The Austral African Races of the Rush Warbler Bradypterus Baboecala.Pdf

VOL. XI, PART 0 ISSUED 30th SEPTEM BER, 1976 MISCELLANEOUS TAXONOMIC NOTES ON AFRICAN BIRDS XLV b y P. A. CLANCEY (Director, Durban M useum , Durban) THE RACES OF THE W HITETHROAT SYLVIA COMMUNIS L A T H A M REACHING THE SOUTH AFRICAN SUB-REGION Following the findings of Stresemann and Stresemann , Journ.f. Ornith., vol. cix, 3, 1968, pp. 303 - 314, nom inate Sylvia communis Latham , 1787: Kent, England, is currently not consi dered to reach the South A frican Sub-R egion during its non-breedin g soj ou m in E th i opian Africa, the tw o races wintering in the Sub-Re gion being S.c. volgensis Domaniewski, 1915: Saratov, Volga R., U.S.S.R., an d S.c.icterops Menetries, 1832: Talych=Talyshskiye Gory, south eastern Azerbaydzhan, U.S.S.R. I have recently rese a r c h e d the races of S.communis to be adm itted to the South A frican list and conclude on the basis of m aterial from Rhodesia and Botswana, in addition to specim ens from Zam bia and southern-west ern Tanzania, that while it is true enough that m ost specim ens ar e clearly attri butable to both volgensis a n d icterops, som e elem ents of S.c.communis do reach the drier interior of southern A frica duri ng their non-breed ing stay in Africa, where they m oult, and that the exclusion of this taxon from the list is indefensible. W hile m uch of the m aterial available is in a seriou sly abraded and insolated condition, a sufficiency of m oulting or c om pletely m oulted [P rice R l , 5 0 nett] Reproduced by Sabinet Gateway under licence granted by the Publisher (dated .) 1 2 0 Miscellaneous Taxonomic Notes on African Birds Atlantic or, better highland Britain, population is sufficiently dis crete as to be recognised as a fourth subspecies. S.c.jordansi differs from S.c.communis in the male having the pileum m uch darker and greyer (H air Brown (pi. xlvi ) , versus D r a b (same pi.)); dorsum , dark Light Brownish Olive (pi. xxx) or redder, against B uffy Brow n (pi. xl). Ventrally, generally with the breast deeper pale vinaceous-cinnam on, and flanks darker a nd browner. In the wings, the red-brow n outer vanes and tips of th e greater-coverts and remiges are m ore saturated and ochraceous, and there is little or no developm ent of a pale wing-bar across the api ces of the said coverts. Fem ales are sim ilarly darker and rather re dder above, the head-top likewise darker and;greyer. Ventrally they do not differ, but the wings are also m ore saturated reddish over the coverts and rem iges, and the w ing-bar is lacking. Juveniles als o show the darker head-top character. W ings of 15 68,5 - 72mm. In its cold grey head-top colouration jordansi shows closer affinity w ith S.c.icterops t h a n w i t h S.c.communis. The range of S.c.jordansi is highland Britain in Ireland, W ales, north-western and northern England, and Scotland an d the Inner H ebrides. It does not reach eastern or southern A fr ica on m igration, and apparently winters in far W est Africa. Som e spe cim ens in the paratypical series taken in M ay in Scotland are in fresh contour plumage, but with the wing-tips and tails relativel y abraded, suggesting that in a proportion of this race the au tum nal m oult is arrested and only com pleted shortly before departur e from the African wintering grounds. South-eastern England breeders, topotypical of S.c.communis, a r e slightly interm ediate tow ards jordansi in that some males show a darkening of the pileum , but otherwise they agree w ell w ith Conti nental birds. This race is in a sense the link betw e e n jordansi a n d volgensis, having the short wing of the form er and the colour a t i o n o f the latter. A m ajor problem in appreciating the nature of the v ariation in the west of Europe is the industrial grim e which se riously contam i nates the birds on their arrival on the breeding gr ounds. For purposes of this study all British, D utch and Germ an breeder s were first dry c l e a n e d . THE AUSTRAL AFRICAN RACES OF THE RUSH W ARBLER BRADYPTERUS BABOECALA (VIEILLOT) The (Little) R ush W arbler is a largely sedentary sp ecies of perm anent marshes, papyrus swamps, and reedbeds alongside riv e r s a n d Reproduced by Sabinet Gateway under licence granted by the Publisher (dated .) by P. A. Clancey 1 2 1 lagoons, w hich extends in a series of m inor races f rom Niger and Chad in the west and the Sudan and Ethiopia in the east, south, in the w est, to southern A ngola, and in the east to the so uthern and eastern Cape and N atal. The precise num ber of races it is m eaningful to ad m it is still undecided, although m any have been des cribed, owing to the sm allness of the series in m ost instances. T he races occurring in southern Africa have at no tim e been studied in depth. Roberts, Birds of South Africa, 1940, p. 253, adm itted som e five subspecies for the Sub-Region, giving the characters believed to distinguish the taxa and an assessm ent of the ranges as he saw them on the very lim ited m aterial available in South African m useum s in the days im m ediately prior to the Second W orld W ar. A study of m aterial available to m e in the m id-1960’s indicated that at least four races o f B.baboecala were acceptable in the South African Sub-Region, these being in due course recognised in m y Catalogue of Birds of the South African Sub-Region, part iv, 1966, pp. 472, 473, and in the S.A.O.S. Check List of the Birds of South Africa, 1969, pp. 220, 221. Recent study of a series of 138 specim ens from sout h-central and southern Africa carried out in the Durban Museum su ggests the treatm ent of the populations adopted in m y Catalogue in 1966 is fundam entally correct, though the ranges of the fou r taxa adm itted require to be adjusted som ew hat, and the revised di agnostic charac ters are in need of publication. Variation of m om en t in grouping the populations into acceptable subspecies affects the level of saturation of the dorsum , the relative whiteness or buffiness of the ground to the venter, and the degree of streaking over the lo w er fore-throat. There is a m easure of variation in size and the len gth of the bill, the largest and longest billed birds occurring in the p opulation resident in the W inter Rainfall D istrict of the Cape. R obert s used bill-length to distinguish two large south-western races: B.b.baboecala a n d B.b.brachypterus (V ieillot), from those occurring further north in t h e east in South Africa: B.b.transvaalensis R o b e r t s , B.b.tongensis Roberts, and B.b.bedfordi Ogilvie-Grant=B.6.wsin Neave, but, while the m eans of this variable are statistically significantly differ ent, the wide range of individual variation and ove rlap in m easure m ents are such that I do not believe that bill-leng th on its own can be used w ith assurance in the recognition of subspe cific taxa. Individual variation is relatively high in the pres ent warbler, w hich, correlated w ith environm entally induced colo ur m odification and the sm allness of sam ples from single localities taken at one tim e, renders grouping of populations into satisfactory r aces difficult. Contamination from plant dust and carbon from grass fires also obscures differences unless m aterial is dry-cleaned in advance of Reproduced by Sabinet Gateway under licence granted by the Publisher (dated .) 1 2 2 Miscellaneous Taxonomic Notes on African Birds critical exam ination. On the other hand, “foxing” s carcely affects the Rush W arbler. A specim en collected by Lucas at P ot chef stroom in 1877 examined agrees remarkably well with recent l y - t a k e n m aterial of the same taxon. The population of the W inter Rainfall District of t he Cape is not divisible on the basis of colouration into west ern and southern races. R oberts, loc. cit., recognised tw o subspecies from the south western and southern Cape, respectively, the form er a s B.b.baboecala and the latter as B.b.brachypterus, but the arrangem ent is invalid, because, apart from the under tail-covert character used to dif ferentiate them not holding up in series, both nam e s have virtually the sam e type-locality: B.b.baboecala: Knysna, and B.b.brachypterus Knysna, or better, perhaps, Plettenberg Bay. They a re, therefore, absolute synonym s. The eastern lim its of this relat ively large, long billed population appear to be the East London dist rict of the eastern Cape, a specimen from East London being of n o m i n a t e B.baboecala, while one from further up the coast from M tafufu R .

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