The herons are long-legged, long-necked, freshwater and coastal

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

s in the family Ardeidae, with 72 recognised

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...

, some of which are referred to as

egret Egrets ( ) are herons, generally long-legged wading birds, that have white or buff plumage, developing fine plumes (usually milky white) during the breeding season. Egrets are not a biologically distinct group from herons and have the same buil ...

s or bitterns rather than herons. Members of the genera ''Botaurus'' and ''Ixobrychus'' are referred to as bitterns, and, together with the zigzag heron, or zigzag bittern, in the monotypic genus ''Zebrilus'', form a monophyletic group within the Ardeidae. Egrets do not form a biologically distinct group from herons, and tend to be named differently because they are mainly white or have decorative plumes in breeding plumage. Herons, by evolutionary adaptation, have long beaks. The classification of the individual heron/egret species is fraught with difficulty, and no clear consensus exists about the correct placement of many species into either of the two major genera, '' Ardea'' and '' Egretta''. Similarly, the relationships of the genera in the family are not completely resolved. However, one species formerly considered to constitute a separate

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...

family, the Cochlearidae or the boat-billed heron, is now regarded as a member of the Ardeidae. Although herons resemble birds in some other families, such as the storks,

ibis The ibises () (collective plural ibis; classical plurals ibides and ibes) are a group of long-legged wading birds in the family Threskiornithidae, that inhabit wetlands, forests and plains. "Ibis" derives from the Latin and Ancient Greek word ...

es, spoonbills, and

cranes Crane or cranes may refer to: Common meanings * Crane (bird), a large, long-necked bird * Crane (machine), industrial machinery for lifting ** Crane (rail), a crane suited for use on railroads People and fictional characters * Crane (surname ...

, they differ from these in flying with their necks retracted, not outstretched. They are also one of the bird groups that have powder down. Some members of this group nest colonially in trees, while others, notably the bitterns, use reed beds. A group of them is called a "siege."

Description

The herons are medium- to large-sized birds with long legs and necks. They exhibit very little

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most an ...

in size. The smallest species is usually considered the dwarf bittern, which measures in length, although all the species in the genus '' Ixobrychus'' are small and many broadly overlap in size. The largest species of heron is the

goliath heron The Goliath heron (''Ardea goliath''), also known as the giant heron, is a very large wading bird of the heron family, Ardeidae. It is found in sub-Saharan Africa, with smaller, declining numbers in Southwest and South Asia. Description This ...

, which stands up to tall. The necks are able to kink in an S-shape, due to the modified shape of the cervical vertebrae, of which they have 20–21. The neck can retract and extend and is retracted during flight, unlike most other long-necked birds. The neck is longer in the day herons than the night herons and bitterns. The legs are long and strong and in almost every species are unfeathered from the lower part of the

tibia The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it conn ...

(the exception is the zigzag heron). In flight, the legs and feet are held backwards. The feet of herons have long, thin toes, with three forward pointing ones and one pointing backwards. Eastern reef egrets in Ko Tao

The

bill Bill(s) may refer to: Common meanings * Banknote, paper cash (especially in the United States) * Bill (law), a proposed law put before a legislature * Invoice, commercial document issued by a seller to a buyer * Bill, a bird or animal's beak Pla ...

is generally long and harpoon-like. It can vary from extremely fine, as in the agami heron, to thick as in the

grey heron The grey heron (''Ardea cinerea'') is a long-legged wading bird of the heron family, Ardeidae, native throughout temperate Europe and Asia and also parts of Africa. It is resident in much of its range, but some populations from the more north ...

. The most atypical bill is owned by the boat-billed heron, which has a broad, thick bill. The bill and other bare parts of the body are usually yellow, black, or brown in colour, although this can vary during the breeding season. The wings are broad and long, exhibiting 10 or 11 primary feathers (the boat-billed heron has only nine), 15–20 secondaries, and 12 rectrices (10 in the bitterns). The feathers of the herons are soft and the plumage is usually blue, black, brown, grey, or white, and can often be strikingly complex. Amongst the day herons, little sexual dimorphism in plumage is seen (except in the pond-herons); differences between the sexes are the rule for the night herons and smaller bitterns. Many species also have different colour morphs. In the Pacific reef heron, both dark and light colour morphs exist, and the percentage of each morph varies geographically. White morphs only occur in areas with coral beaches.

