WILDFOWL 21 Published by the Wildfowl Trust, Slimbridge 1 9 7 0 Editors: G. V. T. Matthews and M. A. Ogilvie The Wildfowl Trust, Slimbridge, Gloucester, England Cover painting by Peter Scott Line drawings by Peter Scott, Thierry Robyns de Schneidauer, Robert Gillmor and others. Price 25/Od. (£1.25) ($3.40). Postage extra Issued free to Life and Full Members of the Wildfowl Trust Printed f o r th e w il d f o w l t r u s t by THE BERKSHIRE p r in t in g Co. l t d ., Reading, Berkshire, England, 1970 Contents The endemic ducks of remote islands. David Lack page 5 The swans and geese of Alaska’s Arctic Slope. James G. King 11 Distribution and numbers of the Pink-footed Goose in central Iceland, 1966-69. C. J. K. Bulstrode and D. E. Hardy 18 Winter wildfowl counts in south-east Europe and western Turkey. Alan Johnson and Heinz Hafner 22 Redbreasts in Rumania. Peter Scott 37 Ecology of the Danube, with special reference to waterfowl in Lower Austria. Antal Festetics and Bernd Leisler 42 The waterfowl of Mongolia. Eugeniusz Nowak 61 The comparative ecology of waterfowl in north Queensland. H. J. Lavery 69 The Auckland Islands Merganser. Janet Kear and R. J. Scarlett 78 The Marbled Teal. Brian Hawkes 87 Wildfowl distribution, conservation and research in southern Africa. W. R. Siegfried 89 The moult migration of Yorkshire Canada Geese. A. F. G. Walker 99 The daily pattern of display in a wild population of Eider Duck. Martyn L. Gorman 105 Field trials of the reactions of sheep to goose droppings on pasture. J. B. A. Rochard and Janet Kear 108 Dispersal of phytoplankton by ducks. Kathleen M. Atkinson 110 A ‘Slimbridge’ in British Columbia. B. A. Leach 112 The hand-rearing of young Blue Duck. W. J. Pengelly and Janet Kear 115 Double wing-moult in the Alaccoa Duck. IV. R. Siegfried 122 Studies on the development of young Tufted Duck. Janet Kear 123 Current Reports, 1969: Slimbridge Wild geese and wild swans, 1969-70 133 Other research and conservation 136 Education 137 The wildfowl collection breeding results 138 Peakirk The wildfowl collection breeding results 141 Borough Fen Decoy, Welney Wildfowl Refuge, Dersingham Decoy, Abberton Reservoir, Loch Leven 142 Wildfowl ringing in Britain 148 Wildfowl censuses and counts in Britain, 1969-70 148 International research and conservation 150 Wildfowl survey in south-west Asia 150 Bewick’s Swans in the Netherlands, March 1970 152 Annual Report of the Wildfowl Trust, 1969 154 THE WILDFOWL TRUST SLIMBRIDGE, GLOUCESTER The aims of the Wildfowl Trust are : 1. To maintain and breed wildfowl in captivity, especially those species which are in danger of extinction. 2. To carry out scientific study of wildfowl in the wild state and in captivity. 3. To apply that scientific knowledge and experience to the conservation of wildfowl at home and overseas. 4. To educate the public by all available means to a greater appreciation of wildfowl in particular and nature in general. Ducks of remote islands 5 The endemic ducks of remote islands DAVID LACK Introduction with the names and measurements of the This paper is concerned with all those resident forms of Anas. On large islands and on islands near continents many ducks which have formed distinctive sub­ species of ducks coexist. For instance, 13 species restricted to one particular small species, 7 in the genus Anas, breed regu­ and remote island or archipelago. Only larly in Britain (Parslow 1967), 16 species, dabbling ducks in the genus Anas are 6 in the genus Anas, in Iceland (F. involved. Many species in this genus have Gudmundsson pers, com.), 8, 5 in the an extremely wide range, but the average genus Anas, in the Falkland Islands number of subspecies per species is as (Cawkell and Hamilton 1961) and 7, with low as 1.9 for the 38 species recognised 2 more in the nineteenth century, 4 in the by Delacour (1954-64). Hence the fact genus Anas, in New Zealand (Williams that nearly all the ducks on remote small 1964). Some of the Falklands and New islands are separate subspecies means that, Zealand forms are endemic, not so those for ducks, they belong to relatively of British or Iceland. Although the isolated populations. In contrast, on some various species of ducks look superficially of the archipelagos concerned, notably alike, especially when seen together in a the Hawaiian Islands and Galapagos, collection of living waterfowl, they have various of the land birds are distinctive in fact evolved an adaptive radiation species or even genera. Ducks evidently within the limits imposed by their aquatic wander widely and frequently, being life, and even the species of Anas helped by their powerful flight and their