Effects of water depth, cover and food resources on habitat use of marsh birds and waterfowl in boreal wetlands of Manitoba, Canada / Mark S. Baschuk, Nicola Koper, Dale A. Wrubleski, and Gordon Goldsborough.

Includes bibliographical references (pages 53-54).

To evaluate water-level manipulations as a management tool in boreal wetlands, marsh bird and
waterfowl habitat use were studied in the Saskatchewan River Delta, Manitoba, Canada, during 2008 and 2009.
Call-response and aerial surveys were used to estimate densities of marsh birds and waterfowl, respectively, within
six wetland basins undergoing two different water-level treatments. Generalized linear models were used to determine
relationships between presence and densities of birds to water depth, vegetation characteristics, and relative
forage fish and invertebrate abundances at two spatial scales. American Bittern (Botaurus lentiginosus) and Piedbilled
Grebe (Podilymbus podiceps) densities were positively influenced by water depth and relative fish abundance.
American Coots (Fulica americana) and diver waterfowl (Aythya, Bucephala) also responded positively to increased
water depth, whereas dabbler waterfowl (Anas, Aix) were negatively influenced by increasing water depth. Densities
of Sora (Porzana carolina) and Virginia Rail (Rallus limicola) were positively correlated with the relative abundances
of invertebrates, but negatively correlated with relative fish abundance. Due to the high avian biodiversity in the
region, managers should focus on providing a variety of wetland habitats. Using a combination of partial waterlevel
drawdowns and high water, habitat for numerous avian species can be created simultaneously within wetland
complexes.