251 
WATERFOWL BREEDING GROUND SURVEYS IN MICHIGAN 
Herbert J. Miller 
Introduction 
Personnel of the Michigan Department of Conservation have repeated the 
surveys that have been carried on for the past five years to determine production 
of waterfowl. In addition, an extensive aerial survey was made as a pilot study to 
obtain an index of breeding pairs for the entire State, and a more limited aerial 
brood survey was also conducted. 
Methods of Sampling 
Dense cover and extensive forested areas dotted with permanent lakes, 
swales, and beaver ponds, and traversed by a multitude of streams, typify the 
habitat to be censused in Michigan. Breeding birds are scattered and difficult to 
locate. Experience has demonstrated that under these conditions there are limita- 
tions to the accurate determination of waterfowl production. In view of these 
limitations, efforts were extented to obtain comparative indexes through three types 
of surveys: 
1. Spring migration observations. 
2. Potential breeding population surveys. 
3. Brood censuses. 
For each of the three types of survey, aerial censuses (both extensive and on 
sample check areas) were carried on together with ground surveys by District 
Game Biologists. The sample check areas were carefully selected several years 
ago and the same survey techniques have been applied each year to provide an index 
of change. Standard methods of censusing were used. Locations of the sample 
check areas and the extensive aerial transects are shown on the map (Figure 1.). 
Breeding Population Trends 
The movement of migrants through Michigan this spring appeared to progress 
at an accelerated pace due to an early break-up of ice and the prolonged periods of 
high temperatures which occurred throughout the month of April. The U. S. Weather 
Bureau reported mean temperatures of April as 3.4° warmer than average. 
The number of migrants returning to their nesting grounds through Michigan 
showed a slight increase, judging from observations throughout the State. 
Interviews with 119 selected observers indicated a favorable trend. These 
observers, scattered throughout the State, are contacted each year. More than 
50 percent of these observers believed that there were more migrants this spring 
compared to last year or two years ago: 
Percent Dabblers Divers Geese All Species 
Opinions on numbers } More 44 60 63 50 
43 31 28 38 
compared to the previous) Same 
spring (1951) ) Fewer 7 9 4 7 
