Species of Thailand

Eastern cattle egret

Bubulcus coromandus, Pieter Boddaert, 1783

(In Thai: นกยางควาย)

The eastern cattle egret (Bubulcus coromandus) is a species of heron (family Ardeidae) 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 (including the International Ornithologists' Union) 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.

It is a white bird adorned with buff plumes in the breeding season. It nests in colonies, usually near bodies of water and often with other wading birds. The nest is a platform of sticks in trees or shrubs. Eastern cattle egrets exploit drier and open habitats more than other heron species. Their feeding habitats include seasonally inundated grasslands, pastures, farmlands, wetlands and rice paddies. They often accompany cattle or other large mammals, catching insect and small vertebrate prey disturbed by these animals. Some populations of the cattle egret are migratory and others show post-breeding dispersal.

The adult eastern cattle egret has few predators, but birds or mammals may raid its nests, and chicks may be lost to starvation, calcium deficiency or disturbance from other large birds. This species maintains a special relationship with cattle, which extends to other large grazing mammals; wider human farming is believed to be a major cause of their suddenly expanded range. The cattle egret removes ticks and flies from cattle and consumes them. This benefits both species, but it has been implicated in the spread of tick-borne animal diseases.

Taxonomy

Its genus name Bubulcus is Latin for herdsman, referring, like the English name, to this species' association with cattle. Ibis is a Latin and Greek word which originally referred to another white wading bird, the sacred ibis, but was applied to this species in error.

The eastern cattle egret, described by Pieter Boddaert in 1783, breeds in eastern and southern Asia and Australasia.

Despite superficial similarities in appearance, the cattle egret is more closely related to the genus Ardea, which comprises the great or typical herons and the great egret (A. alba), than to the majority of species termed egrets in the genus Egretta.

Description

The cattle egret is a stocky heron with an 88 - 96 cm wingspan; it is 46 - 56 cm long and weighs 270 - 512 g. It has a relatively short thick neck, a sturdy bill, and a hunched posture. The non-breeding adult has mainly white plumage, a yellow bill and greyish-yellow legs.

The eastern cattle egret differs from the western species in breeding plumage, when the buff colour on its head extends to the cheeks and throat, and the plumes are more golden in colour. The bill and tarsus are longer on average. It is also smaller and shorter-winged. It has white cheeks and throat, but the nuptial plumes are golden. The positioning of the egret's eyes allows for binocular vision during feeding, and physiological studies suggest that the species may be capable of crepuscular or nocturnal activity. Adapted to foraging on land, they have lost the ability possessed by their wetland relatives to accurately correct for light refraction by water.

This species gives a quiet, throaty rick-rack call at the breeding colony, but is otherwise largely silent.

Distribution and habitat

In Australia, colonisation began in the 1940s, with the species establishing itself in the north and east of the continent. It began to regularly visit New Zealand in the 1960s.

The expansion of the eastern cattle egret's range is due to its relationship with humans and their domesticated animals. Originally adapted to a commensal relationship with large grazing and browsing animals, it was easily able to switch to domesticated cattle and horses. As the keeping of livestock spread throughout the world, the cattle egret was able to occupy otherwise empty niches. Many populations of cattle egrets are highly migratory and dispersive, and this has helped the species' range expansion.

Although the cattle egret sometimes feeds in shallow water, unlike most herons it is typically found in fields and dry grassy habitats, reflecting its greater dietary reliance on terrestrial insects rather than aquatic prey.

Migration and movements

Some populations of cattle egrets are migratory, others are dispersive, and distinguishing between the two can be difficult for this species. In many areas populations can be both sedentary and migratory. In the northern hemisphere, migration is from cooler climes to warmer areas, but cattle egrets nesting in Australia migrate to cooler Tasmania and New Zealand in the winter and return in the spring. Populations in southern India appear to show local migrations in response to the monsoons. They move north from Kerala after September. During winter, many birds have been seen flying at night with flocks of Indian pond herons (Ardeola grayii) on the south-eastern coast of India, and a winter influx has also been noted in Sri Lanka.

