known-hand-reared birds have a significantly higher adult rate of 
mortality than the wild-reared birds. Although the 271 birds in the 
latter sample may contain some hand-reared individuals, their mean 
adult mortality rate, 58 per cent, is of the same order as that 
(65 per cent) for 305 birds reported by Hthn (198) as banded as 
adults. Some difference, therefore, does exist between wild-reared and 
hand-reared birds but this in itself demands an explanation of the 
similar rates computed for the first year of life. 
Table 27.~-Mortality Reported for Mallards Banded in Great Britain 
(after Ht6hn 19,8) 
“~Kge ~ Reported as Wild-reared ~~ Hand-reared Birds 
Inter—- Rept. Alive Annual ept.e ve nnu 
val in as at Mortality Rate as at Mortality Rate 
Years Dead Start % Per Year Dead Start % Per Year 
0-1 239 271 88 497 557 89 
1-2 20 32 T 60 60 100 
2=3 5 12 58 0 0 - 
+L 3 7 { 4) oO. - 
bea5 \ F fo) 0 - 

According to H8hn (in litt.), mallards may hatch in England 
from early April to early August, the juveniles in his samples being 
banded from May to August (the majority during the latter month). He 
also estimates (in litt.) that the young were ringed when approximately 
2-3 months old. Since the British wildfowling season opens in August l, 
one is tempted to conclude that the vulnerability of all young birds 
to the gun is so great that even wild-reared young face a tremendous 
disadvantage in Great Britain. Such a situation almost implies that 
the 65 per cent mortality rate for adults reported by HShn is in 
itself unusually high by North American standards. With an adult 
mortality rate of this order and a theoretical first-year mortality 
rate of 75 per cent, all British mallards would have to raise at 
least 5.2 young per pair to the "flapper" stage (date of ringing). 
This productivity may be compared to theaverage of about l per suc- 
cessful female reported by Girard (191) for conditions involving dili- 
gent predator control in western Montana and 7 young (rearly ready to 
fly) per successful female observed by Stoudt (1946) in Minnesota. 
The actual age ratio in mallard populations is certainly much less 
than the values per successful female. Crude estimates of second- 
nest possibilities, carried out in an earlier section, suggast to 
me that the high degree of reproductive success necessary to maintain 
the British mallard population is within the limits of reproductive 
efficiency in this species. (Girard's data indicate, however, that 
this level of efficiency is not always attained in North America even 
when diligent predator control is exercised. 

