
67 
Table IV. - Summary of Active Nests Only. 

Total Number Percent of Success 
Species of Active Nests Destroyed Hatched 1953 1954 1955 
Mallard 245 150 95 48.9 24.1 38.8 
B-w. Teal 36 18 18 37.0 25.6 50.0 
Pintail 13 > 8 59.1 36.8 61.5 
Canvasback 19 3 16 70,8 52.0 84.0 
Baldpate 7 2 5 25.0 16,7 71.4 
L. Scaup 19 9 10 57.1 57.1 52.6 
G-w. -Teal 5 4 1 66.7 0.0 20,0 
Ringneck 10 4 6 60.0 44.4 60.0 
Redhead i 0 l 25.0 100.0 100.0 
Shoveler 1 l 0 100.0 40.0 0.0 
Gadwall 6 l 5 100,90 60. 0 83.3 
Total 362 213 149 50.1 28.0 41,2 
Fram Table [V. we see that nesting success in 1955 was higher for 
‘nearly all species than it was in 1954 and for most species better than in 1953. 
However, mallard success did not reach the high of 1953, The 1955 season was 
early with mallards, pintails and canvasback getting an early start at nesting. 
First nesting attempts of mallards were hit very hard but later on the species 
did very well as did all other late nesting species. 
Table V.- Causes of Nest Destruction - Active Nests Only. 
Percent of Total 

1952 1953 1954 1955 
Crows and Magpies 33 43 33 50 
Skunk 40 24 32 31 
Ground Squirrels 16 lz 12 5 
Other Mammals 4 ae 4 8 
Flooding 0 3 11 ] 
Agriculture 2 7 1 2 
Unknown 5 6 6 3 
Total 100 100 100 100 
The data in Table V. indicates that crows and magpies were responsible 
for 50 percent of the nest destruction in 1955. However of the destroyed-when- 
found nests, skunks took nearly 60 percent. This is not a true measure of predation, 
however, because destroyed-when-found nests taken by skunks are easier to find 
than those where crows have removed all epgs. It does indicate a heavier loss to 
skunks early in the season before mice litters, insects and beetles were available 
as skunk food. 
