Assessing river habitat selection by waterfowl wintering in the South Platte River, Colorado

Abstract

We assessed river habitat selection of waterfowl wintering in the South Platte River below the Metro Wastewater Reclamation District treatment plant in Adams County, Colorado to determine potential impacts of proposed river channel modifications. Daily mean number of waterfowl was 711 per km of river over the study area, and 19 species of waterfowl were observed. We describe use of a resource selection model to evaluate whether a habitat type is selected more than expected based on its availability. Habitat selection indices indicated that Canada geese (Branta canadensis) used all habitats in proportion to their availability. Dabbling ducks selected large pools, secondary channels, riffles and sandbars, avoided smaller pools and islands, and used runs in proportion to their availability. Diving ducks selected large pools, small pools, and runs; they avoided secondary channels, riffles, sandbars, and islands. Due to different habitat preferences between diving and dabbling ducks, changes that alter river habitat structure may favor some species and not benefit others. The optimum way to maintain diversity and abundance of waterfowl wintering in the South Platte River is to maintain a variety of habitat types.