Non-breeding waterbirds of the delta of the Rio Colorado, Mexico

The delta of the Rio Colorado was a very important area for water birds until early in the century after which damming and upstreams diversion caused significant habitat modifications in the area. Although recent information suggested the area was still important to many birds, detailed data on such use was lacking. Between the fall of 1993 and the summer of 1994 we made 14 surveys and two aerial flights over the area. The largest numbers of birds occured during the winter, when we counted over 100,000 birds. Shorebirds dominated the bird community, with Western Sandpipers accounting for the majority of the individuals. The areas most used by shorebirds were the extensive mudflats at the mouth of the delta. interior habitats were important mostly to herons and ducks.