Characteristics of the samples studied 
About 85 per cent of the mallard recoveries in North America 
occur during the hunting season. It is thus very difficult to test 
the selective bias of the shot samples for age groups. The varied 
history of North American waterfowl in the past 25 years also suggests 
that a host of different factors have affected the survival of mallards. 
Thrae of these are well known: the great drought of the 1930's, changes 
in hunting regulations, and a marked increase in hunting pressure. They 
inply that a mallard life table may vary from decade to decade and from 
one part of the country to another. This possibility will be explored 
in Chapter XIV. In general, the recoveries tend to have a monthly peak 
in November. Birds affected with botulism at the time of banding were 
excluded from all the analyses that follow for this species. 
Survival of birds banded as young 
Wild-reared birds.--The samples of wild-reared juvenile-banded 
mallards used in this study do not include any birds known or even sus- 
pected to be hand-reared. This culling out severely reduced what 
originally seemed to be a statistically satisfactory sample. In a pre- 
liminary review, I found that in a sample of 81 birds banded as juveniles 
in Utah 87 per cent were shot in their first year of life in contrast 
to 68 per cent for 133 baded at random elsewhere on the continent. 
This randomized sample (table 28) represented birds banded about as 
follows: in Alaska (2), British Columbia (4), Alberta (29), Sas- 
katchewan (15), Manitoba (15), Michigan (11), Wisconsin (3), Minnesota 
(2), North Dakota (18), South Dakota (17), Nebraska (2), Washington (10), 
and Oregon (5). It yielded a first~year mortality rate of 68 per cent 
and a mean adult mortality rate of 50 per cent per year. With the Utah 
bandings added, these would become 73 and 52 per cent. 
Table 28.--Mortality Reported for Mallards Banded as Juveniles 
in North America 
All birds banded pricr tc September 1; Utah bandings excluded. 
Age Wild-reared Hand-reared 
Tnterval (banded through 1939) (banded through 1938) 
in Reported Alive at Mortality Reported Alive at Mortality 
Years Shot Start Rate (%) Shot Start Rate (%) 


Qu1 1 163 68 366 Lbs 82 
1-2 26 52 56 80 ~ 70 
23 13 26 | 16 2h 
3-1 8 13 1 g 
Les 1 5 50 3 7 
ie 1 mf | 2 h 49 
6-7 3 3 0 2 
7-8 0 0 1 2 
8-9 0 1 
9-10 (12/1 
Total Adults 52 103 50 80 129 62 
17 data Tor this age interval were technically TIncomeLete at the 
~ __ time this table was compiled in the fall of 1947 

68 
