376 Identification of some scarce or difficult west Palearctic species in D. I. M. Wallace

INTRODUCTION Following the joint initiatives of Dr D. A. Scott and P. A. D. Hollom, and through the courtesy and assistance of the Iranian Department of Environmental Conservation, an expedition visited Iranian Baluchistan between 31st March and 19th April 1972. Its members were L. Cornwallis, Stanley Cramp, P.A.D.H., R. F. Porter, D.A.S. and myself, supported by conservation officers and staff, and together we explored all major habitat zones from the Mekran coast of the Gulf of Oman to mountain slopes at an altitude of over 3,000 metres on Kuh-i-Taftan (29°N, 6i°E) during a journey of about 1,500 kilometres. Over 200 species of were identified and, since there were many opportunities to study little known ones, this illustrated paper has been prepared as a digest of the more use­ ful advances in, or additions to, the field diagnosis of 16 such species. Information on several others will be published later in more specialised papers. All the British members of the expedition read drafts of this paper and I am grateful to them for their many comments.

GREATER AND LESSER SANDPLOVERS The separation of Greater Sandplovers Charadrius leschenaultii from Lesser Sandplovers C. mongolus requires particular care. The coast of Iranian Baluchistan offers a number of areas where the two species intermingle, and we had several opportunities to study them together. At a distance it was impossible to be certain of the species in­ volved, but at closer range, particularly when comparison with other small plovers was possible, a size difference was apparent on the ground. Charadrius mongolus looked as small as the Ringed Plovers C. hiaticula we saw (probably of the northern race ttmdtae), but leschenaultii appeared distincdy bulkier and heavier. In flight mongolus looked larger than hiaticula because of its longer and broader wings, and then it was difficult to discern much difference in size between it and the smaller individuals of leschenaultii (which, how­ ever, still appeared heavier about the head and larger-tailed). Both species are perceptibly longer-legged than hiaticula, moving West Pakarctic birds in Iran 377 more like ponderous Kentish Plovers C. alexandrinus, but on most flying leschenaultii the feet projected noticeably farther beyond the tail than in mongolus. As we expected, there was a clear increase in bill size from hiaticula through mongolus to leschenaultii, that of the last being always noticeably long and thick, usually with a markedly bulbous tip. The shorter, tapering bill and less angular appearance of the head of mongolus give it an endearing expression which leschenaultii lacks. As for plumage differences, it must be repeated that sandplovers in immature and winter dress lack any really noticeable marks. They exhibit a mixture of dun-grey and various tones of off-white. Slater (1971), writing of eastern populations, included in a useful summary of characters an opinion that both the upper- and under- parts of leschenaultii are lighter in tone than those of mongolus. Such a difference was not evident to us, however, and D.A.S. doubts if it holds good for western populations.

TEREK SANDPIPER Although several handbooks make it clear that the Terek Sandpiper Xenus cinereus is a fast-moving, lively wader, and they and the modern field guides all stress that its teetering recalls the Common Sandpiper Tringa kppoleucos, there seems to be no clear statement on the striking gait that marks the species. In Iranian Baluchistan, close observation of up to 30 Terek Sandpipers was possible on four days in early April. The birds were new to several observers, and we were constantly struck by their dashing mien. P.A.D.H., who had previous experience of the species, confirmed that this was typical and pointed out that it was made particularly obvious by the impression that they were about to topple forward as they moved. It became clear that this was caused by the short, twinkling, bright yellow legs set well back, the prominent chest held low, the thrusting of the bill well forward and below the horizontal, and the frequent changes in speed and direction. By the fourth day we were using the manner of gait before any other character to pick out Terek Sandpipers among other waders. It was most obvious when the birds were feeding on open mud, but little sub­ dued when they were following a leading line such as the tide edge or a lagoon channel.

