217 
Table IV. - Indices to Duck Brood and Water Area Densities in Mid-July, 1954 
and 1953-1954 Trends, 


Duck Broods Water Areas* 
Water Areas 
Physiographic Broods Per Square Mile Per Sq. Mi. * 
Division 1953 1954 Change 1953 1954 Change 
Minnesota Valley 0.00 0.33 + 3.33 1.78 -~ 47% 
Prairie Hills 1,04 1.45 + 39% 4.59 3,05 - 34% 
James River Valley 0.72 0.46 - 36% 3.81 2.07 - 46% 
Missouri Hills 0.48 0.19 - 60% 2.57 Ltd ~ 33% 
East-River Total 0.71 0.65 - 8% 3.72 2.23 - 40% 

* Total water areas excluding streams. 
Water Area Densities and Trends 
The numbers of water areas observed during the mid-July brood survey 
provide estimates of the densities of water areas existing at that time of the season. 
The 1953 and 1954 densities are shown in Table IV and refer to densities of all types 
of water areas excluding streams. During the current survey an average density of 
2.23 water areas per square mile was observed. This is 40 percent below the 1953 
density of 3.72 per square mile. 
The decrease in mid-July water area density was general throughout the 
east-river coverage. The decreases in mid-July water area densities were 47 
percent in the Minnesota Valley, 46 percent in the James River Valley, 34 percent 
in the Prairie Hills, and 33 percent in the Missouri Hills. 
Summary 
The density of water areas at the start of the waterfowl breeding season in 
South Dakota has built up over the past three years to a peak of 7,23 water areas per 
square mile in 1953. During the past winter snowfall was light, especially in the 
western part of the State. Rainfall during the early spring failed to bring water 
levels to their previous point, and as a result there were only 4.64 water areas per 
square mile at the start of the breeding season. This represents a decrease of 36 
percent below the 1953 density and is 22 percent below the 1950-1953, four-year 
average of 5.93 water areas per square mile. 
