Bighorn sheep

from Wikipedia, the free encyclopedia
Bighorn sheep
BigHorn Sheep in Alberta CA.jpg

Bighorn sheep ( Ovis canadensis )

Systematics
without rank: Forehead weapon bearer (Pecora)
Family : Horned Bearers (Bovidae)
Subfamily : Antilopinae
Tribe : Goatsies (Caprini)
Genre : Sheep ( Ovis )
Type : Bighorn sheep
Scientific name
Ovis canadensis
Shaw , 1804

The bighorn sheep ( Ovis canadensis ) is a wild sheep that lives in western North America . It is a predominantly mountain-dwelling species, but there are also populations living in deserts and other arid regions.

features

Bighorn sheep (Ovis canadensis canadensis) in Banff National Park

Bighorn sheep reach a head body length of 150 to 180 centimeters, to which a 10 to 15 centimeter long tail comes, and a shoulder height of 80 to 100 centimeters.

The weight varies from 35 to 140 kilograms and depends on gender and habitat - males are always significantly heavier (average 120 kilograms) than females (average 70 kilograms) and desert bighorn sheep are smaller than the mountain-dwelling animals. This means that bighorn sheep are much larger and heavier than European wild and domestic sheep .

The fur is from dark brown to beige, almost white, colored differently depending on the subspecies or lines. The Rocky Mountains bighorn sheep has dark brown fur in summer that fades to gray-brown in winter. In southern populations, depending on the region, the fur is brown or light beige all year round.

Both sexes have horns, but those of the females are much smaller and protrude backwards like a saber - they never twist. The horns of the males are massive and twist backwards over the ears, then downwards and forwards. In older males, the horns begin a second twist. In old males, the horns can weigh 14 kilograms and extend for more than 80 centimeters.

distribution and habitat

Distribution map of the bighorn sheep

Bighorn sheep are found in southwestern Canada , the western United States, and northwestern Mexico . In Canada, their distribution area includes the south of British Columbia and Alberta , in the USA they inhabit the western parts of the country (approximately to North Dakota and New Mexico ) and in Mexico they live on the Baja California peninsula and in the northern regions from Sonora to Coahuila .

Bighorn sheep are predominantly mountain dwellers. They are commonly found on grassy mountain slopes near rocky cliffs. In summer they occur at altitudes up to over 2500 meters above sea level, in winter they migrate to lower regions. Desert bighorn sheep, in contrast, are native to deserts and other arid habitats.

Way of life and food

Bighorn sheep are mainly diurnal animals that are well adapted to life in the mountains. They are excellent climbers and good swimmers. They live in groups of around 10 animals that are separated according to sex. Only in winter can groups of up to 100 animals come together.

Bighorn sheep in the mountains

In the groups of males a strict hierarchy develops , which depends primarily on the size of the horns. If two males have roughly the same horn size, fights occur in which they attack each other with their heads down and bump their heads together. The massive horns absorb the force of the impact, so injuries in the fights are rare. Sometimes there is also homosexual behavior in groups of males: The dominant male plays the role of an old ram, a subordinate male that of a female willing to mate.

The diet of these animals consists mainly of grass. They also eat herbs and other plants.

Reproduction

The mating takes place mainly in autumn. At this time, the fighting between the males intensifies. These fights - with five clashes per hour - can drag on for more than 24 hours. Females naturally prefer males with larger horns, but they sometimes mate with several bucks in a row.

Head of a cub

After a gestation period of five to six months, a single lamb is usually born. In contrast to European sheep, twin births are very rare exceptions. The lamb is suckled for about six months. Females can be sexually mature at one year of age, but rarely mate before the age of two or three. Males usually do not become strong enough to mate with a female until they are seven years old.

The service life can be over twenty years; Aries usually die much earlier than females because of the exhausting fighting.

