Intermediate egret

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Intermediate egret
Ardea intermedia, Katsushika, Tokyo 20080914-02.jpg
Tokyo, Japan
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Pelecaniformes
Family: Ardeidae
Genus: Ardea
Species:
A. intermedia
Binomial name
Ardea intermedia
Wagler, 1829
Ardea intermedia map.svg
  Breeding range
  Year-round range
  Wintering range
  Present during migration
Synonyms
  • Mesophoyx intermedia(Wagler, 1827)
  • Egretta intermedia(Wagler, 1827)

The intermediate egret, median egret, smaller egret or medium egret (Ardea intermedia) is a medium-sized heron. Some taxonomists put the species in the genus Egretta or Mesophoyx. It is a resident breeder in southern and eastern Asia.

Contents

Taxonomy

Some authorities classify the intermediate egret in its own monotypic genus, Mesophoyx, while others place it with the smaller egrets in Egretta . [2]

There were three recognised subspecies, [2] [1] and these are sometimes raised in to species: [3]

A.(i.) intermedia differs from A.(i.) brachyrhyncha and A. (i.) plumifera by having a black bill when in breeding plumage, while A.(i.) plumifera has a yellow-and-pink bill and A. (i.) brachyrhyncha has much yellower lores and face. A further difference between this species and the "yellow-billed" species is that the intermediate egret has black at the top of the legs compared to reddish in the yellow-billed egret. [3]

The split of intermediate egret into 3 species was accepted by the IOC on 26 September 2023, this form was given the common name medium egret by the IOC. [4]

Description

This species, as its scientific name implies, is intermediate in size between the great egret and smaller white egrets like the little egret and cattle egret, though nearer to little than great. It is about 56–72 cm (22–28 in) long with a 105–115 cm (41–45 in) wingspan and weighs c. 400 g (14 oz), [5] with all-white plumage, generally dark legs and a thickish yellow bill. Breeding birds may have a reddish or black bill, greenish yellow gape skin, loose filamentous plumes on their breast and back, and dull yellow or pink on their upper legs (regional variations). The sexes are similar. [6]

Differences from other egrets

Sketch comparing gapes of intermediate and great egrets Large Intermediate Egrets.svg
Sketch comparing gapes of intermediate and great egrets

The non-breeding colours are similar, but the intermediate is smaller, with neck length a little less than body length, a slightly domed head, and a shorter, thicker bill. The great egret has a noticeable kink near the middle of its neck, and the top of its longer bill nearly aligns with the flat top of its head. Close up, great egret's gape line extends behind the eye, while the intermediate's is less pointed and ends below the eye. The intermediate tends to stalk upright with neck extended forward. The great is more patient, often adopting a sideways-leaning "one-eyed" stance. Little egrets have yellow-soled feet and black bills. They often run after fish in shallow water. Breeding birds have long nuptial plumes on the back of their heads. [7]

Behaviour

The intermediate egret stalks its prey methodically in shallow coastal or fresh water, including flooded fields. It eats fish, frogs, crustaceans and insects. It often nests in colonies with other herons, usually on platforms of sticks in trees or shrubs. The typical clutch size is 2 or 3 eggs but there can be as many as 6 eggs in a clutch, the colour of the eggs is pale green, with a smooth, slightly pitted shell. Both parents incubate the eggs and they hatch after between 24 and 27 days. The eggs hatch asynchronously, after hatching the adults brood the semialtricial young for 12 days, defending the nests from aerial predators during both incubation and brooding, they crouch over the nest and raise their plumes and point their bill towards the threat. The parents regurgitate the food to feed the young, initially onto the floor of the nest but later the chick takes the food from the parent's mouth. There may be competition for food within the brood. Pinfeathers may appear on the chicks as early as 4 days old and the young are able to leave the nest at 24 days old, although they return to be fed. Fledging occurs at around 40 days old and they leave the colony after 70 days. In Africa and Australia they are reported to be quite successful breeders with 96% and 88% of nests fledging at least a single chick. Intermediate egret populations are more successful in wet years than in dry years. [7]

Related Research Articles

<span class="mw-page-title-main">Egret</span> Type of bird of the heron family

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

<span class="mw-page-title-main">Great blue heron</span> Species of bird

The great blue heron is a large wading bird in the heron family Ardeidae, common near the shores of open water and in wetlands over most of North and Central America, as well as far northwestern South America, the Caribbean and the Galápagos Islands. It is occasionally found in the Azores and is a rare vagrant to Europe. An all-white population found in south Florida and the Florida Keys is known as the great white heron. Debate exists about whether this represents a white color morph of the great blue heron, a subspecies of it, or an entirely separate species.

