Social Behavior

Bighorn sheep are social animals that live in groups. Group living can reduce the risk of predation. Groups contain more eyes and ears, allowing members to spend less time surveying for predators and more time feeding. Two studies of this phenomenon found that increases in group size of up to six (or more) bighorn sheep conferred an advantage, shown by a decline in the time an individual spent exhibiting vigilant behavior.

Another advantage of group living is the dilution effect: the probability that an individual is the one killed should a predator make a successful attack is less than if an individual is alone.

Group size is limited by the distribution of sufficient forage; the largest groups occur during the peak of the growing season and group size shrinks to a minimum during the hot season.

Below are videos demonstrating several different types of social behavior in desert bighorn sheep.

• Head-butting behavior in both ewes and rams (YouTube). This behavior is a competition to establish dominance within the herd. Video shared with permission from Daniella Dekelaita, Oregon State University.
• Interspecies interaction between ewe and raven, as well as a lamb suckling (YouTube). The ewe scaring away the raven could be interpreted as a behavior to protect her lamb. Video shared with permission from Daniella Dekelaita, Oregon State University.
• A dominant ewe keeps other ewes away from water (YouTube) The dominant ewe happens to be part of a CDFW study and has a GPS and VHF collar and an ear tag to uniquely identify her. Video shared with permission from Daniella Dekelaita, Oregon State University.
• Interactions between ram and lamb, as well as ram dominance behavior (YouTube) Video shared with permission from Daniella Dekelaita, Oregon State University.
• As they forage bighorn will continuously interact with one another (YouTube) One of the ewes is part of a CDFW study and has a GPS and VHF collar and 2 ear tags. Video shared with permission from Daniella Dekelaita, Oregon State University.
• Two ewes drink water while pushing each other (YouTube). The two collared ewes are part of a CDFW study. They have a GPS and VHF collar and 2 ear tags to uniquely identify them. Video shared with permission from Daniella Dekelaita, Oregon State University.

Ecological niche, habitat selection, habitat variation, surface water use, life history, and nutritionall also play important roles in desert bighorn natural history. CDFW has learned much about desert bighorn behavior through our monitoring efforts.