THE TENTH ANNUAL REPORT OF THE WILDFOWL TRUST 1 9 5 7 - 1 9 5 8 EDITED BY PETER SCOTT AND HUGH BOYD Price Ten Shillings Net Printed for The Wildfowl Trust by F. BAILEY & SON, LTD., Dursley, Glos. 1959 THE WILDFOWL TRUST SLIMBRIDGE : GLOUCESTERSHIRE Patron : HER MAJESTY THE QUEEN President : Field-Marshal the Rt. Hon. the Viscount Alanbrooke, K.G., G.C.B., O.M., G.C.V.O., D.S.O. Vice-Presidents : Sir Percy Lister Capt. R. G. W. Berkeley Trustees'. The Rt. Hon. the Lord Kennet of the Dene, G.B.E., D.S.O., D.S.C. His Grace the Duke of Beaufort, K.G., P.C., G.C.V.O. Hon. Treasurer : Guy Benson Hon. Director : Peter Scott, C.B.E., D.S.C. Council : J. Berkeley R. E. M. Pilcher Michael Bratby Miss P. Talbot-Ponsonby Dr. Bruce Campbell Sir Landsborough Thomson, Michael Crichton C.B., O.B.E. H. H. Davis Major-General C. B. Wainwright, Harley C. Drayton C.B. James Fisher J. E. H. Blackie K. Miller Jones (Ministry of Education Assessor) James Robertson Justice Scientific Advisory Committee : Sir Landsborough Thomson, C.B. A. R. Jennings O.B.E. (Chairman) *Dr. David Lack, F.R.S. Prof. H. G. Callan R. M. Lockley Dr. Bruce Campbell *Prof. Konrad Lorenz Dr. James W. Campbell, M.B.E. Sir Philip Manson-Bahr, C.M.G , Dr. F. Fraser Darling, F.R.S.E. D.S.O. *Jean Delacour Dr. L. Harrison Matthews, F.R.S. *Prof. W. H. Elder *Dr. Dillon Ripley Dr. D. J. Finney, F.R.S. H. N. Southern Prof. Sir Ronald A. Fisher, F.R.S. *Prof. G. A. Swanson Prof. John E. Harris, F.R.S. Dr. W. H. Thorpe, F.R.S. Dr. Jeffrey G. Harrison Dr. N. Tinbergen Prof. H. R. Hewer J. A. J. Venn Dr. Edward Hindle, F.R.S. Prof. C. H. Waddington, F.R.S. *H. Albert Hochbaum Prof. V. C. Wynne-Edwards, R. C. Homes F.R.S.E. Sir Julian Huxley, F.R.S. G. K. Yeates. Corresponding Members CONTENTS Section I: The Trust Collections Page New development at Slimbridge 4 Notes on the 1958 breeding season. S. T. Johnstone 5 Obtaining new birds 12 Section II : Trust Wildfowl Research Winter wild geese at the New Grounds 1957-58 16 Ringing 1957-1958 18 Duck Adoption Scheme 20 National Wildfowl Counts. G. L. Atkinson-Willes 21 Basic data from Wildfowl Counts. G. V. T. Matthews 24 Aerial Survey techniques. S. K. Eltringham 26 Techniques in wildfowl taxonomy. G. V. T. Matthews 31 Causes of death of birds at Slimbridge, 1955 - 1957. A. R. Jennings 37 The control of aspergillosis in bird collections. J. V. Beer 41 Greylag Geese in Britain in winter. H. Boyd 43 Movements of marked Sea and Diving Ducks in Europe. H. Boyd 59 Section III : Conservation and Research at home and abroad Wildfowl conservation in Denmark. G. V. T. Matthews 71 The conservation of waterbirds and their habitat in New Zealand. F. L. Newcombe 78 Establishing Canada Geese in West Kent and their use of nesting rafts. J. M. Harrison and J. G. Harrison 89 Brent Geese in Essex, 1957-1958. P. J. K. Burton 91 Recent research on Brent Geese. H. Boyd 93 What makes plumage waterproof? E. Fabricius 105 A goose-watching visit to northern Iceland. R. Gillmor and N. G. Blurton Jones 114 Some observations on wild geese in Spitsbergen. N. G. Blurton Jones and R. Gillmor 115 Waterfowl at Cold Bay, Alaska, with notes on the display of the Black Scoter. F. McKinney 133 Wildfowl of the Hemiarctic. P. M. Driver 141 Impressions of wildlife in Canada in the spring of 1958. S. K. Eltringham 144 A visit to some European Zoos. C. N. Vaisey 151 British literature on European wildfowl. G. V. T. Matthews 162 Section IV : Administration Eleventh Annual General Meeting 176 Membership 178 Obituary 179 Balance Sheet, 31st December, 1957 180 Income and Expenditure Account, 1957 182 Staff 184 NEW DEVELOPMENT AT SLIMBRIDGE T h e most important development in the Trust’s year has been the substantial expansion of the grounds at Slimbridge. In November, 1957, through the co-operation of Mr. O. W. Fisher and the Berkeley Estates Ltd., we were able to enclose a further eight acres of marshy ground adjoining the Big Pen and here, during the past twelve months, the wardens and maintenance staff have with extended effort and much physical application constructed roads, pens, ponds, and an aviary eighty yards long. Not the least of the tasks was the taking down and re-erecting on the new site five hundred yards of perimeter fencing, which feat was accomplished in one day. The ponds and lay-out were carefully designed by the Director to combine the optimum scenic effect with conditions most beneficial to the birds. We are now in a position to allocate pens to the birds of Australia, New Zealand, Africa, Asia and