Great emu
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Great Emu ( Dromaius novaehollandiae ) |
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| ( Latham , 1790) |
The Great Emu ( Dromaius novaehollandiae ) is a flightless bird art from the group of flightless birds and the only surviving member of the family of emus ( Dromaius ). It is the largest species of bird in the fauna of Australia and the second largest ratite after the African ostrich . Despite their similar appearance, ostriches and emus are not closely related. Their similarity results from a convergent evolution .
Emus are opportunistic migratory birds that undertake long migrations to find suitable feeding grounds. Occasionally there are mass migrations in which sometimes several thousand birds migrate together to regions that are rich in food. Emus cover long distances in an evenly fast and energy-saving trot. Their maximum running speed is 50 kilometers per hour, which they can maintain over some distance.
The name
Emus were first described in Arthur Phillip's travelogue " Voyage to Botany Bay, " which appeared in 1789. Phillip referred to them as " New Holland Cassowaries ". This bird species received its scientific name from the ornithologist John Latham , who described a number of Australian bird species for the first time and also worked on Phillips' book, among other things. Translated, the scientific species name means " New Dutch runner ".
The origin of the term “emu”, which is used in many languages, is unknown. It is believed that the name "Emu" is derived from an Arabic term for large birds. This is how Portuguese explorers originally called the cassowaries, which are related to the emu, in New Guinea . The name was later transferred in this way.
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features
Emus reach a height between 150 and 190 centimeters with a shoulder height of 100 to 130 centimeters. Males and females look very much alike; on average, females are slightly larger, heavier and darker than males. With a weight between 30 and 45 kilograms, emus are lighter than helmet cassowaries despite their greater height . The largely featherless neck and legs are long. Only rudimentary stubs are left of the wings. Their length is only 20 centimeters.
The emu's powerful legs end in three toes that point forward. This toe position is also found in other bird species that predominantly move on the ground, such as quail. The African ostrich even has only two toes. Well-developed pelvic muscles enable the high running speed of 50 kilometers per hour that emus can achieve. The proportion of the pelvic muscles in the total weight of an emus corresponds to the ratio of the flight muscles to the body weight of an airworthy bird. The emu is also the only species of bird that has the gastrocnemius muscle , the two-headed calf muscle, on the back of the lower legs .
The gray-brown, shaggy-looking plumage of the emus is dark after moulting . The plumage pigmentation, however, brightens over time due to the sun's rays into brown. In addition to the primary spring, Emus are developing a secondary or anus spring that attaches to the base of the main spring and is just as long as it. Sunlight is absorbed by the outer feathers of the plumage, while the loose structure of the plumage isolates the skin. This adaptation allows the birds to be active even during the hot time of the day. The plumage of the breast is usually much lighter in color than the rest of the body's plumage. The neck and head are usually very dark and often even black in color. On both sides of the neck there are often two 15 to 20 cm long and 3 to 4 cm wide white stripes.
The young animals are streaked in black and white along the length for camouflage, the head is speckled in black and white. The beak is very dark and slightly curved towards the tip.
voice
Adult emus develop an opening in the throat between the windpipe and the cervical air sacs . Through this opening, emus can use the air sacs as a resonance space and thus give out deep, piercing and booming calls. which can be heard up to a distance of two kilometers. The birds also make grunts and sibilants. Emus are most likely to be heard during the breeding season, while the rest of the time they are mostly silent.
Distribution, subspecies and habitat
Emus are common across most of Australia. However, they are rarely found in the densely forested tropical north. The population declined on the more densely populated east coast of Australia. In Tasmania , the subspecies of the great emus was exterminated in the 19th century. The great emu was also introduced by humans to Kangaroo Island , where the now extinct species Kangaroo Island Emu was originally native, and to Maria Island near the Tasmanian coast.
Three subspecies are distinguished in the large distribution area:
- In the southeast of Australia Dromaius novaehollandiae novaehollandiae occurs. It is the nominate form of this bird species and differs from the other subspecies by a white ruff that is shown during the reproductive period.
- In the north, the subspecies D. n. Woodward occurs, which is slightly more delicate than the nominate form and has lighter plumage.
- D. n. Rothschildi has the darkest plumage of all subspecies and is found in southwest Australia.
The habitat of the emus is formed by eucalyptus forests, open plantings, heather land, rarely dry plains or even deserts , which they only visit after heavy rains and the resulting large supply of fruits and berries. Emus are absent from the tropical rainforest where the cassowary is native.