Breeding

The eastern cattle egret nests in colonies, which are often, but not always, found around bodies of water. The colonies are usually found in woodlands near lakes or rivers, in swamps, or on small inland or coastal islands, and are sometimes shared with other wetland birds, such as herons, egrets, ibises and cormorants. The breeding season varies within South Asia. Nesting in northern India begins with the onset of monsoons in May. The breeding season in Australia is November to early January, with one brood laid per season.

The male displays in a tree in the colony, using a range of ritualised behaviours such as shaking a twig and sky-pointing (raising his bill vertically upwards), and the pair forms over three or four days. A new mate is chosen in each season and when re-nesting following nest failure. The nest is a small untidy platform of sticks in a tree or shrub constructed by both parents. Sticks are collected by the male and arranged by the female, and stick-stealing is rife. The clutch size can be anywhere from one to five eggs, although three or four is most common. The pale bluish-white eggs are oval-shaped and measure 45 x 53 mm. Incubation lasts around 23 days, with both sexes sharing incubation duties. The chicks are partly covered with down at hatching, but are not capable of fending for themselves; they become capable of regulating their temperature at 9–12 days and are fully feathered in 13–21 days. They begin to leave the nest and climb around at 2 weeks, fledge at 30 days and become independent at around the 45th day.

In Australia, Torresian crows, wedge-tailed eagles and white-bellied sea eagles take eggs or young, and tick infestation and viral infections may also be causes of mortality.

Feeding

The cattle egret feeds on a wide range of prey, particularly insects, especially grasshoppers, crickets, flies (adults and maggots), and moths, as well as spiders, frogs, and earthworms. In a rare instance they have been observed foraging along the branches of a banyan tree for ripe figs. The species is usually found with cattle and other large grazing and browsing animals, and catches small creatures disturbed by the mammals. Studies have shown that cattle egret foraging success is much higher when foraging near a large animal than when feeding singly. When foraging with cattle, it has been shown to be 3.6 times more successful in capturing prey than when foraging alone. Its performance is similar when it follows farm machinery, but it is forced to move more. In urban situations cattle egrets have also been observed foraging in peculiar situations like railway lines.

A cattle egret will weakly defend the area around a grazing animal against others of the same species, but if the area is swamped by egrets it will give up and continue foraging elsewhere. Where numerous large animals are present, cattle egrets selectively forage around species that move at around 5–15 steps per minute, avoiding faster and slower moving herds.

The cattle egret may also show versatility in its diet. On islands with seabird colonies, it will prey on the eggs and chicks of terns and other seabirds. During migration it has also been reported to eat exhausted migrating landbirds.

Relationship with humans

A conspicuous species, the cattle egret has attracted many common names. These mostly relate to its habit of following cattle and other large animals.

The cattle egret is a popular bird with cattle ranchers for its perceived role as a biocontrol of cattle parasites such as ticks and flies. A study in Australia found that cattle egrets reduced the number of flies that bothered cattle by pecking them directly off the skin.

Not all interactions between humans and eastern cattle egrets are beneficial. The cattle egret can be a safety hazard to aircraft due to its habit of feeding in large groups in the grassy verges of airports, and it has been implicated in the spread of animal infections such as heartwater, infectious bursal disease and possibly Newcastle disease.

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Category / Seasonal Status

BCST Category: Recorded in an apparently wild state within the last 50 years

BCST Seasonal status: Resident or presumed resident

Scientific classification

Kingdom
Animalia
Phylum
Chordata
Class
Aves
Order
Pelecaniformes
Family
Ardeidae
Genus
Bubulcus
Species
Bubulcus coromandus

