Changes in Waterfowl, Wetlands, Demographics, and Land Use on the Waubay Study Area, Day County, South Dakota: 1950-53 vs. 1992-93

During 1950-53, Evans and Black (1956) conducted the Waubay Study, one of the first comprehensive studies of waterfowl and wetlands on private lands. During 1992-93, we repeated this study to assess the changes that have occurred relative to waterfowl populations, wetland characteristics, land use, and demographics, after a time-lapse of 40 years. Permission was granted to access 97.8% of the original 7,200-acre Waubay Study Area (WSA). The number of occupied farms and different landowners on the WSA have decreased while the average farm size has increased since 1950-53. Annually cropped land on the WSA has decreased substantially since 1950-53 and has largely been replaced by Conservation Reserve Program (CRP) grasslands. Row crops (corn, soybeans) and alfalfa (Medicago sativa) did not occur on the WSA during the early-1950's but now occupy a large percentage of the cropped land. Substantially fewer small grains (wheat, barley, oats, rye) are currently being planted on the WSA. A total of 504 wetlands occur on the WSA. Class III natural basin wetlands were the most common wetland on the WSA in 1992. Wetland drainage on the WSA has been minimal in recent years compared to earlier years and 28 wetlands have been restored. The majority of wetland drainage on the WSA is due to agriculture. A large number of wetlands on the WSA are also tilled for crop production during drier years. Many more class IV wetlands on the WSA were dominated by dense, monotypic stands of cattail (Typha spp.) in 1992-93 than in 1950-53.. Two breeding pair counts were conducted in 1992 and 1993 and compared to similar data from 1950-53. Pairs/km2 averaged 34.5 during 1992-93 compared to 25.0 during 1950- 53. Breeding pair densities were significantly higher (P<0.05) in 1992 compared to 1951 and in 1993 compared to 1953. Over-water nest searches of 55 wetlands (40 class IV and 15 class III) were conducted during 1992 and 1993. Sixty-six active over-water nests were found in 1992 and 64 in 1993. Redheads (Avthya americana) were the most abundant over-water nester during both years. Over-water Mayfield nest success for all species combined was 14.2% in 1992 and 23.6% in 1993. Forty upland nests were incidentally found with blue-winged teal (Anas discors) being the most common nester. Upland Mayfield nest success for all species combined was 8.2% in 1992 and 5.7% in 1993. Mammalian predation was the leading cause of over-water and upland nest losses. Two brood counts were conducted in 1992 and 1993 and compared to similar data from 1950-53. Broods/km 2 averaged 4.9 in 1992-93 compared to 9.1 in 1950-53. Mean brood densities for 1992-93 were significantly lower (P<0.10) than 1950-53 mean brood densities. Dabbler broods were more abundant than diver broods in all years, however, a larger percentage of the broods were divers in 1992-93 than in 1950-53. In conclusion, pair densities on the WSA have remained equal to or above 1950-53 levels because of the improvements in upland and wetland habitats. However, brood densities have not had a similar response and have decreased significantly, apparently because of extremely high nest destruction rates by mammalian predators. The largest forseeable change in the near future is the expiration of CRP contracts beginning in 1996 and its effects on the waterfowl populations of the WSA.

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Thesis - University Access Only

Discipline thesis:degree_discipline

Wildlife and Fisheries Science

Year

1994

Author dc:creator

• McLeod, Scott J.

Contributors dc:contributor

• Kenneth F. Higgins

• Natural Resources and Conservation

Statement dc:rights

• Copyright © 1994 Scott J. McLeod All rights reserved.

Language dc:language

en

Repository record dc:identifier

https://openprairie.sdstate.edu/etd/535

OAI identifier oai:identifier

oai:openprairie.sdstate.edu:etd-1535