Duration
Before the colonization of Australia by Europeans, a total of three emu species occurred in Australia. "Dromaius baudinianus" and "D. ater ”died out shortly after the arrival of the first Europeans. In Tasmania, the subspecies of the great emus found there was exterminated around 1865. In his book The Birds of Australia , published in 1865, John Gould not only regrets the disappearance of the Tasmanian subspecies, but also the decline of the great emus around Sydney. At that time, he proposed that this bird species should be protected. The great emu was hunted until the 1960s. Today it is protected by the "Environment Protection and Biodiversity Conservation Act 1999".
Despite the earlier common hunting, the great emu has benefited from the increase in agricultural area in the last two centuries: the increased water supply originally created for sheep has led to a significant expansion of the breeding areas. It is believed that today's population is larger than that before the European settlement. The population figures vary, however, and depend on the amount of rainfall. It is estimated that between 625,000 and 725,000 birds live in Australia, with about 100,000 to 200,000 birds in Western Australia. In the case of individual small populations in regions where only a few emus live and which are so isolated that no birds migrate from other areas, progressive changes in their habitat and road accidents contribute to the threat to their survival. The state government of New South Wales has therefore classified the isolated populations of the New South Wales North Coast Bioregion and Port Stephens as endangered.
Way of life
activity
Emus spend most of the day eating. They are diurnal birds whose greatest activity occurs at dawn and dusk. On hot summer days they rest in the shade during the midday heat. Then they lift their stubby wings and get some coolness. On very hot days, emus maintain their body temperature by panting . In contrast to many other animal species, the resulting low level of carbon dioxide in the blood does not seem to cause alkalosis in them . With normal breathing, the inhaled air is drawn through the nasal passage. This warms the air before it reaches the lungs. During exhalation, the moisture is extracted from the air and absorbed here.
Typically, emus are solitary or appear in pairs. They only come together in small groups on hikes or at watering places, which quickly break up again. If two emus come too close to each other, the dominant bird indicates this by stretching out its neck and making a growl; usually one of the birds then takes a step back, but occasionally there is also aggression in the form of beak pecking or kicking.
nutrition
Emus are among the largest herbivores in Australia and eat food with a comparatively high nutritional value. Plants originally native to Australia as well as plants introduced by Europeans are used.
Younger animals have a more carnivorous diet and, in addition to plant food, increasingly eat caterpillars , grasshoppers and other invertebrates , while older animals mainly eat fruits, berries, seeds , flowers , young saplings, fresh grass and herbs. The food composition varies depending on the season. In the case of emus in Western Australia, it has been shown that they prefer to eat seeds of Acacia aneura until it rains . After the rainfall they prefer grass saplings and caterpillars. In the Australian winter, their diet consists mainly of the leaves and seeds of cassia . In spring, grasshoppers and quandong fruits are the main components of their diet. It is believed that emus make a significant contribution to the spread of plant diaspores and thus have an impact on the conservation of Australian biodiversity.
For better chopping of the food in the gizzard , they often take in smaller stones ( gastroliths ), sometimes also charcoal . As a precaution against bad times, the birds can build large reserves of fat ; in times of need they can lose more than half their weight. Emus have a high water requirement and have to drink almost every day. Both the failure of their food sources and the shortage of water can lead to the mass migrations feared by Western Australian farmers.
Mass migrations
With the exception of breeding males, emus are not tied to one place, but roam around in search of food. If the food supply becomes scarce and the search becomes more and more extensive, the normally solitary emus meet other conspecifics more and more frequently. As soon as emus meet other emus several times a day, the birds begin to leave the respective region. The direction you take on these hikes depends largely on the weather. Emus optically perceive clouds in a precipitation area and move in this direction. But they are also based on the distant rumble of thunder from thunderstorms or the smell of damp earth. The migratory movements are particularly pronounced in western Australia. In summer, low pressure areas move south and west from the north coast in this region . In winter, on the other hand, the Antarctic low pressure areas move north from the southwest. Similar migratory movements, in which the emus sometimes move considerable distances, also exist in eastern Australia. However, they are not as noticeable there as in the west.
Since the emus move in the same direction on their migration and often meet each other, the migration movement initially increases. All birds move in the same direction at a speed of about seven km / h. Therefore, at least in the western part of Australia, there are migrations in which thousands of animals can take part. The migration movement does not end until the emus have reached a region with an abundant food supply or are stopped by the State Barrier Fence (SBF, see below).
The migrations are probably caused at least in part by humans and the water supply created by them. Thanks to artificial water points, emus were able to colonize regions that used to be too dry for them or where only small populations could survive. However, this has also increased the number of migrating individuals, sometimes massively. This poses a problem for some agricultural areas. In the south-west of Australia, the grain-growing areas are protected by the State Barrier Fence.
