Cattle egret
| Cattle egret | ||||||||||||
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A cattle egret in East Timor |
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| Systematics | ||||||||||||
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| Scientific name of the genus | ||||||||||||
| Bubulcus | ||||||||||||
| Bonaparte , 1855 | ||||||||||||
| Scientific name of the species | ||||||||||||
| Bubulcus ibis | ||||||||||||
| ( Linnaeus , 1758) |
The cattle egret ( Bubulcus ibis ) belongs to the heron family from the order Pelecaniformes . It is distributed worldwide and is only absent in Antarctica ; its range has expanded significantly, especially in the course of the 20th century. A distinction is made between two subspecies, which some authors also regard as separate species. This article follows the traditional notation that the cattle egret is the only species in the genus Bubulcus .
The IUCN classifies the cattle egret as not endangered ( least concern ).
Appearance
The cattle egret reaches a body length of 46 to 56 centimeters and weighs between 300 and 400 grams. The wingspan is 88 to 96 centimeters.
At first glance, the cattle egret to the recalls Rallenreiher which, however, is somewhat darker and smaller. Adult animals have mostly white plumage, yellow beak, and yellow legs. Outside the breeding season, the area around the eyes is greenish to yellow. The cattle egret wears tufts of feathers on its head and reddish-brown feathers on its back, chest and head in its splendid robe during the breeding season. The eye area is then blue, while the high balz also the beak and the reins are reddish.
distribution
Distribution worldwide
Originally the cattle egret was only native to the ancient world. The nominate form Bubulcus ibis ibis occurred in southern Europe , northwest Africa, the region south of the Sahara , on Madagascar and other islands of the Indian Ocean as well as in southern Turkey and in southwest Asia and in southern Russia. The subspecies Bubulcus ibis coromandus is widespread from the Indian suburbs to southern China to southern Japan, Korea and the Sunda Islands.
The cattle egret has spread rapidly over the course of the 20th century. He has benefited greatly from the conversion of forest areas into pastureland. The population has increased especially in regions with high annual rainfall. The population increase was particularly favored if the region previously had a low density of mega- herbivores and is now used intensively as pastureland. The expansion of the area into African and Australian regions with lower rainfall was supported by the creation of artificial bodies of water and irrigation systems. Farmers usually appreciate the settlement of cattle egrets as they eat pasture pests. A high density of cattle egrets helps reduce the number of ticks that suckle on cattle.
Spread in America, Australia and New Zealand
Around the year 1877 the first cattle egrets were seen in South America, from 1930 populated the kind of British Guiana starting North and South America . The American distribution area extends today from Canada, where this species immigrated from 1940, over Central America to Chile. The species was introduced in Hawaii in 1949. The cattle egret is now one of the most common species of heron in the warm temperate regions of America.
In 1933, 18 cattle egrets from India were released in the Australian Northern Territory . However, this introduction is considered unsuccessful. In 1949, cattle egrets were observed for the first time in the sparsely populated district of Oenpelli in the Northern Territory. The herons were already so numerous here that it is considered unlikely that they descended from the herons that were released in 1933. Between 1949 and 1979, wanderers were repeatedly observed in the Western Australian region of Pilbara . However, the first brood in Western Australia was not observed near Wyndham until 1980 . As early as 1954, breeding cattle egrets were observed in New South Wales in southeastern Australia, where the population grew to 2,300 breeding pairs within 20 years. The cattle egret is now a widely distributed and locally common species of heron in Australia. A main area of distribution is the north of Australia from Wyndham to Arnhemland and the east of Australia from Bundaberg in Queensland to the extreme south-east of Australia and Tasmania. Cattle egrets are also abundant in a region of southwest Australia that stretches from Perth to Esperance .
Starting from Australia, New Zealand was also colonized by cattle egrets. The first reliable observation was made in 1963. In the meantime, random visitors to New Zealand regularly reach the west coast of New Zealand between April and May. The number fluctuates very strongly. In 1986, for example, more than 3,200 cattle egrets were counted; in 1988 the number fell to 1,142 herons. Broods were not found in New Zealand in the 20th century.
