CENTRAL FLYWAY 
Production Indices - 
Ground counts were made July 15 and 16 over routes in the eastern and 
western sandhill areas. Fifty-four broods were observed on 169 miles of routes 
indicating 1.3 broods per square mile. This represents a decrease of only seven 
percent from the 1955 index of 1.4 broods per square mile and a decrease of 38 
percent from the average index of 2.1 for the eight-years prior. 
Conclusions - 
Indications are that production success is down significantly in total 
ducklings due mostly to a decrease in brood size. 
It is concluded that there will be a Significant decrease in the fall flight 
from Nebraska as compared to 1955, 
MONTANA 
Weather and Water Conditions - 
In contrast to the last two years, the water conditions in 1956 throughout 
the northern and eastern breeding ground areas in Montana have suffered a severe 
setback. (See Table I.) At the time of the aerial survey in late May, only the 
more permanent type of pothole or reservoir held water. Conditions have become 
steadily worse through May and June, which were marked by hot, dry weather and 
high winds. The total number of water areas in the northeastern prairie pothole 
region decreased 38 percent from May 9 to July 2. 
Table I - Comparative Numbers of Water Areas Observed Over the Same Routes 
During the 1954, 1955 and 1956 Aerial Breeding Ground Survey -~ Part I. & fl 




Reservoirs Potholes 
Per Square Mi. Per Square Mi. 
Physiographic Area 1954 1955 1956 1954 1955 1956 
Eastern Hi-Line 229 so3 242 1.05 1.41 .33 
Central Hi-Line 55 .76 #«.85 Sc 18 2475 455 
Great Falls Piedmont’. 81 84 .76 .94 1.69 .47 
Other Total 
; Per Square Mi. Per Square Mi. Percentage Change 
Physiographic Area 1954 1955 1956 1954 1955 1956 © 1955 to 1956 
_ Eastern Hi-Line 68 .51 .67 2.03 2.25 1.42 . $f 
Central Hi-Line 48 .96 .53 4.21 5.48 1.94 - 65 
Great Falls Piedmont -38 .49 .65 2.12 3.02 1.88 - 38 
Fa EE 
41 
