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five years computed on the basis of the number of ducks observed per square 
mile. The total areas of the various regions were approximated by means of 
a planimeter by D. A. Munro. Included in Table II are population indices for 
1955 as figured by methods outlined in "Instructions for Conducting 1955 Aerial 
Waterfowl Surveys in the Southern Portions of Alberta, Saskatchewan and 
Manitoba", issued by the U. S. Fish and Wildlife Service April 5, 1955. The 
number of birds per square mile of aerial sample is down in all areas this year. 
This may be explained by the inclusion of more barren areas in the larger sample 
this spring. However, it is the opinion of the author that the method, used for 
the first time this year, of recording the sample, not only by species but by 
pairs, single drakes, flocked drakes, and flocked birds of mixed sexes, may 
have been partially responsible for the lower count. The time taken to segregate 
and record the various components of the population caused a time lag in the 
survey, and some birds were probably missed on this account. 
