The Green Heron (Butorides virescens) is found throughout Kentucky, but populations are lower in heavily forested areas where suitable nesting habitat is less available.
The Green Heron, a member of Family Ardeidae, first identified in the scientific literature by Swedish biologist and naturalist Carl Linnaeus in 1758, includes 72 species of freshwater and coastal birds, some of which are referred to as egrets or bitterns rather than herons.
Size and coloration
Compared to most herons, Green Herons are rather short and stocky, with short legs and thick necks that are often drawn up against their bodies.
They have broad, rounded wings and a long, dark, dagger-like bill. They sometimes raise their crown feathers into a short crest.
Their body length is about 17 inches, and they weigh on average about 8 1/2 ounces, with a wingspan of 25 to 27 inches.
Adults have a glossy, greenish-black cap, a greenish back and wings that are grey-black grading into green or blue, a chestnut neck with a white line down the front, grey underparts and short yellow legs.
Female adults tend to be smaller than males, and have duller and lighter plumage, particularly in the breeding season.
Juveniles are browner, with pale streaking on the neck, spots on the wings, underparts streaked brown and white, and greenish-yellow legs and bills.
Range and distribution
Green Herons breed in all the states in the eastern half of the Lower 48, with year-round populations along the Gulf Coast and up the Atlantic Coast through the Carolinas into Virginia. Breeding birds are also present in states along the Pacific Coast, from Washington state, south to Baja California.
Habitat
In Kentucky, Green Herons live around wooded ponds, creeks, rivers, reservoirs, and wetlands.
Food habits
Green Herons eat mainly small fish, including minnows, sunfish, catfish, pickerel, carp, perch, shad, and brook silversides, which prefer clear water in streams and lakes with aquatic vegetation.
They also feeds on insects, spiders, crustaceans, snails, amphibians, reptiles, and rodents. They hunt by standing still at the water’s edge, in vegetation, or by walking slowly in shallow water. When a fish approaches, the heron lunges and darts its head under water, grabbing or sometimes spearing the fish with its heavy bill.
They hunt day and night, foraging among thick vegetation in water that is less than four inches deep, avoiding the deeper and more open areas frequented by longer-legged herons.
Calls and songs
Green Herons give a harsh, explosive call sounding like …skeow.
They give this call while perched, when flying, or when disturbed by an approaching predator.
When disturbed at the nest they utter a series of raspy clucks…kuk-kuk-kuk-kuk. Males often snap their bills before mating.
Courtship and nesting
Green Herons that nest in Kentucky overwinter along the Gulf Coast southward into the tropics.
Nesting birds return to their breeding grounds by mid-April, with egg laying commencing in May, and late clutches continuing into late June.
Each breeding season, Green Herons pair up with one mate, performing courtship displays that include stretching their necks, snapping their bills, flying with exaggerated flaps, and calling loudly. They often nest solitarily, although they may join colonies with other Green Herons.
They defend breeding areas from each other and from birds like crows and grackles that prey on their nests. Other predators include snakes and raccoons.
Both the male and female feed the chicks, which may stay with their parents for more than a month after leaving the nest, as they learn to forage.
Green Herons protect their feeding areas by driving away other species, such as American Coots, that approach too closely.
The male selects a secluded site within his territory, usually in a large fork of a tree or bush, with overhanging branches to conceal the nest. Green Herons use many plant species as nest sites, anywhere from ground level to 30 feet off the ground.
The male begins building the nest before pairing up to breed, but afterward passes off most of the construction to his mate. As the male gathers long, thin sticks, the female shapes them into a nest 8 to 12 inches across, with a shallow depression.
The nest varies from solid to flimsy, and has no lining. Green Herons sometimes renovate old nests, or build in old nests of Black-Crowned Night-Herons or Snowy Egrets. Occasionally they take sticks from nearby old nests and re-fashion them into new nests. They keep adding sticks throughout the breeding season.
The female lays three to five pale green to bluish eggs. The incubation period is 19 to 21 days, and the hatchlings are covered with grayish brown down on top and white down beneath.
Green Herons are not highly visible. They don’t wade as often as larger herons, and typically stand motionless at the water’s edge as they hunt for food.
Their plumage blends in with the shoreline vegetation so they are naturally camouflaged.