Distribution and habitat

Lava Heron (Butorides sundevalli) Galapagos2

The herons are a widespread family with a cosmopolitan distribution. They exist on all continents except

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest cont ...

and are present in most habitats except the coldest extremes of the Arctic, extremely high mountains, and the driest deserts. Almost all species are associated with water; they are essentially non-swimming waterbirds that feed on the margins of lakes, rivers, swamps, ponds, and the sea. They are predominantly found in lowland areas, although some species live in alpine areas, and the majority of species occur in the tropics. The herons are a highly mobile family, with most species being at least partially migratory; for example, the

is mostly sedentary in Britain, but mostly migratory in Scandinavia. Birds are particularly inclined to disperse widely after breeding, but before the annual migration, where the species is colonial, searching out new feeding areas and reducing the pressures on feeding grounds near the colony. The migration typically occurs at night, usually as individuals or in small groups.

Behaviour and ecology

Diet

The herons and bitterns are carnivorous. The members of this family are mostly associated with wetlands and water and feed on a variety of live aquatic prey. Their diet includes a wide variety of aquatic animals, including fish, reptiles, amphibians,

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapoda, decapods, ostracoda, seed shrimp, branchiopoda, branchiopods, argulidae, fish lice, krill, remipedes, isopoda, isopods, barnacles, copepods, ...

s, molluscs, and aquatic insects. Individual species may be generalists or specialize in certain prey types, such as the yellow-crowned night heron, which specializes in crustaceans, particularly

crab Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all th ...

s. Many species also opportunistically take larger prey, including birds and bird eggs, rodents, and more rarely carrion. Even more rarely, herons eating acorns, peas, and grains have been reported, but most vegetable matter consumed is accidental. Balck Heron canopy crop

The most common hunting technique is for the bird to sit motionless on the edge of or standing in shallow water and to wait until prey comes within range. Birds may either do this from an upright posture, giving them a wider field of view for seeing prey or from a crouched position, which is more cryptic and means the bill is closer to the prey when it is located. Having seen prey, the head is moved from side to side, so that the heron can calculate the position of the prey in the water and compensate for

refraction In physics, refraction is the redirection of a wave as it passes from one medium to another. The redirection can be caused by the wave's change in speed or by a change in the medium. Refraction of light is the most commonly observed phenomen ...

, and then the bill is used to spear the prey. Heron tricol 01

In addition to sitting and waiting, herons may feed more actively. They may walk slowly, around or less than 60 paces a minute, snatching prey when it is observed. Other active feeding behaviours include foot stirring and probing, where the feet are used to flush out hidden prey. The wings may be used to frighten prey (or possibly attract it to shade) or to reduce glare; the most extreme example of this is exhibited by the

black heron The black heron (''Egretta ardesiaca''), also known as the black egret, is an African heron. It is well known for its habit of using its wings to form a canopy when fishing. Description The black heron is a medium-sized (42.5–66 cm ...

, which forms a full canopy with its wings over its body. Some species of heron, such as the little egret and grey heron, have been documented using bait to lure prey to within striking distance. Herons may use items already in place, or actively add items to the water to attract fish such as the banded killifish. Items used may be man-made, such as bread; alternatively, striated herons in the

Amazon Amazon most often refers to: * Amazons, a tribe of female warriors in Greek mythology * Amazon rainforest, a rainforest covering most of the Amazon basin * Amazon River, in South America * Amazon (company), an American multinational technolog ...

have been watched repeatedly dropping seeds, insects, flowers, and leaves into the water to catch fish. Three species, the

black-headed heron The black-headed heron (''Ardea melanocephala'') is a wading bird of the heron family Ardeidae, common throughout much of sub-Saharan Africa and Madagascar. It is mainly resident, but some west African birds move further north in the rainy seaso ...

, whistling heron, and especially the

cattle egret The cattle egret (''Bubulcus ibis'') is a cosmopolitan species of heron ( family Ardeidae) found in the tropics, subtropics, and warm-temperate zones. It is the only member of the monotypic genus ''Bubulcus'', although some authorities regard ...

