the ducks banded as juveniles, tables 1 and 2. A comparison of mortality rates of the two groups 
discloses that in the first 4 years after the year of banding the average yearly rate of loss was 
42 per cent in the group banded as juveniles (average of 43.9, 43.1, 38.9, and 42.0), and 41 per 
cent in the group banded as adults (average of 38.8, 37.6, 42.9, and 44.5). The significant fact 
these figures reveal is that senescence is not an important mortality factor in wild mallard popu- 
lations. Shooting, accidents, and predation are responsible for most of the deaths, and juveniles 
are more subject to these causes of mortality than are older ducks. 
The higher year-of-banding mortality rate in juvenile populations is partly, but not 
entirely, the result of a higher proportion of juveniles taken by hunters. The mortality rate is 
about 1-1/2 times as high for juveniles as for adults, tables 1 and 2, and the hunting vulnerabil- 
ity* rate is approximately in the same proportion. Differences in the survival rates of mallard 
drakes banded as adults and those banded as juveniles are presented graphically in fig. 2. 
100 
90 
80 
70 
60 
ADULTS 
50 ---- JUVENILES 
40 
30 
PER CENT ALIVE 
20 
_ 
= 
0 | 2 3 4 5 6 7 8 
YEARS FOLLOWING BANDING 
Fig. 2.--Survival rates of mallard drakes banded at Lake Chautauqua, 
1939-1944, one group banded as adults and the other banded as juveniles. 
There was a higher rate of loss among mallard hens than among mallard drakes, as 
shown by differences in the mortality rates, tables 3 and 4. This loss in hens occurred despite 
the fact that current-season or year-class O-1 band data derived from figures in tables 3 and 
4 show that drakes in this year-class are 4 per cent more vulnerable to hunting than are hens. 
It would appear, then, that the greater hen mortality occurs outside of the hunting season. 
Field studies indicate that hens during the breeding season are subject to more hazards than 
* The term vulnerability in this paper refers to the deaths of birds bagged by hunters, whereas 
mortality refers to deaths from all causes, including deaths resulting from crippling by hunters. 
15 
