Table 11.--Per cent of black ducks banded at McGinnis Slough, 1940-1945, bagged in 
year of banding, as determined by band recoveries. 
Year of ; Number of Black Per Cent of Black Ducks Bagged 
Banding Ducks Banded in Year of Banding* 
*Corrected to compensate for time and place of banding: during the hunting season and 
halfway down the flyway. Not corrected to compensate for bands not reported. 
Table 12.--Per cent of blue-winged teals banded at McGinnis Slough, 1940-1945, bag- 
ged in year of banding, as determined by band recoveries. 
Number of Blue-Wings Per Cent of Banded Blue-Wings 
Banded Bagged in Year of Banding* 
*Not corrected to compensate for bands not reported. 
EVALUATION OF POPULATION SURVIVAL AND LOSSES 
Available records show that birds live longer in captivity than in the wild state. 
Flower (1926) reported that the length of life of 20 pintails and widgeons in aviaries was 21 
years and 5 months, and 5 of the 20 were still alive at the time of his report. Jean Delacour 
of the American Museum of Natural History (letter, February, 1947) stated that in a well-run 
aviary there is a yearly loss of 5 per cent of the ducks from illness and another 5 per cent 
from accidents. The larger species of ducks begin to show signs of old age at 20 years. In 
the wild, decimating factors are so great that few ducks ever reach senescence. From the 
tens of thousands of wild mallards banded, Cooke (1942, 1943) listed the length of life of the 
four individuals living the longest from banding to reported deathas 8,8,10,and 14 years. 
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