40 
Distribution of Nests 
Diving Ducks -- All of the 27 diving-duck nests found on the area were in the 
emergent vegetation of potholes. Table 22 shows the use and percent acreage use 
value of each pothole type for these nests. Although most of the nests were in 
Type A3, four were in Type B2 and six in Type A2. Neither of these latter types 
was known to be used by breeding pairs of diving ducks and they were very little 
used by broods, Although no broods were seen in B2 areas, two marked broods were 
hatched in potholes of this type and both were seen in other areas, one on the day 
after hatching. These data indicate that these species may nest on areas used 
neither for territory nor brood rearing. ; 
River Ducks -- Since, with the exception of one mallard nest found in the 
white top margin of an Al pothole, the 2); known nests of river ducks found were 
on the uplands, it was impossible to assign any of them to individual potholes. 
They were apparently randomly scattered and usually lay at some distance from 
water, often as far away as possible. 
Two blue-winged teal nests found adjacent to pothole No. 31 furnished some 
infomation. This pothole was under observation several times each day owing to 
its proximity to the camp, which overlooked it. At no time were adult blue-winged 
teal or broods seen on this pothole except when feigning injury after being flushed 
from the nest. One of these hens was observed twice after leaving the nest on her 
own volition. She flew directly from the nest, not resting on the pothole, and 
continued southeastward until out of range of 10-power binoculars (1/2 to 3/) 
mile). 
Table 22. Use of potholes for diving-duck nests. 


Species 
Pothole type Canvasback Redhead Ruddy Total 
AL 3 
Number of nests 1 -- -- 1 
% Acreage-use 0.3 0.1 
A2 
Number of nests -— 3 3 6 
% Acreage-use -- 1.6 5.1 3.0 
A3 
Number of nests 5 1 5 11 
% Acreage-use 2.5 0.6 3.1 2.0 
Al, 
Number of nests -- 2 -- 2 
% Acreage-use -- 269 -- 1.0 
Bl 
Number of nests 1 2 -- 3 
% Acreage-use 0.7 1.6 - 0.8 
B2 
Number of nests 3 1 — h 
% Acreape-use 9.) 3.5 -- 4.6 

Note--No nests found in Types B3, Bl, C, or D. 
