

i 

63 
Table IX. - Aerial VS Ground Counts of the Adult Breeding Population 
Le a a a 
Adjusted Total Population 

Species Ground Count Aerial Count Percent Seen from Air 
Mallard 516 181 35 
Blue-winged teal 300 70 23 
Pintail 110 51 46 
Baldpate 62 12 19 
Green-winged teal 68 1 1 
Canvasback 48 25 52 
Lesser scaup 26 21 81 
Shoveler F 24 17 71 
Gadwall 12 2 17 
Redhead 8 2 25 
Ringneck 8 0 0 
Ruddy duck 2 0 0 
Unidentified 0 32 a 
Total 1,184 414 35 
In further analyzing the data we find that from 45 to 57 percent of the lone drakes 
were observed from the air while only 23 to 30 percent of the pairs were visible, This 
parallels observations made on the same area in 1952. Time of day enters into this 
picture but it is believed that lone drakes are more easily seen from the air due to the 
fact that they spend more of their time in open water, on muskrat houses and other 
exposed places while pairs are nesting and feeding in areas of heavier cover. 
As in 1952 certain species were more easily picked up from the air than others. 
This is especially true of diving ducks and the brighter colored and larger ducks such 
as the mallard, pintail and shoveler. The total percent of ducks seen from the air 
agreed very closely with 1952 data and if we can assume the error between aerial 
counts and actual populations to be constant from year to year then aerial censuses 
are indeed the answer to any extensive breeding pair survey program. 
Brood counts from the air have always posed a problem. In 1952 aerial brood 
transects were cut down to 1/16-mile wide in order to decrease the angle of observa- 
tion. In 1953 broods observed from the ground "beat out'' census were recorded 
separately depending upon whether they were seen on the "inner" 1/16-mile (nest to 
the road) or the "outer" 1/16-mile strip of the 1/8-mile transect. Comparative data 
are shown in Table X. 
A larger percentage of broods were seen on the outer strip where the angle of 
observation was greater but this "lowered observability'' may have been offset by the 
area on the inner strip "blacked out" by the plane itself. 
Banding Data 
Incidental to the regular survey work 306 ducks were banded. Nearly all of 
these were retrieved by the dog and represent broods from all over the study area 
and adjacent areas, 
