Rhea
| Rhea | ||||||||||||
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A group of greater rheas ( Rhea americana ) |
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| Systematics | ||||||||||||
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| Scientific name of the order | ||||||||||||
| Rheiformes | ||||||||||||
| Forbes, 1884 | ||||||||||||
| Scientific name of the family | ||||||||||||
| Rheidae | ||||||||||||
| Bonaparte , 1849 | ||||||||||||
| Scientific name of the genus | ||||||||||||
| Rhea | ||||||||||||
| Brisson , 1760 |
The rheas ( Rhea ) or rheas are in South America -based genus or family (Rheidae) of ratites with three types. They all have gray plumage.
Rheas are similar to the African ostrich . Anatomically and taxonomically, however, they differ significantly from the ostriches. The similarity is the result of a convergent evolution . However, they are related to the cockroaches . The typical features of a flat-chested bird include the relatively large eyes and the wide and flat beak. Rheas belong to the characteristic large animals of the grasslands in subtropical and temperate latitudes of South America.
The name Nandu is borrowed from the language of the Guaraní , an ethnic group in Paraguay and northern Argentina.
features
Nandus are so similar in shape to African ostriches that they were also referred to as "South American ostriches" in older literature. There are a few noticeable differences, however. First of all, even the great rhea is much smaller than an ostrich; at a height of 1.4 m, it is only half as large. The maximum weight depends on the respective subspecies. The smallest subspecies can weigh up to 20 kilograms, while a subspecies common in Argentina can weigh up to 50 kilograms.
Rheas have a feathered neck, head and thighs, while these are bare in the ostrich. Like most other ratites, rheas have three toes on each foot, the back toe is missing; in the ostrich there are only two toes. The wings of the rhea are the largest of all ratites. The total of 28 wing feathers (12 hand wings and 16 arm wings) are formed into long, flowing splendor feathers. A rhea cannot fly due to its weight that is far too high, but its wings can be used to keep balance while running fast. In addition, each wing has a sharp claw that can be used as a weapon.
Nandus are not as fast runners as the African ostrich, but they can reach considerable speeds of up to 60 km / h. They are also good swimmers who can easily cross a river.
Foot ( Rhea pennata )
Skeleton ( R. americana )
Feathers ( R. americana )
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voice
The call of the rhea is more like the roar of a big cat than the sound of a bird. Roosters in particular expel it during courtship. Otherwise rheas produce hoarse sounding warning calls and, combined with threatening gestures, a hissing sound.
distribution and habitat
Natural spread
Nandus are native to Argentina , Chile , Paraguay , Uruguay , Brazil and Bolivia - the Darwin rhea is also in the southernmost tip of Peru . They inhabit open, savannah-like habitats , i.e. they inhabit the pampas , the Chaco , the Patagonian lowlands and the Andes plateaus . The greater rhea prefers lower altitudes in warmer climates, while the Darwin rheas can also live at high altitudes up to 4500 m and in the subpolar extreme south of South America.
Free-ranging rheas in Germany
In 2000, three pairs of rheas broke out of a breeding enclosure in Groß Grönau near Lübeck. The animals fled to the nearby, largely natural Wakenitztal on the former inner-German border and multiplied quickly there, despite the weather conditions. Five years later, the stock had grown to over 60 specimens, giving Northwest Mecklenburg an unusual attraction. The current figures (as of December 2018) speak of 566 animals, of which 294 are young, most of them live to the east, some also to the west of the Wakenitz. Legally, the rhea is now considered a species native to Germany i. S. d. 7 Para. 2 No. 7 BNatSchG, since it has survived as a population in the wild and without human help for several generations. In addition, it is a particularly protected species i. S. d. Section 7 (2) No. 13 BNatSchG, so that the rheas living in the wild in Germany enjoy not only the general protection of Section 39 BNatSchG, but also the special protection of Section 44 BNatSchG.
Nonetheless, in 2019, two farmers were given permits to shoot up to 10 rheas each. In total, they shot 17 of the possible 20 rheas.
