Podicipedidae

The Podicipediformes order is a widely distributed order of freshwater diving birds, some of which visit the sea when migrating and in winter. This order contains only a single family, the Podicipedidae.

They are small to medium-large in size, have lobed toes, and are excellent swimmers and divers. Although they can run for a short distance, they are prone to falling over, since they have their feet placed far back on the body.

Grebes have narrow wings, and some species are reluctant to fly; indeed, two South American species are completely flightless. They respond to danger by diving rather than flying, and are in any case much less wary than ducks. Extant species range in size from the Least Grebe, at 120 grams and 23.5cm to the Great Grebe, at 1.7kg and 71cm.

The North American and Eurasian species are all, of necessity, migratory over much or all of their ranges, and those species that winter at sea are also seen regularly in flight. Even the small freshwater Pied-billed Grebe of North America has occurred as a transatlantic vagrant to Europe on more than 30 occasions.

Bills vary from short and thick to long and pointed, depending on the diet, which ranges from fish to freshwater insects and crustaceans. The feet are always large, with broad lobes on the toes and small webs connecting the front three toes. The hind toe also has a small lobe. Recent experimental work has shown that these lobes work like the hydrofoil blades of a propeller.

Grebes have unusual plumage. It is dense and waterproof, and on the underside the feathers are at right-angles to the skin, sticking straight out to begin with and curling at the tip. By pressing their feathers against the body, grebes can adjust their buoyancy. Often, they swim low in the water with just the head and neck exposed.

In the non-breeding season, grebes are plain-coloured in dark browns and whites. However, most have ornate and distinctive breeding plumages, often developing chestnut markings on the head area, and perform elaborate display rituals. The young, particularly those of the Podiceps genus, are often striped and retain some of their juvenile plumage even after reaching full size. In the breeding season, they mate at freshwater lakes and ponds, but some species spend their non-breeding season along seacoasts.

When preening, grebes eat their own feathers, and feed them to their young. The function of this behaviour is uncertain but it is believed to assist with pellet formation, and to reduce their vulnerability to gastric parasites.

GThey make floating nests of plant material concealed among reeds on the surface of the water. The young are precocial, and able to swim from birth.

The IOC considered there to be 20 extant species in this family, which are:

Little Grebe Tachybaptus ruficollis
Tricolored Grebe Tachybaptus tricolor
Australasian Grebe Tachybaptus novaehollandiae
Madagascan Grebe Tachybaptus pelzelnii
Least Grebe Tachybaptus dominicus

Pied-billed Grebe Podilymbus podiceps

White-tufted Grebe Rollandia rolland
Titicaca Grebe Rollandia microptera

Hoary-headed Grebe Poliocephalus poliocephalus
New Zealand Grebe Poliocephalus rufopectus

Great Grebe Podiceps major
Red-necked Grebe Podiceps grisegena
Great Crested Grebe Podiceps cristatus
Horned Grebe Podiceps auritus
Black-necked Grebe Podiceps nigricollis
Silvery Grebe Podiceps occipitalis
Junin Grebe Podiceps taczanowskii
Hooded Grebe Podiceps gallardoi

Western Grebe Aechmophorus occidentalis
Clark's Grebe Aechmophorus clarkii