Yellow-crowned night heron

The breeding range of the yellow-crowned night-heron extends from Massachusetts and Connecticut south along the Atlantic and Gulf Coasts to Central and South America. Yellow-crowned night-herons which nest in New Jersey will usually winter in southern Florida, the Gulf Coast, and Central America. Some may winter as far north as North Carolina.

The yellow-crowned night-heron was not officially documented as a breeding species in New Jersey until 1927. During the 1940’s and 1950’s, the species expanded its range northward along the Atlantic Coast, increasing in numbers in the Northeast. Currently, yellow-crowneds occur along the New Jersey coast from Bergen County to Cape May, with most colonies located in coastal Cape May and Atlantic Counties.

Yellow-crowned night-herons nest on barrier islands, dredge spoil islands, and bay islands that contain forested wetlands or scrub/shrub thickets. Colonies may be located in dense shrubby thickets, forests with an open understory or suburban parks and yards that offer suitable habitat. Yellow-crowned night-herons use similar habitat types for both nesting and roosting, avoiding areas lacking enough cover. When nesting in mixed species colonies in habitats with low vegetation height, yellow-crowneds tend to nest closer to the ground and group with other yellow-crowned night-herons.

Yellow-crowned night-herons hunt along the shores of tidal creeks and tide pools within salt and brackish marshes. They also wade in shallow water and mudflats in search of prey and seek food along the wrack line during low tides. Yellow-crowned night-herons have been observed nesting in residential neighborhoods, parks, campgrounds, and other areas in close association with humans in recent years.

Yellow-crowned night-herons are specialist feeders and prey almost exclusively on crustaceans, such as fiddler crabs, marsh crabs, and blue crabs in marine habitats, and on crayfish in freshwater habitats. The large bill of the night-heron is well adapted for crushing the shells of crustacean prey. Other items comprising minor amounts of the diet include leeches, marine worms, aquatic insects, snails, fish, frogs, toads, tadpoles, newts, snakes, lizards, turtles, rodents, and other birds.

Yellow-crowned night-herons search for food primarily during the evening but are also active around dawn and dusk. Feeding activity is based on the tidal availability of prey, driving birds to search for food during daytime hours as well. They are solitary hunters and will either stand still and wait for prey or slowly stalk prey. Once prey is sighted, the night-heron lunges at it with its bill. Upon capture, the night-heron shakes a crab to detach its pincers before swallowing the animal whole.

Yellow-crowned night-herons arrive on their breeding grounds and begin to form pairs and establish territories by mid-April. Because breeding activity depends upon prey availability, nesting may be delayed due to cold weather that prohibits the emergence of crabs.

Yellow-crowned night-herons nest in pairs or in single- or mixed-species colonies. Colonies often occupy the same sites each year but may be abandoned due to disturbance, predation, or poor nesting success. Pairs may use the same nest and increase its size each year. Both the male and female construct the stick nest within trees or shrubs. Only one pair may nest in each tree, possibly to reduce the risk of predation. The male gathers nesting materials and transfers them to the female, which intertwines them into the nest. The male may also fit sticks into the nest while the female watches. The pair lines the nest with grasses, twigs, leaves, and rootlets.

Yellow-crowned night-heron females lay three to six pale blue-green eggs approximately three weeks after their arrival at breeding territories. The eggs are incubated by both adults for 21 to 27 days. Each parent may incubate the eggs for 14 to 18 hours before being relieved by its mate.

Both the male and female care for the chicks at the nest for about two weeks after hatching. At 30 to 44 days old, the young fledge, seeking cover in vegetation near the nest site. They return to the nest to roost and receive food for an additional two to three weeks, spending more time away from the nest as they grow older. Once independent, the young disperse and do not return to their breeding grounds until they are able to breed, at two years of age.

Yellow-crowned night-herons were killed by hunters who sold the birds’ feathers and meat in city markets during the late 1800’s and early 1900’s. The year 1910 marked the end of the feather trade and the start of the birds’ population recovery.

The yellow-crowned night-heron was rare prior to the 1900’s in the northeastern United States. The species may have nested in small numbers in New Jersey during this time, but breeding was not officially documented in the state until 1927. Over the next several decades, populations in New Jersey began to increase, leveling during the mid-1950’s and 1960’s.

The surge in coastal development in the latter half of the 20th century destroyed much of the suitable habitat for nesting yellow-crowned night-herons in New Jersey. The number of breeding birds in the state dropped from the late 1970’s throughout the 1980’s. The yellow-crowned night-heron was listed as a threatened species in New Jersey in 1984 due to population declines and habitat loss.

The conservation of nesting habitat is imperative to 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 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.