Northern Prairie Wildlife Research Center
| Table 20. Comparison of pair/brood ratio and hen success (broods/100 pairs) in the Waubay study area, Day County, South Dakota, 1950-1953, 1992-1993. | ||||||||||
| Species | Pair/Brood Ratio | Hen Successa | ||||||||
| 1950s Mean | 1992 | 1993 | 1990s Mean | 1950s Mean | 1992 | 1993 | 1990s Mean | |||
| Dabbling ducks | ||||||||||
| Mallard | 4.3 | 8.1 | 9.6 | 8.3 | 23.5 | 12.3 | 10.4 | 12.0 | ||
| Gadwall | 2.8 | 9.4 | 4.6 | 6.3 | 35.9 | 10.6 | 22.0 | 15.9 | ||
| Northern pintail | 3.4 | 0.0 | 7.5 | 11.0 | 29.2 | 0.0 | 13.3 | 9.1 | ||
| Green-wing teal | 2.5 | 0.0 | 5.0 | 10.0 | ||||||
| Blue-wing teal | 2.5 | 15.4 | 6.9 | 8.9 | 39.8 | 6.5 | 14.5 | 11.3 | ||
| Northern shoveler | 4.5 | 9.0 | 4.8 | 6.3 | 22.2 | 11.1 | 21.1 | 15.8 | ||
| Total dabblers | 2.9 | 11.5 | 6.8 | 8.4 | 34.7 | 8.7 | 14.7 | 11.9 | ||
| Diving ducks | ||||||||||
| Redhead | 4.0 | 5.3 | 14.3 | 8.0 | 25.0 | 18.9 | 7.0 | 12.5 | ||
| Canvasback | 5.0 | 1.5 | 1.0 | 1.0 | ||||||
| Lesser scaup | 4.0 | 0.0 | 1.0 | 1.0 | ||||||
| Ruddy duckb | 1.1 | 4.0 | 2.2 | 2.8 | ||||||
| Total divers | 2.1 | 4.6 | 4.9 | 4.6 | 47.8 | 21.6 | 20.3 | 21.8 | ||
| Total | 2.7 | 9.1 | 6.0 | 7.0 | 36.4 | 11.0 | 16.6 | 14.2 | ||
| a Not calculated
for species with pair densities < 0.7 pairs/km² because they
were not calculated by Evans and Black (1956). b Hen success not calculated for ruddy duck because of difficulty in accurately censusing the breeding population. |
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U.S. Department of the Interior |
U.S. Geological Survey
URL: http://www.npwrc.usgs.gov/resource/birds/waubay/tab20.htm
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