° 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 by the aerial 
crews. Work is presently in progress to develop methods for 
measuring the proportion of birds present that are seen but these 
studies. have not progressed to the point where visibility factors 
can be determined throughout the breeding range. Therefore, the 
indices presented in this report are based on birds actually seen, 
and it is emphasized that they do not constitute an estimate of 
total population present. 
The results of the breeding population and the production 
surveys are combined to form the basis for forecasting changes in 
the relative size of the fall flight of ducks and coot in the three 
western Flyways. In the Atlantic Flyway it is not possible to rely 
on the breeding ground information to the same degree as in the 
western Flyways due primarily to the lack of survey data from 
Quebec and Labrador, which are important contributors of birds to 
the Flyway. 
The breeding ground surveys are cooperative in nature. 
The Bureau of Sport Fisheries and Wildlife, the Canadian Wildlife 
Service, the Provincial Game Branches, Ducks Unlimited, and the 
State Conservation Agencies combine their equipment and manpower 
to conduct the necessary surveys throughout the vast extent of the 
waterfowl breeding range. 