<span class="mw-page-title-main">Heron</span> Family of birds

Herons are long-legged, long-necked, freshwater and coastal birds in the family Ardeidae, with 72 recognised species, some of which are referred to as egrets 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.

<span class="mw-page-title-main">Grey heron</span> Long-legged predatory wading bird

The grey heron 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 northern parts migrate southwards in autumn. A bird of wetland areas, it can be seen around lakes, rivers, ponds, marshes and on the sea coast. It feeds mostly on aquatic creatures which it catches after standing stationary beside or in the water, or stalking its prey through the shallows.

<span class="mw-page-title-main">Great egret</span> Species of bird

The great egret (Ardea alba), also known as the common egret, large egret, or great white egret or great white heron is a large, widely distributed egret. The four subspecies are found in Asia, Africa, the Americas, and southern Europe. Recently it is also spreading to more northern areas of Europe. Distributed across most of the tropical and warmer temperate regions of the world, it builds tree nests in colonies close to water.

<span class="mw-page-title-main">Snowy egret</span> Species of bird

The snowy egret is a small white heron. The genus name comes from Provençal French for the little egret, aigrette, which is a diminutive of aigron, 'heron'. The species name thula is the Araucano term for the black-necked swan, applied to this species in error by Chilean naturalist Juan Ignacio Molina in 1782.

<span class="mw-page-title-main">Little egret</span> Species of water bird

The little egret is a species of small heron in the family Ardeidae. It is a white bird with a slender black beak, long black legs and, in the western race, yellow feet. As an aquatic bird, it feeds in shallow water and on land, consuming a variety of small creatures. It breeds colonially, often with other species of water birds, making a platform nest of sticks in a tree, bush or reed bed. A clutch of three to five bluish-green eggs is laid and incubated by both parents for about three weeks. The young fledge at about six weeks of age.

<span class="mw-page-title-main">Cattle egret</span> Cosmopolitan species of heron

The cattle egret is a cosmopolitan species of heron found in the tropics, subtropics, and warm-temperate zones. It is the only member of the monotypic genus Bubulcus, although some authorities regard its two subspecies as full species, the western cattle egret and the eastern cattle egret. Despite the similarities in plumage to the egrets of the genus Egretta, it is more closely related to the herons of Ardea. Originally native to parts of Asia, Africa, and Europe, it has undergone a rapid expansion in its distribution and successfully colonised much of the rest of the world in the last century.

<span class="mw-page-title-main">Western reef heron</span> Species of bird

The western reef heron, also called the western reef egret, is a medium-sized heron found in southern Europe, Africa and parts of Asia. It has a mainly coastal distribution and occurs in several plumage forms: a slaty-grey plumage in which it can only be confused with the rather uncommon dark morph of the Little egret ; a white form which can look very similar to the little egret although the bill tends to be paler and larger and the black form with white throat E. g. gularis of West Africa. There are also differences in size, structure and foraging behaviour. There have been suggestions that the species hybridizes with the Little Egret, and based on this, some authors treat schistacea and gularis as subspecies of Egretta garzetta. Works that consider the Western Reef Heron as a valid species include the nominate gularis and schistacea as subspecies.

<span class="mw-page-title-main">White-faced heron</span> Species of bird

The white-faced heron also known as the white-fronted heron, and incorrectly as the grey heron, or blue crane, is a common bird throughout most of Australasia, including New Guinea, the islands of Torres Strait, Indonesia, New Zealand, and all but the driest areas of Australia.

<span class="mw-page-title-main">Reddish egret</span> Species of bird

The reddish egret is a medium-sized heron that is a resident breeder in Central America, the Bahamas, the Caribbean, the Gulf Coast of the United States, and Mexico. The egret is known for its unusual foraging behavior compared to other herons as well as its association with mud flats, its habitat of choice.

