Characters and taxonomic position of D. J. Pearson and G. C. Backhurst

n , the arundinaceus ranges I widely and breeds south to the Mediterranean, extending also to northwest . In , it breeds through the USSR east to about

continued .

[Brit. Hints 81: 171-178, April 1988] 171 172 Characters of Basra Reed Warbler 85CE; farther south, it is replaced in the Near East and from Iran to the western Himalayas by the A. stentoreus, and in Iraq by the much smaller, slender-billed Basra Reed Warbler A. (arundinaceus) griseldis. The Basra Reed Warbler was described by Hartlaub, not from Asia but from a specimen collected by Emin Pasha at Nguru, some 200 km west of Dar-es-Salaam, Tanzania (Hartlaub 1891). The was subsequently found in Lower Iraq (Ticehurst 1920, 1922), to which its breeding appears to be restricted and where Vaurie (1959) gave its range as 'the marshes along the Euphrates and Tigris from north of Baghdad to Basra and Fao'. Hartlaub called his new taxon Calamoherpe griseldis. The bird continued to be treated as a full , though within the Acrocephalus, by, for example, Ticehurst (1922), Jackson (1938), and Mackworth-Praed & Grant (1960). Vaurie (1959), White (1960) and Williamson (1968), however, among others have preferred to regard it as a race of the Great Reed Warbler, and it has been accorded similar status in the recent eleventh volume of Peters's Check-list of of the World (Mayr et al. 1986). As a result, it has been of limited interest to European ornithologists, and has received scant attention in the popular literature.

Basra Reed Warbler Two other forms of the Great Reed Warbler complex have often been lumped under A. arundinaceus. The Eastern Great Reed Warbler A. (arundinaceus) orientalis of eastern Asia, treated as a race of arundina­ ceus by Vaurie (1959), Williamson (1968) and Voous (1977), but separated by Mayr et al. (1986), has a shorter and rather more rounded wing than Great Reed. In voice, habits, plumage coloration and bill size and shape, however, it resembles Great Reed very closely. The Clamorous Reed Warbler A. stentoreus is treated as a full species by Vaurie, Williamson and Voous, but was lumped under arundinaceus by, for example, Dementiev & Gladkov (1954) and Meinertzhagen (1954). Its wing is still more rounded, and the bill, although as long as that of Great Reed, is narrower (but not so slim as that of Basra Reed, see fig. 1). Fig. 1 Bill profiles and plans of Basra Reed The Clamorous Reed Warbler Warbler Acrocephalus (arundinaceus) griseldis breeds east and southwest of the (top) and Great Reed Warbler A. arundinaceus Basra Reed and is less strongly (bottom) Characters of Basra Reed Warbler 17 3 migratory. It is larger, and heavier-billed than Basra Reed; and the Red Sea and Near Eastern populations are much more warmly coloured. Its grating and clucking call notes recall those of Great Reed rather than Basra Reed. The Basra Reed Warbler winters in eastern parts of Africa. Fewer than 30 individuals had been recorded from that continent up to 1970, but movements and wintering range have since become much better known. From late October/December to March/early April, it occurs from southern Somalia through eastern Kenya and eastern Tanzania to Malawi and Mozambique to at least 17°S (Pearson et al. 1978; Hanmer 1979; Ash & Miskell 1981; Pearson 1982), with one record from the Transvaal (J. C. Sinclair in litt.). There are now also many records from Ethiopia for the period September-November (Ash 1981 and in litt.) and it is regular on autumn passage on the Sudan coast during late August to mid October (Nikolaus 1981; Nikolaus & Backhurst 1982; G. Nikolaus in litt.); it is also known from Saudi Arabia (Jennings 1981). The bird is particularly well known to us in Kenya, where over 700 have been caught on southward passage at the Ngulia ringing site in Tsavo West National Park (Pearson & Backhurst 1976), and where it appears to be the commonest wintering Acrocephalus on the Lower Tana floodplain (Pearson et al. 1978). The purpose of this paper is to describe the features of this West Palearctic breeding bird, in the hand and in the field, as observed in Kenya, and to stress reasons for our view that this and the Great Reed Warbler are decidedly different species. The coloration of the Basra Reed Warbler is best appreciated on recently moulted individuals. Moult occurs in Africa, but some 70-80% of those caught in Kenya and Malawi during November- December are already in fresh plumage or have moulted all except their outer primaries. Most thus appear to moult during an autumn stopover in Ethiopia, and only a minority do so in their final winter quarters. Plumage is already some­ what worn by the time that they return to their breeding grounds. The upperparts are uniform cold olivaceous-brown, lacking the warm

93. Basra Reed Warbler Acrocephalus (arundi- naceus) griseldis (after moult), Kenya, Decem­ ber 1982 (G. C. Backhurst) 174 Characters of Basra Reed Warbler

