
18] 
Table I. - Index to Water Conditions. * 
Percent Change 
Average Index 1955 From 
1950 to 1954 1954 Index 1955 Index Average 1954 
456,309 — 239,874 343,432 -24.7 443.2 

“* Index based on the number of water areas per square 
mile times the square miles in the aréa sampled. 
_ Breeding Pair Inventory 
Sampling Methods and Area Covered 
Sampling techniques in 1955 were identical to those used in other 
years. Both air and ground counts were employed. 
The state-wide aerial count consisted of 18 east-west transects which 
are 12 miles apart. All waterfowl within a one-fourth mile strip are counted. 
The aerial transects furnish a two percent sample of the State's land surface and 
gives an index to the number of waterfowl in the State. 
The ground count is made along with the aerial count and furnishes 
the information on species composition, sex ratios, and breeding cycle develop- 
ment, The ground transects are one-fourth mile wide and sample the various 
physiographic regions of the Btate. 
The census (both air and ground) were made during the period May 4 
to 20. This was a little earlier than on the previous years but was necessary 
because the breeding cycle for mallards and pintails was a little earlier and new 
vegetation growth was to the point where it would interfere with breeding pair 
counts. 
Breeding Population 
The 1955 inventory disclosed an increase of 35.7 percent over that 
of 1954. However, the breeding population was still 14.3 percent less than the 
previous five-year average. 
Table II shows the breeding survey indices for 1955 in comparison to 
1954 and to the previous five-year average. The 1955 data in this table includes 
a 30.2 percent correction necessary to account for absent females but does not 
correct for birds missed by the aerial survey. 
