Desert bighorn sheep
Desert bighorn sheep | |
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In Anza-Borrego Desert State Park, California | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Artiodactyla |
Family: | Bovidae |
Subfamily: | Caprinae |
Tribe: | Caprini
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Genus: | Ovis |
Species: | |
Subspecies: | O. c. nelsoni
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Trinomial name | |
Ovis canadensis nelsoni Merriam, 1897
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The desert bighorn sheep (Ovis canadensis nelsoni) is a
The trinomial of this species commemorates the American naturalist Edward William Nelson (1855–1934). The characteristics and behavior of the desert bighorn sheep generally follow those of other bighorn sheep, except for adaptation to the lack of water in the desert. They can go for extended periods of time without drinking water.
The desert bighorn sheep is the state mammal of
Distribution
The range of the desert bighorn sheep includes habitats in the
Populations of the desert bighorn sheep declined drastically with European colonization of the American Southwest beginning in the 16th century. These declines were followed by a period of population stabilization ascribed to conservation measures.[6] As of 2004, desert bighorn sheep numbers remained extremely low, although the overall population trend had increased since 1960.[6]
Characteristics
Desert bighorn sheep are stocky, heavy-bodied
Both sexes develop horns soon after birth, with horn growth continuing more or less throughout life. Older rams have curling horns measuring over three feet long with more than one foot of circumference at the base. The ewes' horns are much smaller and lighter and do not tend to curl. After eight years of growth, the horns of an adult ram may weigh more than 30 pounds.[7] Annual growth rings indicate the animal's age. The rams may rub their own horns to improve their field of view.[7] Both rams and ewes use their horns as tools to break open cactus, which they consume, and for fighting.[8]
Desert bighorn sheep typically live for 10–20 years.
Desert adaptations
The desert bighorn has become well adapted to living in the desert heat and cold and, unlike most mammals, their body temperature can safely fluctuate several degrees. During the heat of the day, they often rest in the shade of trees and caves.[8]
Southern desert bighorn sheep are adapted to a desert mountain environment with little or no permanent water. Some may go without visiting water for weeks or months, sustaining their body moisture from food and from rainwater collected in temporary rock pools. They may have the ability to lose up to 30% of their body weight and still survive. After drinking water, they quickly recover from their dehydrated condition. Wildlife ecologists are just beginning to study the importance of this adaptive strategy, which has allowed small bands of desert bighorns to survive in areas too dry for many of their predators.[8]
Social life
Desert bighorn sheep are social, forming herds of eight to 10 individuals; sometimes herds of 100 are observed.[7]
Rams battle to determine the dominant animal, which then gains possession of the ewes. Facing each other, rams charge head-on from distances of 20 ft (6.1 m) or more, crashing their massive horns together with tremendous impact, until one or the other ceases.[8]
Desert bighorn sheep live in separate ram and ewe bands most of the year. They gather during the
Conservation status and trends
The number of desert bighorn sheep in North America in prehistoric times is unknown, but most likely was in the tens of thousands.
In 1939, after intense lobbying by Frederick Russell Burnham and the Arizona Boy Scouts, President Franklin D. Roosevelt signed a proclamation to establish two desert areas in southwestern Arizona to help preserve the desert bighorn sheep: Cabeza Prieta National Wildlife Refuge and the Kofa National Wildlife Refuge.[11][12] In 1941, the San Andres National Wildlife Refuge in New Mexico was added.[13]
State | 1960 | 1993 | 2018[14] |
---|---|---|---|
Arizona | 3,000-3,500 | 6,000 | 5,000-5,500 |
California | 2,140-2,450 | 4,300-4,325 | 5124 |
Colorado | 0 | 475 | 540[15] |
Nevada | 1,500-2,000 | 5,294 | 10,300 |
New Mexico | 400–500 | 295 | 1,200 |
Texas | 25 | 401 | 1,500 |
Utah | Remnant | 2,200-2,250 | 2,900[16] |
Total | 7,065-8,475 | ~19,000 | ~26,800 |
Desert bighorn sheep populations have trended upward since the 1960s. The upward trend was caused by conservation measures, including habitat preservation. In 1980, desert bighorn sheep populations were estimated at 8,415-9,040. A state-by-state survey was conducted a few years later and estimated the overall US desert bighorn sheep population at 15,980. The 1993 estimate of the population is 18,965-19,040. The results of the state-by-state survey are shown to the right.[6]
In Southwestern Utah, desert bighorns were largely
In southern California, by 1998, only 280 individuals of the peninsular bighorn sheep population remained, and that population was added to the list of the United States' most imperiled species.
