Breeding Population and Production Surveys 
The extensive breeding ground surveys initiated several years ago 
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 impor- 
ant 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 sampling 
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 Stetes with important numbers of 
breeding ducks are similar in most respects to those employed in Canada 
and Alaska. 
In 1958, aerial crews sampled approximately 2,375,000 square 
miles of the best duck breeding habitat on the continent. Ducks were 
ecunted 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 cf the total, sampling error was less than 20 per- 
cent of the average population density in most survey areas, and was con- 
siderably less then 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 tc estimate the number which have been missed. The indices, there- 
fore, are based on birds actually seen, and it is emphasized that they do 
not constitute an estimate of total population present. The "index" 
figures are not a measure of total populations, but they are representa- 
tive of relative population levels tc the extent that data from one loca- 
tion can be compared with those from another, and year-to-year changes 
can be detected. Although a measure of total population would have 
certain advantages, a determination of relative change is adequate for 
practical management. 
the breeding ground surveys are cooperative in nature. The 
Bureau of Sport Fisheries and Wildlife, the Canadian Wildlife Service, 
the provincial game branches, and Ducks Unlimited, combine their manpower 
and equipment to cover all of the important waterfowl breeding areas in 
Canada. Bureau biologists cover the important areas in Alaska, while the 
State conservation agencies, with some help from the Bureau, carry on 
surveys in about 25 States. 
