
189 
Waterfowl Densities 
Breeding Duck Population 
The current deterioration of water conditions was accompanied by an 
equally severe reduction in the breeding duck population. The annual survey of 
the breeding population in May indicated an average, state-wide, observed density 
of only 4.08 ducks per square mile. The correction factor for unobserved 
females on nests was determined to be 1.18. Correction of the observed duck 
density for unobserved females indicated an average, state-wide minimum density 
of 4.81 ducks per square mile. This is 56 percent below the 1954 density of 
10.85 ducks per square mile, and is 54 percent below the 1950-1954, five-year 
average of 10.50 ducks per square mile. 
Application of the average, minimum state-wide duck density of 4. 41 
to the 74,778 square miles in the State excluding the Black Hills indicates a 
minimum state-wide population of 360,000 ducks. This is 56 percent below the 
1954 population of 826,000 ducks, and is 54 percent below the 1950-1954, five- 
year average of 787,000 ducks. 
Waterfowl Distribution 
The geographic distribution of the breeding duck population is depicted 
in Figure 1. 
The physiographic distribution of the breeding population appears in 
Table [I[. The decrease in the breeding duck population was general over the 
entire State, ranging from 33 percent on the Missouri Plateau to 66 percent in 
the James River Valley. The physiographic distribution was such that 36 percent 
of the population was in the James River Valley, 25 percent on the Missouri 
Plateau, 24 percent in the Prairie Hills, 13 percent in the Missouri Hills, and 
two percent in the Minnesota Valley. 
Waterfowl Species Composition 
The species composition of the breeding duck population as indicated 
by the number of males of each species observed on the ground transects appears 
in Table III]. Increases in the percent composition over that of 1954 occurred for 
the blue-winged teal (six percent), mallard (three percent), shoveler (one percent), 
and ruddy duck (one percent). Decreases occurred for the scaup (seven percent), 
pintail (three percent), and redhead(one percent). 
Minimum Species Populations 
Minimum populations of the various species of ducks in the breeding 
population are presented in Table IV along with comparisons with the minimum 
species populations in 1954 and with the average, minimum populations over the 
five-year period from 1950 through 1954. These minimum populations were 
