Bighorn Sheep
Kristen Mayers
WIS 4943
What Will Be Covered:
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Introduction
Background Information
Ecology
Management
The Future
Current Event
Introduction: Classification and
Taxonomy
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Order-Artiodactyla
Family- Bovidae
Genus- Ovis
Species- canadensis
7 subspecies:
- O. c. auduboni (Extinct)
- O. c. californiana (California Bighorn)
- O. c. canadensis (Rocky Mountain Bighorn)
- O. c. cremnobates (Peninsular Bighorn)
- O. c. mexicana (Mexicana Bighorn)
- O. c. nelsoni (Nelson Bighorn)
- O. c. weemsi (Weems Bighorn)
Map: From Hall’s The Mammals of North America, Volume II, 1981. Based on
Cowan
Introduction: Range
Range: Canada, Northwestern North America, Mexico
Introduction: Origin
• History
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discovered by Lewis and Clark around 1805
Ovis canadensis auduboni (Audubon’s Mountain Sheep)
Range: Western Dakotas and E. Montana
extinct in late 1890s
Introduction: Physical Characteristics
- Males and Females have horns
(Rams are bigger)
- Large muscular bodies
- Brown coats (change color)
- Distinct white rump patch
- White muzzle
- Dark brown tail
- great eyesight
Introduction: Identification
• Weight
– Males (Rams) 119-127kg
– Females (Ewes) 53-91 kg.
• Length (head to tail):
– Rams 160-180 cm
– Ewes 150 cm
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Physical Characteristics
Horns:
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Curved *big distinction* (slight in Ewes)
Light brown in color
found on both males and females
show ranking in males
Desert species- wider
Horns consist of a bony core with a permanent sheath of keratin- Sheaths grow from the base
Physical Characteristics
• Pelage:
– Dark Brown
faded brown
• White during winter
– Two coats
1.) brittle guard hairs
2.) fleece underfur (this
sheds)
Introduction: Value & Hunting
(legal and conservation status)
• Big game species in N. America
– Ecotourism
• Food, clothing
– Native Americans
• least concern
– IUCN Red List
Ecology
• Reproduction and courtship:
– Ewes estrus cycle ~ 28 days
– males can breed as young as 6 months
– females produce 1 lamb (twins uncommon)
• fertility decreases with age
• gustation around 175 days ( 6 months)
– Courtship:
• flehmen
• licking
• rubbing bodies and horns
– Rut:
• August-November (Desert)
• October- January (Rocky Mountain and California)
– Social groups
• Bachelor groups= Males
• Nursery groups =Females stick with other females,
lambs and sub-adult males
– Females isolate themselves
• with proper food availability
– Lambs
• usually single (twins not common) *have been
recorded
• weigh between 3.5-5 kg
• walk within hours
• weaned by 6 months
– stay with mom first year
• Survival and longevity
• all depending on limiting factors, disease, predation,
drowning ect.
– males up to 12 years
• more aggressive during rut
– Females up to 15 years
Ecology: Behavior
• Communication
– Males fight during rut
• Head butts (usually not to the death)
• Tongue licks and body kicks, “low-stretch” posture
• Fighting technique
• Interspecific interactions
– mule deer
– cattle, horses, domestic goats
– humans
• Predators
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Mountain Lions
Wolves
Bobcats
Coyotes
Golden Eagles
• lambs
• Response to humans
– Minimal direct interaction
– Accidents
– Urbanization and development
• casing habitat fragmentation
• disturbance
Ecology: Populations Biology
• Population dynamic
• Growth (K)
• Limiting factors
– small numbers in herds
– Cattle (domestic sheep)
• Pneumonia (case study)
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Harsh winters
Fire suppression
Poaching
Habitat loss and degradation
roads
Urban Development
Ecology: Population Dynamic
continued
• Competition
– domestic livestock
– introduced animals
– invasive plants
• Tamarisk- “salt cedar”
• Harvest:
– Super slam
– Hunting season
• archery (Dec-Jan)
• fire arms (Aug- Oct.)
– Ram hunting
• common
• distinguish between
male and female
Disease and Parasites
• Disease
– Pneumonia
• cattle, domestic sheep
– Chronic sinusitis
– psoroptic scapies
– blue tongue
• Weather
– can withstand cold temperatures
– range elevation
• 800 m to 2500 m
• changes from winter to summer
– double layered coat
• insulation
• protection
• Starvation and malnutrition
–competition
–lack of food during the winter
• select browse
–no waterhole presence
Ecology: Habitat
• Food:
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shrubs
forbs
grasses
cacti (desert subspecies)
water
• Water:
– summer
– desert species can go 5-15 days without water
Management
• Population Management
– Capture
• more research
– Translocation
• is it feasible and a successful approach?
– Disease Investigations
Management
• Habitat Management
– Restoration
– Corridors
• reduce car fatalities
– Water management
– Removal of invasive plant species
Management
• Ranching– on going battle with ranchers and conservationists
– domestic livestock
• disease
– fencing
• mortality
• injury
• Damage control
– limiting interactions with domestic livestock
– fencing at least 10ft high and 2 feet off ground
Case study:
Who does the future look for Bighorn
Sheep?
• Population outlook
– overall, the future looks bright
• decrease interactions with domestic livestock
• more management implications
• Management programs
Current event
Resources:
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Idaho Park & Game. Bighorn Sheep Management Plan. 2010
Cole, Ken. Are Domestic Sheep responsible for the Bighorn Sheep Die-off in the
Mojave? The Wildlife News. 2013
Kauffman Lab, “Teton Bighorn Sheep Project.” Wyoming Cooperative Fish and
Wildlife Research Unit. http://www.wyocoopunit.org/index.php/kauffmangroup/search/teton-bighorn-sheep-project/ .
Super Slam of North American Big Game. Bighorn Sheep.
http://www.superslam.org/know-your-game/desert-bighorn-sheep
Enk, Terrence A., Picton, Harold D., Williams , James S. Factors Limiting a Bighorn
Sheep Population in Montana Following a Die-off. Norwest Science. Volume 75,
No. 3. Northwest Scientific Association. 2001.
Dewey, Tanya., Ballenger, Liz. University of Michigan- Museum of Zoology.
http://animaldiversity.ummz.umich.edu/accounts/Ovis_canadensis/ . 2013.
• Foreyt, William J., Jenkins, E.J., Appleyard, G.D. TRANSMISSION OF
LUNGWORMS (MUELLERIUS CAPILLARIS) FROMDOMESTIC GOATS TO
BIGHORN SHEEP ON COMMON PASTURE. Journal of Wildlife Diseases.
Volume 45 (2). pg. 272-278. Wildlife Disease Association. 2009.
• The IUNC Red List of Threatened Species. Bighorn Sheep.
http://www.iucnredlist.org/details/full/15735/0. 2013.