
205 
censuses to determine production in typical southern Michigan habitat appear question- 
able. The hatch was late this year and cover was heavy. These factors and the fact 
that aerial censuses were made in mid-morning should be taken into account in 
appraising these results. 
Summary and Conclusions 
On the basis of comparative results, assuming that errors were constant 
each year, the potential breeding population showed a slight increase, but the brooding 
success was below that of last year. It appears questionable whether accurate brood 
counts can be obtained in habitat typical of Michigan by aerial surveys. 