BROAD-BILLED SANDPIPER During a count of waders near Govatar on 9th April, two grey Calidris-like birds were found feeding around the edge of a small pool. At 40 metres one, which was up to its belly in the water, appeared to be a Curlew Sandpiper C. ferruginea, while the other, walking along the edge, seemed to be a Dunlin C. alpina. We ap­ proached to 20 metres, and by then both birds were up to their bellies in the pool and probing delicately downwards with their 378 West Palearctic birds in Tmn bills, like Curlew Sandpipers. Suddenly they turned head-on to us and showed instantly the prominent double supercilia of Broad- billed Sandpipers Limicolafalcinellus. A few minutes at closer range were sufficient to see also the bulk of their bills and the delicate scaling on their upperparts. There could be no doubt of their identity. Later we saw them in flight, when they showed quite prominent whitish wing-bars and called with low, trilled chiprit or pirrit notes. A dark patch at the front of the folded wing was apparent on careful inspection, and their precise carriage compensated well for their rather short legs.

Fig. i. Broad-billed Sandpipers Limicolafalcinellus, south Iran, April 1972, re­ taining much winter plumage and wading in a manner that recalled Curlew Sandpipers Calidris ferruginea The point of this tale and the accompanying sketch (fig. 1) is to indicate how, on their own, the birds seemed different from their widely accepted image, in both appearance and actions; since they evidently retained much winter plumage, they did not look dark, and above all they appeared neither small nor sluggish (cf. the 1966 edition of the Field Guide). The rarity of this species in Britain is annually confirmed, but perhaps we should take a little more care with what are often dismissed as 'odd Dunlins'.

GREAT BLACK-HEADED GULL One of our particular hopes was to study Great Black-headed Gulls LOTUS ichthyaetus, known to frequent the Mekran coast fairly com- West Palearctic birds in Iran 379

Fig. 2. Sub-adult Great Black-headed Gulls Laws ichthyaetus, Mekran coast, south Iran, April 1972: note variable head markings, massive hunched appearance, long heavy bills and striking flight pattern monly. In the event few were seen, but of six or seven immature and sub-adult birds at the mouth of the Zarbarz River three were closely watched for 40 minutes on 6th April. Standing or sitting in a crowded roost of assorted gulls and terns, the birds were easily con­ fused with young Herring Gulls L. argentatus (of at least one of the dark eastern races). Picking them out was not a matter of a brief search. While all three shared a massive, hunched appearance, rather long legs and strikingly long and deep bills, a somewhat similar combination of characters was also exhibited by the largest of the Herring Gulls, at least at certain angles. Furthermore, the pattern of head marks was variable, and those of at least one were faint enough for it to be overlooked initially. Finally, the pat­ tern of die folded wings was not obviously different. In the end we were agreed that, without a clear sight of their bills—always longer, tipped darker, apparently narrower in section and with a heavier gonys—it would be difficult to be certain of the identity of smaller individuals. In flight they were much more distinctive, their larger size and the broad, dark tail band being immediately striking. Their flight action was somewhat reminiscent of a Grey Heron Ardea cinerea, the stroke of their very bowed wings coming from the body and with little evident flexing at the carpal joints; this feature had pre­ viously struck P.A.D.H. The accompanying sketch (fig. 2) attempts to illustrate the above points.

SWIFT AND LESSER CRESTED TERNS We saw seven species of terns on the Mekran coast, and to most of us die Swift (or Greater Crested) Tern Sterna bergii and the Lesser Crested Tern S. bengalensis were new. Both were exhibiting adult and immature plumages and we were able to make reasonably complete notes. Sterna bergii is highly unlikely to occur in European waters but, since it is liable to confusion both widi bengalensis and with the 38o West Palearctic birds in Iran

Fig. 3. Sea terns, Mekran coast, south Iran, April 1972: Caspian Hydroprogne caspia (top left, third from left at foot); Lesser Crested Sterna bengalensis (three upper right, upper main figure, and first and third from right at foot); Swift S. bergii (three upper left below Caspian, lower main figure and head inset, and first, second and fourth from left at foot); and Sandwich S. sandvicensis (second from right at foot). For descriptions see text

