My hometown, Cheverly, MD, is typical of many older Washington, DC, suburbs. There are plenty of mature trees, with small houses on modest-size lots. It’s a great community with friendly neighbors, three churches, two schools and a busy community center.
Unlike most suburbs, though, the neighborhood includes a pair of nesting yellow-crowned night-herons.
Improbably enough, the nest sits in the front yard oak tree of a typical Cheverly home on a quiet side street. Yellow-crowned night-herons (Nyctanassa violacea) typically nest in wetlands or adjacent to streams or ponds. None of those water features are evident, yet the yellow-crowns have successfully bred here for a couple of years.
From my vantage point across the street, I watched the breeding pair through my binoculars.
The female was busy refurbishing last year’s nest. The male provided the branches that she used to reinforce the nest. Later, she will add some leaves as lining. This construction phase takes about 10 days before she lays two to six eggs.
Nests need to be sturdy. Yellow-crowns stand 2 feet tall and have 4-foot wingspans. They are chunky birds, quite different from the grace-ful snowy egrets or similar species
we usually associate with the word heron.
The male stood on stocky red legs. This night-heron has a body of purple-gray feathers and a short, thick neck. His head is black with prominent white cheek patches and red eyes. The crown is more white than yellow, but it has trailing plumes, giving the bird a sense of elegance. The black bill is relatively short and quite thick. The red legs and eyes are only seen during breeding season, though. Usually the legs are yellow and the eyes, orange.
Yellow-crowns produce one brood annually, and it is a lengthy affair.
The female incubates the eggs 24–25 days. After hatching, the helpless young will stay in the nest for another month or more before they are ready to go out on their own.
Juvenile yellow-crowns share the same body shape as their parents, but they are brown with white spots on the wings and back. The underside is heavily streaked brown on white.
Although the breeding pair is in Cheverly now, the birds spent the winter much farther south.
Yellow-crowns have a permanent range that covers much of coastal South and Central America as well as the Caribbean and south Florida. Some head north in the spring and breed in the southeastern United States, up through the Chesapeake region and into New England. They favor mangrove habitat, coastal marshes, barrier islands like Chincoteague, and other wetlands, but can regularly be found inland all the way into the Midwest.
The migratory yellow-crowns in the Chesapeake region primarily come from their winter homes in the West Indies. Those that are found farther inland usually come from Central America or Mexico.
Crabs are the mainstay of yellow-crowned night-herons’ diets. The birds forage during both day and night for these crustaceans. Typically, the herons stand alone or walk slowly, with their head hunched over, in pursuit of food.
Night-herons stalk all kinds of crabs. Farther from shore, crayfish are the dietary staple. These forage species require warm weather to come out of their burrows. If an extensive cold snap hits, the night-herons become more opportunistic in their hunting, eating snails, fish, insects and the like.
With such a crustacean-dependent diet, it is little wonder that night-herons build their nests over or near water. They are seeking locations with abundant food supplies, and the target species all rely on wet habitats.
So why the nest in the suburbs? Like all animals, yellow-crowned night-herons have a clear preferences for habitat. But clear preferences are not ironclad rules.
Ornithologists can describe with astonishing accuracy the many attributes of yellow-crowned night-herons. They can tell us where these birds live, what they eat and how they behave.
But as with all living creatures, there are exceptions that stretch the limits of what is considered normal.
The yellow-crowned night-herons of Cheverly live on this peaceful street because they can. They can find suitable trees, which are plentiful, and suitable food, which isn’t. They will need to travel farther than most of their species to find a good supply of crabs, but it is evident that such distances are not prohibitive.
I watch birds, in part, to learn more about the world in which we live, discovering what principles apply and what common patterns can be discerned.
But just as important are the exceptions. What are the limits to their life and behavior?
As a person living with a rare disease, I am drawn to outliers and how they adapt. I suspect I am not alone, but I know for certain that my neighborhood night-herons fit into my worldview perfectly.