, are less tied to watery environments and may feed far away from water. Cattle egrets improve their foraging success by following large grazing animals, catching insects flushed by their movement. One study found that the success rate of prey capture increased 3.6 times over solitary foraging.

Breeding

While the family exhibits a range of breeding strategies, overall, the herons are monogamous and mostly colonial. Most day herons and night herons are colonial, or partly colonial depending on circumstances, whereas the bitterns and tiger herons are mostly solitary nesters. Colonies may contain several species, as well as other species of waterbirds. In a study of little egrets and cattle egrets in India, the majority of the colonies surveyed contained both species. Nesting is seasonal in temperate species; in tropical species, it may be seasonal (often coinciding with the rainy season) or year-round. Even in year-round breeders, nesting intensity varies throughout the year. Tropical herons typically have only one breeding season per year, unlike some other tropical birds which may raise up to three broods a year. Courtship usually takes part on the nest. Males arrive first and begin the building of the nest, where they display to attract females. During courtship, the male employs a stretch display and uses erectile neck feathers; the neck area may swell. The female risks an aggressive attack if she approaches too soon and may have to wait up to four days. In colonial species, displays involve visual cues, which can include adopting postures or ritual displays, whereas in solitary species, auditory cues, such as the deep booming of the bitterns, are important. The exception to this is the boat-billed heron, which pairs up away from the nesting site. Having paired, they continue to build the nest in almost all species, although in the

little bittern The little bittern or common little bittern (''Ixobrychus minutus'') is a wading bird in the heron family, Ardeidae. ''Ixobrychus'' is from Ancient Greek ''ixias'', a reed-like plant and ''brukhomai'', to bellow, and ''minutus'' is Latin for " ...

and least bittern, only the male works on the nest. Some ornithologists have reported observing female herons attaching themselves to

impotent Erectile dysfunction (ED), also called impotence, is the type of sexual dysfunction in which the penis fails to become or stay erect during sexual activity. It is the most common sexual problem in men.Cunningham GR, Rosen RC. Overview of male ...

mates, then seeking sexual gratification elsewhere. The nests of herons are usually found near or above water. Although the nests of a few species have been found on the ground where suitable trees or shrubs are unavailable, they are typically placed in vegetation. Trees are used by many species, and here they may be placed high up from the ground, whereas species living in reed beds may nest very close to the ground. Generally, herons lay between three and seven eggs. Larger clutches are reported in the smaller bitterns and more rarely some of the larger day herons, and single-egg clutches are reported for some of the tiger herons. Clutch size varies by latitude within species, with individuals in temperate climates laying more eggs than tropical ones. On the whole, the eggs are glossy blue or white, with the exception being the large bitterns, which lay olive-brown eggs.

Name

The word ''heron'' first appeared in the English language around 1300, originating from Old French ''hairon, eron'' (12th century), earlier'' hairo ''(11th century), from Frankish ''haigiro'' or from Proto-Germanic ''*haigrô'', ''*hraigrô''. Herons are also known as ''shitepokes'' , or euphemistically as ''shikepokes'' or ''shypokes''. '' Webster's Dictionary'' suggests that herons were given this name because of their habit of defecating when flushed. The 1971 '' Compact Edition of the Oxford English Dictionary'' describes the use of ''shitepoke'' for the small green heron of North America (''Butorides virescens'') as originating in the United States, citing a published example from 1853. The ''OED'' also observes that ''shiterow'' or ''shederow'' are terms used for herons, and also applied as derogatory terms meaning a ''thin, weakly person''. This name for a heron is found in a list of game birds in a royal decree of James VI (1566–1625) of

Scotland Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to ...

. The ''OED'' speculates that ''shiterow'' is a corruption of ''shiteheron''. Another former name was ''heronshaw'' or ''hernshaw'', derived from Old French ''heronçeau''. Corrupted to ''handsaw'', this name appears in

Shakespeare William Shakespeare ( 26 April 1564 – 23 April 1616) was an English playwright, poet and actor. He is widely regarded as the greatest writer in the English language and the world's pre-eminent dramatist. He is often called England's nation ...