Royal Tern S. maxima, it should be noted that it is a large rakish bird, much closer in size to the Royal and Caspian Terns Hydroprogne caspia than to bengalensis. In adult plumage its best field marks are its long, dagger-like, yellow bill, prominent white forehead (giving it an awkward facial expression), thick ragged black hind- cap, and dark dusky-grey mantle and inner wing-coverts contrasting with silvery primaries. In immature plumage the first three of these West Palearctic birds in Iran 381 field marks are evident, but the upperparts are more variegated, with dark primaries and a blackish bar across the secondaries. Several birds seen by us were in the strikingly variegated plumage known as 'portlandica'. The flight is strong, with much shearing into the wind, but not as powerful as that of caspia, the wings often being sharply angled at the carpal joints. The flight calls are loud and raucous, even crow-like (though not deep), and might be written as kerrack or kerrerer; other notes recall those of Black-headed Gulls Lams ridibundus. None closely resembles the calls of maxima or of the Sandwich Tern S. sandvicensis, which are respectively bass and tenor equivalents of the same sounds. Sterna bengalensis occurs along the southern Mediterranean coast and in Morocco; it has wandered north as far as southern France and Switzerland, and there was a report of one in Co. Wexford in July 1971 (T. Ennis and R. J. Johns in litt.). In contrast with the hulking appearance of bergii, it is a truly beautiful tern; most individuals appear smaller than sandvicensis, their general character being between that species and a large Common Tern S. hirundo. In adult plumage the most diagnostic field marks are its fairly long and slightly drooping, but not particularly deep, pale orange bill, narrow white forehead, crested black crown (not as obvious as that of bergii), and pale bluish-grey mantle and inner wing-coverts contrasting with silvery-white primaries. Even in immature dress the bird's grace is still very evident and, although the pattern of the upperparts is variegated, we saw no striking 'portlandica' plum­ ages. The flight is fast and direct, the action recalling hirundo as much as sandvicensis. Its voice was not heard by us. Adults of the two species lack white rumps, the grey of their mantles continuing down to their tails. In the bright light of the Mekran coast, however, both (particularly bengalensis) could appear to have whitish rumps, and certainly immatures of both species often showed whitish patches above their tails. Clearly it is as diffi­ cult to be sure of rump colour in these terns as in hirundo and the Arctic Tern S. paradisaea. Neither species could easily be mistaken for caspia, the weight of whose head and wine-red bill (often with a dark tip) is unique among terns. They could quite possibly be confused with maxima, however, which has some of the marks of both but whose character is that of a large sandvicensis: like that species, maxima is mainly white in all plumages, its grey mantle lacking the duskiness of bergii or the bluish tone of bengalensis. The bill of maxima is even stronger than that of bergii and deeper orange (at least in adults) than that of bengalensis. The general appearance and underwing pattern of most of the species discussed above are illustrated in fig. 3 opposite. It must 382 West Palearctic birds in Iran be stressed, however, that the mantle tone of terns is much affected by the strength and angle of the sunlight: at midday on the Mekran coast, the normally strikingly dark mantle of bergii can look as pale as that of bengalensis.

INDIAN SAND LARK On gth April we passed through a community of Indian Sand Larks Calandrella raytal near Kolani in the Das Tiari, and on the next day we found others near Bahu Kalat. They were immediately distinguishable from both Short-toed C. cinerea and Lesser Short- toed Larks C. rufescens, showing much paler plumage as bleached as their light-coloured, silty habitats. Their pallidity was due not only to the silver-sand tone of their faintly marked upperparts and the general whiteness of their underparts, but also to the lack of dis­ tinct marks anywhere in their plumage. The relative absence of streaks was most obvious on the wing-coverts, which are well marked in the other two species, particularly cinerea, even in its pale eastern forms. The chest sides were faintly smudged with dusky marks, but the only obvious field-character was in the tail where, in flight, blackish outer feathers (not the outermost) showed in striking contrast with the rest of the upperparts and were much more conspicuous than in either European congener. The voice is closely similar to that of rufescens and, by the same token, quite unlike that of cinerea. To P.A.D.H., who has paid the most attention to the subject (aided by recordings), the calls and songs of raytal and rufescens have similar structures, components and presentations, though the individual notes of the former's song sound slightly higher in pitch and more delicate or clearer in tone to some ears. Contact calls were written as cherrup and chiprip. The song-flights that we saw (shortly after dawn and in the early eve­ ning) appeared similar to that of rufescens, the birds flying busily round in low, flat circles, and not dipping and rising like cinerea.

