Wednesday 23 November 2011

Eastern Black Redstart: A Valid Species?

This autumn I’ve been doing a fair bit of reading on the Black Redstart Phoenicurus ochruros complex, I think I’ve got is sussed now. A good place to start was Russell Slack’s Rare Birds Where and When, which provides a really good summary. The various races are all generally fairly distinct and some may warrant full species status. Essentially there are three ‘species groups’, Western European forms ‘Western Black Redstart’ including gibraltariensis and aterrimus, Eastern European/West Asian forms ‘Middle Eastern Black Redstart’ including ochruros and semirufus and Central and Eastern Asian forms ‘Eastern Black Redstart’ including phoenicuroides, rufiventris and xerophilus.

Daniele Occhiato has some incredible pictures of some of the above (e.g. gibraltariensis, ochruros and semirufus) and the Oriental Bird Club has some good pictures of the others (e.g. rufiventris, phoenicuroides), reproduced below (images are copyright to named photographer), the images show how variable the above are!

'Western Black Redstart' gibraltariensis© Daniele Occhiato 2010

'Middle Eastern Black Redstart' ochruros© Daniele Occhiato 2011

'Middle Eastern Black Redstart' semirufus© Daniele Occhiato 2011

'Eastern Black Redstart' phoenicuroides© Jaysukh Parekh Suman 2011

'Eastern Black Redstart' rufiventris© Sunil Singhal 2010

The Black Redstart recorded in the UK is ‘Western’ Black Redstart Phoenicurus ochruros gibraltariensis, it is a rare resident/migrant breeder (e.g. approximately 60 pairs) and fairly common passage/winter visitor. Check out this awesome bird caught by Jack Ashton-Booth:

Adult male 'Western Black Redstart' gibraltariensis© Jack Ashton-Booth

A couple of weeks back I noticed a post on the Surfbirds forum from Sweden about several birds from various locations within the country seemingly showing a very good set of characteristic features that appeared to rule out the [allegedly] fairly common pit-fall Common Redstart x Black Redstart hybrid (Phoenicurus phoenicurus x Phoenicurus ochruros) and looked very good for ‘Eastern’ Black Redstart Phoenicurus ochruros phoenicuroides, a very rare vagrant to Western Europe. Four previous British records of potential ‘Eastern’ Black Redstart (Scillies 1975, Lincolnshire 1978, Kent 1981 and Lincolnshire 1988) have all been removed from the British List. It may have been possible that some of these records may have actually been the real deal rather than hybrids; however the lack of documentation on these birds means they’ve been binned unfortunately.

Accepted records of Eastern Black Redstart within Western Europe have occurred in Sweden (1986), Belgium (1993), Germany (1995), Sweden (2000), The Netherlands and Guernsey (both in 2003) and Sweden (2005). Interestingly there is also a potential record, which in all likelihood would represent the first record for the UK of Eastern Black Redstart – a bird found by James McCallum at Clay in Norfolk – incidentally also in 2003 (complete with some cracking paintings/drawings), presumably 2003 was a bit of an influx year.

It appears as though eight years later in 2011 we (in Western Europe) are experiencing another influx year with at least one bird in Germany (13th – 17th October 2011), a staggering five birds in Sweden and now two birds in the UK. The first, at Foreness Point, Kent from 11th – 17th November 2011 and the second on Holy Island, Northumberland from 16th November - 21st November 2011. I will admit to having been tempted to travel down for the Kent individual but am glad I didn’t because as luck would have it the Holy Island bird would enable me the opportunity to connect. As stated in the post below, Dave and I had a very enjoyable and successful trip to see the Northumberland bird which was showing phenomenally well on the beach near the school last Sunday.

Seeing the bird was the first part of the Black Redstart conundrum, the second was ruling out a hybrid, the third to get it elevated to full species status!

Eastern Black Redstart is a long distance migrant from its central Asian breeding grounds to wintering areas in central India west to northeast Africa. Its breeding and wintering distribution is comparable to species that occur regularly in northwest Europe, including Desert Wheatear and Isabelline Shrike (Slack 2009), both of which seem to have been recorded in fairly decent numbers within the UK and other areas within northwest Europe this autumn.

Adult male phoenicuroides are very distinctive birds that show a unique number of features, typically males of phoenicuroides differ markedly from gibraltariensis by fully deep rufous-cinnamon sides of breast, belly, flanks, vent, axillaries and under-wing coverts, sharply contrasting with black chest; forehead often white, contrasting with black rim along base of the upper mandible (Snow & Perrins 1998). First winter males (in ‘paradoxus plumage’ – those immature birds in a plumage largely representing adult males) differ from adult males in that fringes to tertials, secondaries and primaries are brown, they are paler on the vent, the throat is mottled grey with black, the upperparts are influenced by brown feathers and the distal black shaft on the outermost tail feather is extensive and larger (Slack 2009, Evans & Lawrence 2011).

As mentioned above the possibility of a hybrid needs to be ruled out: The best way to assess if the bird is a hybrid is to take a look at the wing formula. Steijn (2005) proposed differences based upon the emarginations on p3-6 for phoenicuroides and a ratio for spacing between p5-6 and p6-7. The set of photos below, kindly provided by Tristan Reid (AKA Binocularface) provides a good indication that the bird in question is not a hybrid, as appears to be the case in the Kent bird also.

Eastern Black Redstart © Tristan Reid 2011 Holy Island, Northumberland

Eastern Black Redstart © Tristan Reid 2011 Holy Island, Northumberland

Eastern Black Redstart © Tristan Reid 2011 Holy Island, Northumberland

Eastern Black Redstart © Tristan Reid 2011 Holy Island, Northumberland

Eastern Black Redstart © Tristan Reid 2011 Holy Island, Northumberland

Eastern Black Redstart © Tristan Reid 2011 Holy Island, Northumberland

Eastern Black Redstart © Tristan Reid 2011 Holy Island, Northumberland

Eastern Black Redstart © Tristan Reid 2011 Holy Island, Northumberland

Eastern Black Redstart © Tristan Reid 2011 Holy Island, Northumberland

There is an interesting paper on the taxonomy of Black Redstarts by Ertan (2006) which concluded that Eastern Black Redstart, phoenicuroides (and rufiventris) were the most divergent subspecies in the Black Redstart complex, and that they appear to be more closely related to Hodgson’s Redstart Phoenicurus hodgsoni than Western Black Redstart gibraltariensis (and aterrimus) and as such may warrant full species status. Steijn (2005) also suggested there might be merit in treating phoenicuroides (and rufiventris) as a separate species. This is also reported in Slack (2009).

In summary, this very smart, distinctive bird represents potentially the second or third UK record of this plausible new species, I’m glad I’ve seen it (and even if it never gets split it was certainly a ‘looker’ in any case!).

1 comment:

  1. Thanks for your review of Eastern Black Redstart Andy, very helpful. Do you have any further thoughts on this given the influx of them this winter?