^{|  Story by Meghan McMahon |}

^5/5/2025

In the heron family, it’s the “greats” that get most of the attention. Great egrets and great blue herons are a familiar presence in our wetlands, but there’s another heron with an elusive lifestyle that’s worth getting to know.

Like its more well-known relatives, the black-crowned night heron is a wetland bird inhabiting marshes, swamps, ponds, lakes, rivers and streams. But unlike the great egret, the great blue heron and even the green heron, black-crowned night herons aren’t often seen wading in shallow waters as they forage for food. That’s because they are mostly nocturnal, active at a time when most of us are not out and about and when the places they inhabit are largely inaccessible to the public.

Adding to their mysterious nature is that black-crowned night herons aren’t as common in Illinois as they once were and are now endangered in the state. In the Will County preserves, their population has dwindled, and they are only seen sporadically, said wildlife ecologist Becky Blankenship.

Meet the black-crowned night heron

Black-crowned night herons are short and stocky, much closer in size to a green heron than a great blue heron. They are slightly larger than green herons, about 23 inches to 28 inches long from bill tip to tail, according to the Illinois Department of Natural Resources. 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. Their eyes are a piecing red, and their legs are a yellowish-green color for most of the year, but they turn pink in breeding season. They also develop two long white plumes on the back of their heads during breeding season, IDNR reports.

Juvenile black-crowned night herons look quite different from their adult counterparts. They are brown in color and covered 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 choose a nocturnal lifestyle because it allows them to forage for food without competition from other herons and birds, the American Bird Conservancy reports. Instead, they hunt for fish, insects, crayfish, mussels, amphibians, reptiles, rodents and birds under the cover of darkness, starting around dusk.

While nighttime foraging is the norm, they may be seen on the hunt during daylight hours in breeding season, when they require more energy for nest building and rearing their offspring. They don’t use their long bills to stab their prey as some other herons do. Instead, they snatch it in their bills before swallowing it, the Cornell Lab of Ornithology reports.

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, which may be how these birds were given the scientific name Nycticorax nycticorax, which translates to “night raven,” according to the American Bird Conservancy.

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 and it’s time to forage for food.

Where they live

Black-crowned night herons have an expansive range, the largest 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 occupy 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. Birds that live in southern locales do not all migrate, but populations from northern regions migrate to the southern United States, Mexico, Central America and the Caribbean for the winter, the bird conservancy reports.

Black-crowned night herons need access to wetlands both to forage for food and for shelter and protection, according to the Cornell Lab. 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, according to the Illinois Department of Natural Resources. 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. Sometimes the colonies can be dense with nests, with dozens in each tree, the American Bird Conservancy reports.

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, performing a ritual of erecting their head feathers and fluffing their feathers as they change positions, the American Bird Conservancy reports.

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. Interestingly, they do not learn to fly until after, when they are about 6 weeks old, the Cornell Lab reports. 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 here because of habitat destruction and harassment and indiscriminate killing by humans, IDNR reports. 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 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 in subsequent years, now numbering more than 600 of these herons. 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.