GREAT AND CLAMOROUS REED WARBLERS The of large Acrocephalus warblers has half-blinded many a museum worker (see the discussion in Williamson 1968a). Although recent authors have usually treated the Great and Clamo­ rous Reed Warblers A. arundinaceus and A. stentoreus as separate species, this past confusion has been no real encouragement to the field ornithologist to try his hand in assistance. British observers making spring visits to the Azraq oasis in Jordan in the mid-1960's and working in or visiting Iran during 1966-72 have been fortunate in finding both species together at least twice and in seeing and hearing a lot of Clamorous Reed Warblers on many other occasions. The results of their observations are summarised below. The discus- West Palearctic birds in Iran 383 sion here follows Williamson (1968a) in recognising the following races (approximate breeding ranges in brackets): A. a. arundinaceus (north-west Africa, Europe, west Asia), griseldis (restricted to lower ), zarudnyi (central Asia) and orientalis (east Asia), all migratory; and A. s. stentoreus (Palestine and Egypt, resident), brunnescens (Caspian to north-west , migratory), and several other forms of this species in the Indo-Australian region. At first glance in the field, it is difficult to distinguish the two species: at a distance they are both large, heavy-billed, long-tailed, brown or brownish warblers. At close range, however, a number of differences can be detected which appear to be consistent with Williamson's detailed analysis:

BILL The bill of stentoreus, both of the form occurring at Azraq (probably the nominate) and of brunnescens, looks paler, longer and slimmer than that of arundi­ naceus, at least of the nominate race and zarudnyi. It can also appear slightly down- turned. SUPERCILIA Some stentoreus show well-marked supercilia, but in general they are less obvious than on arundinaceus. The bill shape and comparative lack of supercilia combine to give a gentler expression to the face of stentoreus. UPPERPARTS The mantle and mid-upperparts of stentoreus, particularly of brunnescens, are paler than those of arundinaceus. Racial variations in plumage tone make such judgement difficult, but in Iran brunnescens looks cold olive-grey in full sunlight, with a warm tone detectable only on the head. This race, at least, appears paler in the field than any other large acrocephalus in the Palearctic and lacks the yellowish-buff suffusion of arundinaceus. The stentoreus at Azraq were sandier than those in Iran but again paler than nominate arundinaceus. UNDERPARTS The underparts of stentoreus are paler than those of arundinaceus, and again this is most marked in brunnescens which in Iran frequently shows only a mixture of off-whites and pale greys. TAIL AND WING SHAPE The tail of stentoreus often looks strikingly long and always very rounded. It is also waved about in sexual display, and one's eyes are frequent­ ly drawn to it. Contributing to this impression may be the much shorter wings of nominate stentoreus and brunnescens compared with nominate arundinaceus and zarudnyi, the mean measurements given by Williamson differing by 8-18%. It should be noted, however, that griseldis and orientalis have wings as short as stentoreus, but both of these have correspondingly short tails, particularly the former. GENERAL APPEARANCE Probably because of its bill length and tail prominence, stentoreus, both at Azraq and in Iran, has often struck observers as being generally long and slim in the field. Thus, while it looks large-headed, it lacks the particularly robust character of arundinaceus. While perhaps none of the above points is easy to be certain of in isolated birds, their total effect is to give stentoreus a rather distinct character which I find is consistently conveyed in my three series of sketches made over the last nine years; the drawing overleaf (fig. 4) attempts to illustrate the differences. L.C., who has the most comparative experience in recent years, has repeatedly distin­ guished the two species in Iran on these points since 1967. Much more helpful than any plumage feature, however, are the 384 West Palearctic birds in Iran

Fig. 4. Clamorous Reed Warbler Acrocephalus stentoreus (left) and Great Reed Warbler A. arundinaceus, from sketches made at Azraq, Jordan, April 1963, and in south Iran, April 1972. Note paler tones and longer-looking bill of former songs of these two warblers. While both may be subject to local dialect, field notes and tape recordings disclose a clear dichotomy. The song of arundinaceus is well known, with a deep, throaty karra- karra-gurk-gurk-gurk theme which appears constant in the west Palearctic. The song of stentoreus, both at Azraq and in Iran, has a similar strength but is thinner and higher-pitched. Its rhythm is more broken, with many grace notes and squeaky cackles, and its most characteristic theme may be written as ro-do-peek-kiss with an accent on the third or last syllable. This difference is clearly audible in the case of both a single songster and a loud chorus. It is worth underlining the fact that stentoreus shows a wider tolerance of habitats than arundinaceus. Its occurrence in papyrus swamps has long been known. In Iran it is common in mangroves and in bushes along irrigation ditches and appears to like shrubs and trees in the vicinity. It used to be the practice of the Rarities Committee to publish in its annual report a caveat mentioning the virtual impossibility of separating arundinaceus from stentoreus. The separation of singing birds is, however, clearly possible and the distinction of others at least worth attempting. I personally doubt that stentoreus has ever been overlooked in western Europe; the nominate race is resident and brunnescens migrates south and south-east to southern Iran and the Indian sub-continent, even reaching Malaya (Vaurie 1959). West Palearctic birds in Iran 385 The latter is the more distinct form, particularly in comparison with nominate arundinaceus of Europe.

