Bighorn Sheep (Ovis canadensis) Fact Sheet: Physical Characteristics

Body measurements

Horns

• Both sexes have horns that grow throughout their lives:
• Male horns are massive, curling and diverging.
• Female horns are smaller, thin and curved.
• Horns consist of a bony core with a permanent sheath of keratin. Sheaths grow from the base
• Mountain bighorns have by far the biggest horns. Longest horn length recorded measured 52 inches with a basal circumference of 18 inches (horn tips are often broken, splintered or broomed)
• Clark (1940) reports a weight of 44 lbs (upper skull and horn) for a Canadian Rocky ram
• Growth rings (annuli) are formed in the fall and are associated with hormone and diet changes.
• First visible annulus is 2.5 years.
• Fourth year is the first heavy, dark ring.

Pelage

• Smooth outer coat of brittle guard hairs and short, gray, crimped fleece underfur
• Fur is a pale brown, paler in appearance than other bighorn sheep
• The summer coat is a rich, glossy brown but can fade by late winter
• Female fur is often lighter than the males
• Whitish patch on rump
• Molting usually occurs in June and July. Molting progresses from posterior region with chest the last to shed.

Horns

• Male horns become a full curl by 7-8 years of age and spread of up to 33 inches (up to 30-40 lbs.)
• Female horns are smaller than the rams and never exceed half a curl.

• Compact and muscular body
• Climbing, cloven hooves providing amazing jumping ability
• Acute eyesight

As an adult, a male bighorn sheep's horns are nearly 3 feet across.

Image credit: © San Diego Zoo Wildlife Alliance. All rights reserved.

Image credit: © San Diego Zoo Wildlife Alliance. All rights reserved.

Bighorn Institute website (2002)