172 
WATERFOWL BREEDING GROUND SURVEY IN WYOMING, 1955 
Robert M. Ballou 
and 
George F. Wrakestraw 
Introduction 
With the objective of achieving an accurate index to the duck breeding 
population in the more important waterfowl habitat in Wyoming, permanent 
random sample areas were selected by the Statistics Department of the University 
of Wyoming. The sample plots were flown for ducks by project personnel and 
results analyzed by the University. The Canada goose inventory was conducted in 
the same manner as in past years. 
Methods 
As in 1954 the duck breeding ground survey this year was based 
entirely upon breeding pair counts. No organized brood surveys were made. 
Sample plots of varying size, totalling 2,239 square miles, were randomly 
selected from all of the potential waterfowl habitat within the State accessible to 
a plane--a total of 54, 249 square miles, approximately one-half of the total State 
area. Yellowstone National Park and the National Forests were excluded from 
the sampled area, as were known desert areas of little waterfowl value. No 
stratification of the sample area was attempted. All sample plots were bounded 
by roads, streams, or hydrographic divides for ease of location, accuracy, and 
future reference. Sample areas were flown during the last half of May and duck 
counts taken by the observer and pilot. 
To derive a correction factor for the aerial inventory, ground crews 
thoroughly covered 22.7 square miles of representative portions of certain aerial 
sample plots throughout the State immediately following the aerial census. The 
correction factor was used on the aerial data to obtain the total State population 
index. | 
All of the known Canada goose breeding habitat was again flown this 
year in early May to obtain a total State breeding population. 
Weather and Water Conditions 
Wyoming experienced a late spring this year, delaying the breeding 
season to some extent throughout the State, and as much as three to four weeks 
in some areas. The prolonged cold weather may have had an adverse effect upon 
early nesting birds. 