PADDYFIELD AND BLYTH'S REED WARBLERS No group of small warblers in the west Palearctic presents more identification problems than the unstreaked Acrocephalus. Because of the rarity of Paddyfield and Blyth's Reed Warblers A. agricola and A. dumetorum in easily accessible parts of Europe, only limited progress has been made in the solution of these problems, though Sharrock et al. (1970) showed that Blyth's Reed was much more dis­ tinctive than had been supposed, and their analysis drew support from Finnish observers. Even so, no general review has updated the remarks of Alexander (1955), anc^ some of the published notes on recent British records even appear to conflict with his views, at least in the case of agricola. Given this situation, recent observa­ tions in Iran in winter and during our spring visit in 1972 have been carefully searched for new criteria. The points that have emerged are shown below in fig. 5 and described overleaf.

Fig. 5. Blyth's Reed Warbler Acrocephalus dumetorum (upper three) and Paddyfield Warbler A. agricola (lower three), south Iran, April 1972, showing noticeably stronger, more rufous plumage tone of latter and differences in bill shape and head pattern. Also illustrated (upper left, top to bottom) are scaled structures of Marsh Warbler A. palustris, Reed Warbler A. scirpaceus, Blyth's Reed and Paddyfield, showing progressive reduction in wing-length (for details see text) 386 West Palearctic birds in Iran STRUCTURE AND SHAPE Williamson (1968a) published full details of structure, showing that the average wing-length decreased from the Marsh Warbler A. palustris through the Reed Warbler A. scirpaceus and Blyth's Reed to the Paddy- field. Wings also become more rounded as length decreases, and agricola, the shortest-winged, has the longest tail (for an illustration of this, see Gooders 1970). The differences are not dramatic, but there is a parallel situation in Hippolais warblers where structure has proved a valuable character in field identification (Wallace 1964). Furthermore, it was such structural features that contributed most to the discussion of dumetorum by Sharrock et al. Iranian observations fully support the view that ornithologists experienced in identifying western Acrocephalus will be surprised by the shorter wings and longer tails of agricola and dumetorum. This combination is particularly striking in the former, and one that we watched closely in bushes and on the ground in Zahedan on 31st March 1972 looked very different in shape from scirpaceus. At first sight it was likened to a bush robin Cercotrichas, looking large as it cocked its tail on landing. Such an appearance clearly echoes the character of the Fair Isle bird of 1953 (Williamson 1954) and, though Alex­ ander (1955) was puzzled by this, it now seems that the structure of agricola and its bright, warm plumage may combine to give an illusion of increased size. At close range or in the hand, this is corrected and the bird appears small. R.F.P. comments that agricola, in addition to flicking its tail, also raises its crown feathers. In Iran dumetorum did not show the wren-like appearance referred to by Sharrock et al., and looked normal in size. The length of its tail was, however, a striking feature, again exaggerated by upward flicks. Finally, agricola and dumetorum show a surprisingly obvious difference in bill shape, the former's being short and stout (contributing to the occasional chat illusion) and the latter's long and rather fine. PLUMAGE Discussions of plumage differences between unstreaked Acrocephalus are often mere semantics. In adults from March to late April, however, it appears that there is a cline in the shade of the upperparts from bright rufous (even orange) in agricola through dull rufous-brown in scirpaceus and olive-brown in palustris to greyish-brown in dumetorum. In birds of the year in reasonably fresh plumage, this variation is much subdued and all species share more tawny or rufous colours; only agricola is still exceptionally bright. Iranian observations, uncluttered by the presence of scirpaceus and palustris, fully confirm that spring agricola and dumeto­ rum exhibit quite different plumage tones in the field. The former looks warm and bright in any reasonable light, but the latter always appears cold and olive-grey, particularly in strong sunlight. Furthermore, the underparts of the former, particularly the flanks and undertail-coverts, are strongly suffused with yellowish and buff tones, while those of the latter appear almost clear. In addition, the tertials of adult agricola are more strongly marked than those of adult dumetorum, their dark centres and pale bright fringes contrasting vividly (for illustrations see Witherby et al. 1938-41, Flint et al. 1968), but unfortunately young dumetorum also seem to show this character (at least in skins) and its use in autumn is there­ fore suspect. Finally, and most importantly, agricola sports the most prominent supercilium of the four species. On spring birds in Iran it is striking, extending from the bill over the eye to at least half-way along the ear-coverts (once again chat-like). It varies in width, and also in colour from off-white to a full cream. In contrast the supercilium of spring dumetorum in Iran is an insignificant mark hardly visible at any range.

