These Endangered Herons Are Creatures of the Night
- mmcmahon09
- May 16
- 4 min read
Updated: May 23
In the heron family of birds, great egrets and great blue herons get a lot of attention, but there’s another heron that’s worth getting to know.
Like its more well-known relatives, the black-crowned night heron is a wetland bird that lives in marshes, swamps, ponds, lakes, rivers and streams. But unlike those relatives, black-crowned night herons aren’t often seen wading in shallow waters as they forage for food. That’s because they are mostly nocturnal.
Adding to their mysterious nature is that black-crowned night herons aren’t as common in Illinois as they once were. They are now endangered in the state. In the Will County preserves, their population has dwindled, and they aren’t seen very often.
Meet the black-crowned night heron
Black-crowned night herons are short and stocky. They are much closer in size to a green heron than a great blue heron. They are about 23 inches to 28 inches long from bill tip to tail. Their wingspan approaches 4 feet wide.
Their plumage is light gray, with shades of lighter gray on the breast and darker shades on their wings. They have black caps, or crowns, and black bills, and their eyes are red. Their legs are a yellowish-green color for most of the year, but they turn pink in breeding season. They also grow two long white plumes on the back of their heads during breeding season.
Young black-crowned night herons look different from the adults. They are brown with large white spots on their wings and white streaks underneath. The bills of the juveniles are yellow and black.
Life after dark
Black-crowned night herons are active at night because it allows them to forage for food without competition from other herons and birds. Instead, they hunt for fish, insects, crayfish, mussels, amphibians, reptiles, rodents and birds under the cover of darkness, starting around dusk.
Words to know
Forage: To widely search for food.
Nocturnal: Active at night.
Plumage: A bird’s feathers collectively.
Roost: To settle or congregate for rest or sleep.
Stocky: Broad and sturdily built.
While nighttime foraging is the norm, they may be seen hunting during daylight hours in breeding season, when they require more energy. They don’t use their long bills to stab their prey as some other herons do. Instead, they grab it in their bills before swallowing it.
Because they are most active at night, it’s often their barking “quok” calls that alert people to their presence. The sound is similar to that of the common raven. This may be why they were given the scientific name Nycticorax nycticorax, which translates to “night raven.”
By day, the night herons roost in dense trees. They often roost together in groups with other night herons, tucking themselves away until the sun sets.
Where they live
Black-crowned night herons have the largest range of any heron species in the world. They live and breed on every continent except Antarctica and Australia, according to the American Bird Conservancy. They live across much of the United States and parts of Canada, but they do not live in most coastal areas in North America.
Night herons are partially migratory. The birds that live in southern areas do not all migrate, but populations from northern regions migrate to the southern United States, Mexico, Central America and the Caribbean for the winter.
Black-crowned night herons need wetlands to forage for food and for shelter and protection. Among wetland habitats, they are not too particular. You may spot these birds in marshes, ponds, rivers, streams, swamps and even flooded fields.
Breeding and nesting
In Illinois, nesting season for black-crowned night herons is in May and June. They nest in trees, and it’s the males that choose a nesting site and begin constructing it. Then they try to attract a mate through a series of displays, including bowing and stretching their necks. Like other herons, night herons typically nest in colonies, setting up nests near great egrets, great blue herons, double-crested cormorants and more.
Once the male night heron has attracted a mate, he will continue to collect sticks and twigs for the nest, but he gives them to the female to finish construction. Once the nest is complete, the female will lay a clutch of three to five eggs, and both the male and female incubate them.
The eggs hatch after about 25 days, and both the male and female bring food to the hatchlings. Because of fierce competition between the hatchlings, the entire brood does not always survive the hatchling stage.
The young birds leave the nest about a month after hatching, but they do not learn to fly until they are about 6 weeks old. Because they can’t yet fly, they leave the nest on foot, traveling to feeding areas to live in flocks with other herons.
Locally endangered
Worldwide, the black-crowned night heron is designated as a species of least concern on the IUCN Red List of Threatened Species. However, that status does not tell the full story.
Despite an estimated worldwide population of about 3 million birds globally, black-crowned night herons are state endangered in Illinois and other states in the Great Lakes region. In the late 1800s, they were common across Illinois, but their population has declined dramatically because of habitat destruction and harassment and killing by humans. Protection of their nesting areas and feeding sites are key to preservation of these herons in Illinois.
The Lincoln Park Zoo in Chicago is home to a colony of about 600 black-crowned night herons, making it the largest colony in Illinois. The colony established itself at the zoo in 2010 with about 100 birds and has grown considerably since. For many years, scientists from the Urban Wildlife Institute have been monitoring and studying the Lincoln Park Zoo colony to better understand how to manage conservation efforts for the herons.
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