Summary

Description

A decrease in breeding population was recorded in most survey areas as compared to 1964. The aerial breeding population indices by areas, shown in table 1, have not been corrected for birds present that were not seen by aerial crews. Using the results of the airground comparison studies to adjust the aerial index figures for birds not seen provides a somewhat different estimate of the change between 1964 and 1965. The adjusted total suggests that between 1964 and 1965 the duck breeding population decreased from about 35,588,000 to about 27,500,000, a decrease of 23 percent. The 1965 index is 42 percent below the peak number reached in 1956 and 28 percent below the average of the previous 10 years. It is 8 percent below the 1962 index, which was as low as the breeding population should be allowed to go.