naumann’s thrush in essex:new to britain

Although it is now 19 years ago, mymemories of the event are stillremarkably fresh. It could have been just

any old ‘Saturday morning after the nightbefore’, a typical and otherwise quite forgettablewinter’s day, with heavy rain and a northwesterlygale. Except that this particular Saturdaymorning, 3rd February 1990, was a day that Ishall never forget. As I savoured a breakfastgrapefruit segment, I noticed a movement in theivy Hedera hedge through the rain-spatteredwindow. Although the driving rain reducedvisibility from the kitchen window almost tozero, I managed to make out a rear-facing,downward tugging, thrush-sized bird, showingprominent ‘rusty wedges’ either side of a darkbrown, fanned tail. The hangover vanished in ananosecond. I tore up the stairs, choking on thegrapefruit as I aimed for the bedroom window.Nervously peering over the windowsill with mybinoculars, I was relieved to find the bird stillpresent just 10 m away.

Immediately, I asked my wife to call P. Vines(PV), C. Fentiman and T. Wilson, and I began tomake some notes. PV was the first to arrive, butby then the bird had been missing for about 15minutes. Needless to say, my angst was probablyequal to PV’s frustration. Knowing that there

are no guaranteed returns in this situation, Iwas beginning to feel somewhat depressed butthen the bird suddenly reappeared, swooping infrom my neighbour’s garden, and landed backin the hedge. The bird was feeding avidly on theivy berries and showing really well. There weremutterings of American Robin Turdusmigratorius, and Red-throated Thrush T.ruficollis, even though we both knew that thebird was clearly neither of these. The possibilityof some sort of hybrid seemed more plausible,but these musings were born out of sheerfrustration and the initial euphoria wasbeginning to dissipate… we just didn’t knowwhat it was! Poring over the illustrations andtext in Heinzel et al. (1972) and BWP, weconcentrated on all the plates and the onlyimages that were somewhat comparable were,unbelievably, those of Naumann’s Thrush T.naumanni. Although there were somediscrepancies – the image in Heinzel et al.showed a longer bill, more contrasting headpattern, whiter belly, flank and undertail-coverts, a dull red tail and shallower forehead –this was the closest match we could find.

PV was strongly supportive of this identi-fication and, with no other obvious contender,it seemed the most likely candidate. As the

435© British Birds 102 • August 2009 • 435–440

ABSTRACT A first-winter male Naumann’s Thrush Turdus naumanni discoveredat Woodford Green, Essex, on 3rd February 1990 remained until 9th March

1990, although it transpired that the bird had been present since 19th January.During its stay, it frequented gardens and an adjacent playing field, where it waswatched by several hundred observers. Until recently, Naumann’s Thrush andthe closely related Dusky Thrush T. eunomus were treated as races of a singlespecies; Dusky Thrush had already occurred in Britain but this was the first

occurrence of Naumann’s Thrush. Following a review of diagnosable plumagedifferences, and after considering the relatively infrequent occurrence of

hybrids, BOURC concluded that Naumann’s and Dusky Thrushes representmonotypic species, and both were accepted into Category A of the BritishList.This paper describes this record, and also discusses the distribution of

Naumann’s and Dusky Thrushes and the occurrence of hybrids.

Naumann’s Thrush in Essex: new to Britain

Ken Murray

reality sank in, we sat there completely andutterly stunned! We reasoned that it was, in allprobability, a first-winter male, although theillustrations in BWP and Heinzel et al. differedon this point. C. Fentiman arrived shortlyafterwards, by which time the bird haddisappeared again. T. Wilson soon followed,but it was a long 30 minutes before the birdreappeared once more and excellent viewswere had by all. On this occasion the birdstarted to preen and, while doing so, showedoff its red underwing-coverts and rustyuppertail-coverts, features that we had notobserved earlier.

It subsequently transpired that the bird hadfirst been seen (but not identified) on 19th

January in a garden c. 300 m away belonging toa neighbour, Mrs Bridges. These two gardenlocations straddle the boundary betweenWaltham Forest in Greater London andWoodford Green in Essex. During its stay thethrush often frequented a local school playingfield, where it showed extremely well tohundreds of admirers. It was last reported on9th March 1990.

