Yellow-crowned Night Heron

The Yellow-crowned Night Heron, Nycticorax violaceus or Nyctanassa violacea, is a smaller heron, similar in appearance to the Black-crowned Night Heron.

Adults are 61 cm long and weigh 625 g. They have a white crown and back with the remainder of the body grayish, red eyes and short yellow legs. They have a white stripe below the eye. Juveniles resemble young Black-crowned Night-Herons, being mainly brown flecked with white or gray.

Their breeding habitat is swamps and marshes from the eastern United States to north-eastern South America. They often nest in colonies, usually on platforms of sticks in trees or shrubs overhanging water. they lay 3–5 pale blue-green eggs.

In warmer locations, some are permanent residents; others migrate to Central America and the West Indies. They may occasionally wander north to the lower Great Lakes or Ontario after the breeding season.

A related heron was endemic to Bermuda (Bermuda Night Heron), but became extinct following human colonisation. American Yellow-crowned Night Herons have been introduced to fill its ecological niche.

These birds stalk their prey or wait in ambush at the water's edge, mainly at night. They mainly eat crustaceans, mollusks, frogs, aquatic insects and small fish.

Green Heron, Everglades National Park, Florida

The Green Heron (Butorides virescens) is a small heron. Some sources consider this bird and the Striated Heron or Mangrove Heron, Butorides striatus, of tropical Africa and Asia, to be a single species, the Green-backed Heron.

Description
The green heron is relatively small; adult body length is about 44 cm. The neck is often pulled in tight against the body. 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. The bill is dark with a long, sharp point. Female adults tend to be smaller than males, and have duller and lighter plumage, particularly in the breeding season. Juveniles are duller, with the head sides, neck and underparts streaked brown and white, tan-splotched back, and greenish-yellow legs.

Habitat
Their breeding habitat is small wetlands in eastern and midwest North America, Central America, the West Indies and the Pacific coast of Canada and the United States. They nest in a platform of sticks often in shrubs or trees, sometimes on the ground, often near water. The female lays 3 to 5 eggs. Both parents incubate for about 20 days until hatching, and feed the young birds which take a further 3 weeks to fledge.

Northern Green Heron populations of the race B. v. virescens are migratory and winter from the southern United States through to northern South America. This subspecies is an extremely rare vagrant to western Europe.

Behavior
Green Herons stand very still on shore or in shallow water and await prey. They mainly eat small fish, frogs and aquatic insects. They sometimes drop food, insects, or other small objects on the water's surface to attract fish, making them one of the few known tool-using species. Feeding is done during the day. Their call is a loud and sudden kyow.

Green herons are seasonally monogamous. Nests are constructed in forest and swamp patches, over water or in plants near water. Locations in trees are preferred, with nests built up to 20 m off the ground. The clutch is 2 to 4 eggs, which are laid in 2-day intervals. The chicks are fed by both parents, though the frequency of feedings decreases as they become more independent. When chicks are 16 to 17 days old, fledging occurs, and they become independent after 30 to 35 days.

Black-Crowned Night Heron

The Black-crowned Night Heron (in Eurasia, often just Night Heron; in North America, Black-crowned Night-Heron with a second hyphen), (Nycticorax nycticorax) is a medium-sized heron.

Adults are 64 cm long and weigh 800 g. They have a black crown and back with the remainder of the body white or grey, red eyes, and short yellow legs. Young birds are brown, flecked with white and grey. These are short-necked and stout herons.

These birds stand still at the water's edge and wait to ambush prey, mainly at night. They primarily eat small fish, crustaceans, frogs, aquatic insects, and small mammals. During the day they rest in trees or bushes. The New World race is more gregarious outside the breeding season than the nominate race.

They are often found nesting or roosting within cities in avenue trees on busy roads.