evidently differ sufficiently in feeding ability to settle on the sea. habits for up to six to coexist in the same area (Olney 1965). The islands and species concerned In contrast, on the remote small islands set out in Table I, only a single species of The islands concerned, all either tropical duck breeds, on Hawaii, Laysan, Wash­ or subantarctic, are set out in Table I, ington (in the Line archipelago), the Table I. Ducks in the genus Anas on remote islands. male male female weight of egg wing length culmen body weight in proportion in mm. in mm. in gm. clutch to body weight TROPICAL ISLANDS A. platyrhynchos MALLARD A. p. laysanensis LAYSAN 201 39.5 450 5 10.9% A. p. wyvilliana HAWAII 220 46 500 8 8.5% nominate northern 265 53 1000 11 5.4% A. streperà GADWALL A. p. coitesi WASHINGTON (Line Is.) 199 37 ——— nominate northern 271 41.5 —— — A. bahamensis BAHAMA PINTAIL A. b. galapagensis GALAPAGOS 203 42.5 ——— nominate S. America 214 43 ——— A. gibberifrons GREY TEAL A. g. remissa RENNELL (Solomon Is.) 187 33 —— — A. g. gracilis Australasia 202 39 ——— SUBANTARCTIC ISLANDS A. acuta (NORTHERN) PINTAIL A. a. eatoni KERGUELEN & CROZETS 218 32 450 4-5 — nominate northern 271 54 700 8 — A. georgica CHILEAN PINTAIL A. g. georgica SOUTH GEORGIA 217 34 465 5 8.0% A. g. spinicauda S. America 245 42 706 8 6.0% A. castanea CHESTNUT TEAL A. c. aucklandica AUCKLANDS & CAMPBELLS (136) 40 400 3-4 c.18.0% A. c. chlorotis New Zealand 199 44 590 6 10.5% A. c. castanea Australia 218 41.5 500 9 8.0% Notes: A. s. couesi is now extinct. Delacour (1954-64) admitted a separate subspecies near to A. a. eatoni on the Crozets and another near to A. c. aucklandica on Campbell Island, but these cannot be sustained. He also treated A. aucklandica (including the form chlorotis in New Zealand) as a separate species from A. castanea, but I have followed Frith (1967) in regarding them as conspecific. These are the only breeding ducks on the islands concerned except for the Grey Duck A. superciliosa, of which the New Guinea-Polynesian form A. s. pelewensis (male wing 245 mm., culmen 20.5 mm. and female weight 670 gm.) breeds on Rennell, and the New Zealand form A. s. superciliosa (male wing 259 mm., culmen 51.5 mm. and female weight 1000 gm.) breeds on the Aucklands. The measurements of male wing length and male culmen are the middle points between the extremes given by Delacour (1954-64) and the weights are from Lack (1968), assembled by J. Kear. Ducks of remote islands 7 Galapagos, Kerguelen, the Crozets and rather than from one of the continental South Georgia, and only two on Rennell forms independently. and the Aucklands. The second species Delacour (1954-64) followed other on the two latter islands is the Grey Duck authors in treating the Auckland Island A. superciliosa, which is not endemic on Teal as a separate species from the either, and which ranges widely over Australian Chestnut Teal A. castanea, but Polynesia, New Guinea and Australasia, this is a purely taxonomic decision, and and has recently colonised the only im­ it is generally agreed that these two forms portant subantarctic island, Macquarie, are closely related; following Frith (1967) which does not have an endemic duck they are here regarded as conspecific, (Carrick 1957). A. superciliosa is together with the intermediate New Zea­ decidedly larger than the other species land Brown Teal, which is presumably with it on Rennell and the Aucklands the immediate ancestor of the Aucklands (see note to Table I). form. Each of these island ducks belongs At least in Hawaii, Laysan, the Line to a species resident on the nearest main­ islands and the Galapagos, the existence land, except for the unlikely occurrence of only one resident species of duck is of the Northern Pintail A. acuta on Ker­ not due to the failure of other species to guelen and the Crozets, but this island get there. Twelve other species, 8 in the form at times shows the male plumage genus Anas, have occurred in the pattern characteristic of A. acuta, so the Hawaiian archipelago, usually in winter, identification can hardly be doubted. The namely Pintail Anas acuta (regular), Galapagos form of the Bahama Pintail American Wigeon A. americana, Green­ A. bahaniensis and the Rennell form of winged Teal A. crecca, Shoveler A. cly- the Grey Teal A. gibberifrons are much peata (regular), Blue-winged Teal A. dis­ less distinctive than the other island ducks cors, European Wigeon A. penelope, discussed in this paper. Northern Mallard A. p. platyrhynchos Perhaps the most striking point brought (the presumed ancestor of the resident out by Table I is that, while there is only endemic), Garganey A.