Many good photographs were taken tosupport the identification and it was accepted byboth BBRC and BOURC, and added to CategoryA of the British List in 1991 (BOU 1992).Although a summary of the occurrence haspreviously been published (Murray 1990), thatwas prior to its formal acceptance and its

treatment as a species distinctfrom Dusky Thrush T.eunomus.

DescriptionThe following descriptionwas made during initialobservations, and is supple-mented by additional detailsprovided by Brian Small fromnotes and sketches made on16th February 1990.

Size and structureSimilar in size and structureto Song Thrush T. philomelosbut appeared to have adeeper-based and slightlydagger-shaped, dark-tippedbill. It also showed a heavierneck and a slightly longer tail.The forehead seemed steeperthan that of Song Thrush,although the angle changedaccording to posture.

HeadLong, narrow supercilium, adingy pale cream; dark lores,with a creamy crescent underthe eye forming a pale trian-gular area above the malar.Malar stripe of blackishfeathers, which broke intostreaks at the lower edge.Throat off-white or palecream and lightly flecked.Crown and ear-coverts grey-brown.

436 British Birds 102 • August 2009 • 435–440

Naumann’s Thrush in Essex: new to BritainD

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248 & 249. First-winter male Naumann’s Thrush Turdus naumanni,Woodford Green, Essex, February 1990.

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UpperpartsMantle and scapulars grey-brown, faintlymarked with darker feather centres, forming afew dark spots, particularly on lower back.Uppertail-coverts rufous.

WingsGreater coverts with broad, neat, pale grey-cream fringes. Dark grey remiges, with palecreamy-buff fringes, those of the tertials and

secondaries forming a wing panel. Underwing-coverts red.

TailFrom above, central tail feathers dark brown;outer feathers broadly edged rufous. Frombelow the tail looked pale washed-out orange.

UnderpartsBreast, flanks and undertail-coverts rufous-

437British Birds 102 • August 2009 • 435–440


Fig. 1. Notes and sketches of first-winter male Naumann’s Thrush Turdus naumanni, Essex, February 1990.

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orange, feathers edged pale cream, forming aconspicuous ‘chevroned’ or ‘scaly’ effect. Centreof belly pale cream with little orange.

Bare partsBill yellow, with extensive blackish tip and upperedge of upper mandible. Legs and feet darkflesh. Eye dark.

Age and sexThe broadly pale-fringed greater coverts helpedto confirm the age as first-winter. Sexing can bedifficult, but birds lacking prominent darkstreaks on the chin, throat and breast-sides, asthis bird, and with deep rufous-tingedunderparts, should be males (Svensson 1992).

Taxonomic changeUntil BOU (2009) ratified treatment ofNaumann’s and Dusky Thrushes as two distinctspecies, they had both been considered races ofT. naumanni but, confusingly, the English name



Fig. 2. Breeding ranges of Naumann’s Thrush Turdus naumanni (green) and Dusky Thrush T. eunomus (purple).Redrawn from a provisional map provided by Kees Roselaar from the forthcoming Handbook of Geographical

Variation and Distribution of Palearctic Birds by Kees Roselaar and Hadoram Shirihai.

© F

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Art

of Dusky Thrush was used for this species. Thebasis for the decision by BOURC to recogniseboth forms as distinct species was based uponthem being diagnosable in terms of bothplumage and structure (Knox et al. 2008).Although it was acknowledged that birds withintermediate phenotypes do exist in museumcollections, they were considered to occurrelatively infrequently. Furthermore, theexpected interactions between them are poorlydescribed and apparent hybrids are much rarerthan would be expected if they were mergingextensively. Both Naumann’s Thrush and DuskyThrush are now accepted into Category A of theBritish List.

Records elsewhere in EuropeThere has been just one subsequent record ofNaumann’s Thrush in Britain, a first-winter atSouth Woodford, Greater London, on 6th–11thJanuary 1997 (Brit. Birds 91: 503). Remarkably,this bird was found just a few kilometres from

where the Woodford Green bird was discovered.Elsewhere in Europe, Naumann’s Thrush hasoccurred widely, with records in Austria,Belarus, Belgium, the Czech Republic, Finland,France, Germany, Hungary, Italy, Norway andPoland (BWP Concise).

