Acknowledgements 
We appreciate the assistance of Lester Dundas, Refuge Manager, and his 
staff at the Horicon National Wildlife Refuge; James Bell, Game Manager, and 
his staff at the Horicon Marsh Wildlife Area; Richard Hunt, Research Biologist, 
Wisconsin Conservation Department; and local State conservation officers and 
U.S. game management agents in carrying out operational phases of field sur- 
veys. Many other Bureau and State employees offered advice and assistance in 
planning the surveys and analyzing results. Dr. Harold Hanson of the Illinois 
Natural History Survey provided information on population dynamics of the 
Mississippi Valley population. Additional guidance was received from Arthur 
Hawkins, Mississippi Flyway Representative, and information in his files was 
utilized. Dr. Aelred Geis offered suggestions for treatment of data. We 
also wish to acknowledge editorial assistance received from Miss Ruth Hine 
of the Wisconsin Conservation Department. 
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