195689 - ad male, Israel, March 2009

The wing panel continues to wear into the summer and by mid summer may be lacking on the edges of the primaries and proximal fringes of the outer tertials.

http://www.pbase.com/image/63514036 a worn male, Armenia, June 2005

© Nik Borrow from the Surfbirds Galleries

In addition, the newly moulted greater coverts of adult samamisicus in autumn have dark, sooty-black centres that contrast with a frosty-grey outer fringe and an almost white tip, which on some individuals extends along the distal edge. This enhances the contrast with the extensive brilliant white flash across the closed wing. By spring and early summer these tips will have worn to a varying extent, being absent on some birds, while others still retain narrow white tips to the greater coverts.

Adult male phoenicurus with white on the tertials and secondaries are, it seems, not infrequent (and in the UK a number of birds turned up in the autumn of 2008).  The white may be extensive on the outer fringes of the outer tertial and secondaries, but never show the white broadening at the base, an also, though the fringes may appear white from some angles, there is often a buff hue obvious from various angles

http://www.flickr.com/photos/36546142@N05/3371741429/sizes/o/ - wings of adult male phoenicurus trapped in Spain in October 2008 (same as above), showing large amount of white, but exact pattern not right for ad male samamisicus

 

© Simon Chidwick from the Surfbirds Galleries

Nominate phoenicurus can also occur in the spring with white in the wing; an image of such a bird present in Finland in spring 2009 is here http://www.roller.fi/gallery/main.php?g2_itemId=9299

and discussion is here http://surfbirds.com/forum/showthread.php?t=5127

It could well be that spring male phoenicurus with more white than is typical are the reason for claims of intergrades between samamisicus and phoenicurus.

First-winter

Separating first-winter males of both races of Common Redstart is extremely difficult and may only be possible in the hand.  They can be aged as first-winter by the presence of pale fringing on the loral feathering, and, in addition, the worn, brown-fringed juvenile greater coverts usually contrast with two or more newly replaced inner greater coverts and median coverts, which appear distinctly grey and are similar to the newly replaced frosty-grey fringes of an adult. Typically, in comparison with adults, first-winter samamisicus show dramatically less white on the edges to the tertials and secondaries, so understanding the precise pattern of white on the tertials and remiges is extremely important – though on those first-winters that have moulted the tertials the white is comparable with an adult.

By far the majority of first-winter samamisicus show juvenile tertials, on these the outer two tertials show narrow white edges, slightly obscured by narrow buff fringes, particularly near the tips. Similarly, the inner secondaries also show white edges, but these too are often subdued by narrow buff outer fringes. As on adults, the extent of white of the outer edge of the outer tertial and inner secondary can expand towards the base; the outer secondaries have minimal pale buff or creamy-white edges, and the primaries show no white. This pattern may give the effect of a narrow thin triangle of white on the outer tertial and inner secondaries, with the apex towards the wing tip and expanding towards the base of the primaries.

First-winter male samamisicus - David Pearson, Azerbaijan, August 2008.  Note the expansion of white at the base of the outer tertial and inner secondary; also, the moult of the new grey inner greater and median coverts is quite extensive.

By contrast, first-winter male phoenicurus show little contrast between the fringes and centres to the tertials and lack any hint of contrastingly paler edges to the remiges. Consequently, the closed wing presents a largely uniform appearance with the buff tips to the greater coverts being the most contrasting feature – when any tertials have been replaced in the first autmn they are very similar to the juvenile feathers. Occasionally, first-winter phoenicurus can show pale edges to the tertials and secondaries, but they are often pale cream or brown and extend across all secondaries.

Voice

There appears to be distinct differences between the calls and slight differences in the songs of nominate phoenicurus and samamisicus. The call of samamisicus is different to that of phoenicurus, being a less drawn-out ‘heep’ and likened to the call of Collared Flycatcher; this compares with the ‘huit’ of phoenicurus.

I suspect that there may also be differences in song, based upon comparison of the song of samamisicus recorded in Armenia in May 2007 with that of phoenicurus in Europe. This suggested that after an initial phoenicurus-like start, the song of samamisicus has a more protracted series of end phrases. To investigate this further, I contacted Magnus Robb, who commented ‘I do think that samamisicus sings differently (both birds I recorded suggested this), and the whistle calls seem to be less inflected’.

Common Redstart, samamisicus, Dilijan, Armenia, 28 May 2007, recording by Peter Kennerley

Calls of both forms are available here, with one recording of the call of samamisicus showing how distinct it is

http://www.tarsiger.com/ 

Concluding comments

It is interesting to speculate about the reasons for the isolated samamisicus population in the Causacus and the stability of its phenology, with a distinct lack of evidence of hybridisation where it meets phoenicurus.  Isolating mechanisms, such as voice, geography and different migration timings and route may be involved - though greater research is needed to establish if these differences are stable.  The morphology of adult males is diagnostically distinct, but are there genetic differences? 

In a study of the ‘evolutionary history of Eurasian Redstarts’ (Ertan, 2006 ftp://80.57.161.240/artikelen/Z/Zwarte%20Roodstaart1.pdf  ), an attempt is made to ‘resolve their phylogenetic relationships’ using the mitochondrial cytochrome b gene sequence.  As expected, the study closely links samamisicus with phoenicurus, despite the white in the wing being similar to adult male Black P. ochruros and Hodgson’s Redstart P. hodgsoni (which, as the female, immature and non-breeding plumages of both suggest, are relatively closely related to each other http://www.flickr.com/photos/22553111@N07/2251946356/sizes/o/  - male, Bhutan, Dec 2007

http://www.flickr.com/photos/13867089@N03/1633135791/ - female, Kaziranga, Oct 2007). 

Ertan’s data showed samamisicus from Eastern Turkey to be 2.3% different from European nominate phoenicurus; this at first appears to be significant given that ‘a calibration of 2% sequence divergence per million years in the cytochrome b gene of oscine passerines’ (Lijtmaer et al, 2004). However, such a divergence compares with ‘2.3%-4.0%’ divergence amongst subspecies of Black Redstart P. ochruros, and species-level distances ranging between 4.9% and 11.3% within the same study; though it is just below divergence values of 2.5-3.1% between Bright-green Phylloscopus nitidus and Greenish Warbler P. trochiloides (Helbig et al, 1995), a species pair in which a similar level of vocal, geographical and morphological variation occurs. 

I suspect more work will be done on samamisicus and, in addition to voice and plumage, other subtle differences (moult-timing, wintering areas and migration routes) may also prove significant in its identification and perhaps its taxonomic status.

Brian Small – June 2009

Acknowledgments

My thanks go to Mark Adams at NHM, Tring, for allowing access to specimens. I also thank David Pearson for providing data on the appearance and migration of samamisicus in Sudan and Azerbaijan. Paul French, Peter Kennerley and Adam Rowlands assisted with the work at Tring.

References

Ertan, K.. 2006. The evolutionary history of Eurasian Redstarts, Phoenicurus. 52nd Supplement Acta Zoologica Sinica: 310-313.

Helbig, A., Seibold, I., Martens, J., and Wink, M.. 1995. Genetic differentiation and phylogenetic relationships of Bonelli’s Warbler Phylloscopus bonelli and Green Warbler P. nitidus. Journal of Avian Biology 26: 139-153. Copenhagen 1995.

Lijtmaer, D., Sharpe, N., Tubaro, P., and Lougheed, S.. 2004. Molecular phylogenetics and diversification of the genus Sporophila (Aves: Passeriformes). Molecular Phylogenetics and Evolution 33 (2004) 562-579. Elsevier.

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