Yellow-crowned Night Heron Life History

Habitat

Yellow-crowned Night Herons breed in and near wetlands primarily in the southeast United States, in areas of abundant crustaceans. Although concentrated on the southern Atlantic Coast, they are regularly found inland as far north as Ohio, Wisconsin, and Minnesota, and sometimes appear in Michigan and Ontario. Their breeding habitat includes barrier islands, coastal lowlands, inland lowlands, forests with open understories, mangroves, and edges of lagoons. In coastal areas they forage along the edges of tidal marshes, tide pools, calm beaches, and lagoons. Inland, they forage along shallow creeks, rivers, ponds, lakes, and swamps, and occasionally on lawns, plowed fields, and other upland sites. After the breeding season many individuals disperse to the north and west before migrating to wintering grounds. They stay year-round along the coastal edge of their U.S. breeding range, in locations where the climate permits crab activity throughout the year.

Food

Yellow-crowned Night Herons feed primarily on freshwater and saltwater crustaceans, including marsh crabs, fiddler crabs, ghost crabs, mole crabs, mud crabs, blue crabs, lady crabs, green crabs, rock crabs, and toad crabs. In inland areas they feed almost exclusively on crayfish. They also eat smaller amounts of earthworms, leeches, marine worms, centipedes, snails, mussels, insects, scorpions, frogs, tadpoles, marine fish, freshwater fish, small snakes, turtles, young birds, and small mammals. Standing still or walking slowly, they forage within several feet of the water’s edge, separated from other foraging individuals by about 15 feet. When within striking distance of prey they lunge with their bills, swallowing smaller animals whole. They grab larger crabs by the legs or pincers and shake them apart, then swallow the pieces whole or use their bills to break them further. They may also impale crabs, paralyzing them to make them easier to handle.

Nesting

Nest Placement

Yellow-crowned Night Herons nest near or over water in trees such as pine and oak—as high as 60 feet or more off the ground—or on lower vegetation such as mulberry, myrtle, hackberry, and mangrove. On islands with limited vegetation, they may nest on rock ledges. The male chooses the location, and the pair may start several nests before completing one. They nest alone or in colonies of up to several hundred pairs, sometimes with other heron species. Some colony sites remain in use for more than 20 years.

Nest Description

The nest, a platform of sticks with a slight hollow in the center, can measure more than 4 feet across. The male and female build it together as part of their pair bonding. Initially, the male carries sticks to the female, who begins the nest. Later, both gather and place materials on the nest. Where possible, they strip sticks from the limbs of dead trees rather than gathering them from the ground. Sticks can be up to about 20 inches long and an inch thick. The twig nest is sometimes lined with leaves, vines, or Spanish moss. The building process averages about 10 days. Yellow-crowned Night Herons may reuse nests, adding to them each year, or refurbish vacant ones.

Nesting Facts

Behavior

Yellow-crowned Night Herons usually walk slowly, using a bent-over posture when foraging, and fly with slow wingbeats. Courting Yellow-crowned Night Herons perform display flights, along with a neck-stretching display: the male slowly raises and then quickly retracts his head while fanning his long shoulder plumes. The female will sometimes reciprocate. They form socially monogamous pairs, and some maintain their bonds from year to year. Pairs may nest close together, but both adults and young defend the site from intruders, lunging and jabbing with their bills while squawking. Older young may peck or trample younger siblings and even push them out of the nest. After the breeding season, young birds often disperse to the north or west before heading to wintering grounds.

Conservation

Yellow-crowned Night Herons are fairly numerous, but their population trends are hard to assess because nesting birds can be hard to see during large standardized surveys. The North American Breeding Bird Survey identified no statistically significant change in their population between 1966 and 2019, although trends suggest a decline. Partners in Flight estimates the global breeding population at 400,000 and rates them 12 out of 20 on the Continental Concern Score, indicating a species of relatively low conservation concern. Historically, Yellow-crowned Night Herons were hunted as food or for their plumes. Their population fluctuated in the last century or so: shrinking in the southern U.S. in the 19th century, then expanding northward dramatically in the early 20th century before retreating again slightly after 1950. The reasons for these fluctuations are unclear. Like all wetland birds, they are vulnerable to habitat loss or degradation. In residential areas where herons nest over houses, roads, and driveways, people sometimes disturb nesting birds on purpose to drive them away. They are protected in some states near the edge of their range.

Credits

Dunne, P. (2006). Pete Dunne's essential field guide companion. Houghton Mifflin Harcourt, New York, USA.

Kushlan, J. A., M. J. Steinkamp, K. C. Parsons, J. Capp, M. A. Cruz, M. Coulter, I. Davidson, L. Dickson, N. Edelson, R. Elliott, R. M. Erwin, S. Hatch, S. Kress, R. Milko, S. Miller, K. Mills, R. Paul, R. Phillips, J. E. Saliva, W. Sydeman, J. Trapp, J. Wheeler and K. Wohl (2002). Waterbird conservation for the Americas: The North American waterbird conservation plan, version 1. Washington, DC, USA.

Lutmerding, J. A. and A. S. Love. (2020). Longevity records of North American birds. Version 2020. Patuxent Wildlife Research Center, Bird Banding Laboratory 2020.

Partners in Flight. (2020). Avian Conservation Assessment Database, version 2020.

Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2019). The North American Breeding Bird Survey, Results and Analysis 1966–2019. Version 2.07.2019. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.

Watts, Bryan D. (2011). Yellow-crowned Night-Heron (Nyctanassa violacea), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

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