59 
The worst offender causing nest destruction was the crow which accounted for 
43 percent of all nests lost. Skunks took 24 percent, ground squirrels 12 percent, 
5 percent more plowed, 4 percent unknown, and the remaining 11] percent were 
destroyed by fox, coyote, flooding, burning, badger and desertion. Two mallards, 
two baldpates, and three blue-winged teals were killed on the nest by predators, 
Only active nests were used in calculating nest losses from predators, 
Table V. - Mallard Nesting Success for Cover Types 

1952 1953 
omar Type No. of Nests Success Wo. of Nests Success” 
Percent Percent 
Snowberry in Field or Pasture 40 35.0 lll 36.0 
All Grassy Cover Types 47 55, 3 88 47.7 
Carex and VUattail Around Ponds 2 100.0 48 50.0 
Willow and Aspen Reproduction ll 64.0 21 66.7 
Mixed Brush - - 9 44.0 
Mixed Weeds and Grasses 27 40.7 9 22.2 
Stubble Fields - - 4, 50.0 
Total for all cover types 127 47.2 290 44.1 
Assuming that the 47 percent was average success in 1952 and 44 percent in 
1953 then we note that both snowberry (Symphoricorpos racemosa} and mixed weeds 
and grasses were below average both years while all other cover types yielded better 
than average success both years. The "mixed weeds and prass type" was found 
mostly in old abandoned fields where cover was abundant and rank but predators were 
also very prevalent, including skunks, Franklin's ground squirrels and crows. 
Snowberry patches are also heavily used by skunks, badger and Franklin's ground 
squirrels both for dens and for foraging. 
Eighty two or 28 percent of all nests found were along the roadside, between 
the road and fields or pastures. Nesting success in this habitat averaged 47.6 percent 
or 8 percent better than average, 
Brood Production 
Due to the abundance of precipitation and resulting tall exceedingly rank cover, 
broods were very difficult to observe during June and the forepart of July. In addition, 
there were numerous shallow water-filled depressions and wet spots in fields and 
pastures where hens could take their broods and remair undetected. This led to the 
erroneous impression by some observers that the 1953 brood crop was below par and 
not at all in proportion to the breeding pair population. However, our nesting data 
indicated a successful hatch and by the end of July this was borne out by a bumper 
crop of nearly all species of ducks indigenous to the area, 
The brood census in 1953 was conducted exactly ten days later than in 1952 due 
to the delayed hatch this year. Two censuses were taken in July 1] through 17, and 
August 2 through 6 respectively. From these two counts the calculated total brood 
production is shown in Table VI. 
