SCOPE OF INVESTIGATIONS AND METHODS USED 
Waterfowl Kill 
For a number of years the Service has recognized the need for 
a new kill survey method - one which would give a close approach to 
the actual harvest of waterfowl by species in each flyway. It succeeded 
in developing such a method and was able to apply it for the first time 
this year, It is called the waterfowl Hunter Mail Survey and involves 
a statistically sound sampling of. waterfowl] hunters whose names are 
obtained at the time they buy their duck stamps. The new method, in 
contrast to the old system of bag checks and post-season contacts which 
has been in use by the Service and most States in recent years, eliminates 
the serious errors characteristic of judgment sampling methods and 
removes the effects pf prestige, memory, and superstition biases which 
are inherent in all questionnaire methods and which cause the kill reports 
to be greatly inflated, The new plan functions through cooperation of 
the Post Office Department and provides for sampling the hunters in a 
flyway in proportion to their occurrence in the various States, Itis 
aimed at determining the flyway kill by species with an error not to 
exceed 5 percent, Results of the current year's survey are included as 
a part of the report on each flyway, but it should be noted that since this 
is the first year for this method, any comparison in kill trends must be 
drawn from the inflated figures of the bag-check - pos{ season hunter 
contact method. An idea of the importance of sampling and bias errors 
in inflating kill figures can be had by comparing the results of the two 
methods, 
The old method combining bag checks to get the average daily 
kill per hunter and post season hunter contacts to get the average 
number of hunts per season, will be discontinued, As pointed out, the 
results are biased on the high side and at most give only general 
indication of trends, The number of bag checks made by cooperating 
State and Service personnel and the number of post-season hunter 
contacts obtained in each Flyway during the past three years are shown 
in the following tabulation: 
