17} 
WATERFOWL BREEDING GROUND SURVEY IN COLORADO 
Jack R. Grieb, John H. Wampole, Hal M. Boeker, 
John R. Tester, Ladd G. Frary, and Ervin L. Boeker* 
Colorado Game and Fish Department 
Introduction 
In Colorado, waterfowl breeding grounds are logically divided into river- 
bottom and irrigated land on the East Slope, and vast areas of mountain parks, 
valleys, lakes, and beaver-ponds west of the Continental Divide. 
Colorado breeding ground studies in 1952 include three areas covered in 
1951, and three new areas added this year in northwest Colorado. Comparative 
data for 1951 and 1952 are therefore available for the irrigated land type in 
northeast Colorado, for North Park, and for the San Luis Valley. New areas 
included in 1952 studies are the Yampa River Valley, Brown's Park, and high- 
country lakes and beaver dams on the White River plateau. It is hoped that 
coverage in 1953 can be extended to include South Park, the Gunnison-Grand Mesa 
region, and the San Juan Mountains, thus completing the survey of important 
waterfowl breeding grounds in the State. 
Methods and Sample Areas 
Survey methods used in 1951 were retained in 1952, except where physio- 
graphy and size of area necessitated modifications. Thus, the general procedure 
was determination of the breeding population and, later, production, chiefly by 
breeding-pair and brood counts, on selected samples for all breeding grounds 
surveyed. The data so obtained has been used in estimating total production, and 
thus the indicated size, of the 1952 waterfowl crop. 
One variation in this technique, confined to the northeast Colorado and 
North Park samples, involved the correlation of aerial counts of breeding birds 
and broods with ground observations. This phase of study was initiated in 1951 
and is designed to perfect a reliable means for surveying breeding grounds by 
aircraft. Results from this two-year comparison of methods will be found in 
another report. 
* Grateful acknowledgment is made by the authors to Laurence E. Riordan, 
Ferd C. Kleinschnitz, Harry J. Figge, Wayne W. Sandfort, and Norman Huges 
of the Colorado Game and Fish Department, and to Lee E. Yeager, Leader of 
the Colorado Cooperative Wildlife Research Unit, who either supervised the 
studies here reported or assisted with field work. 