LESSER, DESERT LESSER AND HUME'S LESSER WHITETHROATS Our time in Iran provided much experience of the Desert Lesser Whitethroat Sylvia minula, which we saw almost daily and often in good numbers. After much searching, we eventually found migrant West Palearctic birds in Iran 387 Lesser Whitethroats S. curruca (presumably of the race blythi or halimodendri) at Bahu Kalat on 10th and 1 ith April, and we finally caught up with Hume's Lesser Whitethroat S. althaea setded on territories on Kuh-i-Taftan on 17th April. The systematics of this group remain confused: although Vaurie (1959) treated the three forms as separate species since their breeding ranges overlap through a large part of Iran, Williamson (1968b) lumped them all under S. curruca. Sylvia minula usually looked rather small and short-tailed, recalling the Spectacled Warbler S. conspicillata, with dusky or sandy grey- brown upperparts, and with a noticeably dull head in males. The blackish face patch so characteristic of male curruca was restricted to the lores and fore-cheeks in most males and was virtually absent in some. All birds showed sandy-white underparts, and R.F.P. remarked that minula always looked 'washed out'. Judging by our notes and recordings, its voice has a fully specific character. The most frequent contact and alarm calls, written as chee-chee-chee and tirritic, recalled not curruca but tits and notably Tree Sparrows Passer montanus. Some birds scolded like curruca, but the pleasant, rather quiet song was full of varied warbling and completely lacked the monotonous rattle of the European species. When compared directly with minula, the migrant curruca at Bahu Kalat were distinctly bulkier and longer-tailed, their bills also appearing stronger. They had well-marked face masks and were definitely greyer on the mantle and rump, with darker tails. The althaea on Kuh-i-Taftan were even more distinct from minula, being similar in size to curruca or a little bulkier. They were obvi­ ously darker, with even blacker heads and a distinctly bluish or slaty tone to their entire upperparts. The wing panel formed by the light edges of their tertials and inner secondaries was obvious, again recalling some curruca and not minula. In most birds there was a greyish wash on the chest sides (sometimes reaching the edge of the throat) and a buffy tinge on the flanks below the folded wings. The bill was noted as tit-like and noticeably dark, appearing larger than that of curruca and certainly so compared with that of minula. The song we heard was a brief warble written as tru-tru, tru-ee, tru-ee, tru-eee, with a clear, ringing quality reminiscent of the song of the Blackcap S. atricapilla and quite distinct from either the curruca in Europe or the minula heard by us. Other calls included a melodious wheet-wheet-wheet, recalling the Eastern Rock Sitta tephro- nota and used sometimes as a prefix to the song; a churr typical of the genus; and a harsh, unusually loud chatter, again like that of the Tree Sparrow. (It must be stressed that these comments on voice are based on notes and recordings from a short period of time.) The complete absence of the dry rattle of curruca from the songs 388 West Palearctic birds in Iran

Fig. 6. Desert Lesser Whitethroat Sylvia minula (upper), Lesser Whitethroat 5. curruca (centre) and Hume's Lesser Whitethroat S. althaea, south Iran, April 1972, showing increasing size and colour saturation in these three closely related but apparently distinct species of the other two is noticeable and may prove taxonomically signifi­ cant : certainly the three forms looked and sounded like more than just races of the same species, as Williamson treated them. Fig. 6 attempts to illustrate the differences in plumage and structure. It should also be noted that, while the minula and curruca at Bahu Kalat were often alongside each other in the same vegetation, the althaea breeding on Kuh-i-Taftan were in a quite different subalpine habitat 2,300-2,600 metres above sea level.