's ''

Hamlet ''The Tragedy of Hamlet, Prince of Denmark'', often shortened to ''Hamlet'' (), is a tragedy written by William Shakespeare sometime between 1599 and 1601. It is Shakespeare's longest play, with 29,551 words. Set in Denmark, the play depicts ...

''. A possible further corruption took place in the Norfolk Broads, where the heron is often referred to as a ''harnser''.

Taxonomy and systematics

Analyses of the skeleton, mainly the

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...

, suggested that the Ardeidae could be split into a diurnal and a crepuscular/ nocturnal group which included the bitterns. From DNA studies and skeletal analyses focusing more on bones of body and limbs, this grouping has been revealed as incorrect. Rather, the similarities in skull morphology reflect

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last com ...

to cope with the different challenges of daytime and nighttime feeding. Today, it is believed that three major groups can be distinguished, which are: * tiger herons and the boatbill * bitterns * day herons and egrets, and night herons The night herons could warrant separation as subfamily Nycticoracinae, as it was traditionally done. However, the position of some genera (e.g. ''Butorides'' or ''Syrigma'') is unclear at the moment, and molecular studies have until now suffered from a small number of studied taxa. Especially, the relationships among the subfamily Ardeinae are very badly resolved. The arrangement presented here should be considered provisional. A 2008 study suggests that this family belongs to the Pelecaniformes. In response to these findings, the International Ornithological Congress recently reclassified Ardeidae and their sister taxa Threskiornithidae under the order Pelecaniformes instead of the previous order of Ciconiiformes.Gill, F. and Donsker, D. (eds). (2010)
Family Links
. IOC World Bird Names (version 2.4). * Subfamily Tigriornithinae ** Genus '' Cochlearius'' – boat-billed heron ** Genus '' Taphophoyx'' (

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

, Late Miocene of Levy County, Florida) ** Genus '' Tigrisoma'' – typical tiger herons (three species) ** Genus '' Tigriornis'' – white-crested tiger heron ** Genus '' Zonerodius'' – forest bittern * Subfamily Botaurinae ** Genus '' Zebrilus'' – zigzag heron ** Genus '' Ixobrychus'' – small bitterns (eight living species, one recently

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually 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 ...

) ** Genus '' Botaurus'' – large bitterns (four species) ** Genus '' Pikaihao'' - Saint Bathan's bittern (

, Early Miocene of Otago, New Zealand) * Subfamily

Ardeinae Ardeinae is a subfamily of herons, which includes the day herons, night herons, and egrets. Taxonomy * Genus ''Zeltornis'' ( fossil, Early Miocene of Djebel Zelten, Libya) * Genus ''Nycticorax'' – typical night herons (two living species, ...

** Genus ''

Zeltornis ''Zeltornis'' ("Zelten bird") is an extinct genus of heron. It contains a single species, ''Zeltornis ginsburgi''. ''Zeltornis'' probably resembled the modern night herons, but was much larger, standing 2 m (6 ft 8 in) tall and weighing ab ...

'' (

, Early Miocene of Djebel Zelten, Libya) ** Genus ''

Nycticorax ''Nycticorax'' is a genus of night herons. The name ''Nycticorax'' means "night raven" and derives from the Ancient Greek νύκτος, ''nuktos'' "night" and κοραξ, ''korax'', "raven". It refers to the largely nocturnal feeding habits ...

'' – typical night herons (two living species, four recently extinct; sometimes includes ''Nyctanassa'') ** Genus '' Nyctanassa'' – American night herons (one living species, one recently extinct) ** Genus '' Gorsachius'' – Asian and African night herons (four species) ** Genus ''

Butorides ''Butorides'' is a genus of small herons. It contains three similar species, the green heron or green-backed heron, ''Butorides virescens'', the lava heron (''Butorides sundevalli''), and the striated heron, ''Butorides striatus''. A fossil sp ...

'' – green-backed herons (three species; sometimes included in ''Ardea'') ** Genus ''

Agamia The agami heron (''Agamia agami'') is a medium-sized heron. It is a resident breeding bird from Central America south to Peru and Brazil. It is sometimes known as the chestnut-bellied heron, and is the only member of the genus ''Agamia''. In Br ...

