Breeding Population Indices - 
Table 1 presents the data from the aerial breeding ground survey. 
This survey was made over a random transect sample of the major portion 
of the Nebraska breeding grounds. Table 2 presents the population indices 
as computed from the aerial surveys using species composition, breeding 
duck to non-breeding duck ratio and lone male to pair ratio obtained on 
ground counts as correction factors. . 
It must be noted that some changes in the study areas and a change 
from a systematic to a random transect system may have affected the validity 
of comparison between 1954 and 1955 data. 
Table 1 - Aerial Count Trends 
Ducks/Sq. Mi. Ducks/Sq. Mi. Percent Change 

Area 1954 1955... 1954 - 1955 
Eastern 13.51 2.25 - 83.3 
nA ee 9. 00% 202 ~ 21.9 
Western 
Total 10. 30% 5.68 - 44,9 
* The 1954 aerial count did not separate the Central and Western. 
It was not made until one month later than the 
Eastern and 1955 counts. The figures given 
here have been adjusted to compensate for this 
later date by ground counts which showed a 
loss of 31 percent in observed ducks for the 
corresponding period. 
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