English                        -               Black-crowned night Heron 

 Portuguese               -                Savacu

Latin                           -                Nycticorax nycticorax

Seen by day, these chunky herons seem dull and lethargic, with groups sitting hunched and motionless in trees near water. They become more active at dusk, flying out to their foraging sites. Some studies suggest that they feed at night because they are dominated by other herons and egrets by day. 

Adults are approximately 64 cm long and weigh 800 g. They have a black crown and back with the remainder of the body white or grey, red eyes, and short yellow legs. They have pale grey wings and white under parts. The sexes are similar in appearance although the males are slightly larger. Black-crowned night herons do not fit the typical body form of the heron family. They are relatively stocky with shorter bills, legs, and necks than their more familiar cousins, the egrets and “day” herons. Their resting posture is normally somewhat hunched but when hunting they extend their necks and look more like other wading birds. Immature birds have dull grey-brown plumage on their heads, wings, and backs, with numerous pale spots. Their underparts are paler and streaked with brown. The young birds have orange eyes and duller yellowish-green legs. They are very noisy birds in their nesting colonies, with calls that are commonly transcribed as quok or woc.

The Black-crowned Night Heron is found in most parts of the world except for Australasia and Antartica. They tend to live on vegetated margins of shallow freshwater or brackish rivers, streams, ponds, lakes, marshes, swamps, mangroves, and mud flats. It often feeds from on top of aquatic vegetation, for example on kelp beds 500 m offshore in the Falklands. It also uses grasslands and coastal habitats, especially on migration, and high mountains, nesting to 4800 m in Chile – exceptional for a heron. The species frequently, perhaps characteristically, uses human-made habitats. These include pastures, ponds, reservoirs, canals, ditches, fish ponds, rice fields, wet crop fields, and dry grasslands.

They eat mostly fish, but will also eat squid, crustaceans, aquatic insects, frogs, snakes, clams, mussels, rodents, carrion. Sometimes specialises on eggs and young birds, and can cause problems in tern colonies.

They usually first breeds at the age of 2 years. Breeds in colonies. Males choose the nest site and displays there to attract a mate. Displays include stretching neck up and forward with feathers ruffed up and slowly bowing while raising feet alternately, giving hissing buzz at lowest point in bow. Nest sites vary from ground sights to high in trees, shrubs, marsh vegetation. The nest is built mostly by the female with materials supplied by the male and is a platform of sticks. They can lay between 1 - 7 pale green eggs. The eggs are incubation by both sexes for 21 to 26 days.  Young clamber about the nest for the first 4 weeks and are fed by both parents by regurgitation. The chicks are able to fly at about 6 weeks. After 6-7 weeks, may follow parents to foraging areas and beg to be fed there.

Populations had probably declined in the 20th century owing to habitat loss and then in the mid 20th century, effects of DDT and other persistent pesticides. Following the banning of DDT in parts of the world, many local populations have increased in recent years. Water pollution is still a problem in some areas, but overall the population seems to be stable and in some parts of its range areis increasing.

Photo # 1 is of an Adult and was taken at Ilha do Frade - Vitoria - Espirito Santo

Photo # 2 is of a Juvenile and was taken at Passeio Publico - Curitiba - Parana