text: cattle egret the cattle egret ( bubulcus ibis ) is a cosmopolitan species of heron ( family ardeidae ) 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 . 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 . 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 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 the cattle egret was first described in 1758 by linnaeus in his systema naturae as ardea ibis , but was moved to its current genus by charles lucien bonaparte in 1855 . 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 cattle egret has two geographical races which are sometimes classified as full species , the western cattle egret , b. ibis , and eastern cattle egret , b. coromandus . the two forms were split by and bruce , but were regarded as conspecific by almost all other recent authors until the publication of the influential birds of south asia . the eastern subspecies b. ( i . ) coromandus , described by pieter boddaert in 1783 , breeds in asia and australasia , and the western nominate form occupies the rest of the species range , including the americas . some authorities recognise a third seychelles subspecies , b. i. seychellarum , which was first described by finn salomonsen in 1934 . 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 . rare cases of hybridization with little blue herons egretta caerulea , little egrets egretta garzetta and snowy egrets egretta thula have been recorded . description the cattle egret is a stocky heron with an 88 – 96 cm ( 35 – 38 in ) wingspan ; it is 46 – 56 cm ( 18 – 22 in ) long and weighs 270 – 512 g ( 9 . 5 – 18 . 1 oz ) . 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 . during the breeding season , adults of the nominate western subspecies develop orange - buff plumes on the back , breast and crown , and the bill , legs and irises become bright red for a brief period prior to pairing . the sexes are similar , but the male is marginally larger and has slightly longer breeding plumes than the female ; juvenile birds lack coloured plumes and have a black bill . b. i. coromandus differs from the nominate subspecies in breeding plumage , when the buff colour on its head extends to the cheeks and throat , and the plumes are more golden in colour . this subspecies ' bill and tarsus are longer on average than in b. i. ibis . b. i. seychellarum is smaller and shorter - winged than the other forms . it has white cheeks and throat , like b. i. ibis , but the nuptial plumes are golden , as with b. i. coromandus . individuals with abnormally grey , melanistic plumages have been recorded . 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 - rack call at the breeding colony , but is otherwise largely silent . distribution and habitat the cattle egret has undergone one of the most rapid and wide reaching natural expansions of any bird species . it was originally native to parts of southern spain and portugal , tropical and subtropical africa and humid tropical and subtropical asia . in the end of the 19th century it began expanding its range into southern africa , first breeding in the cape province in 1908 . cattle egrets were first sighted in the americas on the boundary of guiana and suriname in 1877 , having apparently flown across the atlantic ocean . it was not until the 1930s that the species is thought to have become established in that area . the species first arrived in north america in 1941 ( these early sightings were originally dismissed as escapees ) , bred in florida in 1953 , and spread rapidly , breeding for the first time in canada in 1962 . it is now commonly seen as far west as california . it was first recorded breeding in cuba in 1957 , in costa rica in 1958 , and in mexico in 1963 , although it was probably established before that . in europe , the species had historically declined in spain and portugal , but in the latter part of the 20th century it expanded back through the iberian peninsula , and then began to colonise other parts of europe ; southern france in 1958 , northern france in 1981 and italy in 1985 . breeding in the united kingdom was recorded for the first time in 2008 only a year after an influx seen in the previous year . in 2008 , cattle egrets were also reported as having moved into ireland for the first time . in australia , the 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 . since 1948 the cattle egret has been permanently resident in israel . prior to 1948 it was only a winter visitor . the massive and rapid expansion of the 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 . the species has been seen as a vagrant in various sub - antarctic islands , including south georgia , marion island , the south sandwich islands and the south orkney islands . a small flock of eight birds was also seen in fiji in 2008 . in addition to the natural expansion of its range , cattle egrets have been deliberately introduced into a few areas . the species was introduced to hawaii in 1959 , and to the chagos archipelago in 1955 . successful releases were also made in the seychelles and rodrigues , but attempts to introduce the species to mauritius failed . numerous birds were also released by whipsnade zoo in england , but the species was never established . 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 . migration in western africa is in response to rainfall , and in south america migrating birds travel south of their breeding range in the non - breeding season . 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 ( ) on the south - eastern coast of india and a winter influx has also been noted in sri lanka . young birds are known to disperse up to 5 , 000 km ( 3 , 100 mi ) from their breeding area . flocks may fly vast distances and have been seen over seas and oceans including in the middle of the atlantic . status this species has a large range , with an estimated global extent of occurrence of 10 , 000 , 000 km2 ( 3 , 900 , 000 sq mi ) . its global population estimated to be 3 . 8 – 6 . 7 million individuals . for these reasons , the species is evaluated as least concern . on the other hand , the expansion and establishment of the species over large ranges has led it to be classed as an invasive species ( although little , if any impact has been noted yet ) . breeding the 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 north american breeding season lasts from april to october . in the seychelles , the breeding season of the subspecies seychellarum is april to october . 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 mm × 53 mm ( 1 . 8 in × 2 . 1 in ) . 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 . the cattle egret engages in low levels of brood parasitism , and there are a few instances of cattle egret eggs being laid in the nests of snowy egrets and little blue herons , although these eggs seldom hatch . there is also evidence of low levels of intraspecific brood parasitism , with females laying eggs in the nests of other cattle egrets . as much as 30 % extra - pair copulations have been noted . the dominant factor in nesting mortality is starvation . sibling rivalry can be intense , and in south africa third and fourth chicks inevitably starve . in the dryer habitats with fewer amphibians the diet may lack sufficient vertebrate content and may cause bone abnormalities in growing chicks due to calcium deficiency . in barbados , nests were sometimes raided by vervet monkeys , and a study in florida reported the fish crow and black rat as other possible nest raiders . the same study attributed some nestling mortality to brown pelicans nesting in the vicinity , which accidentally , but frequently , dislodged nests or caused nestlings to fall . 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 ; in africa , cattle egrets selectively forage behind plains zebras , waterbuck , blue wildebeest and cape buffalo . dominant birds feed nearest to the host , and obtain more food . 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 . birds of the seychelles race also indulge in some kleptoparasitism , chasing the chicks of sooty terns and forcing them to disgorge food . 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 , and it is known variously as cow crane , cow bird or cow heron , or even elephant bird , rhinoceros egret . its arabic name , abu , means " father of ticks " , a name derived from the huge number of parasites such as avian ticks found in its breeding colonies . 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 . it was the benefit to stock that prompted ranchers and the hawaiian board of agriculture and forestry to release the species in hawaii . not all interactions between humans and 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 , infectious bursal disease and possibly newcastle disease .