Species of the Month

Introduction: Summer is road trip season, and many people do a road trip through any of
the western national parks. Most folks have a goal of seeing some wildlife, and one of the
iconic animals of the west is the bighorn sheep. They can be seen picking their way along
sheer cliffs in an amazing feat of agility, but I think more people are impressed by rams
crashing into each other head first as they battle for mating rights.

Scientific name: Ovis canadensis

Kingdom: Animalia (animals)

Bighorn ewe enjoying the view

Class: Mammalia (mammals)

Order: Artiodactyla (even-toed ungulates)

Range: Southern Canada south to Mexico, as far east as Texas

Habitat: Mountain meadows, rocky cliffs, deserts

Bighorn rams

Lifespan: 6-15 years, depending on population status

Diet: Grasses, sedges, forbs

Predators: Mountain lions, wolves, coyotes, bears, lynx

Conservation Status: California bighorn sheep subspecies is listed as endangered.

Bighorn lamb taking a break from frolicking

Other Information: There are three subspecies of bighorn sheep: Rocky Mountain, the most numerous
and widespread; California, which is endangered and can be found in the Sierras; and desert bighorn,
which live in the deserts of the US Southwest and Mexico.

Bighorns use rocky slopes and cliffs to avoid and evade predators. Specially built toes allow them to
navigate along ledges that are only inches wide, and excellent depth perception allows them to
accurately leap from one to another.

Bighorns have a shorter lifespan in dynamic populations with a high birth rate, on average 6 or 7 years.
Those in a more stable population with a lower birth rate tend to live longer, to longer than 10 years.

Ewes lounging at the top of a slope

Bighorns live in segregated herds, males in a smaller herd, while females and lambs (male and female)
form larger herds. The herds mingle during the rut, which takes place in fall and early winter. Lambing
occurs in spring, and newborns are able to keep pace with mom almost immediately.

Sparring for mating rights involves males ramming head first into each other at speeds of up to 20
miles per hour. Horns can weigh up to 30 pounds. The force generated is enough to kill a human. Ram
skulls are made of several plates, like human skulls, but the rams' do not fuse into a single solid piece
of bone. That design lets the plates shift to absorb the shock of the repeated blows. The curl of the
horns might also deflect some of the shock away from the head, while a large tendon connecting the
head and neck helps the head recoil.

Rams battling for a mate (Smithsonian)

This week's information comes from University of Michigan's Animal Diversity Web and
Indiana Public Media. Next week wraps up the energy series with a look at the elephant in the room,
nuclear.