Common names

  • Thai: นกยางควาย

Synonyms

  • Ardea ibis ibis, Les Christidis & Walter E. Boles (2008)
  • Ardeola ibis ibis, Douglas F. Stotz et al. (1996)
  • Ardea ibis ibis, Les Christidis & Walter E. Boles (1994)
  • Cancroma coromanda, Pieter Boddaert (1783)
  • Buphus coromandus, Pieter Boddaert (1783)
  • Lepterodatis ibis, Carolus Linnaeus (1758)
  • Egretta ibis, Carolus Linnaeus (1758)
  • Ardeola ibis, Carolus Linnaeus (1758)
  • Ardea ibis, Carolus Linnaeus (1758)

Photos

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Eastern cattle egret
Cattle egret

Range Map

Distribution map of Eastern cattle egret, Bubulcus coromandus in Thailand
  • Amphawa District, Samut Songkhram
  • Ao Manao-Khao Tanyong National Park
  • Ao Phang-Nga National Park
  • Ban Chang District, Rayong
  • Ban Laem District, Phetchaburi
  • Ban Lat District, Phetchaburi
  • Ban Lueam District, Nakhon Ratchasima
  • Ban Phai District, Khon Kaen
  • Ban Phraek District, Phra Nakhon Si Ayutthaya
  • Ban Sang District, Prachinburi
  • Bang Ban District, Phra Nakhon Si Ayutthaya
  • Bang Kruai District, Nonthaburi
  • Bang Lamung District, Chonburi
  • Bang Len District, Nakhon Pathom
  • Bang Pa In District, Phra Nakhon Si Ayutthaya
  • Bang Pahan District, Phra Nakhon Si Ayutthaya
  • Bang Pakong District, Chachoengsao
  • Bang Phra Non-Hunting Area
  • Bang Pu Recreation Centre
  • Bang Saphan Noi District, Prachuap Khiri Khan
  • Bangkok Province
  • Borabue District, Maha Sarakham
  • Bueng Boraped Non-Hunting Area
  • Bueng Khong Long Non-Hunting Area
  • Chae Son National Park
  • Chaiya District, Surat Thani
  • Chaiyo District, Ang Thong
  • Chaloem Phra Kiat District, Saraburi
  • Chaloem Phrakiat Thai Prachan National Park
  • Chatturat District, Chaiyaphum
  • Chiang Dao District, Chiang Mai
  • Chiang Dao Wildlife Sanctuary
  • Chiang Khong District, Chiang Rai
  • Chiang Saen District, Chiang Rai
  • Doi Inthanon National Park
  • Doi Lo District, Chiang Mai
  • Doi Pha Hom Pok National Park
  • Doi Saket District, Chiang Mai
  • Doi Tao District, Chiang Mai
  • Fang District, Chiang Mai
  • Hala-Bala Wildlife Sanctuary
  • Hat Wanakon National Park
  • Hat Yai District, Songkhla
  • Hua Hin District, Prachuap Khiri Khan
  • Huai Chorakhe Mak Reservoir Non-Hunting Area
  • Huai Kha Khaeng Wildlife Sanctuary
  • Huai Krachao District, Kanchanaburi
  • Huai Talat Reservoir Non-Hunting Area
  • Huai Yang Waterfall National Park
  • In Buri District, Sing Buri
  • Kabin Buri District, Prachinburi
  • Kaeng Khoi District, Saraburi
  • Kaeng Krachan District, Phetchaburi
  • Kaeng Krachan National Park
  • Kamphaeng Saen District, Nakhon Pathom
  • Kantharawichai District, Maha Sarakham
  • Khanom District, Nakhon Si Thammarat
  • Khao Chong
  • Khao Dinsor (Chumphon Raptor Center)
  • Khao Khiao - Khao Chomphu Wildlife Sanctuary
  • Khao Kradong Forest Park
  • Khao Laem National Park
  • Khao Lak - Lam Ru National Park
  • Khao Luang National Park
  • Khao Nam Khang National Park
  • Khao Nan National Park
  • Khao Nang Phanthurat Forest Park
  • Khao Phra - Bang Khram Wildlife Sanctuary
