Every December near the holidays, I take a trip to Wyoming to film and study Bighorn Sheep (Ovis Canadensis). It’s always a fun adventure and this year was no different. Bighorns are a member of the mountain sheep group consisting of three species, the Bighorn Sheep, Dall Sheep and Stone Sheep. There is one other member of this group, the Siberian Snow Sheep but it’s not found in North America.
Wild Sheep crossed the Bering Land Bridge from Siberia into Alaska about a million years ago. They have spread throughout the western half of the country ranging as far south as the Baja of California. These ancient wild sheep diverged into the modern day Dall Sheep and Stone Sheep that lives in Alaska and northwestern Canada and the Bighorn which thrives in the Rocky Mountains all the way to Mexico.
I’m always amazed by the size of these sheep. You might think they look really large but when you get up close to them I’m always struck by how short. They are only about 35 inches tall at the shoulder. That is just under 3 feet. Which makes sense. The Bighorns scamper across snow and ice covered mountain cliffs in search of food and to escape predators, so having a low center of gravity is essential. They may be short but they sure are stocky. An adult male can weight over 400 pounds. Some really big boys can weigh up to 500 pounds.
Both the males, called rams, and the females, called ewe, have horns with the males being much larger than the females. The males horns constantly grow to form a tight circle. At about 5 or 6 years of age the male’s horns are often large enough to complete the circle. At this point the ram is referred to as a full-curl ram. You can actually see the growth rings on the horns. There are many thin lines indicating growth, much like a tree. But there are also larger, thicker lines which mark each year. So you can quickly count the thicker rings to estimate the age of a ram.
A ram’s horns can weigh up to 30 pounds. Remember these are not antlers but rather true horns and don’t fall off each season. They have a boney core with an exterior that continues to grow. It’s the horns that give them their common name and is also at the center of males elaborate mating ritual. The horns play such an important role in a rams life that at full size the horns can weight about the same as all the bones combined in a males body.
Just about everyone knows about how male Bighorns of similar size will challenger each other to a head butting contest. I’ve seen it many times and I still smile every time. One male will walk up to another male and bump his body up against the other male. If the advancing male doesn’t get any response he will use one of his front legs to kick the belly or worst yet the private parts of the other male to illicit a response.
This might go on for several minutes and many kicks. Often the other male will kick the challenger back. They exchange front leg kicks for a couple minutes before one backs up and stand and stares at the other. Their eyes get all buggy and they rear up and charge towards each other. One holds their head to the left and the other to the right as they charge. How they decide who turns which way is not known. Suddenly they crack their heads together which sounds like a gun shot and echoes off the mountain walls.
The impact is often so forceful that it knocks them off their hind feet. Usually right after the impact they need to shake their heads as if to shake off the impact. Usually they don’t bang heads together for at least a few minutes afterwards.
Usually these head butting challenges are only between equally matched rams. Only now and then does a big boy go head to head with a smaller ram. Bighorns live in herds comprised mainly of the females and their offspring. During the rut, the males move around from herd to herd looking for females who are ready to mate. This is when the challenges happen and we see competing rams head butting. And this is always the opportunity I am looking to document. Until next time…
Stan Tekiela is an author / naturalist and wildlife photographer who travels the US to study and photograph wildlife. He can be followed on www.facebook.com and twitter.com. He can be contacted via his web page at www.naturesmart.com