NORTH DAKOTA--Continued 
Comparison of the 1958 Aerial Survey Data with that of 1957%* 
Duck Population Index Coot Index Pond Index 
Stratum 1957 1958 1957 1958 1957 1958 
West 26,389 28, , B44 @) 920 33,140 49,710 
Central 401,796 349,716 10,908 22,424 160,218 180,520 
East 10,664 30,138 0 2,70 18,281 0,910 
TOTAL 438,849 408,698 10,908 26,049 211,639 261,140 
Percent of change 
of the 1958 index -6.87 £138.81 $23.39 
from that of 1957 
*The 1957 data was reworked to make it comparable to the 1958 data. 
Production Indices 
Summary of Air Data - July, 1958 
North Dakota Aerial Survey 
West Central East State Total 
Size in Square Miles 33,861 2.3, 330 0,66 
Sample Size in Square Miles | 38 | 150 | 17 | 20 
Broods Actually Seen ren SP li oy STs nea mea 2 136 
Broods/Square Mile 208 87 ; 

1,600 _ oo 
Brood Index 
Sample Late Nesting Index 
Late Nesting Index/Square Mile 
Late Nesting Index 
Ponds Actually Seen 
Ponds Per Square Mile 
Pond Index 61,318 299,736 
Coot Brood Seen ae) 2 
Coot Brood/Square Mile 1 a eae el 

Coot Brood Index 
68 
