Table 3. -- fF a 0 573 Mallard E Classified =» Coyer e 
i 



Fate known Fate ynknown 
Cover types Hatched Failed to Hatch’ 
No. % ‘No. % No. 
Bul rush 371 61.7 2a0 22.8 431 
Cattail 156 3.4 31 15.6 107 
Grasses and grasslike 
plants €9 60.5 45 39.5 39 
Brushland ce 636.7 38 63.3 ors 
Alfalfa == = 19 100.0 ~= 
Native hay -= -- 15 100.0 a = 
Total all types 618 et 378 MRE 577 
Percent Average 62.0 38.0 

Reasons For Failure To Hatch 
Out of 
Deserted| Nest] Fire le : 
No. % No. % % ‘ 
iT 1 oe cd 
78113.0 
5] 2.7 















Cattail 
Grasses and 
grasslike 
plants 
Brugshland 
Alfalfa 
Native hay 
Total all 
types 

Percent Av. 
An average brood of 7.9 is obtained for 86 mallard nests known to have 
hatched some young. This compares farorably with the 165 nests having com- 
pleted clutches (Table 2). Actual brood counts indicate an average of slightly 
less (Table 4). Thus it appears that with successful nesting pairs an arerage 
of. 8.1 eggs were laid, 7.9 hatched, and 7.2 ducklings were still alive at about 
6 weeks (approximate average age of broods counted). However, the number of 
young produced for each mallard hen attempting to nest is much less. For 142 
nesting attempts observed on the study areas for which final fate of eggs is 
known, only 4.4 young were produced per nest-attempting female. 
In addition to the decimating factors affecting eggs as listed in 
Table 3, several others were observed that destroyed young and adult ducks 
during the nesting season. Approximately 20 ducks were observed that had been 
killed by highway traffic in the valley, one by a great horned owl, two by 
139 