The authorities and nature conservationists have so far disagreed about how to proceed, as the medium-term effects of the involuntarily introduced neozoa on their environment are disputed.
Way of life
activity
As a rule, rheas are diurnal birds. Only on exceptionally hot days do they sometimes shift their activity into the night in order to be able to rest during the greatest heat of the sun. They are sociable birds that live in groups of five to thirty individuals outside of the breeding season, roosters, hens, and young. Every year at the breeding season the associations break up and the cocks become territorial. Some old males do not return to the groups afterwards, but also live as solitary animals outside of the breeding season. A minimum distance is observed between the individuals within the groups. If two animals come too close to each other, the other is asked to step back by stretching out the head with the beak open and making a hissing sound.
In the pampas, rheas often form mixed herds with pampas deer , guanacos and vicuñas , occasionally even with sheep and cattle. The socialization is for both purposes. The good sense of sight of the rhea and the good sense of smell of the mammals complement each other so that approaching enemies can be recognized earlier.
nutrition
Rheas are omnivores: They prefer broad-leaved plants , but also eat seeds , fruits , roots , insects and small vertebrates . That they also prey on poisonous snakes is a rumor that is uttered again and again, but it is not true. Nandus largely cover their water needs from the liquid content of their food, so they rarely or never have to drink. Like other ratites, rheas regularly swallow gastroliths to break up food in the stomach.
Reproduction
The animals become sexually mature at two to three years of age. The mating season of the birds in their natural range is from September to December.
The rheas are polygamous: a rooster secures a territory and gathers as many hens as possible around it. Competing males are driven away with kicks and bills. At the end there are two to twelve hens in the rooster 's territory, which now begins the courtship . Here he goes around his harem, keeps his wings spread and the neck feathers up, and makes the typical nan-du sound. As a result, the rooster mates with all the hens in his harem.
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The hens lay their golden yellow eggs in a nest pit that is laid out by the rooster. It is a depression in the earth that is about 1 m wide and 12 cm deep. At the end there are 13 to 30 eggs, in very rare cases up to 80 eggs in the nest. After the hens lay the eggs, they move on. If they come across the territory of another rooster, the whole thing is repeated there. The male remains alone and is therefore responsible for the breeding business. During the 35 to 40 day breeding season, it is extremely aggressive towards all intruders of the same or different species. This behavior also affects stragglers among the hens, who only now come to lay their eggs. Since the rooster does not let them into the nest, they have to lay the eggs outside the nest. In almost every rhea territory there are numerous eggs that surround the nest in a ring and rot. This apparent waste, however, has its uses: the rotting eggs attract flies, which serve as food for the indispensable male during brood. Every now and then a pair of two roosters, sitting close to each other, incubate their eggs at the same time and then raise the young together.
After hatching, the young stay with their father for about six months, who watches them carefully and continues to drive any intruders out of the area. The chicks are constantly whistling and can be found quickly if they are lost. If this happens anyway, a Nandu chick can be adopted by other roosters.
Systematics
Fossil rheas are known from the Eocene , questionable fossil finds even suggest an existence in the Paleocene (see fossil history ). This makes rheas one of the oldest known bird families. It is all the more difficult to fathom their external systematics. The external resemblance indicates a relationship with the African ostrich. Other zoologists see rheas as a basal group within the ratites, whose sister group forms a collective taxon of all other ratites. Another hypothesis that has only recently been put forward separates the rheas completely from other ratites and sees them as the sister group of the cockles ; according to the latter theory, all similarities between rheas and ostriches would have arisen in convergent evolution . The molecular system based on DNA comparisons puts rheas in a group with other ratites and cocktails.
