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 survey methods vary from statistically designed sampling 
techniques using aerial transects, to ground censuses of selected sample areas. 
Aerial crews cover the bulk of the breeding range with the various crews 
sampling in the neighborhood of Z, 375,000 square miles of prime waterfowl 
habitat. For the most part, the results of the surveys are presented as ‘indices 
to breeding population or number of broods.''. The determination of an '"index'' 
figure representing estimated breeding population or number of broods has 
been done for the purpose of establishing a basis upon which the results of 
surveys in one place can be added to the results from others. When considering 
the "index'' figures, however, it is emphasized that they do not constitute an © 
estimate of total population. The "indices" are based on birds seen, and itis 
known that when making aerial observations a portion of the birds are missed. 
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. Aithough a measure of total popula- 
tion would have certain advantages, a determination of relative changes seems 
adequate for the purpose of practical rnanagement. 
Needless to say, the breeding ground surveys are cooperative in 
nature. The Fish and Wildlife Service, 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. 
Service Biologists cover the importan: areas in Alaska, while the State 
Conservation Agencies, with some help from the Service, carry on surveys in 
about 25 States. 
WI 
