Bighorn Sheep
Kristen MayersWIS 4943
What Will Be Covered:• Introduction• Background Information• Ecology• Management• The Future• Current Event
Introduction: Classification and Taxonomy
• 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– 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
Physical Characteristics• Horns:
– 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 coats1.) brittle guard hairs2.) fleece underfur (thissheds)
Introduction: Value & Hunting(legal and conservation status)
• 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– 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)– Harsh winters– Fire suppression– Poaching– Habitat loss and degradation– roads– Urban Development
Ecology: Population Dynamiccontinued
• 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 betweenmale 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:– 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:• 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/kauffman-group/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.