Distribution in Europe
The European main area of distribution is the Iberian Peninsula. In Central Europe it occurs in small numbers as a breeding and annual bird in Belgium and the Netherlands. In Belgium it has been breeding since 1998, in 2000 there were already 9 nests of this species. In the Netherlands it has also been breeding since 1998. In the other Central European countries it can be observed regularly. This is partly due to the fact that the population in south-western Europe has increased and as a result there is an increasing number of people entering Central Europe. There are also a number of prisoner refugees. In some Central European zoos, such as the Hanover Zoo and the Nuremberg Zoo, cattle egrets are kept in free flight.
hikes
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The cattle egret is a short-range migrant or partial migrant . The breeding birds of Spain migrate in an undirected manner, whereby it is not possible to clearly distinguish between post-breeding dispersal migrations and migration. With the North African cattle egrets there are sometimes very long flights to food grounds, but no migration can be observed. The breeding birds in southern France are also overwintering there. Individual migrations of European breeding birds as far as South Africa have been documented, but here, too, it is more a question of dispersal migrations than a directed migration.
habitat
In contrast to other Palearctic herons, the cattle egret is not very attached to water. He also likes to catch insects in drier areas such as fields and pastures . He often moves between herds of cattle and likes to sit on the back of grazing animals. It also occurs in swampy areas and on flood plains. He very often joins large herbivorous mammals or follows plowing farmers.
Way of life
Cattle egrets are diurnal birds and are also very social. They are regularly in small flocks foraging for food, with group hunting increasing the foraging efficiency. Only individual small territories are defended. Cattle egrets nest in colonies and are often associated with other species of heron.
The food spectrum of the cattle egret includes grasshoppers, spiders, ticks, frogs, reptiles and smaller mammals. In Australia, the cattle egret also eats cane toads . In the winter half-year earthworms play a bigger role in the food spectrum. While foraging for food, cattle egrets follow grazing livestock such as sheep, goats, horses and cows. They also regularly read ectoparasites from grazing cattle.
Cattle egrets reach sexual maturity in their second year of life. They lead a monogamous seasonal marriage, although bigyny can be observed. The nests are built on trees or in bushes as well as in reed beds. The male usually enters the nesting material, which the female builds into a nest in an average of six to seven days. Laying begins in April. The clutches usually contain four to five eggs, with a laying interval of one to two days. The eggs are incubated by both parent birds for 22 to 26 days. The young birds hatch asynchronously and are only left alone by the parent birds from the 10th day onwards. They leave the nest at around 20 days. However, they are only fledged at 25 to 35 days.
Inventory and inventory development
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The total European population was around 50,000 breeding pairs in the 1970s. Since then, the number has increased significantly in some cases. Since the 1990s, there have been more than 80,000 breeding pairs on the Iberian Peninsula alone. There is also an increasing number of breeding birds in France.
supporting documents
literature
- Hans-Günther Bauer, Einhard Bezzel and Wolfgang Fiedler (eds.): The compendium of birds in Central Europe: Everything about biology, endangerment and protection. Volume 1: Nonpasseriformes - non-sparrow birds. Aula-Verlag Wiebelsheim, Wiesbaden 2005, ISBN 3-89104-647-2 .
- PJ Higgins (Eds.): Handbook of Australian, New Zealand & Antarctic Birds , Volume 1, Ratites to Ducks, Oxford University Press, Oxford 1990, ISBN 0-19-553068-3
- James A. Kushlan & James A. Hancock: Herons . Oxford University Press, 2005, ISBN 0-19-854981-4
Web links
- Bubulcus ibis in the endangered Red List species the IUCN 2009. Posted by: BirdLife International, 2009. Accessed on March 10 of 2010.
- Videos, photos and sound recordings of Bubulcus ibis in the Internet Bird Collection
- Age and gender characteristics (PDF; 2.6 MB) by J. Blasco-Zumeta and G.-M. Heinze (eng.)
- Feathers of the cattle egret