There are more records of Dusky Thrush inBritain, eight in total. The first was in 1905 andthe remaining seven have all been since 1959.Nonetheless, Dusky Thrush has been seen byfewer birders in Britain than Naumann’sThrush and only one, at Hartlepool, Durham,which stayed from 12th December 1959 to 24thFebruary 1960, was widely appreciated. All theothers have been difficult to catch up with,being short-stayers or erratic in theirappearance, or appearing in largely inaccessiblelocations. The most recent record was one onSkomer, Pembrokeshire, on 3rd–5th December1987.

DistributionNaumann’s Thrush breeds across a vast regionof central Siberia, in places north to c. 65°N,between the Yenisey and Kolyma Rivers. Thesouthern and western boundaries lie close to the lower Tunguska River, south to c. 54°N andwest to c. 90°E, then east across the Lake Baikalregion and the Stanovoi Mountains, perhapsreaching the Sea of Okhotsk. The breedingranges of Naumann’s and Dusky Thrushes arelargely allopatric in Siberia (fig. 2), with Duskyhaving a more northerly breeding distribution,extending from c. 66°N to c. 72°N. The range ofNaumann’s Thrush does, however, overlap withthat of Dusky Thrush in central Siberia towardsthe northern limit of its range and this ispresumably the source of reported hybrids.

On migration, Naumann’s Thrushes passthrough Mongolia, southeastern Siberia andnortheast China. In coastal northeast China,autumn passage through Beidaihe in Hebeiprovince occurs from late September to earlyNovember, usually peaking in the third week ofOctober. The species winters in northern andeastern China south to the Yangtze River, andthe Korean Peninsula. In irruption years, smallnumbers reach southeast China, including HongKong, where birds have appeared on 11occasions (Carey et al. 2001), although theDusky Thrush is more frequently seen here.Small numbers also reach Japan, where Brazil(1991) reported it to be a very uncommon, evenrare, migrant and winter visitor.

HybridsIndividuals showing characters of bothNaumann’s and Dusky Thrushes are welldocumented in the literature, are represented inspecimen collections, and are noted regularly onmigration and during the winter months ineastern China. Stepanyan (1983) treatedNaumann’s and Dusky Thrushes as distinctspecies, and although he acknowledged that lowlevels of hybridisation occur within regions ofsympatry, he also recognised that they appear todisplay widespread reproductive isolation. Hesuggested that hybridisation occurs only withinlimited areas in the regions where the twospecies overlap, and then only at low levels, andhybrids appear to be genuinely rare. Further-more, in some regions of sympatry, includingthe lower reaches of the Angara River, theAngara–Podkamennaya Tunguska catchmentand in the upper reaches of the NizhnyayaTunguska River, hybrids are apparentlyunknown.

Stepanyan noted that the collection housed inthe Zoological Museum of Moscow Universitycontained 81 specimens of undoubtedNaumann’s Thrush, 62 specimens of undoubtedDusky Thrush, and 27 specimens showing mixedcharacters of both species. In some cases, hybridswere difficult to separate from pure specimens,showing only minor differences in colour tone –for example, some otherwise typical DuskyThrushes with an ochreous tone to areas ofnormally black-brown coloration. Hybridspecimens of otherwise typical Naumann’sshowing features of Dusky were said to be rare.There may be a disproportionately high numberof hybrids held in collections owing to theirnovelty value; collections may tend to retain oractively seek to add hybrids to the collection.

Both species are common migrants inautumn at Beidaihe in coastal northeast China,and smaller numbers remain here throughoutthe winter months. Jesper Hornskov (in litt.)estimated the percentage of apparent hybrids tobe in the region of 4–5% of all Naumann’s andDusky Thrushes observed. However, because oftheir elusive nature and nervous disposition,observation of flocks in open situations whereall birds can be examined in detail is rarelypossible. Consequently, it has not been feasibleto quantify more accurately the relativefrequency with which birds showing mixedcharacters occur. These include birds showing arange of overlapping characters, although others

439British Birds 102 • August 2009 • 435–440


are more subtle – apparently typical Naumann’sThrushes with entirely dark tails, and otherwisetypical Dusky Thrushes with rufous tails andlight cinnamon mottling on the flanks.

As the photographs and illustrations clearlyshow, the Woodford Green bird showed nointermediate or hybrid characters, and wasunanimously accepted as an undoubtedNaumann’s Thrush.

