ACKNOWLEDGEMENTS 
I am indebted to Jerome H. Stoudt, now with the Branch of 
Wildlife Research, who was Service representative with the 
Technical Game Committee of the Upper Mississippi River Conser- 
vation Committee at the time this study was initiated in 1946, 
for his cooperation and efforts in getting the study started. 
I am indebted also to members of the staffs of the Upper 
Mississippi and Mark Twain Refuges for invaluable assistance in 
gathering field data on which this paper is based. I wish 
especially to thank Harvey Neilson and Eric Lawson of the Upper 
Mississippi Refuge and Edward A. Davis of the Mark Twain Refuge, 
who assisted in gathering data for the entire 15 years of this 
study. To all other members of the staffs of both refuges I 
express my thanks for the fine cooperation I received. 
Thanks are due the late Ray C. Steele, former Manager of the 
Upper Mississippi Refuge, and Donald V. Gray, present Manager, 
for their fine cooperation in making the collection of these data 
possible (Mr. Gray also participated in the collection of bag- 
check data from the field and reviewed the manuscript), and Loyal 
A. Mehrhoff, Manager of the Mark Twain Refuge, for cooperating 
in this project since the Mark Twain Refuge was established as 
@ separate administrative unit. 
Kspecial thanks are due D. O. Rettinger of the Illinois 
Department of Conservation for making available data collected 
from all State of Illinois check stations within the area under 
study, and to managers of the Lake Odessa Public Hunting Grounds, 
near Louisa Unit in Iowa, for making data from check stations 
there available. 
I wish to express my appreciation to the following for 
review of this manuscript: Harvey Nelson, Lester Dundas, and 
J. Donald Smith, Branch of Wildlife Refuges, Arthur Hawkins, 
Flyway Representative of the Mississippi Flyway, and William D. 
Carter, Refuge Manager of Horicon Refuge (who participated in 
collection of data while he was assigned to the Upper Mississippi 
Refuge some years ago). Thanks are also due Walter Crissey and 
Aelred A. Geis of the Migratory Bird Populations Station, Patuxent, 
Md., for their review and comments. 
62 
INT.DUP. ,D.C,65= 29673 