94. Basra Reed Warbler Acrocephalus (arundinaceus) griseldis (after moult), Kenya, December 1986 (G C. Backhursl)

95. Great Reed Warbler Acrocephalus arundinaceus (after moult), Kenya, December 1986 (G. C. Backhursl)

96. Reed Warbler Acrocephalus scirpaceus (after moult), Kenya, December 1986 (G. C. Backhursl)

97. Clamorous Reed Warbler Acrocephalus stentoreus, Sudan, September 1981 (D.J. Pearson)

[The inclusion of plates 94-97 in colour has been subsidised by ZEISS West Germany] Characters of Basra Reed Warbler 17 5 Table 1. Measurements (mm) and weights (g) of Basra Reed Warblers Acrocephalus (arundinaceus) griseldis, Great Reed Warblers A. arundinaceus and Reed Warblers .4. scirpaceus trapped in Kenya Reed Warblers: eastern birds, mostly of the racejuscus. Wing and tail measurements made only on fresh-plumaged birds. Weights given only for lean birds with fat rating / (see Pearson & Backhurst 1976) ' BASRA REED WARBI.KR GREAT RK.EI) WARBLER REED WARBLER Attribute n Range Mean n Range Mean n Range Mean

Wing (100) 78-88 (83.8) (100) 89-103 (96.4) (100) 64-75 (68.7) Tail' (24) 58-67 (63.1) (24) 72-81 (76.7) (20) 51-57 (53.8) Tarsus (29) 24-27 (25.2) (24) 27-31 (29.0) (23) 21-24 (22.7) Bill to skull (25) 20-24 (23.0) (24) 20-25 (23.8) (23) 16-19 (18.0) Bill to rear of nostril (22) 13.5-15.5 (14.5) (24) 13.5-16 (14.7) (100) 10-12.5(11.1) Bill width across rear of nostril (22) 4.4-5.4 (4.8) (24) 5.6-6.4 (6.0) (100) 3.7-4.8 (4.2) Weight (100) 13.4-18.8 (15.7) (44) 21.2-33.5 (27.5) (100) 9.0-11.9(10.4) tinge of nominate Great Reed Warbler, and darker and without the greyish tone of the central Asian zarudnyi; in fresh plumage, the tail is very dark. The underparts are much whiter than on nominate Great Reed, with a cold huffish wash confined to the flanks; in contrast to Great Reed, Basra lacks fine streaks on the throat. The supercilium is whitish (not buffish as on Great Reed), and, though narrow, quite prominent, extending from the base of the bill to well behind the eye; a contrasting dark streak through the eye is well emphasised. Bill and eye colour are similar to those of Great Reed, but the legs and feet of Basra are invariably dull greyish, in contrast to the typical pale brown of Great Reed. Wing, tail, tarsus and bill measurements of the Basra Reed Warbler are compared in table 1 with those of Great Reed Warbler and Reed Warbler A. scirpaceus. Except where otherwise stated, figures concern fresh- plumaged individuals caught in Kenya. Weight ranges are also given for lean individuals. Some measurements of sexed museum specimens are summarised in table 2. With respect to most measurements, Basra Reed is just about intermediate between the other two, with weights nearer to those of Reed. The bill, however, is the really distinctive feature: about as long as that of Great Reed, but thin and narrow (see also fig. 1 and plates 93-101). In proportion, the tail is slightly shorter than that of Great Reed, but the wing is long and pointed with a substantial 'primary projection'.

Table 2. Measurements (mm) of sexed museum specimens of Basra Reed Warbler Acrocephalus (arundinaceus) mseldis and Great Reed Warbler A. arundinaceus BASRA RF.F.D WARBLER GREAT REED WARBLER CfCf (5) $$ (4) CfCf (10) $$ (10) Attribute Range Mean Range Mean Range Mean Range Mean

Wing 82-85 (83.0) 78-84 (81.0) 93-99 (95.5) 89-96 (91.3) Tail 62-67 (64.6) 58-64 (62.0) 74-81 (77.5) 73-80 (76.1) Tarsus 25-26 (25.8) 24-26 (24.8) 29-31 (30.0) 27-29 (28.4) Bill (to skull) 20-24 (22.4) 22-23 (22.2) 23-25 (24.1) 20-24 (22.9) 176 Characters of Basra Reed Warbler

