The night herons are medium-sized heron

Heron

The herons are long-legged freshwater and coastal birds in the family Ardeidae. There are 64 recognised species in this family. Some are called "egrets" or "bitterns" instead of "heron"....

s in the genera Nycticorax

Nycticorax

Nycticorax is a genus of night herons. The name Nycticorax derives from the Greek for “night raven” and refers to the largely nocturnal feeding habits of this group of birds, and the croaking crow-like call of the best known species, the Black-crowned Night Heron.These are medium-sized herons which...

, Nyctanassa

Nyctanassa

Nyctanassa is a genus of night herons from the Americas, especially warmer coastal regions. They were formerly included in the genus Nycticorax, but today all major authorities recognize them as different....

and Gorsachius

Gorsachius

Gorsachius is a genus of Old World night herons typically found near water in forested regions. These are medium-sized herons which are migratory in the colder parts of their ranges, but otherwise resident...

. The genus name Nycticorax derives from the Greek

Greek language

Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 for “night raven” and refers to the largely nocturnal feeding habits of this group of bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s, and the croaking crow-like

Crow

Crows form the genus Corvus in the family Corvidae. Ranging in size from the relatively small pigeon-size jackdaws to the Common Raven of the Holarctic region and Thick-billed Raven of the highlands of Ethiopia, the 40 or so members of this genus occur on all temperate continents and several...

 call of the best known species, the Black-crowned Night Heron

Black-crowned Night Heron

The Black-crowned Night Heron commonly abbreviated to just Night Heron in Eurasia, is a medium-sized heron found throughout a large part of the world, except in the coldest regions and Australasia .-Description:Adults are...

.

In Europe, Night Heron is often used to refer to the Black-crowned Night Heron, since it is the only member of the genus in that continent.

Adults are short-necked, short-legged and stout herons with a primarily brown or grey plumage

Plumage

Plumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...

, and, in most, a black crown. Young birds are brown, flecked with white. At least some of the extinct Mascarenes taxa appear to have retained this juvenile plumage in adult birds.

Night herons nest alone or in colonies on platforms of sticks in a group of trees, or on the ground in protected locations such as islands or reedbeds. 3-8 egg

Egg (biology)

An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...

s are laid.

Night herons stand still at the water's edge, and wait to ambush prey, mainly at night. They primarily eat small fish

Fish

Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

, crustacean

Crustacean

Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s, frog

Frog

Frogs are amphibians in the order Anura , formerly referred to as Salientia . Most frogs are characterized by a short body, webbed digits , protruding eyes and the absence of a tail...

s, aquatic insect

Insect

Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

s, and small mammal

Mammal

Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s. During the day they rest in trees or bushes.

There are seven extant species. The genus Nycticorax has suffered more than any other ciconiiform genus from extinction

Extinction

In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...

, mainly because of their capability to colonize small, predator-free oceanic islands, and a tendency to evolve towards flightlessness.