Great Blue Heron

Ardea herodias

  • Version: 2.0 — Published April 28, 2011
  • Ross G. Vennesland and Robert W. Butler

Free Introduction Article Access

The Introduction Article is just the first of 11 articles in each species account that provide life history information for the species. The remaining articles provide detailed information regarding distribution, migration, habitat, diet, sounds, behavior, breeding, current population status and conservation. Each species account also includes a multimedia section that displays the latest photos, audio selections and videos from Macaulay Library’s extensive galleries. Written and continually updated by acknowledged experts on each species, Birds of North America accounts include a comprehensive bibliography of published research on the species.

A subscription is needed to access the remaining account articles and multimedia content.

Subscribe Now

Already a subscriber? Sign In
Figure 1. Breeding, nonbreeding, and year-round ranges of the Great Blue Heron.

The species (A. herodias) is rare in winter in the northern parts of its range.

Adult Great Blue Heron, Everglades NP, FL, January.

Adult Great Blue Herons have clean white crowns, whereas juveniles and immatures are duskier gray, becoming progressively whiter with age. ; photographer Marie Reed

Adult Great Blue Heron (white-morph), Captiva Is., FL.

The 'Great White Heron' is generally considered a color-morph of the Great Blue (A. h. occidentalis), though some authorities suggest it is a distinct species. Where the dark and white forms overlap in Florida, intermediate birds known as 'Wurdemann's Herons' can be found; they have the grayish bodies of a Great Blue Heron, but the white head and neck of the Great White Heron.; photographer William L. Newton

The Great Blue Heron is one of the most widespread and adaptable wading birds in North America.

Up to nine subspecies have been recognized by past researchers, based on differences in plumage color and morphology. Researchers have agreed that Florida's Great White Heron (A. h. occidentalis), the subspecies most distinctive in color (entirely white), and the Pacific Great Blue Heron (A. h. fannini) are distinct subspecies. Recent reviews (see Systematics) have suggested that the remaining Great Blue Herons in North America are composed of either one (A. h. herodias), or two (A. h. herodias, A. h. wardi) subspecies. Owing to this controversy, this account primarily considers 'blue group' Great Blue Herons (A. h. herodias, A. h. wardi, A. h. fannini), usually referred to as the Herodias (or blue) group, and 'white group' Great Blue Herons - the Great White Heron (A. h. occidentalis), referred to here as the Occidentalis (white) group Great Blue Herons.

Equally at home in coastal (marine) environments and in fresh water habitats, the Great Blue Heron nests mostly in colonies, commonly large ones of several hundred pairs. Such colonies are often located on islands or in wooded swamps, isolated locations that discourage predation by snakes and mammals and disturbance from humans. Although the species is primarily a fish eater, wading (often belly deep) along the shoreline of oceans, marshes, lakes, and rivers, it also stalks upland areas for rodents and other animals, especially in winter. It has been known to eat most animals that come within striking range. Its well-studied, elaborate courtship displays have correlates on the foraging grounds, where this species can be strongly territorial.

The Great Blue Heron weathered the impacts of 20th century North Americans relatively successfully. Although it was hunted heavily for its plumes and some of its wetland habitats were drained or otherwise degraded, many populations have recovered well. Nevertheless, breeding colonies remain vulnerable to disturbance and habitat loss, and climate change and increasing predator populations may bring new challenges.

See Butler (1997) for a review of breeding behavior, reproductive success, foraging behavior, and the energetics of growth and reproduction. Foraging ecology and behavior have been covered by Kushlan (1976, 1978), Butler (1995), Gawlik (2002) and Kelly et al. (2003). The effects of contaminants on reproduction are discussed by Harris et al. (2003), Elliott et al. (2005) and Champoux et al. (2006). For discussions of the effects of human and predator disturbance, see Parnell et al. (1988), Vennesland and Butler (2004) and Vennesland (2010).

Recommended Citation

Vennesland, R. G. and R. W. Butler (2011). Great Blue Heron (Ardea herodias), version 2.0. In The Birds of North America (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.