MICHIGAN - Continued 
The 1959 potential breeding population, as indicated by 
censusing sample check areas, shows a decrease from that of last 
year, but is above the past 10 years' average. Semi-drought con- 
ditions and lower water levels of the Great Lakes marshes in 1958 
forced some potential breeders to concentrate. This should be 
taken into consideration in comparing potential breeders of 1959 
to those of 1958. 
The species composition of the potential breeding popu- 
lation as determined on these sample check areas follows: 
Species _ . 1958 LoDo 
Mallard 2k..6% 25.9% 
Black Duck 25.7% 22.7% 
Blue~winged Teal 21.0% 32.8% 
Wood Duck 3.3% 4.8% 
Ring-necked Duck 11.8% 5.6% 
Merganser 2.8% 0.7% 
Goldeneye 1.5% 1.0% 
Unidentified 9.3% 6.5% 
Breeding population changes for wood duck as determined 
by float-trip censuses follow: 
Float Trips 

Lineal miles ‘Potential wood duck 
Year censused breeders per lineal mile 
1950 81.0 makes 
L951 120.0 32 
1952 82.0 Pa D 
1953 95.5 085 
1954 at (56 
1955 BO Be Ree 70 
1956 110.5 28 
1957 , 135.4 46 
1958 121.0 233 
1959 135.0 65 
130 
