173 
Table 1. -- Breeding Population Index 
Ducks per square mile 


Transect No. No. Square Miles 1946 1947 1948 1949 1950 
i 39.2 139.3 ° 9.5 23.5 32:8 31.9 
—— 16.7 11.4 8..0 22h 36,6 26.0 
3 43.7 17.2 18,6 27.6 36.2 40.5 
4 29.7 11.9 10,3 32.5 37.2 29.6 
4 z1.5 23.5 16.2 22.6 43.5 41.5 
: 29.4 31.2 25.5 29.7 
f ram) a ; 20.2 31.9 22.5 
21.5 19.4 46,6 23.1 
9 20.6 29.3 33.0 
Average 15,4 13.1 24.4 35.4 on a § 
Table 2. -- Species Composition, Summation Transects 1 through 9 

Comparative abundance, percent 
Species 1948 1949 1950 
Pintail 28.6 26.8 20.1 
_Blue-winged teal 21.7 .25.6 27.7 
Shoveler 10.2 10.1 6.7 
Mallard 14.0 16.5 24.3 
Scaup 3.5 2.6 3.4 
Baldpate 2.0 1.4 Lwe 
Gadwall 11.5 8.7 9.5 
Redhead 4,8 3.3 2.5 
Canvasback 1.8 1.6 2.3 
Ruddy 1,5 2.7 1.6 
Green-winged teal .4 iad .3 
Ringneck oe 
Bufflehead 1 
I 
These data for this tri-state area as a whole indicate a decrease of approx- 
imately 10 percent over last year in this area. The pintail was responsible for the 
largest portion of the decrease. 
The transects which were established this year consist of four one-fourth mile 
wide transects 48 miles apart extending east and west across the State of South Dakota 
and four similarly arranged across the State of North Dakota. Aside from the fact that 
far better sampling could be accomplished by this system, the objectives behind this 
arrangement were twofold: 
1. A framework was established from which reliable population 
information could be obtained for the entire area regardless 
of the annual variations in water distribution. 
2. It was desirable to obtain comparable information on the 
efficiency and accuracy between transects covering a one- 
fourth mile strip and those covering a one-half mile strip. 
