Green Heron

The **green heron** (*Butorides virescens*) is a small heron of North and Central America. *Butorides* is from Middle English *butor* "bittern" and Ancient Greek *-oides*, "resembling", and *virescens* is Latin for "greenish".

It was long considered conspecific with its sister species the striated heron (*Butorides striata*), and together they were called "green-backed heron". Birds of the nominate subspecies (no matter which taxonomic arrangement is preferred) are extremely rare vagrants to western Europe—for example, a sighting in Pembrokeshire in 2018 was only the second recorded sighting in Wales; individuals from the Pacific coast of North America may similarly stray as far as Hawaii.

## Description

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. 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. 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.

## Biology

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. 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. 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.

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. 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. 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. 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.

## Range and Habitat

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. 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.

## Tool Use

Green herons are one of the few species of bird known to use tools. In particular, they commonly use bread crusts, insects, or other items as bait. The bait is dropped onto the surface of a body of water in order to lure fish. When a fish takes the bait, the green heron will then grab and eat the fish. When green herons catch large frogs, they will drown it before swallowing it whole.