Grebe

Grebe
Black-necked grebe Podiceps nigricollis
Scientific classification
Kingdom Information
Domain	Eukaryota
Kingdom	Animalia
Subkingdom	Bilateria
Branch	Deuterostomia
Phylum Information
Phylum	Chordata
Sub-phylum	Vertebrata
Infraphylum	Gnathostomata
Class Information
Superclass	Tetrapoda
Class	Aves
Sub-class	Neornithes
Infra-class	Neognathae
Order Information
Superorder	Neoaves
Order	Podicipediformes
Family Information
Family	Podicipedidae
Genus Information
Genera	Aechmophorus Podiceps Podilymbus Poliocephalus Rollandia Tachybaptus
Population statistics

Grebes are waterbirds of the family Podicipedidae, found throughout the world, with 20 species on six continents. All grebes breed near fresh water, but many of the species spend the winter on the sea.

Etymology

The word "grebe" is of French origin; some authorities place the first use of this word in the Savoie region in 1766. Although it's debatable, it may be based on krib, a word in the Breton language which meant "comb", and possibly in reference to several species having a comb-like crest on their heads.

Description

Grebes range in length from 8 to 29 inches, and weigh from 5 ounces to 3 pounds, depending on the species. Coloration is a general dark-above/light-below pattern, with principal differences between species in head ornamentation and bill shape. Their feet are not webbed like loons, to which they bear a superficial resemblance; rather, each toe is lobed, and propulsion through the water is done with a rapid figure-8 motion, enabling grebes to swim underwater or on the surface at great speed. On land walking is difficult and awkward due to the position of their legs on the body.

Diet

Grebes are predatory. Many species - especially the larger grebes - eat fish, and of these only the Western grebe has a habit of spearing fish with its beak. The smaller species live nearly-exclusively on invertebrates, such as insects and crustaceans; Pied-billed grebes feed on crayfish, and are the only grebes capable of crushing these hard-bodied shellfish.

Grebes are also noted for their curious habit of swallowing feathers. Plucking them from their own bodies, the feathers collect in the pyloric pocket of the stomach and act as a filter, preventing bones and scales from entering the intestinal tract. The mass of collected indigestible material forms a pellet, which is then regurgitated in a manner similar to owls. Young grebes are fed feathers by the parents almost immediately after hatching.

Species

• Genus Aechmophorus

Clark's grebe, Aechmophorus clarkii

Western grebe, Aechmophorus occidentalis

• Genus Podiceps

Black-necked grebe, Podiceps nigricollis

Colombian grebe, Podiceps andinus (extinct 1977)

Great grested grebe, Podiceps cristatus

Great grebe, Podiceps major

Hooded grebe, Podiceps gallardoi

Horned grebe, Podiceps auritus

Junin grebe, Podiceps taczanowskii

Red-necked grebe, Podiceps grisegena

Silvery grebe, Podiceps occipitalis

• Genus Poliocephalus

Hoary-headed grebe, Poliocephalus poliocephalus

New Zealand grebe, Poliocephalus rufopectus

• Genus Podilymbus

Atitlán grebe, Podilymbus gigas (extinct 1989)

Pied-billed grebe, Podilymbus podiceps

• Genus Rollandia

Titicaca grebe, Rollandia microptera

White-tufted grebe, Rollandia rolland

• Genus Tachybaptus

Alaotra grebe, Tachybaptus rufolavatus (extinct 2010)

Australasian grebe, Tachybaptus novaehollandiae

Least grebe, Tachybaptus dominicus

Little grebe, Tachybaptus ruficollis

Madagascar grebe, Tachybaptus pelzelnii

References

• The National Geographic Field Guide to the Birds of North America (National Geographic Society 2002)