Reproduction
Emus mate during the Australian summer months of December and January and stay together for a period of about five months. The female does not mate until the cooler months of May and June. In the males, the hormonal balance changes very strongly during this period. The testosterone and xx hormone levels rise sharply. The testicle size doubles. The males show a pronounced territorial behavior during this time and defend a territory of about 30 km². When a female enters the territory, courtship takes place . The birds stand next to each other while swinging their necks back and forth. Finally the female sits down and the male reaches behind with his beak for his neck. Then it comes to copulation. The birds mate every one to two days and the female lays an egg weighing between 700 and 900 grams every second or third day.
Between April and June, the female lays around 5 to 15 eggs, initially dark green and later almost black, in the nest, which is made of small sticks, leaves, grass and bark and is often laid out under bushes or trees . After that, however, the male takes over the breeding business . In rare cases the female stays close to the clutch and defends the territory. It is more typical that, despite the initial pair bond, the female migrates to the territory of another male, mates again there and lays eggs in a communal nest. In about half of the chicks that a male hatches, the male is not the father. In years with a high food supply, a female can have up to three clutches.
The male does not eat or drink during the eight week breeding season. It only gets up to turn the eggs regularly, which happens about ten times a day. During this time, the male survives only thanks to his stored body fat and only absorbs the liquid that he can reach from the nest as morning dew. After the young have hatched, the male becomes highly aggressive and at this time can also attack humans or females remaining in the territory. This close father-child bond lasts for a period of five to seven months, in rare cases up to 18 months.
The young can run after about five hours, and after seven days they leave the nest location together with the male. Newly hatched young are already 25 centimeters tall. They show their characteristic, striped plumage for a period of about three months. Emu chicks are endangered by dingoes and birds of prey , to which they can fall prey if they move too far from the male. They are also endangered by a number of human introduced animals, such as non-Australian foxes, domestic dogs and feral pigs.
The young birds are fully grown after 12 to 14 months. They reach sexual maturity in the second to third year of life. In the wild, their life expectancy is 10 to 20 years. However, birds kept in human care can live to be more than twice as old. A wild caught emu lived to be 45 years old in Washington. The oldest known emu had to be euthanized in the Nuremberg Zoo on August 28, 2017 at the age of 46 because of old age. It hatched on February 26, 1971 in the Frankfurt Zoo .
Emus and man
The emu as traditional prey
Emus were one of the sources of food for the native people of Australia, the Aborigines , as well as the early European settlers.
Aboriginal people used a number of different techniques to hunt emus. For example, they shot them at water holes with spears or poisoned the water holes used by emus. Emus were also caught in nets. Emus were attracted by the Aborigines imitating their calls or by hanging a ball of feathers and rags, which from a distance resembled the body contour of an emus, from a tree. The oil obtained from the fat reserves was used by the Aborigines as a lubricant, wound healing agent and as an anti-inflammatory for rheumatoid arthritis . Mixed with ocher, it was used for traditional body painting. The oil was also used to care for the traditional wooden tools.
European settlers also hunted emus for food. A major reason for emus hunting, however, was to protect the farmland when the birds invaded agricultural areas in search of water and food during a period of drought.
The 1932 Emu War
The so-called emu war is the best known example of an attempt to protect agricultural land during a mass migration of emus. During the hot summer months wandered a large number of emus, an estimated 20,000, in the region of Campion and Walgoolan in Western Australia one. The mass gathering of birds unsettled the townspeople of Campion and endangered the wheat fields. The Australian government therefore wanted to reduce the number of birds by using the military with machine guns. However, this attempt failed almost completely. With the first volleys of machine guns, the birds scattered at an escape speed of up to 50 km / h. Few birds were hit by a full volley. Most of the others, however, often hit by several bullets, apparently ran on undeterred. After a week, the deployment of the military was discontinued, only to be resumed later with changed tactics. There is different information about the number of emus shot. They range from a few to hundreds of animals.
The emu fence
The economic damage to farmers that a massive emus invasion of agricultural areas can cause is so great that today a 1,170 km long fence, the State Barrier Fence, exists in southwest Australia to keep emus and dingoes out. The fence was built in several stages, initially as a rabbit-proof fence against the rabbit plague, then also to protect the flock of sheep from the dingoes and to protect the agricultural areas from the emus. It currently extends 180 cm high from the Zuytdorp Cliffs in the north of Kalbarri on the west coast to Jerdacuttup on the south coast in the east of Ravensthorpe . It is maintained by the Agriculture Protection Board (APB) and the Department of Agriculture and Food (DAFWA) of the state of Western Australia. Currently (2016) two gaps are being closed, one in Yigarn shire , a second, 490 km long, around Esperance shire, as an extension to the east. The Northern Mallee Declared Species Group, an interest group of farmers, defends the fence as a non-lethal barrier for emus, kangaroos and dingoes. It is also a fire protection line in case of bush fires, and the construction gives farmers additional income.
