Ardea herodias [ar' dE uh hir O' dE uhs]

Description

The largest heron in North America, the great blue stands 3-4 feet tall and has a wingspan of almost 6 feet. It has blue-gray feathers on most of its body. Adults sport a shaggy ruff at the base of their necks and a black eyebrow extends back to black plumes emerging from the head. Juveniles have a dark crown with no plumes or ruff, and a mottled neck. An all-white color morph found in the Caribbean and southern Florida is often called the great white heron, but it is in fact the same species.

In flight, a Great Blue Heron typically holds its head in toward its body with its neck bent.

Distribution and Habitat

The great blue heron breeds from southern Canada south to the West Indies and Mexico. It winters as far north as southern Alaska and southern New England. It can also be found in the Galapagos Islands. Northern populations east of the Rockies are migratory, going to the Caribbean, Central America, or northern South America. Populations along the Pacific Coast may be permanent residents, even as far north as southeastern Alaska.

It inhabits a variety of habitats, with marshes, rivers, lakes, salt water shores, and ponds being the most common.

Diet

The great blue heron usually stands in water and waits for prey to pass by then grabs it with long bill. It also forages on shore, from floating objects, and in grassland. Fish make up a large part of the diet, but salamanders, lizards, snakes, shrimps, crabs, crayfish, insects, birds, and small mammals are also taken.

Reproduction

This heron breeds in colonies, often of this species alone, sometimes mixed with other wading birds; rarely in isolated pairs. The male chooses a nest site and displays there to attract a mate. Displays include stretching the neck up with bill pointing skyward, flying in circles above the colony with neck extended, and stretching the neck forward with head and neck feathers erected and then snapping bill shut. Pairs are monogamous during the breeding season, but split up after the chicks are raised; new pairs are formed each season.

The nest site is highly variable, usually in trees 20-60 feet above ground or water, but sometimes in low shrubs, on ground (on predator-free islands), or well above 100 feet in a tree. The nest, which is built mostly by the female with material gathered by the male, is a platform of sticks, sometimes quite large.

The 3-7 pale blue eggs are incubated by both parents for about a month. Both parents also share in the feeding and care of the chicks, which fledge at about 2 months and leave the nest at about 3 months.

Scientific Classification

phylum Chordata
subphylum Vertebrata
class Aves
order Ciconiiformes
family Ardeidae
genus & species Ardea herodias

National Audubon Society http://www.audubon.org/field-guide/bird/great-blue-heron
NatureWorks http://www.nhptv.org/natureworks/greatblueheron.htm

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