Siberian Blue Robin: new to Europe
by F.R.G. Rountree

From - British Birds VOLUME 70   NUMBER 9 (pages 361-365)   SEPTEMBER 1977Siberian blue robin

Autumn 1975 was remarkable for rare birds in Western Europe, but the appearance of this east Palaearctic species in the Channel Islands was one of the most unexpected events.

At 12.50 GMT on 27th October 1975, Philip J. Guille approached a mist-net set up under the canopy of sycamores Acer pseudoplatanus alongside scrub consisting of blackthorns Prunus spinosa at the head of the Banquette valley in Sark, Channel Islands.  Hanging in the net was a small passerine and, as he extracted it, PJG realised that the species was unknown to him. Although recalling a small thrush Turdus or rather large, short-tailed robin Erithacus rubecula in form, its basic plumage plumage pattern of dark olive-brown upperparts and mainly white underparts recalled no small turdid regular in the west Palaearctic. Having safely bagged the bird, PJG summoned assistance and shortly afterwards Alan Marsden, Mrs A. Marsden, my wife and I arrived to witness the customary handling of such a bird and its release.  Initially, none of us recognised its identity, but eventually we all agreed that our description and the photograph taken by AM were of a Siberian Blue Robin Luscinia cyane, in what was probably first-autumn female plumage.  The record was accepted by the Sark Rare Bird Panel and, later, by the British Birds Rarities Committee, to which body we submitted it in view of the international importance of the occurrence.  The rest of this paper gives the details of what was perhaps the most astonishing rarity of a great year for extralimital vagrants throughout western Europe. (Photograph above - Siberian Blue Robin, first year female, in the hand of the late Philip Guille, taken by the late Alan Marsden on October 27th 1975.)

The bird in hand.
The bird was obviously a small thrush or chat and, during its extraction from the net, it gave the long, harsh calls typical of such passerines.  Its form most recalled a Robin, but was made distinctive by a rather short tail and noticeably longer and more robust legs.  The following description and measurements were taken: Upper mandible dark horn, lower paler; mouth pinkish with blue cast.  Iris dark brown.  Upperparts including tail uniformly dark olive-brown; sides of neck and face similarly coloured, but with slightly darker lores, a distinctive whitish-buff eye-ring and fine buff streaks on the ear-coverts.  Wings also dark olive-brown, but with a wing-bar formed by reddish-buff tips of the greater coverts and with the folded flight feathers (actually the leading edges of both primaries and secondaries) buffish-olive and appearing much paler than the rest of the upper-parts.  Underparts basically white and vividly so below the breast, but with olive-buff tips on the throat and strong mottling of buff tipped olive on the upper breast and of olive on the flanks and the under-wing.  Plumage fresh and unbraded, except for slightly worn tips to the pointed tail feathers.  Legs and feet pink, darker in front. Weight 15.75 g.  Wing 71 mm (maximum chord), tail 48.5 mm (almost square, but with outer feathers 5.5 mm shorter).  Bill (to skull) 14 mm, tarsus 27 mm.  Approximate length from bill tip to tail tip 123 mm. Wing formula: 4th longest (4 mm longer than primary coverts), 5th  -0.5 mm, 6th -6.5 mm, 7th  -9.0 mm, 8th  -11.5 mm, 9th  -13.5 mm, 10th and secondaries -15.5 mm, 3rd  -2.0mm, 2nd  -8.5 mm; primary emargination obvious on 3rd, 4th and 5th, slight on 6th.

The bird remained silent during handling and we were hopeful of studying it in the field.  Unfortunately, upon release it flew off immediately, calling ‘tchak’ as it did so.  We noted its flight as low and undulating and then it was gone as mysteriously as it had come.

The process of identification.
We could find no hint of what species we had observed in any field guide or other common book of reference, but a wider search of the Palaearctic literature showed us that, in addition to the Red-flanked Bluetail Tarsiger cyanurus, which occasionally reaches the western seaboard of Europe, there were several other small related chats to be considered.  The search for one that was, like Tarsiger, strongly migratory led us to the Siberian Blue Robin and, with the aid of Kobayashi (1956), King et a.l (1975), Dementiev and Gladkov (1968) and other references, we were able to complete the identification.  The bird’s measurements fell within the limited ranges given by Dementiev and Gladkov, except for the bill, which was 2 mm shorter than any of the 12 quoted, and its plumage accorded with that given for the adult female, except that we did not note the rufus tinge of the tail and uppertail-coverts mentioned by Dresser (1902) and Salim Ali and Ripley (1973), or the brown ‘scales’ on the breast stressed by King et al. (1975).  These last discrepancies may indicate that the bird was immature and certainly the presence of a wing-bar, like that of a young Robin, suggests a bird in its first year.  The combination of the eye-ring, the rather short tail and the long, robust and pale legs was central to the diagnosis and any confusion with the Black-throated Robin L. obscurus was prevented by the absence of white bases to the outer tail feathers.

