195 
The current reduction in water levels continued throughout the 
breeding season. At the time of the annual, brood density survey in mid-July 
there were only 1.22 water areas other than streams per square mile in eastern 
South Dakota. This is 45 percent below the average of 2.23 areas per square 
mile at the same time in 1954. It is 59 percent below the 1953-1954, two-year 
average of 2.98 water areas per square mile in mid-July. This reduction in 
mid-July water area densities was general, but was more pronounced in the 
eastern one-third of the State which had not been affected by drought as severely 
as the western portion had in 1954. 
Current duck brood production through mid-July showed a corres- 
ponding reduction similar to that of current water conditions and the current 
breeding population. The mid-July, brood density survey indicated an average, 
observed density of 0.406 brood per square mile in eastern South Dakota. This 
is 40 percent below the 1954 density of 0.677 brood per square mile. It is 42 
percent below the 1953-1954, two-year average of 0.695 brood per square mile. 
Since the current hatch appears to be considerably earlier than that of 1954, it 
seems probable that brood production for the entire 1955 season will be about 
half of the production realized in 1954. 
The average size of the broods currently produced is apparently 
equal to that of former years. Brood sizes through mid-July averaged 7.38 
young per brood which is within five percent of both the 1954 average of 7.77 
young per brood and the 1953-1954, two-year average of 7.76 for broods observed 
through mid-July. 
Table V.- Indices to Water Area Densities and Duck Brood Densities in 
Mid-July and 1954-1955 Trends in Eastern South Dakota. 
Water Areas Duck Broods 
Water Areas Duck Broods 
Physiographic Per Sq. Mile * Per Sq. Mile 
Division 1954 1955 Change 1954 1955 Change 
Minnesota Valley 1.78 0.56 - 69% 0.327 0.556 + 70% 
Prairie Hills 3.05 1.60 - 48% 1.565 0.906 - 42% 
James River Valley 2.07 0. 84 - 59% 0.452 0.181 - 60% 
Missouri Hills 1.71 lL. 77 + 4% 0.186 0.329 + 43% 
East-River Totals 2.23 1.22 - 45% 0.677 0.406 - 40% 

* Water areas of all types other than streams. 
