Identification of Some Scarce Or Difficult West Palearctic Species in Iran D

376 Identification of some scarce or difficult west Palearctic species in Iran 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 birds 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 bird 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.

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