We pulled off congested, six-lane Connecticut Avenue and less than two minutes later found ourselves in an unexpected oasis. The National Zoo in Washington, DC, is just steps from one of the city’s busiest thoroughfares, but its 163 acres sit adjacent to the 1,754-acre Rock Creek Park. It is like being in another world.
Every morning, swarms of joggers hit the zoo’s trails for a workout away from city traffic and the mania of the nation’s most political city. And every year the zoo, with its 2,000 animals representing nearly 400 species, attracts 2 million visitors from around the world. That’s just counting the humans.
The National Zoo’s walking paths are lined with trees and shrubs, serving as ideal habitat for the birds of Rock Creek. I had read recent reports indicating that a wild flock of black-crowned night herons had come to the zoo to roost. We had come to see for ourselves.
Black-crowned night herons (Nicticorax nicticorax) are known as colonial nesters. That term has nothing to do with George Washington’s era. It simply means that they nest in colonies. As their name implies, these birds are most active at dusk and into the night. During the day, they often retreat to their collective roost. And that’s where we found them, loosely clustered in trees that border the park.
Unlike many herons and egrets, these birds are medium-size and stocky, standing about 2 feet tall. They have thick necks, a flat head, and relatively short, sturdy legs. The body is plump and the bill is long and heavy.
As their lengthy name also suggests, these herons have a black cap. The face, forehead and body are white, while the back is black. A bright red eye is distinctive. The wings, which can extend almost 4 feet, are silver-gray. Draping from the back of the black crown are two or three long white feathers. The sexes look similar.
When the zoo’s herons head out to Rock Creek every night, they aren’t picky about eating whatever they find.
The incomparable Cornell Ornithology website describes the black-crowned night heron’s diet this way: “[…it] includes leeches, earthworms, insects, crayfish, clams, fish, amphibians, lizards, snakes, turtles, rodents, birds, and eggs. They also eat carrion, plant materials, and garbage from landfills.” No wonder they’re chunky birds!
The black-crowned night heron’s range is as broad as its diet. They are equally at home near salt and freshwater marshes, estuaries, lakes, streams and reservoirs. They are the most widespread heron in the world, found throughout the Western Hemisphere and in parts of the Eastern.
In North America, black-crowned herons live year-round on the Pacific, Atlantic and Gulf coasts. Some are short– and intermediate-migrants. They may range from as little as 5 miles from their winter home to as much as 1,000 miles away to breed. During the summer, they can be found throughout the lower 48 states and the central Canadian provinces.
Black-crowned night herons build large stick nests in trees. The platform nest extends 12–18 inches across and is 8–12 inches high. The male begins nest construction. Once his mate joins him, he passes sticks and vegetation to her for construction.
Annual broods include three to five eggs. Both parents incubate the eggs for about 25 days. After the chicks hatch, they will remain in the nest for a month with both parents providing warmth, food and protection.
When the young birds leave the nest, they still can’t fly. They form small flocks feeding on the ground for two more weeks. This ground period is dangerous for the young birds as they are subject to predation by foxes and other predators.
In spite of its extraordinary range and diverse diet, black-crowned night herons only number about 50,000 individuals in North America.
Black-crowned night herons can be tough to spot, and not simply because of their modest numbers. At the zoo, scores of visitors passed by the birds without seeing them. With no signs to point them out, the unnoticed birds rested silently as people continued to stroll by without ever looking up.
These herons forage alone, usually at night. When they are away from the roost during daylight, the birds are often hidden behind overhanging vegetation along streams or lakes. They stand motionless and easily blend into the shadows. If they are disturbed, you may hear a loud, hoarse “wok,” one of the few clues in locating the bird.
The zoo is home to unusual and endangered animals from across the globe, attracting people from every nation. But not all of the world’s wonders come with a sign. Luckily, all that is necessary is for us to look up to see the everyday wonders that are often just down the street. As we had discovered anew, amazement often awaits those with open eyes.