
187 
WATERFOWL BREEDING GROUND SURVEY IN SOUTH DAKOTA, 1955 
Ray Murdy and Maurice E. Anderson 
Introduction 
This report constitutes a preliminary, partial summary of the find- 
ings of the 1955 waterfowl breeding ground surveys through mid-July in South 
Dakota. These investigations consisted of a survey of the breeding population, 
a survey of brood density in mid-July, and a brood size survey. 
The current bréeding ground surveys were conducted in exactly the 
same manner as in 1954, A brief description of these methods appear below. 
Breeding Population Survey 
The breeding waterfowl population survey consisted of two phases 
which were run concurrently during the period May 9-17. One phase, a gridded, 
state-wide aerial survey, provided indices to state-wide duck and water area 
densities and distributions. The second phase, a ground survey in better -than- 
average habitat in most of the counties, provided (1) observed sex ratios which 
were used to correct aerially-observed duck densities for unobserved hens on 
nests, and (2) species composition data which were also used to provide indices 
to species densities. 
The aerial survey was based on a system of 16, east-west, one- 
quarter mile wide transects spaced 12 miles apart, north té south. As in 1954, 
all of these transects were flown east of the Missouri River; while west of the 
Missouri only every other transect was covered. The resulting state-wide 
coverage totaled 4,260 linear miles or 1,065 square miles. The transects were 
flown by three pilot-observer teams in light planes. Messrs. J. Donald Smith 
and Arthur S. Hawkins assisted in the survey by flying the east-river portions of 
transects 7-10. 
e 
The ground survey consisted of 41 standard one-quarter-mile, ground 
transects run in 41 counties by 32 State Game Wardens and totaling in the neigh- 
borhood of 2,000 linear miles, or 500 square miles. 
Brood Density Survey 
The mid-July brood density survey was based on the same system of 
gridded aerial transects as was used for the breeding population survey in May. 
The brood survey, however, was restricted to the portion of the State lying east 
of the Missouri River, which usually contains 75 percent to 80 percent of the 
state-wide breeding population. The survey was made by two pilot-observer teams 
during the week of July 11-16, which is approximately the same period during 
which this survey was made in previous years. 
