Green herons live throughout much of central and eastern North America, from South Dakota, Minnesota, Ontario, and Nova Scotia south through Mexico, Central America, and the West Indies, to central Panama. Most green herons in North America migrate southward for winter into Florida, Texas, Mexico and Central America. Green herons breed in Maryland but generally are not seen here during the winter. At the Maryland Zoo, the Green heron is one of many birds that can be found in the Marsh Aviary in the Maryland Wilderness.
Green herons prefer dense, woody vegetation around ponds, lakes, and rivers, or mangrove swamps in southern parts of their range. They are normally solitary and patient hunters that eat small fish, insects, aquatic invertebrates, frogs, and other small animals. They can be hard to spot when hunting because they sit very still and blend well into the background. When hunting, a green heron may sway its head and stir or rake with its foot to stir up prey. It stabs quickly with its bill to catch prey.
Green herons, like many herons, tend to wander after the breeding season. Most wander only a short distance in search of better foraging grounds, but rarely a green heron is spotted far from its breeding ground, as far away as England or France!
In North America, raccoons and snakes have been reported to prey upon green heron eggs and chicks.
Green heron pairs nest alone or together in small, loose colonies. They build their nests – a basket of sticks – in small trees or shrubs, usually over water. Females lay clutches of 2-4 eggs on average. Incubation lasts 21-25 days, and both the male and female take turns incubating the eggs. Chicks are helpless at birth, but are jumping from branch to branch by day 15 and are flying by day 35.
Green herons are common and widespread throughout their range.
Hancock, James and James Kushlan. The Herons Handbook. NY: Harper & Row, 1984, pp. 172-79.