
scattered precipitation during the first two weeks of July was sufficient to 
improve water conditions at the time of the mid-July brood survey. 
Breeding Population Indices - 
The improved State-wide water conditions were accompanied by an 
increase in the number of breeding ducks. .The annual May survey indicated 
an average State-wide observed density of 6.31 ducks per square mile. 
Correction of the observed duck density for unobserved females on the nest 
(correction factor, 1.21) indicated the minimum State-wide density index of 
7.64 ducks per square mile to be 59 percent above the 1955 index of 4. 81 
ducks per square mile, and 20 percent below the 1950-1955, six-year average 
index of 9.58 ducks per square mile. 
- The physiographic distribution of the breeding population appears in 
Table I. The increase in the breeding duck population was general over the 
entire State. The increases for physiographic regions ranged from 37 per- 
-centin the James River Valley to 99 percent on the Missouri Plateau. The 
State-wide population distribution was 2 percent in the Minnesota Valley, 24 
percent in the Prairie Hills, 31 percent in the James River Valley, 12 percent 
in the Missouri Hills, and 31 percent on the Missouri Plateau. 
Table I - Physiographic Distribution of the Breeding Waterfowl Population and 
1955 - 1956 Trends 

ee Uncorrected | Corrected* 
Physiographic Ducks Per Sq. Mi. —... .. Ducks. Per.Sq...Mi. 
Division 1955 1956 1955 1956 Change 
ooo ——eEooooooooeeeeeeeoEEEEoooEoyoEEEoo———————————— eee 
Minnesota Valley 5.45 8.75 6.43 10.59 + 65% 
Prairie Hills 9.28 13.71. 10.95 15.58 + 51% 
James River Valley 5.89 7.89 6.95 9.55 + 37% 
Missouri Hills 5.16 7.27 6.09 8. 80 + 44% 
Missouri Plateau. 1,95 3.79 2.30 4.58 + 99% 
State-wide - 4.08 — 6.31 4.81 7.64 + 59% 
* Corrected from ground transect data (East River) and 
aerial transect data (West River) to compensate for 
-unobserved females on nests. Corrected by 1.18 in 
1955 and 1.21 in 1956. : 
Continued -- 
56 
