landing stations in Alberta, Saskatchewan, 
and Manitoba. 
Relative recovery rates 
The extent to which one banded sex or 
age cohort is more apt to be shot than 
another may be found by comparing re¬ 
covery rates of the two. Table C-4 con¬ 
tains relative recovery rates determined 
by comparing the direct recovery rates of 
immature mallards with those of adults 
and expressed as immature per adult 
rates. The unweighted average relative 
recovery rate from 12 comparable stations 
was 1. 6 in 1963 compared with 1. 8 in 1962. 
(Because the data were highly variable, 
Pacific Flyway banding stations were not 
included). The average rate for seven 
comparable banding stations in the Central 
and Mississippi Flyways decreased from 
2.1 in 1962 to 1.4 in 1963. These data 
suggest that immatures were less vulner¬ 
able during the 1963 hunting season than 
in 1962. However, the magnitude and 
distribution of bandings must be improved 
before we can obtain a precise measure of 
an average relative recovery rate. 
Relative recovery rates based on adult 
and immature rates frequently vary from 
one harvest area to another (table C-5). 
Recovery data from four banding stations 
have been separated into three harvest 
areas generally extending from north to 
south. Recoveries of mallards banded at 
the Souris Refuges in North Dakota show 
that immature birds were relatively more 
vulnerable than adults in Canada, and 
northern and southern United States, but 
the two age groups were equally apt to be 
shot in central United States locations. 
The relative recovery rates of mallards 
banded at Agassiz National Wildlife Refuge 
in Minnesota showed that immatures were 
progressively less likely to be shot as they 
proceeded south; for example, their rela¬ 
tive recovery rate was 2. 91 in the north, 
1.19 in the central States, and 0. 33 in the 
south. The north-south variation in re¬ 
covery rates between the Souris banding 
sites and the Agassiz banding station may 
be partially explained by the fact that both 
mallard populations contribute to the kill 
in the southern Mississippi Flyway but 
birds from the Souris sites have not sus¬ 
tained as high shooting pressure in the 
north as those from Agassiz. Immature 
mallards banded at Horicon National Wild¬ 
life Refuge in Wisconsin appeared to be 
most vulnerable in the vicinity of the band¬ 
ing site (2. 51 times as apt to be shot as 
adults in Wisconsin) but considerably less 
vulnerable (relative to adults) in the re¬ 
mainder of the Mississippi and the Atlantic 
Flyways. Relative recovery rates for 
mallards banded at Shiawassee National 
Wildlife Refuge in Michigan also indicated 
that the chances of shooting an immature 
bird in the south was less than that for an 
adult. 
Relative recovery rates can be calcu¬ 
lated for differences in the vulnerability 
between the sexes also (table C-6). Re¬ 
lative recovery rates, expressed as males 
per female, show that males are more 
likely to be shot than females in most areas. 
Recovery rates from one station, Monte 
Vista National Wildlife Refuge in Colorado, 
suggested that adult females were more 
vulnerable to the gun that adult males. 
Immature birds of both sexes banded at 
that station appeared equally apt to be shot. 
Banding sites such as Monte Vista and 
perhaps Ruby Lake are unique in that mal¬ 
lard populations are nearly resident in be¬ 
haviour and recovery data from then typify 
only these relatively small populations. 
Recovery data from bandings of mallards 
in Minnesota indicated that males and fe¬ 
males were probably about equally vul¬ 
nerable in that region also. Immature mal¬ 
lards banded at Howlands Island in New 
York showed similar recovery rates for 
males and females while those at 
Pymatuning Reservoir in Pennsylvania 
revealed a greater vulnerability for 
females. 
BLACK DUCKS 
Recovery rates 
Direct recovery rates for adult and 
immature black ducks appeared to have 
decreased somewhat in 1963 (table C-7). 
The unweighted mean recovery rate for 
adults from four comparable stations was 
9. 8 in 1962 and 8.2 this year. The average 
23 
