Johnsgard, P. A. 1974. The taxonomy and relationships of the northern swans. 

 Wildfowl 25: 155-161. 



Mary-Rousseliere , G. and J. E. Heland. 1974. The Whistling Swan nesting in 

 northern Baffin Island, Northwest Territories. Can. Field-Nat. 88: 99. 



Ruttledge, R. F. 1974. Winter distribution of Whooper and Bewick's Swans in 

 Ireland. Bird Study 21: 141-145. 



1973 



Evans, M. E. and T. LeBret. 1973. Leucistic Bewick's Swans. Wildfowl 24: 

 61-62. 



Evans, M. E. , N. A. Wood, and J. Rear. 1973. Lead shot in Bewick's Swans. 

 Wildfowl 24: 56-60. 



Gunn, W. W. H. 1973. Environmental stress on the Whistling Swan. Wildfowl 

 24: 5-7. 



King, J. G. 1973. The use of small airplanes to gather swan data in Alaska. 

 Wildfowl 24: 15-20. 



Lensink, C. J. 1973. Population structure and productivity of Whistling Swans 

 on the Yukon Delta, Alaska. Wildfowl 24: 21-25. 



Sladen, W. J. L. 1973. A continental study of Whistling Swans using neck 

 collars. Wildfowl 24: 8-14. 



1970 



Heyland, J. D. , E. B. Chamberlain, C. F. Kimball and D. H. Baldwin. 1970. 

 Whistling Swans breeding on the northwest coast of New Quebec. Can. 

 Field-Nat. 84: 398-399. 



1969 



Ogilvie, M. A. 1969. Bewick's Swans in Britain and Ireland during 1956-69. 

 Brit. Birds 62: 505-522. 



Sladen, W. J. L. and W. W. Cochran. 1969. Studies of the Whistling Swan, 

 1967-68. Trans. N. Am. Wildl. Nat. Resour. Conf. 34: 42-50. 



1968 



Dixon, N. B. 1968. Whistling Swans wintering in central Oklahoma. Bull. 

 Okla. Ornithol. Soc. 1: 10-11. 



Holden, B. L. and W. J. L. Sladen. 1968. Heart worm, Sarconema eurycerca , in- 

 fection in whistling Swans, Cygnus columbianus , in the Chesapeake Bay. 

 Bull. Wildl. Dis. Assoc. 4: 126-128. 



59 



