Eastern great egret

Taxonomy

This species was originally described as the "pure white heron of India", Ardea modesta, by Gray in 1831, but was later generally considered a synonym of Ardea alba, by Ellman in 1861 through to the Peters checklist in 1979. It was elevated to species status again by Sibley and Monroe in 1990, and this was supported by a 2005 revision of the herons. It is still sometimes considered a subspecies of the great egret Ardea alba.

Description

Measuring 83–103 cm in length and weighing 0.7–1.2 kg, the eastern great egret is a large heron with all-white plumage. Its bill is black in the breeding season and yellow at other times, and its long legs are red or black. The colours of the bare parts of the face change to green during the breeding season. The eastern great egret can be distinguished from other white egrets and herons in Asia and Australia by its very long neck, one and a half times as long as its own body.

Distribution and habitat

The eastern great egret has a wide distribution throughout Asia and Oceania, with breeding populations in Australia, Bangladesh, China, Nepal, India, Indochina, Indonesia, Japan, Korea, Myanmar, New Zealand (in the Waitangiroto Nature Reserve), Pakistan, Papua New Guinea, Philippines (Zamboanga), Russia (north-eastern), Solomon Islands, Sri Lanka, Thailand and Taiwan.

The egret breeds across Australia but only rarely in the southwest of the continent or dry interior. The largest colonies within Australia are in the Top End and Channel Country, which can number several thousand pairs. Colonies in the southeast of Australia can number several hundred pairs. The bird is an uncommon autumn and winter visitor to Tasmania.

Behaviour

Feeding

The diet includes vertebrates such as fish, frogs, small reptiles, small birds and rodents, and invertebrates such as insects, crustaceans, and molluscs. The eastern great egret hunts by wading or standing still in shallow water and "spearing" prey with its bill.

Breeding

The eastern great egret often breeds in colonies with other herons, egrets, cormorants, spoonbills and ibises. One brood is raised a year, although the breeding season varies within Australia. In the north of the country it is in March to May, in southern and central Queensland December and January, and October to December in the south. Located atop trees at a height of 20 m or more, the nest is a flat wide platform of dry branches and sticks with a shallow basin for eggs and young. The clutch consists of anywhere from two to six pale blue-green eggs, with three or four being the usual number. They are oval in shape and measure 52 x 36 mm.

Status

The subspecies is protected in Australia under the National Parks and Wildlife Act 1974. In New Zealand the white heron is highly endangered, with only one breeding site at Waitangiroto Nature Reserve in Whataroa. In 2023, there were 56 pairs of kōtuku nesting in the reserve, an increase compared with recent years. The increase was attributed mainly to the effects of predator control around the reserve. The kōtuku shares this site with the kōtuku ngutupapa, or Royal spoonbill. When Queen Elizabeth II visited New Zealand in 1953 to 1954, she was compared to the kōtuku—a compliment to rare, distinguished visitors. The egret is featured on the reverse side of a New Zealand $2 coin.

Gallery

File:Great Egrets I3- Kolkata IMG 1132.jpg|Flock at Kolkata, West Bengal, India File:Chudaisagi 06c1467.jpg|Non-breeding plumage in Japan File:EasternGreatEgretLongNeck.jpg|Extended neck of an egret File:Eastern great egret - kanagawa japan - 2024 feb 26.webm|Eastern great egret in Japan File:Great Egret in Flight.jpg|In flight at Lake Monger, Perth, Western Australia File:Ardea alba modesta Phuket Thailand.jpg|Non-breeding plumage in Thailand File:Kotuku pair greeting each other (at breeding colony near Okarito).jpg|Breeding pair near Ōkārito, New Zealand File:Kotuku flying across water at Waimanu Lagoon.jpg|At Waikanae lagoon, New Zealand

References

References

1. Gray, John Edward. (1831). "The Zoological Miscellany". Published by Treuttel, Wurtz and Co., G.B. Sowerby, W. Wood.
2. Ellman, J. B.. (1861). "Brief Notes on the Birds of New Zealand". The Zoologist.
3. ''Ardea alba modesta'' J.E. Gray; Payne 1979, in ''Peters Check-list Birds World 1'' (2nd edition): 204.
4. (1990). "Distribution and taxonomy of birds of the world". Yale University Press.
5. (2005). "The Herons". Oxford University Press.
6. (2010). "Checklist of the birds of New Zealand, Norfolk and Macquarie islands, and the Ross Dependency, Antarctica". Te Papa Press.
7. [http://www.nzbirds.com/birds/kotuku.html Kōtuku, the white heron]
8. (February 12, 2010). "''Ardea modesta'' - Eastern Great Egret". Department of the Environment, Water, Heritage and the Arts, Commonwealth of Australia.
9. "HeronConservation » Eastern Great Egret".
10. "Visitor impacts on freshwater avifauna in New Zealand".
11. Beruldsen, Gordon. (2003). "Australian Birds: Their Nests and Eggs". self.
12. Watts, Dave. (2006). "Field Guide to Tasmanian Birds". New Holland Press.
13. (8 November 2023). "Nesting season looks promising for critically endangered kōtuku".
14. Andrea Graves. (May–June 2017). "Kōtuku: The story of the bird on our $2 coin". New Zealand Geographic.