67 
Land Use 
For the second consecutive year, a wet fall prevented farmers from 
completing harvesting operations, and many acres of unthreshed grain were left 
until this spring. A dry spring speeded up spring threshing and plowing of stubble 
fields but at the same time left pothole marginal vegetation high and dry and 
susceptible to severe burning, This spring, for the first time during the course 
of this study, cattail cover along pothole margins was severely damaged by burning. 
The spring-burning history of 120 potholes follows: 

Year Percent Burned 
1950 3 
1951 23 
1952 29 
Breeding Population 
Phenology 
Several transect coverages during each breeding season show differences 
in phenology and population numbers as illustrated in Figure 1. Events of the season, 
such as arrival and hatching dates, indicate that 1952 was approximately one week 
earlier phenologically than 1951. 
Figure 1. Phenology of Waterfowl Population Newdale-Erickson District 
1949 - 1952 
5500 
5000 
ee am 
Oo nn 
°o oS 
© © 
Number of Ducks on Transects 
nm nN Ww w 
Oo wn Oo wi 
oO Oo o ra] 
° oO Oo Oo 
1500 
1000 

April May June July 
Date Censused 
