Black-Crowned Night Heron (Nycticorax nycticorax)

During Minnesota’s warmer months, this inconspicuous bird can be spotted around marshlands by keen-eyed observers. However, the species has become less common in recent years, probably due to environmental changes.

Appearance. Hunkered down at water’s edge in a clump of cattails and standing no taller than 2 feet, a stocky adult black-crowned night heron does a decent job of blending in with the rest of the marsh. Its pearly gray underparts and wings seem like a reflection of the water, and its muted black crown, back, and stout bill can look like shadows in the grasses. Its blood-red eyes and yellow legs are the only features that belie its surroundings, the latter visible as the bird takes diligent steps through the water. Young birds are more cryptically colored, exhibiting whitish streaks and spots on their grayish uppersides and brownish streaks on paler undersides, allowing them to effortlessly dissolve into the marsh. Within a year, these streaks and spots will fade away.

Behavior. As their common name implies, black-crowned night herons are more active at night or dawn and dusk than during the daylight hours. They forage in shallow wetlands for prey including aquatic and terrestrial invertebrates, reptiles, amphibians, fish, and even small mammals and birds. During the day, they often roost in a marsh, well concealed among the vegetation, or in a tree near the edge of a wetland. Like most of our other herons and egrets in Minnesota, this species is a colonial waterbird, meaning that it nests in communities near the nests of other black-crowned night herons and sometimes the nests of other herons and egrets, most often in live trees.

Distribution. Black-crowned night herons are found on every continent except Australia and Antarctica, making them the most widely distributed heron in the world. In Minnesota they can be seen statewide during migration, departing Minnesota in September and October to spend the winter in the southern United States and returning in April the following spring. During the breeding season they are encountered sporadically, mostly near a handful of major wetland complexes in southern and western Minnesota.

Numbers in Decline. Just a few decades ago, black-crowned night herons were considerably more common in Minnesota than they are today. In fact, the species has experienced an average decline of more than 5 percent annually in the state since 1980, according to the USGS North American Breeding Bird Survey. Wetland loss and degradation are likely major factors. Community science efforts and platforms like eBird (ebird.org) and iNaturalist (inaturalist.org) allow members of the public to report their own sightings of birds—including black-crowned night herons—and other wildlife; these observations can help biologists understand where the species is still present and thriving in Minnesota during the breeding season.