CENTRAL FLYWAY¥ 
Production Index 
A Comparison of Brood Counts Conducted in North Dakota 
Transect _ 1948 1949 1950 1951 1952 1953 Z 
aoa: 59 98 105 116 77 a 
B 52 ~=—«:109 127 140 77. 33 
C 35 35 43 27 36 14 
D.- 52 49 58 84 43 10. 

Total ~~ 198 291 333 367 = «2332: 105. 
Average per 
Square Mile 1,6 2.4 2.8 3.0 1.9 0.9 
Regarding the production survey, it is stated in the North Dakota 
report '' it was neeessary to conduct this years census approximately two 
weeks in advance of the suggested peak, and direct compardson between. . 
this years data and previous years is not possible.."'.. It appears, therefore, 
that the reduction of approximately 50 percent in the number of broods 
observed.may, in part, be due to the fact that the counts were made before . 
the majority of broods were out. 
Conclusions: The spring breeding population increased about 20 percent 
over 1952, and was about the same as the 1948-53 average, The weather 
‘was wet and cold during May and June which apparently caused heavy losses 
of first nests and subsequent renesting. Due to phenological differences 
between 1952 and 1953 it is not possible to draw conclusions as to changes 
in production between the two years, It is probable, however, that 
* production will not be greater than last year and may be less, Lacking 
‘information to the contrary, it is estimated that the number of birds moving 
southward from North Dakota will be about the same as last year, 
40 