YELLOW-BROWED WARBLER Of four Yellow-browed Warblers Phylloscopus inornatus we saw in Iran, three were not immediately identified as such. The reason for this somewhat surprising situation was the lack of certain characters normally obvious in autumn vagrants in fresh plumage. In the end, we realised that all three birds showed the characteristic shape and behaviour of the species, but they lacked utterly the front or upper wing-bar (on the median coverts) and the whitish tips to the tertials (fig. 7). In the absence of these marks, and also because of a general dullness in colour and an apparent largeness, we had found it difficult to believe that we were not involved with some other species. Only prolonged and close observation showed that partial moult was in progress on all four birds, and that, on at least two, excessive West Palearctic birds in Iran 389 but confusingly even wear was responsible for the loss of marks so long held to be constant and diagnostic. It thus appears that, like some congeners, notably the Arctic Warbler P. borealis, the Yellow- browed Warbler can completely lose certain plumage features, though there is no mention of this in Williamson (1967) or any field guide. Even the trusty Handbook does not quite cover the danger, suggesting that abrasion does not have any real effect before the summer.

Fig. 7. Yellow-browed Warbler Phylloscopus inornatus (probably of subspecies humei), south Iran, April 1972, lacking upper wing-bar and whitish tertial fringes normally present on autumn vagrants to western Europe

Further observations by L.C. and D.A.S. have shown that a population of the race humei winters in Iranian Baluchistan and that these birds are invariably dull and frequently lack the upper wing-bar (or appear to do so in the field). It also seems possible that this race has a vocabulary partly distinct from that of the typical form that occurs as an autumn vagrant in Europe, since one on Kuh-i-Taftan on 17th April uttered a loud chwee, ch-wee or tiss-yip, a rich sparrow-like note quite unlike the voice of the nomi­ nate form, which recalls the Coal Tit Parus ater.

REFERENCES ALEXANDER, H. G. 1955. 'Field-notes on some Asian leaf-warblers—II'. Brit. Birds, 48: 349-356 (354-355)- FLINT, V. E., BOHME, R. L., KOSTIN, Y. V., and KUZNETSOV, A. A. 1968. The Birds of the U.S.S.R. (in Russian). Moscow. Plate 38. GOODERS, J. (ed.) 1970. Birds of the World. London, p 2099. SHARROCK, J. T. R., HUTCHINSON, C. D., PRESTON, K.., and BARBIER, P. G. R. 1970. 'The identification of Blyth's Reed Warbler in autumn'. Brit. Birds, 63:214- 216. (See also full descriptions in Cape Clear Bird Obs. Rep., 11: 34-38.) SLATER, P. 1971. A Field Guide to Australian Birds: Non-. Edinburgh. pp 287-288. VAURIE, C. 1959. The Birds of the Palearctic Fauna: Passeriformes. London, pp 244- 247. 259-263. WALLACE, D. I. M. 1964. 'Field-identification of Hippolais warblers'. Brit. Birds, 57: 282-301, plates 42-43. 39« West Palearctic birds in Iran WILLIAMSON, K. 1954. 'Paddyfield Warbler at Fair Isle'. Brit. Birds, 47: 397-301. 1967. Identification for Ringers, a. The Genus Phylloscopus. B.T.O. Field Guide 8, second edition, pp 17-20. 1968a. Identification for Ringers. 1. The Genera Cettia, Locustella, Acrocephalus and Hippolais. B.T.O. Field Guide 7, third edition, pp 34-42, 44-51, 67. ig68b. Identification for Ringers. 3. The Genus Sylvia. B.T.O. Field Guide 9, second edition, pp 22-30. WITHERBY, H. F.,etal. 1938-41. The Handbook of British Birds. London, vol 2: plate 37- D. I. M. Wallace, g Woodhill Rise, Heads Lane, Hessle, Hull, Yorkshire HU13 OHZ