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First described in 1758 by Linnaeus, the father of taxonomy, the great blue heron Ardea herodias is among Amazonia's largest water birds, between four and five feet high, and a five or six feet wingspan. It's typical of the heron family (Ardeidae): slender and long-necked.

The wings and body are grayish blue, streaked white and black, while the head is white with a black strip over the eye. The bill is dull yellow, whereas the legs are greenish yellow. The great blue heron is known to as a white variant, but this is not known from the Amazon region.

During flight, the heron holds its head close to the body with an S-bend in its long neck. The legs trail behind as the bird flies with slow but strong wing beats.

The great blue heron is migratory in Amazonia and ranges throughout the Americas in temperate and tropical zones, occurring as far north as southern Canada during the North American summer. It ranges up to about 8,500 feet.

Although commonly seen in Central and South America, breeding is restricted to areas of milder weather. The species is rarely seen far from water, preferring marshy areas, swamps, the edges of rivers and lakes. In coastal zones, it is found in tidal flats, estuaries and mangrove forest.

As an ambush predator, the great blue heron is usually solitary, and waits or walks slowly in shallow water grabbing prey that passes by. As with other herons, prey is primarily small fish with lesser quantities of other aquatic animals such as aquatic invertebrates, amphibians or even birds, usually spearing the prey with its pointed bill. It hunts on land for small mammals and reptiles.

An adult heron may form a temporary territory in which it feeds, up to several hundred square yards, which it defends.

This species breeds primarily in the northern part of its range in small colonies or singly, preferring isolated areas.

Males display while standing or sitting on nest sites, with the neck arched over the back and the bill pointing skyward.

The large untidy nest forms a robust platform, lined with twigs and vegetation. Nests are located in trees or shrubs, usually close to water and 30 to 70 feet above ground.

Following courtship, from 3 to 6 pale bluish green eggs are laid, incubated for about 4 weeks. Both parents participate in care, feeding young in the nest by regurgitating food.

Hatchlings are altricial, covered in pale gray down. At hatching, the eyes are open, and chicks take about two months to fledge. Great blue herons live to about 15 years.

The great blue heron is among the commonest large aquatic birds, and populations seem to be trending upwards. Formally, the species is considered to be of "least concern."

Plume hunters in the late 19th and early 20th centuries impacted populations of this species less than of other herons.

The main threat today is from loss of habitat, primarily drainage of wetlands due to urban development or conversion to agriculture.

Some fish farmers consider this species to be a pest because it hangs around fish ponds. However, a study at a Mississippi catfish farm found that the birds take fish near the surface of the water, and these tended to be sick and would have soon died anyway (Glahn et al 2002). The authors conclude that "losses from great blue herons are either insignificant or readily preventable."


(NOTE: Most of the links below refer to the great blue heron in North America.)
Wikipedia: Great Blue Heron
Animal Diversity Web: Ardea herodias
Cornell Lab of Ornithology: Great Blue Heron Great Blue Heron
Hinterland: Great Blue Heron
Enchanted Learning: Great Blue Heron
Wisconsin Department of Natural Resources/EEK!: The Majestic Great Blue Heron
BirdWeb: Great Blue Heron Great Blue Heron
Illinois Natural History Survey: Great Blue Heron
Animal Tracks of Humboldt County: Great Blue Herons
Skulls Unlimited: Great-Blue Heron Skull
California Academy of Sciences Library: Blue Heron Bibliography
Pittsburgh Post-Gazette: Birders say unusual creature is a heron-egret mix
IUCN Redlist: Ardea herodias
ITIS Report: Ardea herodias Linnaeus, 1758
USGS: Great blue heron Ardea herodias
Forbes, S. (1998) The Great Blue Heron: A Natural History and Ecology of a Seashore Sentinel. (Book review) Auk 115(3):815-816
Glahn, J. F. et al (2002) Foraging ecology and depredation management of great blue herons at Mississippi catfish farms. Journal of Wildlife Management 66: 194-201
Harris M. L. et al. (2003) Reproductive success and chlorinated hydrocarbon contamination of resident great blue herons (Ardea herodias) from coastal British Columbia, Canada, 1977 to 2000. Environ Pollut. 121:207-27.
Lin L., et al. (2005) Evidence from nature: interspecies spread of heron hepatitis B viruses. J Gen Virol 86: 1335-42

Mainly photos Great Blue Heron
Nature-Wildlife: Great Blue Heron Page
Nature Stock Shots: Photos of Great Blue Herons
Herons from around the Pacific Northwest
Manzanilla - Travel Photo Gallery: heron in the amazon
Phillip Colla Natural History Photography: Great Blue Heron photos
Pbase: tomsview Great Blue Heron

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