Black-crowned Night-Heron - Nycticorax nycticorax

Black-crowned Night-Heron

Nycticorax nycticorax

Order : Ciconiiformes

Family : Ardeidae ;

Biometrics :

Size : 58 à 65 cm
Wingspan : 115 à 118 cm
Weight : 730 à 1015 gr

Longevity : 21 years

IUCN conservation status :

Extinct

Threatened

Least
concern

Extinc
in the Wild

Near
threatened

Not
evaluated

EX EW CR EN VU NT LC NE

Geographic range :

Synonyms : Kvakva (ru), Natthäger (sv), Martinete (es), Nitticora (it), Nachtreiher (al), Kwak (nl), Black-crowned Night-Heron (en)

Physical description :
Black-crowned Night Heron is a stocky bird with large head, thick and short neck, and short legs.
Adult has black crown and mantle. Wings, rump and tail are grey. Underparts are whitish. Legs and feet are yellow-green.
In breeding season, adult has two long white hind neck feathers. Bill is pointed and black. Lores are blue grey, becoming red in breeding season. Eyes are red. Legs and feet turn pink in the height of breeding season. Its black plumage takes on bluish-green gloss.
Both sexes are similar, but female is slightly smaller than male.
Juvenile has brown upperparts with conspicuous white spotting. Underparts are streaked buff and white. Bill is greenish-yellow. Eyes are yellowish to amber. Legs and feet are dull grey.
Juvenile needs three years to reach adult plumage, loosing year after year the pale spots on upperparts, and underparts becoming less streaked.
When they hatch, chicks are partially covered with white and grey down.

Voice :
Sound from CD 'Tous les Oiseaux d'Europe' by Jean C. Roché by courtesy of Sittelle and CEBA. Black-crowned Night Heron is usually silent. It utters some calls while flying or from a perch. The usual call is a frog-like croaking 'quark', or more sudden 'guk'.

Habitat : Black-crowned Night Heron lives near lakes, marshes and rivers with dense fringe vegetation and cattails. They nest and roost in trees.
When they feed or migrate, we can find them in more open areas such as rice fields and open lagoons, in salt, brackish or freshwater marshes.
GEOGRAPHIC RANGE: Black-crowned Night Heron breeds across United States and southern Canada, southern South America. It is also found in Europe, Asia, Africa and Hawaii.
It winters from southern United States and southwards.
It is widespread except in polar areas, cold temperate areas and Australia.

Behaviour : Black-crowned Night Heron is largely nocturnal, foraging from dusk to dawn. It stands motionless, waiting for prey to pass by, and it snatches them up with its bill. It also raids nests of other herons or species to steal the chicks.
Black-crowned Night Heron shakes vigorously the prey to kill it, and then it swallows it head first. Their strong digestive acids can dissolve bones.
It hunts in shallow water, as other herons, using their thick bills to capture prey. They may remain motionless for long periods, with neck tucked in, standing in the water or on a branch, searching for prey. It usually hunts alone, and defends strongly its feeding area. It may hunt during the day is food is scarce or in high demand in nesting season. It also uses 'bill vibrating', opening and closing the bill quickly into the water, creating disturbances to lure prey and to catch them.
Black-crowned Night Heron is probably monogamous. Male performs an elaborate courtship display often at night. Male walks around in a crouch position, head lowered, and clapping its bill. Then, it flaps its wings, singing and dancing. It hisses while is rocking from foot to foot. When female accepts, they preen each other and engage mutual billing. During display, male can offer sticks to its mate. When pair bond is formed, legs turn pinkish-red. During this period, male is aggressive.
Black-crowned Night Heron migrates at night, resting during the day. When they migrate, they call to keep together, and fly in large flocks.

Flight : Black-crowned Night Heron performs direct flight with slow steady beats of their broad wings.

Reproduction-nesting : Black-crowned Night Heron usually nests in colonies of about 12 pairs. After courtship displays, pair builds the nest near the trunk of a tree, or in a fork of branches. Male starts nest building, as a new nest or arranging and old one. Nest is a platform made with sticks and reeds, and lined with roots and grass. Nest may be located between 5 and 10 metres above the ground.
Female lays 3 to 5 pale blue eggs, at two days intervals. Incubation lasts about 24 to 26 days, shared by both parents. When weather is too hot, parents wet their feathers, probably to keep the eggs cool.
Chicks are brooded by both adults, and fed by regurgitation. As they grow, parents bring whole prey. Young are very noisy when they beg for food.
They leave the nest at about 3 weeks, climbing about and around the nest. They fledge at about 6 or 7 weeks of age and depart to the feeding grounds. Young defend themselves regurgitating food onto intruders when disturbed. They reach their sexual maturity at 2 or 3 years old.
This species produces only one brood per season.

Food habits : Black-crowned Night Heron feeds mainly on fish, but also earthworms, and aquatic and terrestrials insects. It also consumes crustaceans, amphibians, reptiles, small rodents, birds, eggs, carrion and plant materials.

Protection / threats : Adult Black-crowned Night Heron were often killed or trapped near fish culture establishments. Now, other methods have been developed, to avoid their close nesting.
Most populations are now stabilized or increasing, but habitat destruction is the most important threat for this species.

Other links :
Iucn
Birdlife