Variation in use of managed wetlands by waterfowl, wading birds, and shorebirds in Ohio
Tara M. Olson, MS
Advisor: Robert Gates
There is a need to broaden wetland conservation and management to include a greater diversity of wildlife species. Integration of waterfowl and webless wetland bird management under the North American Waterfowl Management Plan (NAWMP) requires an understanding of wetland bird responses to variation in habitat characteristics and management. I compared abundance and composition of 47 species of waterfowl, wading birds, and shorebirds among 47 wetlands in central and northwestern Ohio during March 2001 – June 2002. I used multivariate analyses to describe patterns of wetland bird species abundance and composition associated with wetland size, water level variation, and vegetation characteristics. I compared species composition, species densities, and environmental conditions among coastal and inland landscapes, disturbance levels, cover types, and water management regimes.
Wetland bird communities were structured along water regime and vegetation density gradients in the managed wetlands that I studied. Mean densities (no./visit/ha) of waterfowl (9.84), wading birds (0.72), and shorebirds (3.66) were greatest in unmanaged, open water refuges during autumn. In addition to having the greatest species richness, mean densities of dabbling ducks (5.65) and shorebirds (1.86) were greatest on moist soil wetland during spring. Waterfowl, wading bird, and shorebird use (use-days/ha) was greatest on wetlands managed with a partial drawdown regime.
The compatibility of moist soil management for waterfowl and other guilds of wetland birds was not apparent during autumn because hunting disturbance affected waterfowl habitat use patterns (P<0.10; Multiple Response Permutation Procedure). The value of moist soil management was more apparent during spring. Slow and partial drawdowns should be conducted on moist soil wetland during early spring to attract the greatest diversity of wetland birds. However, traditional waterfowl management cannot provide habitat for all wetland birds throughout the year. Compared to waterfowl, shorebirds require shallower, less densely vegetated habitats during autumn and spring. Therefore, a complex of wetlands managed with different water regimes and vegetation structures will provide habitat for the most diverse assemblage of avian species.