Freshwater Birds

Abstract

There are four orders of birds which may be regarded as freshwater forms. Two of these, the Gaviiformes, the divers or loons and the Podicipediformes, the grebes, contain relatively primitive birds. The divers are, perhaps, not far removed from the Cretaceous Hesperornis, an early flightless toothed bird. In both groups nests are built at water level and the precocial young leave the nest to swim within hours of hatching. These two small orders are both highly uniform, each with a single family.