Black-crowned Night Heron
Pelecaniformes Order – Ardeidae Family
Length: 56-65 cm
Wingspan: 105-112 cm
Black-crowned Night Heron is a stocky heron with large head, short and thick neck and short legs.
PROTECTION / THREATS / STATUS:
Black-crowned Night Heron is relatively common or abundant is most parts of the range.
As all species depending on wet areas, they are threatened by drainage of wetlands and changes in their habitat. But mainly due to protection, populations are increasing in some areas, whereas local declines and decreases are observed, due to habitat destruction and use of pesticides.
The wide range makes difficult to estimate the true numbers.
Fr: Bihoreau gris
Esp: Martinete Común
Ital: Nitticora comune
Jean Michel Peers
Other pictures and text by Nicole Bouglouan
HANDBOOK OF THE BIRDS OF THE WORLD vol 1 by Josep del Hoyo-Andrew Elliot-Jordi Sargatal - Lynx Edicions - ISBN: 8487334105
THE HANDBOOK OF BIRD IDENTIFICATION FOR EUROPE AND THE WESTERN PALEARCTIC by Mark Beaman, Steve Madge - C.Helm - ISBN: 0713639601
On the upperparts, adult male has black head and mantel. Wings and tail are pale grey. Underparts are whitish.
On the black head, we can see two or three elongated white feathers on the nape. Chin, forehead, cheeks and neck sides are white.
The long, straight bill is blackish. Eyes are deep red with dark blue-black lores. Legs and feet are greenish-yellow.
In breeding plumage, legs become red.
In non breeding plumage, crown and back are duller and long nape feathers are absent.
Female has similar plumage with shorter nape feathers. She has paler plumage and she is smaller than male.
Juvenile is heavily spotted and streaked white, grey, brown and buff. Eyes are yellow. Bill is paler, with dark grey upper mandible and yellowish lower mandible.
The 2nd- winter is fairly dull with unmarked greyish-brown upperparts, and pale or partly streaked underparts. Crown is blackish.
We find four subspecies which differ in size and plumage colours.
N.n. nycticorax, from Europe, Asia, Africa and Madagascar.
N.n. hoactli, from North, Central and South America, (from S Canada to N Chile and Argentina), has narrow supercilium and pink legs in breeding plumage.
N.n. obscurus, from South America (N Chile and NC Argentina to Tierra del Fuego), is the darkest with grey forehead and smoky-brown underparts.
N.n. falklandicus, from Falkland Islands, is dimorphic with two morphs, normal and dark phases.
VOICE: SOUNDS BY XENO-CANTO
Black-crowned Night Heron is usually silent outside the breeding season. But it may gives sometimes low, hollow frog-like “quark”, or sudden “guk” in flight or at roost.
Black-crowned Night Heron frequents varied types of wet areas with fresh, brackish or salt water with aquatic vegetation, also the forested shores of shallow streams, lagoons, pools, ponds, lakes, marshes and mangroves.
It also frequents developed areas such as pastures, rice fields, canals…
While migrating, this species occurs along marine coasts and dry lands.
The four races of the Black-crowned Night Heron are spread through all the continents, except Australia and poles.
Black-crowned Night Heron feeds on numerous items, from various aquatic preys to small rodents, bats, eggs and chicks of other birds’ species.
This heron hunts at dawn and dusk, and even at night, and also by day.
It uses the typical techniques such as “standing and wait” on the shore or in shallow water, “walking slowly” along the streams and “bill-vibrating” performed at the surface in order to disturb the preys.
But it also may use aerial technique such as “hovering”, flying over the water and capturing prey while pausing in mid-air. This species also performs “swimming-feeding”, at several metres from the shore, and hunts in deeper water, catching preys with the bill.
Black-crowned Night Heron roosts in leafy trees protected by dense cover. During the day, it often perches within the tree canopy, or trees and large shrubs close to the water, usually in small groups.
During the breeding season, the legs turn red and the nape feathers become longer. The male arrives first at the breeding areas. It starts to search a nest-site and collects nest materials. While defending the site from rivals, it tries to attract a female.
Black-crowned Night Heron is probably monogamous. The male performs an elaborate courtship display often at night. It walks around in crouch position, head lowered, and clapping its bill. Then, it flaps the wings, singing and dancing. It hisses while is rocking from foot to foot. When the female accepts, they preen each other and engage mutual billing. During the displays, the male can offer sticks to its mate.
When pair-bonds are formed, the legs turn pinkish-red. During this period, the male is aggressive.
Black-crowned Night Heron migrates at night and rests during the day. When they migrate, they call to keep together, and fly in small flocks or solitary. We can observe important post-breeding dispersal in all directions.
Black-crowned Night Heron performs steady, quick, shallow wing beats.
In flight, the bird shows stocky appearance with the toes projected beyond the tail. The body is slightly bowed upwards while the bill is slightly pointing downwards.
Breeding season varies according to the range.
Black-crowned Night Heron breeds in colonies which can be very large (up to 5000-6000 nests in Malaysia). These colonies may gather several different species.
This species nests in tall trees, bushes, reedbeds and cliff ledges. The race falklandicus commonly nests on the ground.
The nest is made with sticks, rushes and reeds, and other plant matter found in the area. This nest can be used year after year.
Female usually lays 3-5 eggs. Incubation lasts about 21-22 days.
Chicks are covered in buff-brown down, with dark crown and whitish underparts. Young fledge about 6-7 weeks after hatching. They reach their sexual maturity at 2-3 years.
This species may produce two broods per season.
Black-crowned Night Heron feeds on numerous items, from aquatic preys such as fish, amphibians (frogs and tadpoles), reptiles (turtles, snakes, lizards), insects (adults and larvae), spiders, crustaceans and molluscs, to small rodents, bats, eggs and chicks of other birds’ species.
It feeds mainly at dawn and dusk, and by night or day.