ANIMAL ESTATES: grebe
Pied-billed Grebe {Podilymbus podiceps} Both sexes build a large sodden, floating nest of rotting and green plant material and mud. The decomposition of plant material generates substantial quantities of heat, up to 11-13C higher than the surrounding water, providing enough heat to incubate the eggs in the adults' absence (Davis et al. 1984). Like other grebe species (Nuechterlein and Buitron 2002) this may afford the adults the ability to roost comunally at night to minimize predation risk. Pied-billed grebes inhabit quiet marshes, marshy shorelines of ponds, shallow lakes, or marshy bays and slow moving streams with sedgy banks or adjacent marshes; rarely in brackish marshes with limited tidal fluctuation. Although plant species in breeding marshes may vary, a 50/50 combination ("hemi- marsh") of emergent vegetation interspersed with open water is desirable (Andrle and Carroll 1988). Grebes avoid dense emergent vegetation, and muskrats appear to play an important role in opening up dense cattail stands and providing cut stalks for nest construction. Ideal water depths for nesting range from 25 to 50 cm (Seyler 2003). Grebes set up breeding territories more commonly in wetlands impounded by beavers or humans than in those of glacial origin, and individual pairs appear to favor wetlands of intermediate size (0.6 - 7.0 ha) over very large or small wetlands (Gibbs and Melvin 1992). from the New York Natural Heritage Program