Document Type

Thesis - Open Access

Award Date

1972

Degree Name

Master of Science (MS)

Department

Wildlife and Fisheries Science

Abstract

A study of waterfowl production was conducted on two study areas in the James River Valley of South Dakota in 1971 and 1972. Its objectives were to measure rates of reproductive success and to determine the effect of land use and other influences on duck production. The five most abundant species of nesting ducks were blue-winged teal (Anas discors), mallard (platyrhvnchos), gadwall (A. strepera), shoveler (clypeata), and pintail (acuta). Seventy-two percent of the wetland habitat on the study areas consisted of temporary (Type l and Type 3) water areas. Only 3.9 percent of the wetlands represented semi-permanent (Type 4) and permanent (Type 5) ponds. In 1971, on the Twin lakes Area, only four wetlands held water of sufficient depth for brood-rearing throughout the brood season. In 1972, this area had 48 water areas that served as potential brood-rearing habitat. Wet ponds were sufficiently abundant in early spring to attract modest numbers of breeding pairs. The 2-year average density of surface-feeding ducks was 35 pairs per square mile. This was 60 percent of the average density of surface-feeding ducks on the Waubay Study Area, generally acknowledged to be an area of high duck production in the Prairie Hills region of South Dakota. In 1971, dry conditions were accompanied by an influx of pairs from surrounding lands onto the more stable water areas of the two study areas. Many of these immigrants were believed to be unsuccessful breeding pairs and/or nonbreeding birds. Forty-seven percent of all duck nests were concentrated in tame hay. The most productive nesting cover, however, consisted of game-management lands. These areas made up only 4 percent of the land area, yet contained 17 percent of all nests and 22 percent of all successful nests. Overall nest success in both years combined was 28.9 percent. This was close to the minimum level of nest success under which duck populations are apparently able to maintain their numbers. Predation and hay-mowing were the principal causes of nest destruction. An average of 2 1 successful nests was produced per 100 breeding pairs. Brood observations showed 32 broods per 100 pairs present in late July of 1971 and 50 broods per 100 pairs in 1972. The latter two figures were believed to be inflated by brood ingress. Low rates of duck production in the James River Valley suggest that pioneering birds may be contributing substantially to maintenance of breeding populations in that region. In some years, the region may attract breeding ducks that might otherwise have nested in other areas where better reproductive success could be realized.

Library of Congress Subject Headings

Ducks -- Breedings
Birds -- South Dakota

Description

Includes bibliographical references (pages 43-44)

Format

application/pdf

Number of Pages

62

Publisher

South Dakota State University

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