Black-crowned Night Heron
Nycticorax nycticorax
The Black-crowned Night-Heron is a widespread bird found primarily in coastal and marshy areas on five of the seven continents. It feeds on a wide variety of terrestrial animals, fish and other freshwater and marine organisms. It is a rather chunky bird with short legs for a heron, and a long thick neck that is usually tucked in, so they appear not to have a neck at all, even while flying. When extended, the neck stretches almost the length of the body. Black-crowned Night-Herons spend most days motionless in trees, becoming more active at dusk.
SPECIES IN DETAIL
Black-crowned Night Heron
Nycticorax nycticorax
CONSERVATION STATUS: Least concern
CLIMATE CHANGE:
At the Aquarium
Black-crowned Night-Herons are often seen in the trees in and around the Aquarium, and in nearby Rainbow Harbor.
Geographic Distribution
Europe to Japan, Africa, Asia, and India.
In North America, from Washington State to Eastern Canada and south to coastal Mexico. Also in Central America, the Caribbean and Hawaii.
Largest concentrations are found in coastal areas. Found on five of the seven continents.
Habitat
Black-crowned Night-Herons live around both fresh and saltwater including, marshes, rivers, ponds, tidal flats, and canals. They nest in trees, thickets, sometimes on the ground but usually over water.
Physical Characteristics
The Black-crowned Night-Heron is stocky in its build, with hunched appearance and legs that are relatively short and thick for a heron. Males and females look alike (monomorphic) and females are slightly smaller than males.
Adults have a distinctive black cap and dark upper back and shoulder feathers (scapulars); gray wings, rump, and tail; and white head and neck. The bill is stout and black, and they have red eyes with round black pupils. Their legs are yellow green for most of the year, turning pink at the height of the breeding season. During breeding season, they often sport long white feathers on their cap as well.
Juveniles are a mottled brown with pale spots, and their eyes are yellow in color.
Size
A medium size heron, 22.8 to 26 in in length (58 to 66 cm) and a wingspan of 41.3 to 44 in (105 to 112 cm). Average adult weight: 1.9 lb (883 gr).
Diet
The diet of the Black-crowned Night-Heron is mostly fish, but squid, crustaceans, aquatic insects, frogs, snakes, clams, mussels, rodents, and carrion can also be part of their variable diet. They also may eat eggs and young birds, causing problems in populations of terns.
Reproduction
Black-crowned Night-Herons are social birds that breed in colonies of stick nests usually built over water. The male chooses a nesting site and displays by stretching his neck up and forward with feathers ruffled, slowly bowing, and raising his feet alternatively to attract a female. The male initially begins to build a nest, then he provides the sticks, and the female works them into the nest.
The nests may be in trees or on the ground, beginning December to February in warmer climates and April to May in northern climates. Three to four eggs are laid with both parents incubating.
The first egg hatches in twenty-three to twenty-six days and the rest hatch about one per day. Both parents feed the young by regurgitation. After two weeks, the young can leave the nest.
Behavior
Black-crowned Night-Herons often nest in groups that include other species such as egrets, other herons, and ibises. They walk, hop, and fly as they move about. They can dive feet first or headfirst and can swim or float on the surface of water.
They often forage for food by standing still or walking slowly along the edge of water. They also stand on pilings, stumps or small boats watching for food from above the water. Most of their foraging is done in the late evening and through the night but may also be done during the day during breeding season.
Adaptation
Black-crowned Night-Herons have large, red, light-gathering eyes that enable them to hunt at dawn, dusk and when it is dark. They have a short, stout bill that is made for crushing, such as when hunting and eating crabs.
Longevity
Black-crowned Night-Herons have a relatively long-life span and have been recorded living over 20 years in their natural habitats.
Conservation
Black-crowned Night-Herons are excellent environmental indicators since they are high on the food chain and their distribution is widespread. They may be an indicator of estuarine contamination, particularly organochlorine pollution.
Black-crowned Night-Herons may be vulnerable to changes in climate, mostly due to sea-level rise, increased temperatures, and changes in precipitation all of which would reduce shallow foraging areas and change the availability of prey.
Special Notes
Adult males may steal sticks from other active nests or old nests.
- There are two cases of Black-crowned Night-Herons laying one egg in each of two Snowy Egret nests in Plymouth Harbor, MA, 1977. One hatched and one did not.
