Intermediate egret (Mesophoyx intermedia)
|Also known as:||lesser egret, median egret, plumed egret, short-billed egret, smaller egret, yellowbilled egret, yellow-billed egret|
|Synonyms:||Ardea intermedia, Egretta intermedia|
|Size||Length: 56 - 72 cm (2)|
Wingspan: 105 - 115 cm (2)
|Weight||c. 400 g (2)|
The intermediate egret is classified as Least Concern (LC) on the IUCN Red List (1).
A medium-sized heron with striking white plumage, the intermediate egret (Mesophoyx intermedia) is most attractive during the breeding season when it develops dense breast plumes and elaborate, long plumes on the back that cascade beyond the tail. While nesting, the intermediate egret has a red bill with a yellow tip, green eye lores (the region between the eye and bill), red irises, and red upper legs. At other times of the year, the intermediate egret has a yellow bill, often tipped with brown, while the iris is yellow and the legs and feet are black. The juvenile is similar to the non-breeding adult (2) (3) (4).
As its name suggests, this heron is intermediate in size between the little egret (Egretta garzetta) and great egret (Casmerodius albus) (4). It is also distinguished by its short bill, which is less pointed than that of the great egret, and by its sinuous S-shaped neck, which is approximately equal in length to the body (5).
The intermediate egret is a rather quiet bird, but emits a deep, rasping “kroa-kr” on take-off when disturbed (4).
A widespread species, the intermediate egret occurs across Africa south of the Sahara, as well as in South and Southeast Asia, to China, Japan, New Guinea and Australia (2) (3) (6).
Occupying a great variety of habitats, the intermediate egret is mainly found around shallow inland freshwater areas with abundant emergent aquatic vegetation. This includes habitats such as seasonally flooded marshes, inland deltas, ponds, swamp forests, freshwater swamps, pools, rivers, streams, rice-fields, wet meadows, and flooded and dry pastures near water (2) (7).
This species occurs less often in coastal habitats, but may sometimes be found around mudflats, tidal estuaries, coastal lagoons, saltmarshes, and tidal streams and rivers, and often roosts in mangroves (2) (7).
Active during the day, the intermediate egret forages in water less than eight centimetres deep for a variety of prey, including fish, frogs, crustaceans and aquatic insects (7). It tends to forage around and on vegetation more than some other egrets. However, it also uses the typical heron sit-and-wait strategy of standing patiently at the water’s edge and waiting for prey to come close enough for it to strike with its long bill (3). In drier habitats, the intermediate egret will also take terrestrial prey such as grasshoppers, crickets, bugs and beetles, snakes, spiders, lizards, and sometimes even birds. It typically forages alone, but at night it roosts communally in groups of 20 or more (7).
Timing of breeding varies regionally, but is usually centred around the wet season. During this time, the intermediate egret builds its nest amongst those of other herons and waterbirds, with colonies occasionally numbering as many as several thousand. The nest is a shallow stick platform and is positioned three to six metres above the ground in a tree standing over water or reedbeds (7). Two to six eggs are laid and incubated for 21 to 27 days (2).
Although it is common throughout most of its range and has a stable global population, the intermediate egret is more shy and sensitive to human disturbance than other egrets and, consequently, has declined in some areas (2) (7).
In Japan, the intermediate egret has declined markedly since the 1960s due to pollution and the disturbance of nesting colonies. It is also threatened in the Northern Territory of Australia by the degradation of flood-plains by livestock grazing, burning, invasion by introduced plants, reduced water flows from drainage and water diversion for irrigation, clearing of swamp forest, and pollution from mineral extraction. The intermediate egret is also hunted and traded at traditional medicine markets in Nigeria (7).
Although the intermediate egret has not been the target of any known conservation measures, it is protected under the African-Eurasian Waterbird Agreement (AEWA), which calls upon parties to undertake conservation actions for bird species that depend on wetland habitats for at least part of their annual cycle (8).
Find out more about the intermediate egret and other bird species:
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- Crustaceans: diverse group of animals with jointed limbs and a hard chitinous exoskeleton, characterised by the possession of two pairs of antennae, one pair of mandibles (mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps and barnacles.
- Emergent: aquatic plants whose stems and leaves extend beyond the water’s surface.
- Incubate: to keep eggs warm so that development is possible.
IUCN Red List (January, 2011)
- del Hoyo, J., Elliott, A. and Sargatal, J. (1992) Handbook of the Birds of the World. Volume 1: Ostrich to Ducks. Lynx Edicions, Barcelona.
- McKilligan, N. (2005) Herons, Egrets and Bitterns: their Biology and Conservation in Australia. CSIRO, Australia.
- Mackinnon, J. and Phillipps, K. (2000) A Field Guide to the Birds of China. Oxford University Press, Oxford.
- Harrison, J. and Worfolk, T. (2001) A Field Guide to the Birds of Sri Lanka. Second Edition. Oxford University Press, Oxford.
Critical Site Network Tool (January, 2011)
BirdLife International (January, 2011)
Agreement on the Conservation of African-Eurasian Migratory Waterbirds (January, 2011)