The rheas living today are divided into three types:
- Nandu or Greater rhea ( Rhea americana )
- Darwin rhea or small rhea ( Rhea pennata )
- Puna rhea ( Rhea tarapacensis )
Fossil history
The early rheas are often assigned to their own family, Opisthodactylidae. This taxon is named after Opisthodactylus patagonicus , a South American bird of the Miocene , which, unlike today's rheas had a fourth toe - one of several characteristics that are cited as evidence of a common descent of rheas and cockles. The oldest representative, Diogenornis fragilis , from the Paleocene of South America, is also the oldest known ratite. Also in the ancient ostrich Palaeotis weigelti from the Eocene of Central Europe, paleontologists see more similarities with rheas than with ostriches, which would imply a former spread of rheas beyond South America.
The actual rheas (Rheidae) have been fossilized since the Pliocene . The fossil genera Heterorhea and Hinasuri should be mentioned here in particular .
Humans and rheas
Rheas have probably been hunted and their eggs collected and eaten since the colonization of South America. In the Brazilian state of Piauí there are drawings of these birds in caves, the origin of which dates from 12,000 to 8,000 BC. To be dated. In many places a bola was used for hunting . In the 19th century, when there was a worldwide spring trade, rheas were also hunted intensively. Between 300,000 and 500,000 birds were killed annually and in 1872 alone 61 tons of rhea feathers were exported through a single customs post in Buenos Aires. The relatively plain colored feathers were usually not made into hats or stoles by the fashion industry, but tied into feather dusters.
More recently, the skin of the rheas has also been made into leather . This use, the destruction of the landscapes and the sport hunting that also takes place have resulted in both species becoming rarer in their populations.
The area's ranchers claim that rheas eat their animals' grass, and arable farmers fear for their grain. As a result, rheas are often shot or chased away when seen near fields. In addition, they often get caught in the barbed wire fences that surround the farmsteads, suffering serious injuries and dying.
etymology
“Nandu” is derived from ñandu guasu , Guaraní for “large spider”, as the rhea in courtship pose resembles a large spider. An alternative derivation relates to the call that sounds like Nan-Du .
literature
- Mark Cocker, David Tipling: Birds and People. Jonathan Cape, London 2013, ISBN 978-0-2240-8174-0 .
- W. Grummt , H. Strehlow (Ed.): Zoo animal keeping birds. Verlag Harri Deutsch, Frankfurt am Main 2009, ISBN 978-3-8171-1636-2 .
- 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 .
Individual evidence
- ↑ 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. 38 (title of the original English edition: The New Encyclopedia Of Birds. Oxford University Press, Oxford 2003).
- ↑ Mark Cocker, David Tipling: Birds and People. Jonathan Cape, London 2013, ISBN 978-0-2240-8174-0 . P. 18.
- ↑ Small head, big problem: The wave of immigration of rheas. In: Spiegel Online Video. Retrieved June 9, 2018 .
- ↑ Marc Röhlig : Wild rheas live in MeckPomm - so many that they should now be hunted . Bento , December 11, 2018
- ↑ Ulli Kulke : Nandus - an animal immigration problem . Welt Online , January 2, 2010
- ↑ https://m.youtube.com/watch?v=ikimMRluWIo
- ↑ Bagemihl, Bruce: Biological Exuberance. Animal Homosexuality and Natural Diversity , New York 2000, ISBN 0-312-25377-X , p. 623 (with photo of roosters breeding next to each other)
- ^ SJ Hackett et al.: A phylogenomic study of birds reveals their evolutionary history. In: Science . 320, No. 5884, 2008, pp. 1763-1768. doi : 10.1126 / science.1157704 . ( PDF ).
- ↑ del Hoyo, J., Collar, N. & Garcia, EFJ (1992). Puna Rhea (Rhea tarapacensis). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, DA & de Juana, E. (eds.) (2014). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/467080 on September 9, 2015).
- ↑ Mark Cocker, David Tipling: Birds and People. Jonathan Cape, London 2013, ISBN 978-0-2240-8174-0 . P. 19
- ↑ Mark Cocker, David Tipling: Birds and People. Jonathan Cape, London 2013, ISBN 978-0-2240-8174-0 . P. 19
- ^ Antonio Guasch: Diccionario Castellano-Guarani, Ediciones Loyola, Asuncion 1978
