
204 
Surface Censuses 
Surveys made by boat on 13 sample check areas show an increase in the 
potential nesting population as compared with last year. These scattered check 
areas represent some of the better types of habitat within their respective locations 
in the State. Counts of local nesting ducks on 81 lineal miles of census line averaged 
7.91 potential breeders per mile. The local breeders in 1949 averaged 6.8 per lineal 
mile, 
Nesting Conditions 
Cold weather and ice conditions delayed migration and nesting did not start 
until well into May. In general, nesting activities were approximately ten days later 
than that considered to be normal. Following the delayed spring break-up, water and 
weather conditions appeared to be favorable for waterfowl production. In the "Lake 
States, '' water areas are fairly stable and in general, even the swales retain water 
until broods are able to move to permanent water areas. 
Brooding Surveys 
Following the surveys to determine the potential breeding populations, brood 
censuses were made on the same sample areas to determine the successes of the hatch. 
The information obtained from these brood censuses proved to be disappointing in 
‘certain respects. A comparison of the results of the 1950 brood surveys to those of 
1949 is shown below. i 
Results - Brood Censuses 1949 1950 
Broods per lineal mile - - - - - - = - 47 .34 
Hen and young per lineal mile - - - - 2.75 2. 32 
Adults without broods per lineal mile 6:50 5.50 
Fewer broods were observed this spring although the potential breeders 
determined by the previous survey appeared to be higher in 1950 than in 1949. Itis 
important to note, however, that censuses in several important producing areas did 
not reveal a single brood, although broods were known to be present. Further 
evidence that broods are often unobserved in heavy cover typical of Michigan condi- 
tions is demonstrated by the results of a special study that was carried on this summer. 
Special Study 
The Ingham, Livingston, and Oakland County aerial census area was selected 
for a special study to determine the accuracy of various censusing techniques. Re- 
peated ground checks and aerial censuses were made during the brooding period. 
Attempts to locate broods from the air on this 72 lineal mile census area previously 
covered to determine potential breeding population gave the following results: 
June 5, Aerial Census -- No broods observed 
June 18, " -- Two broods observed 
June 30, "' u -— No broods observed 
Thirty lineal miles of ground check covering potholes, marshes, and lakes 
in the west end of the aerial census area revealed seven broods or 0.23 broods per 
lineal mile. Further intensive ground work on foot followed, This check verified 
locations of a total of 23 broods in the same area previously covered. This intensive 
ground work emphasizes that in dense cover only a small portion of the actual number 
of broods is revealed by a strip census. On the basis of this study, aerial brood 
