92 H. BOYD 



ACKNOWLEDGEMENTS 



Though most of the sums are my own and I have drawn perhaps too heavily 

 on unpubHshed material in the files of the Wildfowl Trust, a review of this 

 kind is largely dependent on the work of others. The list of references is, I 

 hope, complete enough to record my indebtedness to published work. I am 

 particularly grateful to Dr Daniel L. Leedy, Chief, Branch of Wildfowl 

 Research and to Dr John Lynch and Dr Allen G. Smith, all of the Bureau of 

 Sport Fisheries and Wildlife, U.S. Fish and Wildlife Service, for permission 

 to make use of unpublished information. 



APPENDIX: SOURCES OF DATA AND NOTES ON 

 CALCULATIONS 



I. Species Included in Fig. i 



Anser brachyrhynchus Baillon. Boyd (1956). ' 



A. a. albifrons (Scopoli). Boyd (igsjb). 



A. c. caerulescens (L.). Data mostly from unpubUshed material of U.S. Fish 

 and Wildlife Service, supplemented from Cooch (1958), recalculated. 



A. c. atlanticus Kennard. Lemieux (1959). 



Branta canadensis interior Todd. Hanson & Smith (1950), recalculated. 



B. c. moffitti Aldrich. Hanson & Browning (1959), recalculated. 



B. bernicla orientalis Tougarinov. Hansen & Nelson (1957), recalculated. 



Tadorna tadorna (L.). Taylor (1959), with survival calculations by the author 

 from records by Goethe (1957) and British ringing results. 



Anas p. platyrhynchos L. Dutch data calculated from Eygenraam (1957) ^^^ 

 pubhshed ringing recoveries. British data from Boyd & King (i960) 

 and unpublished material. North American data after Hickey (1952). 



A. rubripes Brewster. Wright (1954), Bellrose & Chase (1950). 



A. d. discors L. Iowa data from Bennett (1938) ; Prairie Provinces, recalculated 

 from unpubHshed material of Allen G. Smith, U.S. Fish and Wildlife 

 Service, with survival calculations from unpubHshed recoveries coUected 

 by Dr M. Arellano at Delta Waterfowl Research Station, Manitoba. 



Ay thy a vallisneria (Wilson). Geis (1959). 



A. americana (Eyton). Low (1945) and Hickey (1952). 



A. collaris (Donovan). Mendall (1958), recalculated. 



A.fuligula (L.). Unpublished material on British birds. 



A. m. marila (L.). Calculated from published recoveries of Iceland-ringed 

 birds and Russian material (Y. A. Isakov in Dementiev & Gladkov, 

 1952). 