  • Khao Pra Wihan National Park
  • Khao Sam Roi Yot National Park
  • Khao Soi Dao Wildlife Sanctuary
  • Khao Sok National Park
  • Khao Yai National Park
  • Khao Yoi District, Phetchaburi
  • Khlong Lan National Park
  • Khlong Luang District, Pathum Thani
  • Khok Pho District, Pattani
  • Khok Sung District, Sa Kaeo
  • Khon San District, Chaiyaphum
  • Khuan Khanun District, Phatthalung
  • Khun Chae National Park
  • Khun Korn Forest Park
  • Khura Buri District, Phang Nga
  • Klaeng District, Rayong
  • Ko Lanta National Park
  • Ko Phra Thong
  • Ko Samui District, Surat Thani
  • Ko Tao
  • Kui Buri National Park
  • Kumphawapi District, Udon Thani
  • Kut Thing Non-Hunting Area
  • Laem Pak Bia
  • Laem Son National Park
  • Lam Nam Kok National Park
  • Lan Sak District, Uthai Thani
  • Mae Ai District, Chiang Mai
  • Mae Mo District, Lampang
  • Mae Ping National Park
  • Mae Rim District, Chiang Mai
  • Mae Taeng District, Chiang Mai
  • Mae Tha, Lampang District, Lampang
  • Mae Wong National Park
  • Muak Lek District, Saraburi
  • Mueang Buriram District, Buriram
  • Mueang Chachoengsao District, Chachoengsao
  • Mueang Chaiyaphum District, Chaiyaphum
  • Mueang Chiang Mai District, Chiang Mai
  • Mueang Chiang Rai District, Chiang Rai
  • Mueang Chonburi District, Chonburi
  • Mueang Chumphon District, Chumphon
  • Mueang Kalasin District, Kalasin
  • Mueang Kanchanaburi District, Kanchanaburi
  • Mueang Khon Kaen District, Khon Kaen
  • Mueang Krabi District, Krabi
  • Mueang Lampang District, Lampang
  • Mueang Lamphun District, Lamphun
  • Mueang Lopburi District, Lopburi
  • Mueang Maha Sarakham District, Maha Sarakham
  • Mueang Nakhon Nayok District, Nakhon Nayok
  • Mueang Nakhon Pathom District, Nakhon Pathom
  • Mueang Nakhon Ratchasima District, Nakhon Ratchasima
  • Mueang Nakhon Si Thammarat District, Nakhon Si Thammarat
  • Mueang Nan District, Nan
  • Mueang Nong Khai District, Nong Khai
  • Mueang Nonthaburi District, Nonthaburi
  • Mueang Pathum Thani District, Pathum Thani
  • Mueang Pattani District, Pattani
  • Mueang Phang Nga District, Phang Nga
  • Mueang Phatthalung District, Phatthalung
  • Mueang Phayao District, Phayao
  • Mueang Phetchabun District, Phetchabun
  • Mueang Phetchaburi District, Phetchaburi
  • Mueang Phichit District, Phichit
  • Mueang Phitsanulok District, Phitsanulok
  • Mueang Phuket District, Phuket
  • Mueang Ratchaburi District, Ratchaburi
  • Mueang Rayong District, Rayong
  • Mueang Sa Kaeo District, Sa Kaeo
  • Mueang Samut Sakhon District, Samut Sakhon
  • Mueang Samut Songkhram District, Samut Songkhram
  • Mueang Satun District, Satun
  • Mueang Songkhla District, Songkhla
  • Mueang Sukhothai District, Sukhothai
  • Mueang Suphanburi District, Suphan Buri
  • Mueang Surat Thani District, Surat Thani
  • Mueang Tak District, Tak
  • Mueang Uttaradit District, Uttaradit
  • Nam Nao National Park
  • Nam Phong National Park
  • Namtok Sam Lan National Park
  • Non Sang District, Nong Bua Lamphu
  • Nong Bong Khai Non-Hunting Area
  • Nong Prue District, Kanchanaburi
  • Nong Song Hong District, Khon Kaen
  • Nong Suea District, Pathum Thani
