Species of Thailand
Ardea intermedia, Johann Georg Wagler, 1827
(In Thai: นกยางโทนน้อย)
The intermediate egret, median egret, smaller egret, or yellow-billed egret (Mesophoyx intermedia) is a medium-sized heron. Some taxonomists put the species in the genus Egretta or Ardea. It is a resident breeder from east Africa across the Indian subcontinent to Southeast Asia and Australia.
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 long with a 105 – 115 cm wingspan and weighs c. 400 g, 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.
Differences from great egret
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, the bare skin of the great egret's gape line extends in a dagger shape 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.
Differences from little egret
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.
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. Two to five eggs are laid, the clutch size varying with region.
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Category / Seasonal Status
Wiki listed status (concerning Thai population): Winter visitor
BCST Category: Recorded in an apparently wild state within the last 50 years
BCST Seasonal statuses:
- Resident or presumed resident
- Non-breeding visitor
- Ardea intermedia
- Thai: นกยางโทนน้อย
Ardea intermedia brachyrhyncha, Alfred Edmund Brehm, 1854
Common name: Yellow-billed egret
Range: Africa south of the Sahara
Ardea intermedia intermedia, Johann Georg Wagler, 1829
Common name: Lesser egret
Range: Japan to s India and Greater Sundas
Ardea intermedia plumifera, John Gould, 1848
Common name: Plumed egret
Range: New Guinea, eastern Indonesia and Australia
- Mesophoyx intermedia, Johann Georg Wagler (1827)
- Egretta intermedia, Johann Georg Wagler (1827)
Not Evaluated (IUCN3.1)