The cost of the expansion project is estimated at A $ 10.5 million. A cost-benefit analysis by the consulting firm URS claims that for every dollar spent on the fence and its maintenance, two AU $ are saved in game damage. Upon completion, which is scheduled for mid-2016, the annual net benefit is expected to be AU $ 3 million.
Todays use
Commercial emu breeding began in Western Australia in 1987. The first animals were slaughtered in 1990. The meat is low in fat and tender and can best be compared to beef. In Australia it is mostly processed as grilled sausage and emu burgers. In addition, the eggs are also used, leather is made from the skin, and oil is still extracted from the animals' fat reserves. The oil is used in cosmetics and certain natural healing products. Emu leather has a strikingly grained surface. It is usually processed together with other types of leather for smaller items such as wallets and shoes. Feathers and eggs are widely used in handicrafts.
No wild emus are captured for commercial keeping, only animals bred in captivity are used. With the exception of Tasmania, all Australian states require a license to keep emus.
Emus are not only bred commercially in Australia. Breeding is widespread in North America; around a million emus are kept in the United States. Peru and China are also important in emu breeding.
Emus reproduce very well in captivity. They have to be kept in large open enclosures, as insufficient freedom of movement leads to leg and digestive problems. The birds are usually fed grains that are supplemented with green fodder twice a day. The animals have reached slaughter age after 50 to 70 weeks. Because emus are generally not aggressive, they are often kept in animal parks and petting zoos.
The emu in Aboriginal mythology
In Australian Aboriginal mythology (the so-called dream time ), the emu was one of the three sisters (the three stars of the constellation Orion) who flew to earth at the beginning of dream time. Two of the sisters left the earth again, only the emu remained. Since an emu is a restless and highly temperamental animal, it could not take on the task of giving birth to humans. That is why the emu created the so-called Tnatanja Pol , a star on which human seeds grow; if the wind blows them to the right, they become men; if the wind blows them to the left, they become women. The emu becomes the Earth Mother. In this way the role of the emu and the incarnation are explained in the dream time.
There are a number of other myths about the emus. The Yuwaalaraay and other groups in New South Wales attribute the creation of the earth to an emu egg that was thrown into the sky. The "Kurdaitcha Man", told in the myths of the Aboriginal tribes in Central Australia, wears sandals made of emu feathers to cover his footprints.
Cultural meaning and trivia
The importance of the emus in the life of the Aborigines is not only reflected in their mythology and traditional art. In northern Queensland on the Cape York Peninsula, for example, rock drawings depicting emus can be found. Some of these rock carvings are estimated to be 15,000 years old.
The emu is unofficially considered the national bird of Australia. Together with the red giant kangaroo , he appears as one of the shield bearers on the coat of arms of Australia . The Australian 50 cent coin on which the coat of arms is stamped shows this bird species. Numerous Australian postage stamps depict the emu. The hats of a previous Australian cavalry brigade were also adorned with emu feathers.
About 600 Australian topographical names refer to the bird. These include mountains, lakes, rivers and cities. A number of products were named after this bird, including beers. In Australia you can drink “Emu Bitter”, “Emu Export” and “Emu Draft”. Emu - Austral Ornithology is the name of the quarterly publication of the Royal Australasian Ornithologists Union. The British entertainer Rod Hull, who was occasionally seen on German television, performed with an emu hand puppet. The best-known children's books that deal with this bird include the two picture books Edward the Emu and Edwina the Emu by Sheena Knowles, which tell of the life of an Emu family. In the Simpson episode Lard of the Dance (episode 5F20), Marge encourages the depressed Homer to start an emu farm, thus creating a phrase that is at least occasionally often heard in English.
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Footnotes
The article is in places a translation of the article on English Wikipedia in the version dated December 8, 2006, but has since been updated several times.
- ↑ SJJF Davies: emus , Australian Natural Historiy, Volume 14, 1963, pp 225-229.
- ^ J. Gould: Handbook to the birds of Australia , Volume 2, 1865, reprinted by Landsdowne Presse 1972.
- ^ ADW: Dromaius novaehollandiae: Information . Animaldiversity.ummz.umich.edu. Retrieved November 3, 2008 ..
- ^ Commercial Emu and Ostrich rearing . Poulvet.com. Archived from the original on February 3, 2010. Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved November 3, 2008 ..