Systematics

The Baja California - desert bighorn sheep ( O. c. Nelsoni ) is one of the subspecies of the bighorn sheep

The bighorn sheep is a species of the genus of sheep ( Ovis ) to which 19 more belong according to recent taxonomic studies. It is particularly closely related to the Dall sheep of northern North America and the snow sheep of eastern Siberia. The internal systematics and the number of subspecies is controversial. While Richard Lydekker assumed at least 16 subspecies in 1913, Ian McTaggart Cowan distinguished a total of seven on a morphological basis in 1940:

  • The Rocky Mountains bighorn sheep ( Ovis canadensis canadensis Shaw , 1804) is common from British Columbia to Arizona.
  • The California bighorn sheep, ( Ovis canadensis californiana Douglas , 1829) occurs from British Columbia to California and North Dakota.
  • The desert bighorn sheep ( Ovis canadensis nelsoni Merriam , 1897) inhabits desert areas in the southwestern United States.
  • The Mexican bighorn sheep ( Ovis canadensis mexicana Merriam , 1901) is found mainly in northern Mexico. According to the IUCN, this population is endangered ( vulnerable ).
  • The Audobon bighorn sheep ( Ovis canadensis auduboni Merriam , 1901) lived in North Dakota, South Dakota, Montana, Wyoming, and Nebraska. This population has been considered extinct since 1925.
  • The Baja California bighorn sheep ( Ovis canadensis cremnobates Elliot , 1903) inhabits southern California and the northern part of Lower California. ( EN ).
  • The Weems bighorn sheep ( Ovis canadensis weemsi Goldman , 1937) lives in the southern part of Lower California. ( CR ).

The classification according to Cowan was partly adopted, other systematics recognized only six subspecies, in part the Sierra bighorn sheep ( Ovis canadensis sierrae ), which only occurs in the Sierra Nevada and was introduced by Lydekker in 1912, is considered an independent subspecies (after Cowan it is identical to the California bighorn sheep). As early as the 1960s, however, doubts arose about the high number of subspecies, as Cowan's result was based on an insufficient number of individuals. Later anatomical studies assumed, due to strong overlap of the metric features, that possibly no subspecies existed at all. However, some experts also raised individual subspecies to species status. The desert bighorn sheep in the Los Angeles Zoo is known as Ovis nelsoni .

In 1993, a research team led by Rob Roy Ramey started both morphological and DNA analyzes on bighorn sheep. The scientists found that the classification into seven subspecies is inconsistent. They found no particular differences between the four forms of the desert-dwelling bighorn sheep ( O. c. Nelsoni , O. c. Mexicana , O. c. Cremnobates and O. c. Weemsi ) and listed all of them under O. c. nelsoni . In 2016, a DNA analysis of more than 800 bighorn sheep from almost the entire range was published (only the California bighorn sheep ( O. c. Californiana ) was not taken into account). According to this, there are two strongly deviating clades within the species , the Rocky Mountains bighorn sheep ( O. c. Canadensis ) from the Rocky Mountains of the north-western USA and Canada and the Sierra bighorn sheep ( O. c. Sierrae ) from Sierra Nevada match. Both clades separated from a third group, the desert bighorn sheep ( O. c. Nelsoni ) from the southwestern desert regions of the USA and Mexico during the Illinois glacial period from 315,000 to 94,000 years. The desert bighorn sheep, however, shows a high degree of variability with three clearly separable groups, which probably represent the original lines of the bighorn sheep and, according to the authors of the study, should be managed as separate taxonomic units.

Humans and bighorn sheep

The Indians of the Rocky Mountains used to appreciate both the meat and the horns of the bighorn sheep, from which they made numerous tools and ceremonial objects. Before the arrival of white settlers, there were about two million bighorn sheep. That number declined dramatically in the 19th century by white trophy hunters. Infection with diseases from domestic sheep was also a reason for the massive decline in the population. Around 1900 there were still 60,000 bighorn sheep. Although hunting is strictly regulated today, that number has not increased significantly to this day. The species as a whole is listed as not endangered by the IUCN , but individual subspecies are threatened (see above).

The Canadian province of Alberta has named the bighorn sheep as its official representative animal. The desert bighorn sheep is considered a protected population by the United States government.

Zoological gardens

This article or the following section is not adequately provided with supporting documents ( e.g. individual evidence ). Information without sufficient evidence could be removed soon. Please help Wikipedia by researching the information and including good evidence.

The bighorn sheep is relatively common in American zoos. The Rocky Mountains bighorn sheep are increasingly kept in the north of the USA and Canada. In the southern states the Mexican, Nelsons and Baja California desert thickhorns. In Europe only the Sierra Bighorn Sheep is currently kept.