- In South Carolina a Great Egret nest contained three Great Egret eggs and one two-day old night-heron chick. It was observed that two egrets and one night-heron fledged from the nest.
- In 1973, scientists re-captured a Black-crowned Night-Heron which had been banded in 1952 as a nestling, 21 years prior.
SPECIES IN DETAIL | Print full entry
Black-crowned Night Heron
Nycticorax nycticorax
CONSERVATION STATUS: Least concern
CLIMATE CHANGE:
Black-crowned Night-Herons are often seen in the trees in and around the Aquarium, and in nearby Rainbow Harbor.
Europe to Japan, Africa, Asia, and India.
In North America, from Washington State to Eastern Canada and south to coastal Mexico. Also in Central America, the Caribbean and Hawaii.
Largest concentrations are found in coastal areas. Found on five of the seven continents.
Black-crowned Night-Herons live around both fresh and saltwater including, marshes, rivers, ponds, tidal flats, and canals. They nest in trees, thickets, sometimes on the ground but usually over water.
The Black-crowned Night-Heron is stocky in its build, with hunched appearance and legs that are relatively short and thick for a heron. Males and females look alike (monomorphic) and females are slightly smaller than males.
Adults have a distinctive black cap and dark upper back and shoulder feathers (scapulars); gray wings, rump, and tail; and white head and neck. The bill is stout and black, and they have red eyes with round black pupils. Their legs are yellow green for most of the year, turning pink at the height of the breeding season. During breeding season, they often sport long white feathers on their cap as well.
Juveniles are a mottled brown with pale spots, and their eyes are yellow in color.
A medium size heron, 22.8 to 26 in in length (58 to 66 cm) and a wingspan of 41.3 to 44 in (105 to 112 cm). Average adult weight: 1.9 lb (883 gr).
The diet of the Black-crowned Night-Heron is mostly fish, but squid, crustaceans, aquatic insects, frogs, snakes, clams, mussels, rodents, and carrion can also be part of their variable diet. They also may eat eggs and young birds, causing problems in populations of terns.
Black-crowned Night-Herons are social birds that breed in colonies of stick nests usually built over water. The male chooses a nesting site and displays by stretching his neck up and forward with feathers ruffled, slowly bowing, and raising his feet alternatively to attract a female. The male initially begins to build a nest, then he provides the sticks, and the female works them into the nest.
The nests may be in trees or on the ground, beginning December to February in warmer climates and April to May in northern climates. Three to four eggs are laid with both parents incubating.
The first egg hatches in twenty-three to twenty-six days and the rest hatch about one per day. Both parents feed the young by regurgitation. After two weeks, the young can leave the nest.
Black-crowned Night-Herons often nest in groups that include other species such as egrets, other herons, and ibises. They walk, hop, and fly as they move about. They can dive feet first or headfirst and can swim or float on the surface of water.
They often forage for food by standing still or walking slowly along the edge of water. They also stand on pilings, stumps or small boats watching for food from above the water. Most of their foraging is done in the late evening and through the night but may also be done during the day during breeding season.
Black-crowned Night-Herons have large, red, light-gathering eyes that enable them to hunt at dawn, dusk and when it is dark. They have a short, stout bill that is made for crushing, such as when hunting and eating crabs.
Black-crowned Night-Herons have a relatively long-life span and have been recorded living over 20 years in their natural habitats.
Black-crowned Night-Herons are excellent environmental indicators since they are high on the food chain and their distribution is widespread. They may be an indicator of estuarine contamination, particularly organochlorine pollution.
Black-crowned Night-Herons may be vulnerable to changes in climate, mostly due to sea-level rise, increased temperatures, and changes in precipitation all of which would reduce shallow foraging areas and change the availability of prey.
Adult males may steal sticks from other active nests or old nests.
- There are two cases of Black-crowned Night-Herons laying one egg in each of two Snowy Egret nests in Plymouth Harbor, MA, 1977. One hatched and one did not.
- In South Carolina a Great Egret nest contained three Great Egret eggs and one two-day old night-heron chick. It was observed that two egrets and one night-heron fledged from the nest.
- In 1973, scientists re-captured a Black-crowned Night-Heron which had been banded in 1952 as a nestling, 21 years prior.