Table 58.—-Mean Mortality Rates for Male and Female Mallards 
Wort. hate , ee: 


% per year 
Where When Age at Size of Sample Banders 
Banded Banded Start Male Female Male Female 
Missouri 1923 Adult 169 98 6 4,7 L.V. Walton 
Oklahoma, 1938-1 Adult 592 279 46 47 Davis, Jordan 
Diinois 1/ 1939-k, Unaged 5606 1609 3.2 6.8 Il). Nat. Hist. 
: Survey 
Montana 1928 Unaged 907 589 63.7 62.4 F. H. Rose 
" 1928 = Adult 3443 20 60 S7 F. H. Rose 
British Xl. 1931-39 Adult 614 560 68.5 65.5 A. J. Butler 

1/ The mean mortality rates for Illinois were recalculated from original 
data compiled and adjusted by Bellrose and Chase (1950); their mor- 
tality rates for the two sexes, 1.78 and 46.68 per cent are arith- 
matic means covering rates for the first 5 age intervals; the ones 
shown in this table are geometric means calculated in the standard 
manner (see Chapter I). 
Table 59.--Differential Recovery Rates for Unaged Male and 
Female Mallards 
Males Females 
When Where No. No. q No. on A . 
Banded Banded Banded Shot Shot Banded Shot Shot Bander 
1927 Mont.2/ 2127 416 19.6 1363 2h6 18.0 F. H. Rose 
¥ " 2/ 2127 663 31.2 1363 380 27.9 F. He. Rose 
1928 " y 4,168 56h 13.5 3176 385 12.1 F. H. Rose 
" " / 4168 898 21.5 3176 579 18.2 F. H. Rose 
‘ " 3/ 168 907 21.8 3176 589 18.5 F. H. Rose 
1931-1 B.C. L/ 6308 1137 18.0 6886 1091 15.8 A. J. Butler 
1936—h S.D. y 6762 1257. 18.6 048 532 13.1 Sand Lake Ref. 
Total 19,305 20-5 15,073 2592 16.8 
-1/ Shot same season as banded. 
a) Shot in S-year period. 
Shot in 10-year period. 
ey The number shot should be increased by additional reports after 
this tabulation was made. 
5/ Excluding lines 1, 3, and 4 which in effect are subtotals only. 
in the sexual unbalance suggested by these figures" (Munro 193, 
p. 243). I am unable to follow Munro's reasoning on this point. 
The even sex ratio among the bagged birds, when compared to the 
unbalanced ratios found in the banding traps, clearly indicates 
that more males than females were taken by hunters. 
138 