- ↑ Patak, 1998, pp. 23-37
- ↑ a b Christopher M. Perrins (ed.): The BLV encyclopedia birds of the world. Translated from the English by Einhard Bezzel. BLV, Munich / Vienna / Zurich 2004, ISBN 978-3-405-16682-3 , p. 41 (Title of the original English edition: The New Encyclopedia Of Birds. Oxford University Press, Oxford 2003).
- ↑ Maloney and Dawson, 1995, pp. 381-387
- ^ Australian Museum. 2001. Emu Dromaius novaehollandiae .
- ↑ a b Davies, pp. 225-229
- ↑ Maloney, 1994, pp. 464-472.
- ↑ Maloney, 1998, pp. 712-719.
- ↑ McGrath, pp. 248-252.
- ↑ Christopher M. Perrins (ed.): The BLV encyclopedia birds of the world. Translated from the English by Einhard Bezzel. BLV, Munich / Vienna / Zurich 2004, ISBN 978-3-405-16682-3 , p. 42 (title of the original English edition: The New Encyclopedia Of Birds. Oxford University Press, Oxford 2003).
- ↑ a b c d e Christopher M. Perrins (Ed.): The BLV encyclopedia birds of the world. Translated from the English by Einhard Bezzel. BLV, Munich / Vienna / Zurich 2004, ISBN 978-3-405-16682-3 , p. 43 (Title of the original English edition: The New Encyclopedia Of Birds. Oxford University Press, Oxford 2003).
- ↑ IA Malecki et al. (1998): Endocrine and testicular changes in a short-day seasonally breeding bird, the emu (Dromaius novaehollandiae), in southwestern Australia. Animal Reproduction Sciences 53: pp. 143-155 PMID 9835373
- ↑ Reader's Digest Complete Book of Australian Birds. 1976. Reader's Digest Services, ISBN 0-909486-63-8 .
- ↑ Taylor, pp. 359-364
- ↑ Davies, SJJF 1976. The natural history of the Emu in comparison with that of other ratites. In Proceedings of the 16th international ornithological congress , H. J. Firth and JH Calaby eds. Australian Academy of Science, pp. 109-120, ISBN 0-85847-038-1 .
- ↑ Elder Emu died .
- ↑ [1] , accessed on April 5, 2016.
- ^ R. Lewis: The Beginner's Guide to Australian Aboriginal Art, The symbols, their meanings and some Dreamtime stories. Canning Vale DC, 3rd improved ed. 2007, p. 9. The same: An Introduction in the Dreamtime, Australian Aboriginal mysticism explained and explored. Canning Vale DC 2002, p. 6.
- ^ Wally Caruana: Aboriginal Art , Thames and Hudson, London 1996, ISBN 0-500-20264-8 .
General literature
- Josep del Hoyo et al .: Handbook of the Birds of the World. Volume 1: Ostrich to Ducks. Lynx Edicions, 1992, ISBN 84-87334-10-5 .
- SJJF Davies: Emus , Australian Natural Historiy, Volume 14, 1963, pp. 225-229
Technical articles
- AE Patak and J. Baldwing: Pelvic limb musculature in the emu Dromaius novaehollandiae: Adaption to high-speed running Journal of Morphology 238, 1998, pp. 23-37
- SK Maloney and TJ Dawson: The heat load from solar radiation on a large, diurnally active bird, the emu (Dromaius novaehollandiae) , Journal of Thermal Biology 20, 1995, pp. 381-387
- SK Maloney and TJ Dawson: Thermoregulation in a large bird, the emu (Dromaius novaehollandiae) , Comparative Biochemistry and Physiology, Biochemical Systematic and Environmental Physiology, 164, 1994, pp. 464-472
- SK Maloney and TJ Dawson: Ventilatory accommodation of oxyben demand and respiratory water loss in a large bird, the emu (Dromaius novaehollandiae), and a re-examination of ventilatory allometry for birds . Physiological Zoology 71, 1998, pp. 712-719
- EL Taylor et al .: Genetic evidence for mixed parentage in nests of the emu (Dromaius novaehollandiae) , Behavioral Ecology and Sociobiology 47, 2000, pp. 359-364.
- RJ McGrath and D. Bass: Seed dispersal by Emus on the New South Wales north-east coast , Emu 99, 1999, pp. 248-252
Web links
- Videos, photos and sound recordings for Dromaius novaehollandiae in the Internet Bird Collection
- Dromaius novaehollandiae inthe IUCN Red List of Threatened Species 2013.1. Listed by: BirdLife International, 2012. Retrieved October 20, 2013.