Green heron (Butorides virescens)
|Also known as:||chucklehead, little green heron, poke|
|Size||Length: 25 - 48 cm (2)|
Wingspan: 52 - 60 cm (2)
|Weight||135 - 250 g (2)|
The green heron is classified as Least Concern on the IUCN Red List (1).
Although secretive and skulking while creeping slowly through its wetland habitat, the green heron (Butorides virescens) is actually one of North America’s most recognisable wetland birds (3). So named for its glossy green cap and back, this relatively small, compact, crested heron has black wings washed with blue, grey-brown spots or stripes on the lower-neck and breast, and chestnut-brown patches on the side of the short neck. The wing feathers are edged in pale brown, the tail is blue-green above and greyish-white below, and the feet and short legs are greenish-yellow. The male and female green heron are much alike, but the juvenile is striped with brown on the neck and underparts, with white-spotted brownish upperparts (3) (4). As it stands motionless waiting for small fish to approach within striking range, the green heron can be quite inconspicuous, but often gives its presence away with loud squawks (5).
The green heron breeds from the Pacific states of the U.S. and extreme south-eastern Canada south to Central Panama, the West Indies and islands off the north coast of Venezuela. As a partially migratory species, those most northerly populations travel before winter to reside in the southern U.S. to northern Colombia, northern Venezuela and eastern Ecuador (3) (6).
An extremely adaptable wetland bird, the green heron occupies almost any shallow fresh, brackish or saltwater habitat within its range. It is typically found in swampy thickets, preferring to forage around dense vegetation, but may feed in the open when food is available (3) (6).
Standing alone at the water’s edge or on a branch just above the water, the green heron waits patiently for its prey before driving its head into the water and catching its target in its pincer-like bill (7). Feeding primarily on fish, the green heron is one of very few tool-using bird species and uses a variety of baits and lures, including insects, earthworms, twigs or feathers, to entice fish to where it can grab them (3) (5). This versatile, intelligent predator has a rather large bill for its size and, as such, can feed on a variety of other large prey, including frogs, reptiles, small mammals and crustaceans. It feeds by day and night in shallow waters, often as little as five centimetres deep, and tends to walk between hunting sites in a slow, methodical, deliberate fashion with the body crouched (3).
Nesting alone or in loose groups, the green heron begins breeding with the male bird displaying to spectating females and defending a territory that will eventually become the nesting site (3). Once paired up, the male bird selects the nest site and collects material as the female bird constructs the nest. A clutch of 2 to 5 eggs is laid and then incubated for around 19 to 25 days (2) (3). The chicks are fed regurgitated food by both adult birds and begin hopping around the nest and snapping at insects when they are just two weeks old, before fledging at around 3 weeks (4). As is typical of many heron species, after the breeding season the green heron tends to wander across its range in search of favourable foraging sites. Some birds may not travel far, while others may move greater distances, with some nomadic individuals even occasionally turning up as far afield as Western Europe (5).
While the green heron does not appear to be threatened with extinction, there is currently very limited information available on its populations, primarily due to it being a largely solitary nester and widely dispersed across wetland habitat, which makes surveying difficult. Historically, the green heron was persecuted due to its habit of foraging at fish hatcheries and this may still occur to some degree today. It is possibly also vulnerable to the alteration of wetlands, which can reduce both breeding and foraging habitat, as well as contamination from pesticides and disturbance from the recreational use of rivers (3).
In the absence of any known major threats, the green heron has not been the focus of any conservation measures. It has, however, inadvertently benefited from some developments which have created additional nesting sites, such as artificial islands made of dredged material, and new wetlands, such as the construction of reservoirs and the creation of permanent marshes along coasts for mosquito control. As an inhabitant of wetlands of all sizes, a conservation priority for the green heron is identifying and conserving the areas most important to the species and thereby ensuring this splendid heron continues to thrive (3).
For more information on the green heron and other bird species, see:
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- Brackish: slightly salty water, usually a mixture of salt and freshwater, such as that found in estuaries.
- Crustaceans: diverse group of animals with jointed limbs and a hard chitinous exoskeleton characterised by the possession of two pairs of antennae, one pair of mandibles (mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, and barnacles.
- Incubate: to keep eggs warm so that development is possible.
- Territory: an area occupied and defended by an animal, a pair of animals or a colony
IUCN Red List (November, 2010)
- del Hoyo, J., Elliott, A. and Sargatal, J. (1992) Handbook of the Birds of the World. Volume 1: Ostrich to Ducks. Lynx Edicions, Barcelona.
Davis, Jr, W.E. and Kushlan, J.A. (1994) Green heron (Butorides virescens). In: Poole, A. (Ed.) The Birds of North America Online. Cornell Lab of Ornithology, Ithaca. Available at:
World Association of Zoos and Aquariums – Green heron (November, 2010)
The Cornell Lab of Ornithology – All About Birds: Green heron (November, 2010)
- Blake, E.R. (1977) Manual of Neotropical Birds. Volume 1: Spheniscidae (Penguins) to Laridae (Gulls and Allies). University of Chicago Press, Chicago and London.
- Bond, J. (1993) Birds of the West Indies. Houghton Mifflin Harcourt, Boston, Massachusetts.