<span class="mw-page-title-main">Little blue heron</span> Species of bird

The little blue heron is a small heron of the genus Egretta. It is a small, darkly colored heron with a two-toned bill. Juveniles are entirely white, bearing resemblance to the snowy egret. During the breeding season, adults develop different coloration on the head, legs, and feet.

<span class="mw-page-title-main">Pacific reef heron</span> Species of bird

The Pacific reef heron, also known as the eastern reef heron or eastern reef egret, is a species of heron found throughout southern Asia and Oceania. It occurs in two colour morphs with either slaty grey or pure white plumage. The sexes are similar in appearance.

<span class="mw-page-title-main">Black heron</span> Species of bird

The black heron, 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.

<i>Ardea</i> (bird) Genus of birds

Ardea is a genus of herons. These herons are generally large in size, typically 80–100 cm or more in length.

<i>Egretta</i> Genus of birds

Egretta is a genus of medium-sized herons, mostly breeding in warmer climates.

<span class="mw-page-title-main">Eastern cattle egret</span> Species of bird

The eastern cattle egret is a species of heron found in the tropics, subtropics and warm temperate zones. Most taxonomic authorities lump this species and the western cattle egret together as subspecies of the cattle egret, but some separate them. Despite the similarities in plumage to the egrets of the genus Egretta, it is more closely related to the herons of Ardea. It is native to southern and eastern Asia, and Australasia.

<span class="mw-page-title-main">Yellow-billed egret</span> Species of bird

The yellow-billed egret is a species of heron, a medium sized heron. This species is found in Sub-Saharan Africa. Until 2023 the yellow-billed egret was regarded as a subspecies of the intermediate egret of Asia, as was the plumed egret of Australia and Oceania.

<span class="mw-page-title-main">Western cattle egret</span> Species of bird

The western cattle egret is a species of heron found in the tropics, subtropics and warm temperate zones. Most taxonomic authorities lump this species and the eastern cattle egret together, but some separate them. Despite the similarities in plumage to the egrets of the genus Egretta, it is more closely related to the herons of Ardea. Originally native to parts of Asia, Africa and Europe, it has undergone a rapid expansion in its distribution and successfully colonised much of the rest of the world in the last century.

<span class="mw-page-title-main">Plumed egret</span> Species of bird

The plumed egret is a species of heron native to Australia and Oceania. Previously this species was regarded it as a subspecies of the intermediate egret alongside the Asian intermediate egret and the African yellow-billed egret.

References

  1. 1 2 BirdLife International (2020). "Ardea intermedia". IUCN Red List of Threatened Species . 2020: e.T22727668A181757896. doi: 10.2305/IUCN.UK.2020-3.RLTS.T22727668A181757896.en . Retrieved 19 November 2021.
  2. 1 2 "Storks, ibis, herons". IOC World Bird List version 8.2. International Ornithological Congress. Retrieved 25 December 2018.
  3. 1 2 Martínez-Vilalta, A.; Motis, A.; Kirwan, G.M. (2018). del Hoyo, J.; Elliott, A.; Sargatal, J.; Christie, D.A.; de Juana, E. (eds.). "Intermediate Egret (Ardea intermedia)". Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. doi:10.2173/bow.integr.01. S2CID   240970149 . Retrieved 25 December 2018.
  4. "IOC World Bird List v13.2 Proposed Splits/Lumps". IOC. 26 September 2023. Retrieved 27 September 2023.
  5. del Hoyo, J.; Elliott, A.; Sargatal, J., eds. (1992). Handbook of the Birds of the World . Vol. Volume 1: Ostrich to Ducks. Barcelona: Lynx Edicions.
  6. Ali, S. (1993). The Book of Indian Birds (Eleventh revised ed.). Bombay: Bombay Natural History Society/Oxford University Press. ISBN   978-0195621679.
  7. 1 2 "Intermediate Egret Ardea intermedia (Wagler)". Heron Conservation The IUCN-SCC Heron Specialist Group. Retrieved 11 May 2022.