  • Nong Thung Thong Non-Hunting Area
  • Nong Ya Plong District, Phetchaburi
  • Nong Yai Area Development Project Under Royal Init
  • Omkoi Wildlife Sanctuary
  • Pa Sak Chonlasit Dam Non-Hunting Area
  • Pai District, Mae Hong Son
  • Pak Chong District, Nakhon Ratchasima
  • Pak Kret District, Nonthaburi
  • Pak Phanang District, Nakhon Si Thammarat
  • Pak Phli District, Nakhon Nayok
  • Pak Thale
  • Pak Tho District, Ratchaburi
  • Pak Thong Chai District, Nakhon Ratchasima
  • Pang Sila Thong District, Kamphaeng Phet
  • Pathio District, Chumphon
  • Pha Daeng National Park
  • Pha Nam Yoi Forest Park
  • Pha Taem National Park
  • Phan District, Chiang Rai
  • Phanat Nikhom District, Chonburi
  • Phatthana Nikhom District, Lopburi
  • Phayuha Khiri District, Nakhon Sawan
  • Phi Phi Islands
  • Phra Nakhon Si Ayutthaya District, Phra Nakhon Si Ayutthaya
  • Phra Phrom District, Nakhon Si Thammarat
  • Phu Foi Lom National Park
  • Phu Hin Rong Kla National Park
  • Phu Khiao Wildlife Sanctuary
  • Phu Kradueng National Park
  • Phu Suan Sai National Park
  • Phunphin District, Surat Thani
  • Phutthamonthon District, Nakhon Pathom
  • Pran Buri District, Prachuap Khiri Khan
  • Pran Buri Forest Park
  • Ramkhamhaeng National Park
  • Ratchasan District, Chachoengsao
  • Rattanaburi District, Surin
  • Rattanawapi District, Nong Khai
  • Sai Noi District, Nonthaburi
  • Sai Yok District, Kanchanaburi
  • Sakaerat Environmental Research Station
  • Salak Pra Wildlife Sanctuary
  • Salawin National Park
  • Samut Prakan Province
  • San Kala Khiri National Park
  • San Sai District, Chiang Mai
  • Sanam Bin Reservoir Non-Hunting Area
  • Sanam Chai Khet District, Chachoengsao
  • Sathing Phra District, Songkhla
  • Sattahip District, Chonburi
  • Satuek District, Buriram
  • Sawi District, Chumphon
  • Si Maha Phot District, Prachinburi
  • Si Racha District, Chonburi
  • Si Satchanalai District, Sukhothai
  • Sikao District, Trang
  • Similan Islands
  • Sirinat National Park
  • Sri Nakarin Dam National Park
  • Sri Phang-nga National Park
  • Su-ngai Kolok District, Narathiwat
  • Sung Men District, Phrae
  • Surin Islands
  • Takua Pa District, Phang Nga
  • Taphan Hin District, Phichit
  • Tha Chana District, Surat Thani
  • Tha Chang District, Sing Buri
  • Tha Sala District, Nakhon Si Thammarat
  • Tha Takiap District, Chachoengsao
  • Tha Wung District, Lopburi
  • Tha Yang District, Phetchaburi
  • Thai Mueang District, Phang Nga
  • Thalang District, Phuket
  • Thale Ban National Park
  • Thale Noi Non-Hunting Area
  • Tham Pratun Non-Hunting Area
  • Than Sadet - Koh Pha-Ngan National Park
  • Thanyaburi District, Pathum Thani
  • Thao Kosa Forest Park
  • Thap Lan National Park
  • Thawat Buri District, Roi Et
  • Thong Pha Phum National Park
  • Wang Chan District, Rayong
  • Wang Nam Yen District, Sa Kaeo
  • Wang Noi District, Phra Nakhon Si Ayutthaya
  • Wat Phai Lom & Wat Ampu Wararam Non-Hunting Area
  • Watthana Nakhon District, Sa Kaeo
  • Wiang Chai District, Chiang Rai
  • Wiang Kaen District, Chiang Rai
Range map of Bubulcus coromandus in Thailand