Europe, as well as to provide pens for breeding birds—swans in particular. A feature of the new development is a hillock which in the surrounding flat meadows is reminiscent of a miniature Wrekin. It had been hoped that “ the Tump ” could be raised to some 30 or 40 feet in order that those who are unable to climb the Acrow Tower might have a view of the Severn Estuary by walking up the gentle slope of our Tump. But soil mechanics experts have advised that the summit cannot be raised above its present fifteen feet. Nevertheless, an excellent view of the new area can be obtained from the apex. The aviary, most generously presented to us by Messrs. Arthur Guiness Ltd., has been sited with a southern aspect; it has ten compartments, each with an independent water supply and heating system. Here it is intended to keep Pygmy Geese and other species that are in need of protection against our winter. Large numbers of flowering shrubs have been planted, both to beautify and to give nesting cover, and we are most grateful for the many gifts received— in particular to Bees Ltd. for a large and varied consignment of shrubs. It is hoped to open the new area to the public by Easter, 1959, and perhaps one of the best features of this development is that visitors going to the Acrow Tower will be able to return by a different route from that by which they went. NOTES ON THE 1958 BREEDING SEASON S. T. Johnstone During the breeding season every clutch of eggs is incubated and the effect on every egg is duly recorded as infertile, addled or hatched. Whilst such pre-natal trouble is taken, it is after hatching that the real task commences. The death of all those young birds that succumb is noted and the carcases are sent to the School of Veterinary Medicine at Cambridge University where, through the kind offices of Mr. A. R. Jennings, they undergo a thorough post mortem examination. Finally, a pathological report on each corpse is sent to us. In the 1958 season we lost some 30% of the babies hatched. A great many of these deaths were due to chilling, and “ the wettest June for fifty years ” undoubtedly contributed in no small measure to this loss. It is therefore with some satisfaction that we have to record better figures than in any previous year. Some 850 birds were reared, there being over 230 goslings and cygnets and 640 ducklings. If we combine the figures for Slimbridge with those for our collection at Peakirk we get a total figure of over 1150 birds reared. But perhaps more gratifying than this large number is the fact that 97 kinds bred in our collections and over eighty forms were reared, amongst these being, we believe for the first time, the Black Brant (Branta bernicla orientalis) and the New Zealand Scaup or Black Teal (Aythya novœ-zeelandiœ). Hartlaub’s Duck (Cairina h. hartlaubi) bred for the first time but unfortunately the ducklings were weakly and were not reared. The Mallards did very well, being represented by eleven forms. Magpie Geese (Anseranas semipalmata), Bewicks Swan (Cygnus columbianus bewickii), Chinese Spotbills (Anas pcecilorhyncha zonorhyncha), Brazilian Teal (A mazonetta brasiliensis brasiliensis), Red-breasted Merganser (Mergus senator serrator), and Goosander (Mergus merganser merganser) were among the more interesting species produced. As ever, the early effort and interest was concentrated on the Hawaiian Geese. Nineteen birds were reared out of twenty-one hatched. The casualties were one deformed gosling that lasted three days and a second that was crushed by the hen on hatching. The high losses from gapes that had occurred in 1957 were avoided through the kind offices of our farmer neighbour, Mr. Fisher, who gave us facilities for rearing the birds on some clean pasture in one of his fields. Mr. Terry Jones, who for the last three years has been devoting time and effort to rearing Ne-nes on our behalf, sent us seven fine birds, giving an overall total for the season of 26. The flock at Slimbridge now numbers 53, and we have sent nine pairs to other establishments, at Basle, Cleres, Leckford, Rotterdam, Whipsnade, the United States, and our branch at Peakirk. These figures mean that the birds bred at Slimbridge now represent about 45% of the world population. 6 The Wildfowl Trust Each year all three forms of Brent Goose—hrota, bernicla and orientalis— have become ‘ heavy ’ but no attempt at nesting has occurred. We have even gone so far as to subject likely birds to flood lighting at night in the hope that 24 hours of light might be an encouragement.