In southern Texas, desert bighorn sheep conservation began in 1973 with the release of seven
In popular culture
In 2023 the desert bighorn was featured on a
References
- ^ a b "NatureServe Explorer 2.0. Ovis canadensis nelsoni". explorer.natureserve.org. Retrieved 21 April 2023.
- ^ "Bighorn Sheep (Ovis canadensis nelsoni)" (PDF). Desert Renewable Energy Conservation Plan. California Energy Commission. Archived from the original (PDF) on 2016-09-27.
- ^ "Nevada Facts and State Emblems". Nevada State Legislature. Retrieved 2021-09-10.
- PMID 29899578.
- ^ "Mammals". Capitol Reef National Park. US National Park Service. Retrieved 2024-04-11.
- ^ a b c d e f McCutchen, H.E. (1995). "Desert Bighorn Sheep" (PDF). In Stohlgren, T.J. (ed.). The Interior West. In: Our Living Resources: A report to the nation on the distribution, abundance, and health of U.S. plants, animals, and ecosystems. Washington, D.C.: U.S. Geological Survey. Archived from the original (PDF) on 2007-10-31.
- ^ a b c d e f g "Joshua Tree - Desert Bighorn Sheep". 2006-08-10. Retrieved 2012-01-21.
- ^ a b c d e f "Desert Bighorn Sheep of Cabeza Prieta NWR". Cabeza Prieta National Wildlife Refuge. U.S. Fish and Wildlife Service. Retrieved 2007-08-14.
- ^ "Desert Bighorn Sheep Facts". California Department of Fish and Wildlife. Retrieved 2016-10-08.
- ^ Buechner, H.K. (1960). The bighorn sheep in the United States: its past, present, and future. Wildlife Monograph 4.
- ^ Edward H. Saxton (March 1978). "Saving the Desert Bighorns" (PDF). Desert Magazine. 41 (3). Retrieved 2008-04-27.
- ISBN 978-1-4120-0901-0.
- ^ "San Andres National Wildlife Refuge home page". United States Fish and Wildlife Service. Retrieved 2009-01-18.
- ^ "State Status Reports" (PDF). Desert Bighorn Council Transactions. 55. 2019.
- ^ "Colorado Desert Bighorn Sheep Post-hunt Population Estimates" (PDF). Colorado Parks and Wildlife. 2018.
- ^ "Utah Bighorn Sheep Statewide Management Plan" (PDF). Utah Division of Wildlife Resources. 2018.
- ^ National Park Service, "Bighorn Sheep," Zion National Park.
- ^ "Endangered Peninsular Bighorn Sheep". Bighorn Institute. Archived from the original on 2009-01-30. Retrieved 2009-01-18.
- ^ Lee, Mike (March 23, 2008). "Bighorns facing smaller habitat - Federal agency wants to reduce protected area by more than 50%". San Diego Union Tribune. Archived from the original on February 28, 2017. Retrieved February 28, 2017.
- ^ a b c d "Desert Bighorn Sheep". Texas Parks and Wildlife - Wildlife Management in West Texas. Texas Parks and Wildlife. Retrieved 26 October 2020.
- ^ "Desert Bighorn Sheep 2020-2021 Seasons & Regulations". Texas Parks and Wildlife - OUTDOOR ANNUAL HUNTING, FISHING AND BOATING REGULATIONS. Texas Parks and Wildlife. Retrieved 26 October 2020.
- ^ Wu, Gwendolyn (9 August 2020). "3 state employees dead in helicopter crash in West Texas". Houston Chronicle. Retrieved 26 October 2020.
- ^ "Postal Service Spotlights Endangered Species". United States Postal Service. April 19, 2023. Retrieved May 11, 2023.
External links
- Desert Bighorn Council — Scientific organization for biologists working with desert bighorn sheep.
- Arizona Desert Bighorn Sheep Archived 2007-09-17 at the Wayback Machine — video about desert bighorn sheep in Arizona.
- California Department of Fish and Game: Desert Bighorn Sheep Facts