98. Great Reed Warbler Acrocephalus arundinaceus (after moult), Kenya, December 1985 (D. J, Pearson)

99. Great Reed Warbler Acrocephalus arundinaceus (after moult), Kenya, December 1985 (G C. Backhurst)

100. Basra Reed Warbler Acrocephalus (arundinaceus) griseldis (after moult), Kenya, December 1985 (G C. Backhurst) 101. Basra Reed Warbler Acrocephalus (arundinaceus) griseldis (before moult), Kenya, December 1983 (D. J. Pearson) Characters of Basra Reed Warbler 177 The wing formula, with the 3rd-4th primaries longest and the notch on the inner web of the 2nd primary falling, on the closed wing, between the tips of the 6th-8th primaries, is similar to that of Great Reed; this has presumably been one of the reasons for the 'lumping' of the two forms as one species. The voice of the Basra Reed Warbler is quite different from that of Great Reed. The typical call-note is a harsh 'chaarr', rather louder than the similar note of the Reed Warbler. The song, which may be heard in Kenya from January to March, is a rather subdued sequence of notes, 'chuc-chuc-churruc-churruc-chuc . . .', less squeaky and with a less forceful rhythm than the song of Reed, and quieter than and without the guttural, grating quality of that of Great Reed. In Kenya, wintering Basra Reed Warblers frequent moist green thicket, sedge and rank undergrowth similar to that utilised by Marsh A. palustris and Reed Warblers, and sometimes occur alongside one or other of those species. They have a greater preference, however, for cover adjacent to water, over drying lakes and floodpans and along ditches. On the Lower Tana, where they occur together with Great Reed Warblers, they mainly inhabit bushes and thickets, whereas Great Reeds are more dependent on stands of tall grass. In the field, the Basra Reed Warbler gives the impression of a large, slim, dark-tailed Reed Warbler rather than a small Great Reed Warbler. The long, slender bill is the most distinctive single feature, separating it easily from Great Reed. Additionally, the combination of white-looking underparts, long distinct supercilium and greyish legs should distinguish it readily from Reed and Marsh Warblers. Reed Warblers of the eastern race fuscus are white below and lack warmth on the mantle, but are paler above than Basra, with a shorter bill, a less distinct supercilium and browner legs. In view of its far smaller size, consistent and distinctive plumage differences, very different bill shape, different leg colour and different song, we feel that there is no justification for continuing to regard the Basra Reed Warbler as a race of Great Reed.

References ASH, J. S. 1981. Bird-ringing results and ringed bird recoveries in Ethiopia. Scopus 5: 85-101. & MISKEI.I., J. E. 1981. Basra Reed Warblers Acrocephalus griseldis overwintering in Somalia. Scopus 5: 121-124. HANMER, D. B. 1979. A trapping study of Palaearctic at Nchalo, southern Malawi. Scopus 3: 81-92. HARTI.ACB, G. 1891. Ornithologie der ostlichaquatorialen Lander und der ostlichen Kiistengebiete Afrikas. Abh. naturw. Ver. Bremen 12: 1 -46. JACKSON, F.J. 1938. The Birds of Kenya Colony and the Uganda Protectorate, vol. 2. London. JENNINGS, M. C. 1981. The Birds of Saudi Arabia: a check-list. Cambridge. MACKWORTH-PRAF.D, C. W., & GRANT, C. H. B. 1960. Birds of Eastern and North Eastern Africa. African Handbook of Birds, Series I. vol. 2. Second edn. London. MAYR, E., TRA\'U)R, M. A., & WATSON, G. E. 1986. Check-list of Birds of the World, vol. xi, Cambridge, Mass. MF.INERTZHAGEN, R. 1954. Birds of Arabia. Edinburgh. 178 Characters of Basra Reed Warbler

NIKOI,AI:S, G. 1981. Palaearctic migrants new to the north Sudan. Scopus 5: 85-101. & BAOKHL'RST, G. C. 1982. First ringing report for the Sudan. Scopus 6: 77-90. PEARSON, D. J. 1982. The migration and wintering of Palaearctic Acrocephalus warblers in Kenya and Uganda. Scopus 6: 49-59. & BACKHURST, G. C. 1976. The southward migration of Palaearctic birds over Ngulia, Kenya. Ibis 118: 78-105. , BRITTON, P. L., & BRITTON, H. A. 1978. Substantial wintering populations of the Basra Reed Warbler Acrocephalus griseldis in eastern Kenya. Scopus 2: 33-35, TICEHURST, C. B. 1920, 1922. Acrocephalus babylonicus $p. nov. Bull. Br. Om. CI. 41: 12-13; 43: 46- 47. VAL'RIE, C. 1959. The Birds of the Pakarctic Fauna. Order Passeriformes. London. Voois, K. H. 1977. List of recent Holarctic bird species. Passerines (part 1). Ibis 119: 223- 250. WHITE, C. M. N. 1960. A check list of the Ethiopian Muscicapidae (Sylviinae) Part I. Occ. Pap. natn. Mus. Sth. Rhod. 3 (24B): 399-430. WILLIAMSON, K. 1968. Identification for Ringers, I. The genera , Locustella, Acrocephalus and Hippolais. Third edn. Tring.

D. J. Pearson, Department of Biochemistry, Box 30197, Nairobi, Kenya G. C. Backhurst, Box 24702, Nairobi, Kenya