Overview

Rocky Mountains Bighorn Sheep ( Ovis canadensis canadensis ) - Valley Zoo (Edmonton), Calgary Zoo (Calgary), Buffalo Zoo (Buffalo)

Sierra Bighorn Sheep, ( Ovis canadensis sierrae ) - Burgers Zoo (Arnhem), Zoo Praha (Prague), Zoo Plzen (Plzen)

Desert bighorn sheep ( Ovis canadensis nelsoni ) - The Living Desert Zoo & Gardens (Palm Desert), Dallas Zoo (Dallas), Arizona Sonora Desert Museum (Tuscon)

- Nelsons Desert Bighorn Sheep - Los Angeles Zoo (Los Angeles), The Living Desert zoo & Gardens (Palm Desert), San Diego Safari Park (San Diego)

- Baja California desert rickhorn sheep - no zoological keeping

- Mexican desert bighorn sheep - The Living Desert zoo & Gardens (Palm Desert)

The exact assignment of the individuals to the various subspecies or sub-subspecies has yet to be clarified in the zoological gardens, as most animals are only shown under the name of the species.

literature

  • Ian McTaggart Cowan: Distribution and variation in the native sheep of North America. In: The American Midland Naturalist. Volume 24, No. 3, November 1940, ISSN  0003-0031 , pp. 505-580.
  • Ronald M. Nowak: Walker's Mammals of the World. 2 volumes. 6th edition. Johns Hopkins University Press, Baltimore MD et al. 1999, ISBN 0-8018-5789-9 .
  • Rob Roy Ramey II: Mitochondrial DNA variation, population structure, and evolution of mountain sheep in the south-western United States and Mexico. Molecular Ecology 4, 1995, pp. 429-439.
  • David M. Shackleton: Ovis canadensis. Mammalian Species 230, 1985, pp. 1-9.
  • Don E. Wilson, DeeAnn M. Reeder (Eds.): Mammal Species of the World. A Taxonomic and Geographic Reference. 2 volumes. 3rd edition. Johns Hopkins University Press, Baltimore MD et al. 2005, ISBN 0-8018-8221-4 .

Web links

Commons : Bighorn Sheep  - Album with pictures, videos and audio files

Individual evidence

  1. ^ A b Colin Groves and Peter Grubb: Ungulate Taxonomy. Johns Hopkins University Press, 2011, pp. 1-317 (pp. 108-280)
  2. ↑ Hamid Reza Rezaei, Saeid Naderi, Ioana Cristina Chintauan-Marquier, Pierre Taberlet, Amjad Tahir Virk, Hamid Reza Naghash, Delphine Rioux, Mohammad Kaboli and François Pompanon: Evolution and taxonomy of the wild species of the genus Ovis (Mammalia, Artiodactyla, Bovidae). Molecular Phylogenetics and Evolution 54, 2010, pp. 315-326.
  3. ^ Richared Lydekker: Catalog of the ungulate mammals in the British Museum (Natural History). Volume I. London, 1913, pp. 1–249 (pp. 109–129) ( biodiversitylibrary.org )
  4. ^ Ian McTaggart Cowan: Distribution and variation in the native sheep of North America. The American Midland Naturalist 24 (3), 1940, ISSN  0003-0031 , pp. 505-580 (pp. 532 ff)
  5. ↑ David M. Shackleton: Ovis canadensis. Mammalian Species 230, 1985, pp. 1-9.
  6. ↑ Don E. Wilson and DeeAnn M. Reeder: Mammal Species of the World. A taxonomic and geographic Reference. Johns Hopkins University Press, 2005 ( departments.bucknell.edu )
  7. ↑ a b Michael R. Buchalski, Benjamin N. Sacks, Daphne A. Gille, Maria Cecilia T. Penedo and Holly B. Ernest: Phylogeographic and population genetic structure of bighorn sheep (Ovis canadensis) in North American deserts. Journal of Mammalogy 97 (3), 2016, pp. 823-838 doi: 10.1093 / jmammal / gyw011
  8. ↑ Los Angeles Zoo, Botanical Gardens: Sheep, Desert Bighorn (Ovis nelsoni). ( lazoo.org ), last accessed June 24, 2017
  9. ↑ John D. Wehausen and Rob Roy Ramey II: A morphometric reevaluation of the Peninsular bighorn sheep subspecies. Desert Bighorn Council Transactions 37, 1993, pp. 1-10.
  10. ^ Rob Roy Ramey II: Mitochondrial DNA variation, population structure, and evolution of mountain sheep in the south-western United States and Mexico. Molecular Ecology 4, 1995, pp. 429-439.
  11. ↑ US Fish, Wildlife Service: Peninsular bighorn sheep (Ovis canadensis nelsoni). ( ecos.fws.gov ), last accessed on June 24, 2017