192 


Table III. - Species Composition of the 1955 Breeding Population in South Dakota 
and 1954-1955 Trends. 

No. of Males . Percent Composition 
Species Tosa —«S 55 19a 1955 Change 
Blue -winged teal 3, 165 2,447 41.84 47.75 + 6% 
Mallard 1,000 825 13.22 16.10 + 3% 
Pintail 1,049 563 13, 86 10.99 - .3% 
Shoveler 781 561 10. 32 10,95 + 1% 
Gadwall | 353 234 4.66 4.57 - 
Scaup 815 97 10.77 3. 84 - 7% 
Ruddy duck 98 127 1,29 2.48 + 1% 
Redhead 244 91 3.22 1.78 - 1% 
Baldpate 33 44 0.43 0.86 ~ 
Canvasback 23 33 0.30 0,64 - 
Green-winged teal 3 2 0.04 0. 04 None 
Total 7, 564 5, 124 100.00 100. 00 
All of the species in the breeding population were less abundant than 
in 1954. Species which decreased considerably more than average were the 
pintail (65 percent), redhead (76 percent), scaup (84 percent), and green-winged 
teal (67 percent). Species which declined about average were the blue-winged 
teal (50 percent), shoveler (54 percent) and gadwall (57 percent). Species which 
decreased less than average were the mallard (47 percent), canvasback (eight 
percent), ruddy {17 percent), and baldpate {14 percent). It should be pointed out 
that the slight (eight percent) decrease in the canvasback population from that of 
1954 could be misleading. The current decrease in the canvasback population is 
slight because this population had declined considerably in 1954 (minus 40 percent) 
when the total duck population declined only moderately (21 percent). The 
apparent extreme reduction in the scaup population does not have much significance 
because the number of late migrants present at the time of the breeding population 
survey varies considerably from year to year. 
The comparison of current minimum species population with the 
average minimum species populations for the past five years is similar to the 
1954-1955 comparison described above. This is due to the fact that the 1954 
populations were close to average for the past five years. The comparison with 
average minimum, species populations appears in Table IV, 
