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New Jersey Endangered and Threatened Species Field Guide
Black-crowned night heron
Species Group: Bird
State: Threatened (Breeding)
The black-crowned night-heron is a stocky, medium sized, black, gray and white wading bird. The legs and neck of the night-heron are relatively short when compared to other egrets and herons. Adult black-crowned night-herons have a black back and crown, gray hind neck and wings, and a white cheek and underparts. During the breeding season, long white streamers extend from the crown down the back beyond the neck. The bill is black in adults and is thick, stout, and spear-shaped. The legs are greenish-yellow, but turn pink in breeding adults. Eye color changes from yellow in young birds to red in adults. The call of the black-crowned night-heron is a loud, guttural woc!
Although their body shape is similar, young black-crowned night-herons look quite different than adults. The young are buff below with brown streaking and brown above with buff-white markings and their bill is grayish-yellow at the base with a dark tip. Adult colors are acquired by two years of age.
Black-crowned night-herons look similar to yellow-crowned night-herons (Nyctanassa violacea). The yellow-crowned has a longer neck and more slender body than the stocky black-crowned night-heron. The adult yellow-crowned lacks the black back of the black-crowned and has a black head with a white cap and cheek patch. Young yellow-crowned night-herons are darker brown above, with smaller buffy markings on the back and more brown below. The bill of the yellow-crowned is shorter than that of the black-crowned. Only the black-crowned night-heron’s toes extend beyond the tail during flight. When the yellow-crowned night-heron is in flight, the legs and feet extend beyond the tail.
Young black-crowned night-herons may also be confused with American bitterns (Botaurus lentiginosus). In flight, the night-heron shows a solid brown upperwing, while that of the bittern is two-toned. The bill of the bittern is also longer, thinner, and lighter colored. The back of the bittern is chestnut brown and lacks buffy spotting.
Distribution and Habitat
Breeding black-crowned night-herons occur throughout the United States and southern Canada, as well as Central and South America. They winter from southern New England along the Atlantic Coast, along the Gulf and Pacific Coasts, in the West Indies, and in Central and South America. The Atlantic Coast breeding population winters largely in the Bahamas and the Greater Antilles, including Cuba, Jamaica, and the Dominican Republic.
In New Jersey, black-crowned night-herons nest primarily along the Atlantic Coast. They also occasionally nest along the coast of the Delaware Bay and River and will rarely nest inland. Nonbreeding individuals may reside in the state during the summer months.
Black-crowned night-herons feed in marshes and along the edges of ponds and creeks. Forests, scrub/shrub, marshes, and ponds serve as nesting and roosting habitats for black-crowned night-herons. They avoid nesting at exposed sites that offer little cover. When nesting in mixed-species colonies with low vegetation height, they tend to nest closer to the ground than other species. When in mixed-species colonies, black-crowned night-herons tend to nest nearby other black-crowned night-herons due to their similar habitat preferences.
Black-crowned night-herons are generalist predators whose diet ranges from insects to other birds. Fish and crustaceans, including shrimp, crabs, and crayfish, comprise much of the birds’ diets while feeding in coastal marshes. They also pursue aquatic and terrestrial insects, earthworms, leeches, mollusks, frogs, toads, tadpoles, salamanders, snakes, lizards, eggs, and young of other birds, small mammals, and carrion. Algae and fruit, such as beach plums, are rarely consumed.
Night-herons are largely nocturnal but may also hunt during the day, especially when prey is abundant or when their hungry chicks demand food. Feeding activity is strongly influenced by tidal cycles, as prey availability varies with the tides. Black-crowned night-herons often sit and wait for prey or slowly stalk prey before striking at it with their daggerlike bills.
Black-crowned night-herons arrive at their colonies in March and April. They are one of the first species to appear at wading bird colonies each Spring. They nest in single- or mixed-species colonies that typically include other herons, egrets, and the glossy ibis. Nesting pairs often occupy the same rookery each year. Previous nest failures, predation, or disturbance may cause birds to abandon and relocate.
Nests are located within dense cover in trees, shrubs, or thickets and may be placed on the ground. The nest is built by both the male and female and is constructed of sticks, twigs, and reeds and lined with thinner twigs, roots, grasses, and pine needles. The female lays three to four greenish blue eggs during early May. Both adults incubate the eggs for 24 to 26 days. The eggs then hatch and the chicks are cared for by both adults by early to mid-June. The young branch out from the nest, climbing and hopping about in the surrounding vegetation, by two or three weeks of age. Chicks that fall to the ground during this time are vulnerable to ground predators such as dogs, cats, raccoons, and foxes. Young night-herons return to the nest to receive food from their parents until they are about four weeks old. The young, now feathered, are fed away from the nest at four weeks of age. They are quite capable of flight at about six weeks old (usually by late July).
Some young may disperse far from the colony where they were born following fledging. They are able to breed at two to three years of age. Some individuals may breed when only one year old. Black-crowned night-herons exhibit strong fidelity to the site where they were born, often returning to these areas as adults.
Fall migration of black-crowned night-herons peaks from mid- or late September to mid-October and may extend through mid-November. Small numbers overwinter in New Jersey but are forced south during harsh winters.
Current Threats, Status, and Conservation
The black-crowned night-heron was historically a common breeding species along the New Jersey coast. The species was frequently shot at nesting and roosting sites for its feathers and as food during the late 1880s. Populations began to quickly recover following the 1910 ban of feather sales in New York markets. The species was once again common along the Atlantic Coast by the 1930s. However, the destruction of coastal dune forests for a growing number of summer cottages along the Atlantic shore greatly reduced habitat for black-crowned night-herons. Habitat loss caused their populations, as well as inland breeding populations, to decline during the 1940s and 1950s. Contaminants, including DDT, caused further reductions of black-crowned night-herons in the northeast during the 1950s and 1960s. As with many bird species, the pesticideDDT caused reduced clutch size and lower productivity due to the breakage of thinned-shelled eggs.
The black-crowned night-heron population in New Jersey declined from about 1,500 individuals in the late 1970s to only 200 in the late 1990s, nearly a 90% loss, despite a ban of DDT in the United States in 1972. This reduction was caused largely by habitat destruction, disturbance to nesting colonies, and contaminants. This led to the inclusion of the black-crowned night-heron on the New Jersey list of threatened species in 1999.
The conservation of nesting habitat is important for the long-term survival of black-crowned and yellow-crowned night-herons in New Jersey. Existing nesting colonies or areas of potentially suitable habitat should be protected from development or other human activity. Strong enforcement of existing environmental laws is needed to protect wetlands from development, filling, draining, illegal dumping, pollution, and other forms of human disturbance. Surveys are also necessary in order to find additional breeding sites, check existing nesting areas, and determine whether the population might be decreasing or increasing.
Text derived from the book, Endangered and Threatened Wildlife of New Jersey. 2003. Originally edited by Bruce E. Beans and Larry Niles. Edited and updated Michael J. Davenport in 2010.
Species: N. nycticorax
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