The Cattle egret (Bubulcus ibis) is a cosmopolitan species of heron named for its association with cattle. 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.
The Cattle egret is a stocky bird. It has a relatively short, thick neck, a sturdy bill, and a hunched posture. The nonbreeding 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.
Cattle egrets are native to parts of Asia, Africa, and Europe but they have undergone a rapid expansion in their distribution and successfully colonized much of the rest of the world in the last century. Many populations of Cattle egrets are highly migratory, while others are dispersive, and distinguishing between the two can be difficult. 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.
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Populations in southern India appear to show local migrations in response to the monsoons. Cattle egrets inhabit wetlands, dry grassy habitats, semi-arid steppes, floodplains, freshwater swamps, shallow marshes, and mangroves. They are often found in fields, croplands, and pastures with poor drainage. When nesting, Cattle egrets are found in woodlands near lakes or rivers, in swamps, or on small inland or coastal islands.
Cattle egrets are diurnal, feeding by day and sleeping at night. They are highly social; they feed in flocks and nest in colonies. Cattle egrets share roosting colonies with other colonial waterbirds. Adapted to foraging on land, Cattle egrets have lost the ability possessed by their wetland relatives to accurately correct for light refraction by water. They are usually found with cattle and other large grazing and browsing animals and catch small creatures disturbed by the mammals. Cattle egrets weakly defend the area around a grazing animal against others of the same species, but if the area is swamped by egrets, they 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 prefer to forage behind Plains zebras, Waterbuck, Blue wildebeest, and Cape buffalo. Dominant birds feed nearest to the host and thus obtain more food. Cattle egrets are usually silent but will produce a quiet, throaty ‘rick-rack’ call at the breeding colony.
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