Black-crowned Night Heron, Nycticorax nycticorax
Black-crowned Night Heron, Nycticorax nycticorax hoactli, Juvenile. Photographs taken off a dock in Puerto Adolfo Lopez Mateos, May 2017.
Black-crowned Night Heron, Nycticorax nycticorax hoactli. Photographs taken in the greater Zihuatanejo area, Guerrero, March 2018. Photographs courtesy of Ron Woheau, Zihuatanejo.
Black-crowned Night Heron, Nycticorax nycticorax hoactli. Birds photographed in the greater Mexico City area, March 2021. Photographs and identification courtesy of Marina Sutormina, Stockholm, Sweden.
Black-crowned Night Heron, Nycticorax nycticorax hoactli. Bird photographed in the coastal region of San Diego, California, February 2017.
Background and Identification
The Black-crowned Night Heron, Nycticorax nycticorax hoactli, is a member of the Ardeidae Family of Herons, Egrets, and Bitterns, which has forty-nine members placed in fourteen genera, and one of five global species of the Nycticorax Genus. They are opportunistic foragers that feed on a wide variety of terrestrial and marine organisms such as birds, crayfish, fish, large aquatic insect larvae, and mammals. Large groups roost together of up to a thousand individuals, and they are known to practice cannibalism, feeding on the smallest nestlings. They are known in Mexico as Martinet Común.
The Black-crowned Night Heron is mid-sized in stature, with lengths ranging from 58 cm (23 inches) to 66 cm (26 inches), with the adults weighing 883 g (1 lb 15 oz). They have a stocky build with relatively short necks and legs. The sexes appear similar, but the males are larger than the females. The adults have a distinctive black cap, upper back and scapulars, gray wings, rump and tail white head and neck sides, and white to pale gray underparts. Their bill is stout with the upper mandible being entirely black during the breeding season and olive green when not breeding. The lower mandible is black, the iris is bright red, and the legs are yellow-green when not breeding. Juveniles lack the distinctive black head cap and often have a green hue surrounding their bills. An example of a juvenile individual can be seen above, if the reader scrolls to the first two images taken in Puerto Adolfo Lopez Mateos.
Habitat and Geographical Range
The Black-crowned Night Heron is found in a wide variety of habitats. These include freshwater, brackish water, and saltwater environments in areas with aquatic vegetation or on forested margins of shallow rivers, streams, lagoons, pools, ponds, lakes, swamps, marshes, and mangroves. They are also common in zones of human habitation, relying on easy sources of food in urban areas.
The Black-crowned Night Heron has a very extensive geographical range, covering much of North and South America, Europe, Asia, and Africa. They breed in southern Canada through the United States and into Mexico. Usually, populations in Mexico are spotted during the winter months, primarily in coastal regions at elevations below 4,800 m (15,700 feet). Their migration patterns vary depending on climate and food availability, moving either short distances or long distances. Some populations living in mild southern climates are non-migratory, known as resident birds.
Common Misidentifications
The Black-crowned Night Heron is a straightforward identification but is similar in size and appearance to the Yellow-crowned Night Heron, Nyctanassa violacea. This species can be distinguished from the Black-crowned Night Heron by its yellow-colored crown and bold black and white face.
Conservation Status
From a conservation perspective the Black-crowned Night Heron is currently considered to be of Least Concern with stable, widely distributed populations. Their populations are declining in certain areas of its geographical range, but populations are stable and even increasing in certain areas in the continental United States. Black-crowned Night Herons are indicator species, indicative that they are utilized as environmental indicators and an indicator of estuarine contamination by herbicides, pesticides, and heavy metals. Their long-term viability is threatened by habitat destruction.