Against the possibility that must now exist of further occurrences, additional description of the Siberian Blue Robin is essential.  Only the adult male earns its name, its upperparts being almost wholly slaty-blue (palest on the forehead and crown) and interrupted only by black lores, cheeks and throat sides (providing a noticeable band through the face on to the neck) and olive-brown flight feathers.  The male’s underparts contrast markedly with the upperparts, being basically white, but often tinged with bluish-slate or grey-brown on the flanks and across the chest.  Like he Red-flanked Bluetail, young males and old females may have their uppertail-coverts and tail washed with blue (King et al. 1975) and such birds would be confusable with Tarsiger on a brief rear view, particularly since they also share a prominent eye-ring with that species.  The Red-flanked Bluetail, however, shows orange-red flanks at all ages and it is not so short-tailed or noticeable long-legged. 

D. I. M. Wallace tells me that the character of captive males reminded him of a rather plump, long-legged, short-tailed redstart Phoenicurus and certainly most texts stress the frequent movement of the tail in both ‘quivering’ and ‘cocking’ actions.  The alarm call of the Siberian Blue Robin is normally written ‘chuck-chuck-chuck’, but our experience indicates that it can sound sharper than that.  In its normal range, the Siberian Blue Robin is a secretive, apparently rather silent chat, which spends most of its time on the ground.  Clearly, it is another small rarity that may elude the sharpest-eyed observer.

Notes on the species.
The systematics of robins, nightingales and other related small chats remain confused, but Dementiev and Gladkov (1968), Flint et al. (1968 and Vaurie (1959) all placed the Siberian Blue Robin in the genus Luscinia – with 10 other species, among which are the more familiar Nightingale L. megarhynchos and Bluethroat L. svecica.  The Siberian Blue Robin forms a species-pair with the Indian Blue Robin L. brunnea (but the latter undertakes a shorter migration from the Himalayas to Ceylon at most and is a very unlikely candidate for vagrancy) and, like all its congeners, it favours dense ground cover al all times of the year.  The Siberian Blue Robin is apparently the most terrestrial of its kind, with the adaptations of a relatively strong bill, long legs and short tail to show for such a niche.  In its breeding range, which stretches east of the Altai across southern Siberia to Korea, it is a fairly common, occasionally abundant species of mixed forest.  The breeding cycle begins in May, with the males singing ‘sweetly and melodiously’ from low cover or the ground.  The nest is on the ground and is usually well hidden.  Eggs are laid in late May and through June; they are plain greenish-blue and range in size from 19.0 x 13.7 to 18.2 x 15.0 mm (Dresser 1902).  Details of incubation and fledging periods are apparently unknown.  Adults moult in the breeding range from the last ten days of July to mid August.  Details of dispersal from the nesting areas are incomplete, but autumn arrivals are noted in Burma in October.  The winter range of the Siberian Blue Robin stretches from Assam eastwards through southeast Asia to southern China; it includes Borneo, Sumatra and the Philippines.

Acknowledgements
I express my gratitude to Dr A. S. Cheke, C. E. Davies. J.N. Dymond, R. R. Kersley, Dr J. T. R. Sharrock, D. I.M. Wallace and the Rarities Committee for their invaluable assistance. 

Summary
An account is given of the first known European occurrence of Siberian Blue Robin Luscinia cyane, mist-netted on Sark in the Channel Islands on 27th October 1975.

References
ALI, S., and RIPLEY, S. D.    1973    Handbook of the Birds of India and Pakistan Vol. 8 Bombay
DEMENTIEV, G. P., and GLADKOV, N. A. (eds)    1968    Birds of the Soviet Union  Israel Program for Scientific Translations, Jerusalem
DRESSER, H. E.,    1902    A Manuel of Palaearctic Birds  London
FLINT, V. E., BOHME R. L., KOSTIN, Y. V., and KUZNETSOV, A. A.    1968    The Birds of the USSR   Moscow (in Russian)
KING, B., WOODCOCK, M., and DICKINSON, E. C.,    1975     A Field Guide to the Birds of Southeast Asia  London
KOBAYASHI, K.     1956    Birds of Japan in Natural Colours  Osaka
VAURIE, C.,    1959    The Birds of the Palaearctic Fauna.  Passeriformes  London

F. R  .G.  Rountree, La Perronerie, Sark, Channel Islands

UPDATE 19/07/2009
25 years later the first Siberian Blue Robin for Great Britain was seen by several observers at Minsmere, Suffolk on 23rd October 2000.  It was a first winter female. There has been one more since.  On 2nd October 2001 a first winter male was seen and photographed on North Ronaldsay, Orkney.

Many thanks to Tony Bisson of the Société Guernesiaise for the update.