Chapter VI.-—-Order Anseriformes (Family Anatidae: Ducks, 
Geese, and Swans) 
Mallard 
Literature on productivity 
Anas platyrhynchos apparently breeds at the end of one year. 
The most complete set - nesting statistics has been furnished by 
Girard (1941), who reported a mean clutch size of 7.13 eggs, 71.2 per 
cent of these hatching and about young reaching the "flapper stage' 
(the age at which banding of the young often takes place). These 
data were acquired on refuges in western Montana where "diligent" 
predator control was exercised. Average clutch sizes elsewhere have 
been higher, usually around 8.5 (table 2). Nesting studies in Utah 
(Williams and Marshall 1938) and Montana (Girard 191) each yielded 
Sl young per successful nest at the time of hatching. 
Table 2l4..—-Reproductive Success of North American Mallards—I 


Boo. ~sask. Saskatchewan Utah ont. Totals 
Where Studied Cowan Kalmback Furniss Lynch Girard Sowls ~ and 
Reference 1948 1937 1938 1948 1941 1948 Means 
Nests 
Number noted 19 188 33 - ~ - 36 276 
Number hatched 9 105 25 - - - 12 151 
% hatched 7 56 76 = - - 33 552/ 
Eggs 
Number noted 191 3532/ 2683/ yeisse2 1797 = 4230 
Number nests 23 LS 31 5 185 7252 ~ Sul 
Mean clutch 8.3 7.8 8.6 8.4 (8.67 7.1 = 7.82. 
Number hatched 76, - - - 953 12793/ - 2308, ; 
% hatched 32 - - - 60 71.2 «= 66 
Brood Size Hatched ~~ ~ ~ - s.12/ 5.13/ - Sel 
1/ Williams and Marshall (1938) 
-2/ Kalmback (1938) has reported 46.9 per cent and 62.2 per cent for 
7 nests in North Dakota in 2 successive years 
3/ calculated from other statistics published by the authors 
L/ based on 121 eggs in 19 nests 
5/ for Utah and Montana data only (2232=3379m66 per cent) 
Brood sizes have been reported by still other investigators, 
especially by Stoudt (196) for Minnesota from 1937 to 191 and by 
Fish and Wildlife Service biologists who carried out continental 
surveys in 1947 and 1948 (table 25). On the whole, these reflect much 
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