'' – Agami heron ** Genus ''

Pilherodius The capped heron (''Pilherodius pileatus'') is a water bird endemic to the neotropics, inhabiting rainforest from the center of Panama to the south of Brazil.Ridgely, R. S., & Gwynne, J. A. (1989). ''A guide to the birds of Panama: with Costa Ric ...

'' – capped heron ** Genus ''

Ardeola Pond herons (''Ardeola'') are herons, typically long with an wingspan. Most breed in the tropical Old World, but the migratory squacco heron occurs in southern Europe and the Middle East and winters in Africa. The scientific name comes from L ...

'' – pond herons (six species) ** Genus '' Bubulcus'' – cattle egrets (one or two species, sometimes included in ''Ardea'') ** Genus '' Proardea'' (

) ** Genus '' Ardea'' – typical herons (11–17 species) ** Genus ''

Syrigma The whistling heron (''Syrigma sibilatrix'') is a medium-sized, often terrestrial heron of South America. There are two subspecies, the southern ''S. s. sibilatrix'' and the northern ''S. s. fostersmithi''. Description The whistling heron meas ...

'' – whistling heron ** Genus '' Egretta'' – typical egrets (7–13 species) ** Genus undetermined *** Easter Island heron, Ardeidae ''gen. et sp. indet.'' ( prehistoric) ; Fossil herons of unresolved affiliations: * ''"Anas" basaltica'' (Late Oligocene of Varnsdorf, Czech Republic) * '' Ardeagradis'' * '' Proardeola'' – possibly same as ''Proardea'' * ''Matuku'' (Early Miocene of Otago, New Zealand) Other prehistoric and fossil species are included in the respective genus accounts. In addition, '' Proherodius'' is a disputed fossil which was variously considered a heron or one of the extinct long-legged

waterfowl Anseriformes is an order of birds also known as waterfowl that comprises about 180 living species of birds in three families: Anhimidae (three species of screamers), Anseranatidae (the magpie goose), and Anatidae, the largest family, which ...

, the Presbyornithidae. It is only known from a sternum; a tarsometatarsus assigned to it actually belongs to the paleognath ''

Lithornis ''Lithornis'' is a genus of extinct paleognathous birds. Although ''Lithornis'' was able to fly well, their closest relatives are the extant tinamous (which are poor flyers) and ratites (which are flightless birds). Fossils of ''Lithornis'' ar ...

vulturinus''. File:White-faced heron in flight.jpg, White-faced heron (''Egretta novaehollandiae''), demonstrating the retracted neck that is typical of herons in flight. File:Bird-001-rj.jpg, Bare-throated tiger heron (''Tigrisoma mexicanum'') File:Botaurus stellaris (Marek Szczepanek).jpg,

Great bittern The Eurasian bittern or great bittern (''Botaurus stellaris'') is a wading bird in the bittern subfamily (Botaurinae) of the heron family Ardeidae. There are two subspecies, the northern race (''B. s. stellaris'') breeding in parts of Europe a ...

(''Botaurus stellaris'') File:Great Egret (Casmerodius albus)- Non-breeding plumage in Kolkata W2 IMG 4341.jpg, Eastern great egret ('' Ardea modesta'') File:The wounded heron.jpg, ''The Wounded Heron'' by George Frederic Watts, 1837 (

Watts Gallery Watts Gallery – Artists' Village is an art gallery in the village of Compton, near Guildford in Surrey. It is dedicated to the work of the Victorian-era painter and sculptor George Frederic Watts. The gallery has been Grade II* listed on th ...

) File:Coat of Arms of Priozersk (2020).jpg, Heron pictured in the coat of arms of Priozersk, Russia File:IMG 3999-01 el Qanater waterfalla.jpg, Squacco Heron from Egypt File:Čaplja u Zagrebu.JPG, Heron in Zagreb Zoological Garden, Croatia

References

External links

HeronConservation
Heron Specialist Group of IUCN
Heron videos
on the Internet Bird Collection {{Authority control * * Extant Paleocene first appearances Taxa named by William Elford Leach