Herons often have been noticed throughout history. From the fabulous Phoenix to the very peculiar booming of bitterns, numerous legends mention them.
Outside the gastronomic qualities of some species appreciated in the Middle Ages, herons, and especially egrets, were persecuted for their silky nuptial feathers used as ornaments.
Today, thanks to the protection of these birds and their habitat, numbers increase and become stable in several parts of the range, even if the plume-trade continues in Central and South America with the European request of feathers.
Text and photographs by Nicole Bouglouan
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HANDBOOK OF THE BIRDS OF THE WORLD vol 1 by Josep del Hoyo-Andrew Elliot-Jordi Sargatal - Lynx Edicions - ISBN: 8487334105
Herons, egrets, bitterns, night herons
According to the different continents and countries, the Heron is the symbol of strength, purity, patience and long life in China, whereas in Africa, he « talks » to the Gods.
Egyptian people honour this bird as the creator of the light and Native American tribes make him the symbol of wisdom.
Considered as a lucky sign by Iroquois tribe, the Heron is finally recognized as an expert fisher/hunter.
Both qualities are common to the members of the Family Ardeidae, and in addition, they are beautiful, graceful and noble birds.
The Family Ardeidae belongs to the Order Pelecaniformes, and includes herons, egrets, bitterns, night-herons and allies.
Day herons and egrets are medium-sized to large birds. They have long neck and legs, rather short tail and broad wings. The bill is long, dagger-shaped, allowing these birds to hunt aquatic preys, but also small mammals and reptiles.
According to the species, the plumage may vary from pure white to black, through more or less dark grey, blue or brown.
Bitterns and night-herons are slightly different with plumper body and shorter neck. The large bitterns (Botaurus) have cryptic plumage adapted to their behaviour and their life in reedbeds.
The Boatbill belongs to the night-heron group, and shows broad and heavy bill adapted to his feeding behaviour by using it as a spoon.
Usually, both sexes are similar in all species, with only shorter nape feathers in female, and males are slightly larger than females. The plumage is characterized by elongated feathers on nape, foreneck and breast, mainly during the breeding season. During the displays which usually take place at nest, these feathers “dance” around the body and the colour of the bare parts of the face becomes brighter.
Several kinds of displays occur at nest-site such as “stretch” display with neck and head raised upwards and elongated feathers strongly exposed, and “forwards” displays with raised wings.
The most common is the “snap” display with the bird moving the head up and down, all the feathers bristling and extended neck, often accompanied by bill-clappering.
Ardeidae also perform aerial displays with the typical “circle-flight”. Some egrets, such as the Great Egret, continually shake the long nuptial feathers making undulating movements.
Once the pair is formed, both mates build the nest where copulation takes place. According to the species, the nest may be built by both sexes with male bringing nest materials to female, and she places them in the nest. But in some species such as Little and Least Bittern, the nest is built only by the male.
During the construction, male and female usually perform some “greeting ceremonies” as contact behaviour.
The nest is a platform made with sticks, often situated in trees, bushes or reeds, and first, it is rather a flimsy structure. But several large species reuse the nest year after year, and the platform becomes huge. The Purple Heron nests in reedbeds. Usually, all species nest near water at variable heights above the ground, from low level in reedbeds to 20-30 metres in trees.
Usually, the clutch consists of three to seven eggs, sometimes more in the small bitterns. Other species such as tiger-herons lay only one egg. But the clutch size varies from temperate zones to tropical and equatorial regions.
Incubation is performed by both sexes and lasts between 18 and 30 days in most species. It is shorter, about 14 to 20 days, in the small bitterns.
Chicks are altricial and the nesting period varies from 25 to 30 days in small bitterns, to several weeks (12-13) in the large herons. They are fed by regurgitation. The first days, adults regurgitate directly into the mouth, and later, into the nest where the young take partially digested food or whole preys.
Herons are carnivorous and feed on live preys, especially aquatic animals such as fish and amphibians, but also reptiles, small terrestrial mammals, insects, crustaceans and molluscs. There are some variations according to the species.
These birds use a wide variety of techniques for feeding, related to each species. The long-legged birds frequent deeper water than short-legged. The bill shape is very important. It is used as a dagger to harpoon the prey.
Herons usually stand motionless at the edge or in shallow water, and wait for preys coming close to the bill. They can use “upright” or “crouched” posture, the latest allowing better view and capture.
Other technique consists of walking slowly in shallow water or on land, and even among vegetation. They rarely use aerial techniques but some species such as the Snowy Egret, use the largest repertoire of aerial methods.
On the other hand, the Black Heron uses its wings as “canopy”, in order to provide shade for attracting preys, but probably to improve the visibility too.
The Green-backed Heron uses bait such as insect, holding it just above the water to attract some fish.
But if the different species have distinct feeding behaviours, they usually defend their foraging areas, mainly the solitary feeders. Others members of the family are gregarious and large flocks occur at food sources.
These birds feed mostly by day in the early morning and in the late afternoon, but some of them such as the Grey Heron, also forage at night. Night-herons are crepuscular.
Ardeidae are gregarious birds, forming mixed communal roosts in tall trees or reedbeds. They also nest in colonies, often with other birds’ species, and some colonies may reach great numbers, several hundreds of birds. These large numbers allow the birds to protect themselves against predators.
Within the flock, herons have short vocal repertoire often associated with courtship and behaviours. Most of them are silent outside the breeding season.
However, herons utter series of guttural honks, harsh croaks, coos or growls. Bill-snapping is also often heard.
The large bitterns produce typical booming calls which are low frequency sounds, transmitted over long distances. These calls are used for attracting females and to maintain the territory.
Most species perform seasonal migrations after dispersive post-breeding movements, mainly by the young birds. They usually migrate by night, individually or in small groups in linear formation.
Ardeidae perform strong, but slow and heavy flight. They use flapping flight and are able to cover great distances. In spite of their heavy flight, they can land on water and take off again easily, thanks to the broad large wings.
Ardeidae have mainly tropical distribution, and they are more or less widespread all over the world, except in poles.
These birds live in all kinds of wetlands, from open marshlands with shallow water to coastal areas, through tidal flats and mangroves. Some species are able to live on high plateaux, but the most part of the members of this family avoid mountainous areas and prefer lower regions. According to the species and the range, they may frequent freshwater wetlands or salt waters in coastal areas.
They are threatened by habitat loss by drainage of wetlands for agriculture expansion. They are persecuted at fish farms, especially the Grey Heron. Human developments and disturbances at colonies play an important role in some decreases.
Ardeidae are protected by laws but they are still threatened in several countries.
It would be such a pity that these beautiful and smart birds disappear. It is so amazing to see a bittern hidden among the reeds, similar to them in upright posture, following slowly the reed’s movements and swaying as them with the wind…