Acknowledgments

I would like to thank: Jesper Hornskov for his commentson the status of Naumann’s and Dusky Thrushes, and theoccurrence of apparent hybrids, at Beidaihe; Kees Roselaarfor allowing BB to reproduce the map shown in fig. 2;Jevgeni Shergalin for translating the Russian literature; andBrian Small for the use of his artwork in fig. 1 and forcontributing to the written description.

References

Brazil, M.A. 1991. The Birds of Japan. Christopher Helm,London.

British Ornithologists’ Union (BOU). 1992. Records

Committee: 16th Report. Ibis 134: 211–214.— 2009. Records Committee: 37th Report. Ibis 151:

224–230.Carey, G. J., Chalmers, M. L., Diskin, D.A., Kennerley, P. R.,

Leader, P. J., Leven, M. R., Lewthwaite, R.W., Melville, D. S.,Turnbull, M., & Young, L. 2001. The Avifauna of HongKong. Hong Kong Bird Watching Society, Hong Kong.

Heinzel, H., Fitter, R., & Parslow, J. 1972. Birds of Britain andEurope with North Africa and the Middle East. Collins,London.

Knox,A. G., Collinson, J. M., Parkin, D.T., Sangster, G., &Svensson, L. 2008.Taxonomic recommendations forBritish birds: Fifth report. Ibis 150: 833–835.

Murray, K. 1990. Naumann’s Thrush in London – a Britishfirst. Birding World 3: 50–53.

Roselaar, C. S., & Shirihai, H. In prep. Handbook ofGeographical Variation and Distribution of Palearctic Birds.A&C Black, London.

Stepanyan, L. S. 1983. [Superspecies and Sibling Species inthe Avifauna of the USSR]. Nauka Press, Moscow.(In Russian)

Svensson, L. 1992. Identification Guide to EuropeanPasserines. Privately published, Stockholm.

Vinicombe, K., & Cottridge, D. M. 1996. Rare Birds in Britainand Ireland: a photographic record. HarperCollins,London.



Ken Murray, Woodford Green, Essex

EDITORIAL COMMENT Bob McGowan, Chairman of BOURC, commented: ‘European records of theNaumann’s Thrush tend to be in southern countries and it has been recorded only twice in Britain, bothtimes in London. In contrast, Dusky Thrush is more frequent in northern Europe and the eight Britishrecords, of which three were in Shetland, reflect this distribution. Interestingly, the temporaldistribution of British records also differs markedly: the two records of Naumann’s in the 1990s contrastwith seven of Dusky in the 28-year period between 1959 and 1987.

‘The Woodford Green Naumann’s Thrush was well observed and photographed. After some initialconfusion, its distinctive plumage made determination of subspecies (as then) relativelystraightforward. Subsequent assessment by BOURC raised no particular problems. Good photographssupported the submission and the bird was accepted as a first-winter male. Captive status of this taxonwas not considered a significant factor and as there were no concerns over provenance it was added toCategory A.

‘The adoption of Naumann’s and Dusky Thrush as separate species by the BOU had beenanticipated for some time. Despite the clear differences in plumage of adult birds, however, the degreeof hybridisation and existence of intermediates made consideration of the issue more complex,particularly as some “intermediates” were reported in areas where no hybridisation occurs. TheTaxonomic Sub-committee’s recommended treatment was based on three main factors: plumage andstructure are distinctive; intermediates (in museum collections) are relatively uncommon; andinteractions between the taxa are poorly described and the number of apparent hybrids suggests thatcontact is low. In consequence, the adoption of Naumann’s and Dusky Thrush as separate species waspromulgated in the BOURC’s 37th Report.’

Adam Rowlands, Chairman of BBRC added: ‘This bird was enjoyed by many past and presentmembers of BBRC and was a straightforward record to assess. Any observer fortunate enough to find aNaumann’s or Dusky Thrush in the UK could be forgiven for savouring the moment and not being tooconcerned about some of the finer colour detail alluded to above as useful for separating hybridindividuals. Given that both species are rarities, BBRC will consider and publish any acceptable recordsof hybrids in the future, alongside any claims that can be confidently assigned to species. Following thesplit, BBRC will need to review past records of Dusky Thrushes to ensure that the birds did not showhybrid characters. It has been suggested that at least one individual (the 1975 Shetland bird) showedcharacters suggesting a hybrid origin (Vinicombe & Cottridge 1996).’

naumann’s thrush in essex:new to britain

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