About Bubulcus ibis (Linnaeus, 1758)
Bubulcus ibis, commonly called the cattle egret, is a stocky heron species. It measures 46–56 cm (18–22 in) in length, has an 88–96 cm (35–38 in) wingspan, and weighs 270–512 g (9.5–18.1 oz). This bird has a relatively short thick neck, a sturdy bill, and a hunched posture. Non-breeding adults have mostly white plumage, a yellow bill, and greyish-yellow legs. During the breeding season, adults of the nominate western subspecies grow orange-buff plumes on their back, breast, and crown; for a brief period before pairing, their bill, legs, and irises turn bright red. The sexes have similar appearance, though males are slightly larger and have marginally longer breeding plumes than females. Juvenile birds have no coloured plumes and a black bill. The positioning of this egret's eyes supports binocular vision during feeding, and physiological studies indicate the species may be active at dawn, dusk, or during the night. Adapted for foraging on land, cattle egrets have lost the ability their wetland-relatives have to accurately correct for light refraction caused by water. This species is mostly silent, only producing a quiet, throaty "rick-rack" call at breeding colonies. The cattle egret has undergone one of the most rapid, far-reaching natural range expansions of any bird species. It was originally native to parts of southern Spain and Portugal, tropical and subtropical Africa, and western Asia. In the late 19th century, it began expanding its range into southern Africa, and first bred in Cape Province in 1908. Cattle egrets were first spotted in the Americas on the border between Guiana and Suriname in 1877, having apparently flown across the Atlantic Ocean, and the species is thought to have become established in this region only in the 1930s. It first arrived in North America in 1941, and these early sightings were initially dismissed as reports of escaped captive birds. It bred for the first time in Florida in 1953, then spread rapidly, breeding in Canada for the first time in 1962, and is now commonly seen as far west as California. It was first recorded breeding in Cuba in 1957, Costa Rica in 1958, and Mexico in 1963, though it was likely established in these areas before those dates. In Europe, the species historically declined in Spain and Portugal, but in the second half of the 20th century it expanded back across the Iberian Peninsula, then began colonising other parts of Europe: southern France in 1958, northern France in 1981, and Italy in 1985. The first recorded breeding in the United Kingdom happened in 2008, just one year after a large influx of the birds in 2007; cattle egrets were also reported in Ireland for the first time in 2008. The cattle egret's massive, rapid range expansion is linked to its relationship with humans and domesticated animals. Originally evolved to have a commensal relationship with large grazing and browsing wild animals, it easily adapted to associate with domesticated cattle and horses. As livestock keeping spread across the world, the cattle egret was able to occupy previously unoccupied habitats. Many cattle egret populations are highly migratory and dispersive, a trait that has further supported range expansion. The species has been recorded as a vagrant on multiple sub-Antarctic islands, including South Georgia, Marion Island, the South Sandwich Islands, and the South Orkney Islands. A small flock of eight cattle egrets was also observed in Fiji in 2008. Beyond natural range expansion, cattle egrets have been deliberately introduced to a small number of areas. The species was introduced to Hawaii in 1959. Successful introductions were also carried out in the Seychelles and Rodrigues, but introduction attempts to Mauritius were unsuccessful. Numerous cattle egrets were released by Whipsnade Zoo in England, but the species never established a population there. While cattle egrets sometimes feed in shallow water, unlike most herons they are typically found in fields and dry grassy habitats, a pattern reflecting their greater dietary reliance on terrestrial insects rather than aquatic prey.
