ASSESSING RIVER HABITAT SELECTION BY WATERFOWL WINTERING IN THE SOUTHPLATTE RIVER, COLORADO

We assessed river habitat selection of waterfowl wintering in the Sout h Platte River below the Metro Wastewater Reclamation District treatme nt plant in Adams County, Colorado to determine potential impacts of p roposed river channel modifications. Daily mean number of waterfowl wa s 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 evalu ate whether a habitat type is selected more than expected based on its availability. Habitat selection indices indicated that Canada geese ( Branta canadensis) used ail habitats in proportion to their availabili ty. Dabbling ducks selected large pools, secondary channels, riffles a nd sandbars, avoided smaller pools and islands, and used runs in propo rtion to their availability. Diving ducks selected large pools, small pools, and runs; they avoided secondary channels, riffles, sandbars, a nd islands. Due to different habitat preferences between diving and da bbling ducks, changes that alter river habitat structure may favor som e species and not benefit others. The optimum way to maintain diversit y and abundance of waterfowl wintering in the South Platte River is to maintain a variety of habitat types.