Naturalist Fact: Pied-billed Grebe

 

(photo by P. Lourenco)

Pied-billed Grebes are a fairly common wintering bird on Little St Simons, and are often seen swimming and diving in the island’s ponds and creeks.  While grebes may superficially resemble loons, DNA evidence suggests they are more closely related to pelicans, petrels and storks, but at a very ancient point in their phylogeny.  Fossils of modern grebes have been found in Chili from as long as 30 million years ago.  Grebes are well adapted to swimming and diving, usually chasing prey underwater.  They have lobed toes rather than webbed feet like ducks, and rarely spend time on dry land. 

(Preening, shows lobed foot, www.aviansources.com)

 Small grebes, like Pied-billed Grebes, eat smaller prey such as aquatic invertebrates, crustaceans and little fish.  Interestingly, many grebes will also ingest their own feathers, although larger fish-eating grebes do this more often than others.  It is thought that the feathers may protect the stomach from damage by fish bones or other hard items that the bird may have consumed.   It is often common for Pied-billed Grebes to submerge themselves when they feel threatened.  They can literally sink themselves from a resting position by contracting their abdominal muscles, compressing their plumage and exhaling.  By adjusting their buoyancy, it is possible for them to remain below the surface with only their heads visible. 

Female grebe with chick, by Joe Kegley

Pied-billed Grebes are much more common in the winter, but some reports of breeding grebes have been documented in the coastal plain.  Nests are built on floating mats of vegetation in the spring, and they usually lay 5-6 eggs.  Both adults incubate the eggs but after hatching the chicks will often ride on the back of their mother, usually concealed by her wings.  The population of this species appears to be stable, but there is a concern of loss of habitats as many wetlands are developed and altered.

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