
Breeding Population and Production Surveys 
The extensive breeding ground surveys of the past few years 
have been continued. These surveys now include two coverages of 
most of the important waterfowl breeding areas, the first coverage 
occurring in May for the purpose of measuring the distribution and 
relative size of the breeding population, and the second being made 
during July for the purpose of measuring the production of broods. A 
combination of data from important breeding areas forms the primary 
basis for forecasting changes in the relative size of the fall flight in 
each of the four flyways. 
The bulk of the important waterfowl breeding areas in Alaska 
and Canada are surveyed from the air using statistically designed same 
pling techniques and similar methods of collecting and analyzing data. 
Survey methods vary somewhat among the 25 States conducting surveys, 
although the methods employed in the majority of States with important 
numbers of breeding ducks are similar in most respects to those 
employed in Canada and Alaska. 
In 1957, aerial crews sampled approximately 2,375,000 square 
miles of the best duck breeding habitat on the continent. Ducks were 
counted on approximately 16,000 square miles of habitat, or somewhat 
less than one percent of the total breeding area. Although this may 
seem like a rather small portion of the total breeding habitat actually 
surveyed, sampling error was less than 20 percent of the average 
population density in most survey areas, and was considerably less than 
20 percent when considering the breeding range as a whole. 
The results of the breeding ground surveys are presented as 
"index'' figures. When conducting aerial surveys of breeding birds, or 
of broods, not all birds present are seen and recorded. No attempt has 
been made to estimate the number which have been missed. The indices, 
therefore, are based on birds actually seen, and it is emphasized that 
they do not constitute an estimate of total population present. Even 
though the "index" figures are not a measure of total populations, it is 
believed that they are representative of relative population levels to 
the extent that data from one location can be accumulated with those from 
another, and that year-to-year changes can be detected. Although a 
measure of total population would have certain advantages, a determina- 
tion of relative change seems adequate for the purpose of practical 
management. | | 
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