Black-crowned Night Heron (Nycticorax nycticorax)
Black-crowned Night Heron adults are approximately 25 inches long and weigh 28 oz. They have a black crown and back with the remainder of the body white or grey, red eyes, and short yellow legs. They have pale grey wings and white under parts. Two or three long white plumes, erected in greeting and courtship displays, extend from the back of the head. The sexes are similar in appearance although the males are slightly larger. Black-crowned Night Herons do not fit the typical body form of the heron family. They are relatively stocky and about 25 inches tall with shorter bills, legs, and necks than their more familiar cousins the egrets and "day" herons. Their resting posture is normally somewhat hunched but when hunting they extend their necks and look more like other wading birds.
Immature birds have dull grey-brown plumage on their heads, wings, and backs, with numerous pale spots. Their underparts are paler and streaked with brown. The young birds have orange eyes and duller yellowish-green legs. They are very noisy birds in their nesting colonies, with calls that are commonly transcribed as quok or woc, woc.
The breeding habitat is fresh and salt-water wetlands throughout much of the world. Black-crowned Night Herons nest in colonies on platforms of sticks in a group of trees, or on the ground in protected locations such as islands or reedbeds. Three to eight eggs are laid.
This heron is migratory in the northernmost part of its range, but otherwise resident. The North American population winters in Mexico, the southern United States, Central America, and the West Indies.
These birds stand still at the water's edge and wait to ambush prey, mainly at night or early morning. They primarily eat small fish, crustaceans, frogs, aquatic insects, small mammals and small birds. During the day they rest in trees or bushes.
Great Blue Heron (Ardea herodias)
The Great Blue Heron is a large wading bird common near the shores of open water and in wetlands over most of North and Central America An all-white population found only in the Caribbean and southern Florida was once treated as a separate species and known as the Great White Heron.
It is the largest North American heron and among herons it is surpassed only by the Goliath Heron and the White-bellied Heron. It has head-to-tail length of 38 - 54 inches, a wingspan of 66-79 inches, a height of 45 - 54 inches and a weight of 4.6 - 7.3 lbs. Notable features include slaty flight feathers, red-brown thighs, and a paired red-brown and black stripe up the flanks; the neck is rusty-gray, with black and white streaking down the front; the head is paler, with a nearly white face, and a pair of black plumes running from just above the eye to the back of the head. The feathers on the lower neck are long and plume-like; it also has plumes on the lower back at the start of the breeding season. The bill is dull yellowish, becoming orange briefly at the start of the breeding season, and the lower legs gray, also becoming orangey at the start of the breeding season. Immature birds are duller in color, with a dull blackish-gray crown, and the flank pattern only weakly defined; they have no plumes, and the bill is dull gray-yellow. Among standard measurements, the wing chord is 17 - 19 inches, the tail is 6.0 - 7.5 inches, the culmen is 5.2 - 6.0 inches and the tarsus is 6.2 - 8.3 inches.
The heron stride is around 9 inches, almost in a straight line. Two of the three front toes are generally closer together. In a track the front toes as well as the back often show the small talons.
The call is a harsh croak. The heron is most vocal during the breeding season, but will call occasionally at any time of the year in territorial disputes or if disturbed.
The primary food for Great Blue Heron is small fish, though it is also known to opportunistically feed on a wide range of shrimp, crabs, aquatic insects, rodents and other small mammals, amphibians, reptiles, and small birds. Herons locate their food by sight and usually swallow it whole. Herons have been known to choke on prey that is too large. It is generally a solitary feeder. Individuals usually forage while standing in water, but will also feed in fields or drop from the air, or a perch, into water. As large wading birds, Great Blue Herons are able to feed in deeper waters, and thus are able to harvest from niche areas not open to most other heron species.
It feeds in shallow water or at the water's edge during both the night and the day, but especially around dawn and dusk. It uses its long legs to wade through shallow water, and spears fish or frogs with its long, sharp bill.
This species usually breeds in colonies, in trees close to lakes or other wetlands. Often such colonies include only Great Blue Herons, sometimes they nest alongside other species of herons. These groups are called heronry (a more specific term than "rookery"). The size of these colonies may be large, ranging between 5 - 500 nests per colony, with an average of approximately 160 nests per colony.
Great Blue Herons build a bulky stick nest, and the female lays three to six pale blue eggs. One brood is raised each year. If the nest is abandoned or destroyed, the female may lay a replacement clutch. Reproduction is negatively affected by human disturbance, particularly during the beginning of nesting. Repeated human intrusion into nesting areas often results in nest failure, with abandonment of eggs or chicks.
Both parents feed the young at the nest by regurgitating food. Parent birds have been shown to consume up to four times as much food when they are feeding young chicks than when laying or incubating eggs.
Eggs are incubated for around 28 days and hatch asynchronously over a period of several days. The first chick to hatch usually becomes more experienced in food handling and aggressive interactions with siblings, and so often grows more quickly than the other chicks. Predators of eggs and nestlings include turkey vultures, several corvids, hawks, bears and raccoons, the latter two also potential predators of adults. Adult herons, due to their size, have few natural predators, but can be taken by Bald Eagles, Golden Eagles and, less frequently, Great Horned Owls and Red-tailed Hawks. When predation on an adult or chick occurs at a breeding colony, the colony can be abandoned by the other birds, but this does not always occur.
Yellow-crowned Night Heron (Nyctanassa violacea)
Yellow-crowned Night Heron adults 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.
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.
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
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. They lay 3 - 5 pale blue-green eggs.
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