Description
Adults 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 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.
During the day they rest in trees or bushes. N. n. hoactli is more gregarious outside the breeding season than the nominate race.
Distribution and Habitat
The black-crowned night heron (Nycticorax nycticorax), or black-capped night heron, commonly shortened to just night heron in Eurasia, is a medium-sized heron found throughout a large part of the world, except in the coldest regions and Australasia (where it is replaced by the closely related nankeen night heron, with which it has hybridized in the area of contact).
The breeding habitat is fresh and salt-water wetlands throughout much of the world. The subspecies N. n. hoactli breeds in North and South America from Canada as far south as northern Argentina and Chile, N. n. obscurus in southernmost South America, N. n. falklandicus in the Falkland Islands, and the nominate race N. n. nycticorax in Europe, Asia and Africa. 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 (even in the cold Patagonia). The North American population winters in Mexico, the southern United States, Central America, and the West Indies, and the Old World birds winter in tropical Africa and southern Asia.
Feeding
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. They are among the seven heron species observed to engage in bait fishing; luring or distracting fish by tossing edible or inedible buoyant objects into water within their striking range – a rare example of tool use among birds.
Breeding
It nests on the Danube and Black Sea coasts. It breeds mainly in mixed colonies of herons, glistening ibises, sparrows and small cormorants. The nests are located in hard-to-reach reeds or on willows and poplars. Sometimes it occupies ready-made nests of other birds. In April, the female lays 3-5 light blue eggs, which the two birds incubate in shifts for 20-25 days. On the tenth day, the young get to their feet, and a few days later they begin to move through the vegetation. They learn to fly only at the age of 40 days.
Conservation Status
In Bulgaria: vulnerable VU [A2 + B1 (bii)]; ZBR-II, III; Red Book of the Republic of Bulgaria; international: BeK-II; DP-I; ECS-spec 3, decreased. The species and habitats are protected under the BDA. Some of the nesting colonies are within protected areas.
