The Red-necked Grebe is a nearly circumpolar inhabitant of northern waters. In North America, it winters on northern Atlantic and Pacific coastlines. It moves inland to breed on small lakes and other suitable water bodies in the northern prairies, western parklands, and forests, north to near tree line. It is a large, highly pugnacious grebe that takes a variety of aquatic prey with its robust bill. North American and east Asian Red-necked Grebes are larger than their counterparts in Europe and western Asia; until 1957 this larger subspecies was known in North America as Holboell's Grebe (Am. Ornithol. Union American Ornithologists' Union 1931 , American Ornithologists' Union 1957 ).
On its breeding lakes, this boldly marked grebe betrays its presence with frequent raucous calls. It is territorial and interspecifically aggressive, commonly threatening or making underwater attack dives against other waterbirds that enter its breeding territory. Outside of migration, it is rarely seen in flight, spending most of its time swimming and diving. Away from breeding areas, it is generally quiet and unobtrusive, although groups of spring migrants may engage in calling and courtship at stopover areas.
Red-necked Grebes have elaborate courtship rituals, but many individuals arrive on their breeding grounds already paired, and their early pair-formation displays are only infrequently observed on breeding lakes. Pairs cooperate in territorial defense, nesting activities, and rearing of young. Parents carry newly hatched young on their backs, where they are brooded and fed until they learn to swim and dive on their own.
Important information on the breeding biology and behavior of this species in North America is available from graduate studies conducted at nesting areas in the southern portion of its breeding range (e.g., Kevan 1970 , Riske 1976 , De Smet 1983 , Ohanjanian 1986 , Garner 1991 ). A study in the Northwest Territories provides data on nesting ecology in boreal subarctic wetlands ( Fournier and Hines 1998a ). Only since 1989, however, have studies been undertaken on nesting populations with marked individuals ( Garner 1991 , B. Eichhorst pers. comm., P. Klatt, GLN, and D. Buitron unpubl., BES). The discovery of a large fall diurnal migration of Red-necked Grebes through Lake Superior in 1989 by the Whitefish Point Bird Observatory (Michigan) provided a unique opportunity for direct ob-servation of the migration behavior of this species, which typically migrates nocturnally ( Stout 1995 ). Although the winter habits of these birds are known to some extent from European studies, basic information on winter biology in North America and eastern Asia is lacking. The development of micro-satellite DNA markers for this species ( Sachs 1998 ) will provide a valuable tool for further studies of Red-necked Grebe ecology and populations.