84 
Table V. - Duck Nest Histories - 1953 
Species Percent Success No. of Nests 
Mallard 37 186 
Canvasback 77 77 
Pintail 28 | 29 
Redhead 54 26 
Ruddy duck 83 23 
Blue-winged teal 44 23 
Lesser scaup 32 19 
Others | 37 19 
Ia rl a i pte an hey a aie ee PE Ee a 
Total 402 
Air-Ground Comparisons 
During the brood season, a 10-mile transect was flown 4 times in a period of 
18 days (see Table V). Aerial observations were made by Alvin Noltemeier, pilot 
and Charles D. Evans on July 17, 21, and 22, and by John Lynch, pilot and Charles 
Evans on August 3. A Piper Cub aircraft was used. Broods were counted in 1/16- 
mile sfrips on each side of the plane; hence two flights were necessary to cover the 
1/4-mile-wide transect. 
The aerial counts giving the highest number of broods were made either early 
or late in the day. Generally, regular aerial brood surveys are not limited to these 
optimum brood-counting periods. This 10-mile transect represents the open type of 
pothole habitat and is not representative of the district as a whole. 
The same transect was censused by a ground beat-out method during the period, 
July 20-27, and by a road count on August 5. The data indicate that approximately 
30 percent of the broods present were countable from the air under the conditions 
prevailing: 
Table VI. - Air-Ground Comparisons --Transects II, 1953 
(2.5 square miles - 10 linear miles) 
Method Date . Time Wind (mph) No. Broods 
Aerial 7/17 10:00 am 25 16 
Aerial 7/21 5:45 pm 25-35 25 
Aerial 7/22 8:00 pm 0-5 34 
Aerial 8/ 3 6:20 am 1-5 36 | 
Ground road-count 8/ 5 5:15 am to 3-5 52 
7:45 am 
Ground beat-out 7/20 to Throughout the day - 113 
7/27 Weather variable 
gm ye fe Set pS SS i PP SS LT 
Another comparison of aerial and ground methods was made on 120 stu dy 
potholes. These potholes are scattered throughout the 4,000 square mile district 
and represent the various types of potholes found in this habitat. The results of this 
comparison of brood survey methods are given below: 
