How Have Bighorn Sheep Adapted to Their Environment?


Bighorn sheep

On a recent trip to the Colorado Rocky Mountains, I saw a large herd of desert bighorns.  I was amazed by the way that they had adapted to their surroundings as they ascended the cliff faces.

The horns on bighorn sheep are useful for protection from predators and are also used to get into difficult plants such as cacti.  Bighorn sheep have a soft and hard part on their hooves to allow them to grip cliff faces.

I wanted to find out some more about what makes these great creatures so adapted to the terrain they live in and have put this information below for you.

For more information on bighorn sheep, here I have written 101 facts you may not know.

How Do Bighorn Sheep Hooves Grip?

Bighorn sheep, although not as agile as mountain goats are very well adapted for climbing and descending the steep terrain that they live.  The distance they can keep from the ground keeps most predators at bay.  Golden eagles will sometimes attack and kill lambs.

The bighorn sheep’s hooves are in two-part so that they can cling firmly to steep and rocky terrain.  The hooves are spongy in the center with a hard outer edge.  As a result, the padded, soft, rubbery soles help them to keep their traction and balance as they move up sheer rock faces and through the uneven and slippery ground. 

The pad feels like the heel of the human foot and digs into the terrain, molding and conforming to the surroundings and helping the bighorn grip.  The harder toenail-like outer hoof snag any slight protrusion in the rock face helping the bighorn grip on surfaces smaller

Tracks

The hoof prints are similar to a deer with hind prints slightly smaller than the fore prints.  Bighorn prints are less heart-shaped, less pointed, have straighter edges and are more splayed than deer prints. 

If the print has been taken from a bighorn descending on soft ground, their claws may sometimes print two dots behind their hoof print. The bighorns walking stride is approximately 18 inches.

Bighorn sheep can clear a jump of 15 foot, but down a steep incline, this can increase to nearer 30 feet.  This enables the bighorn to get away from predators quickly

The bighorns foot axis is between the third and fourth digits, and they walk on the tips of these with the claws taking the weight.  The second and fifth digits are vestigial while the first has disappeared completely.  The two more significant digits are the same size forming the cloven hoof. 

The vestigial third and the fourth digit are used as a brake when descending steep slopes.  The harder outer edge of the hoof makes contact with the ground first.

When the hoofs are off the ground, the cloven hooves are together, but when the sheep are on the ground, then they spread apart with the transfer of the body weight to the foot.  The sole only bears weight on soft ground, where the perimeter skin can sink in.  The hooves spread apart without much resistance.

How Do Bighorn Sheep Deal With Predators?

Bighorn sheep have adapted to live in the western mountainous regions of North America, ranging from southern Canada to Mexico. 

The predators of the bighorn sheep are wolves, coyotes, cougars and occasionally the gray fox, bobcat, lynx, black and grizzly bears, jaguar, ocelot, and the wolverine. However, the bighorn sheep have adapted to their terrain well.

The bighorn sheep use the steep mountainous habitat to their advantage, using ledges sometimes only two inches (five centimeters) wide. 

The use of this terrain is very effective against coursing predators such as wolves and coyotes, but stalking predators such as cougars may be able to overcome this.

Bighorn sheep photo
The magnificent horns can be used against predators

How Do Bighorn Sheep Deal With Wolves?

The steep, rugged terrain is an ideal adaptation to the predation of coursing predators such as wolves.  Wolf predation on other animals such as caribou and moose is much higher as they cannot seek the protection they need from the wolves in mountainous territory. 

When bighorn sheep forage away from escape terrain such as the rocky ridges and into heavily timbered areas, a wolf can cause severe damage to a herd however.

How Do Bighorn Sheep Deal With Coyotes?

After wolves, coyotes are the most successful predator of bighorn sheep.  Coyotes primarily restrict themselves to lambs with most predation appearing to be incidental. 

Coyotes are not thought to be a likely cause of any limits in sheep populations.  As such, they are not considered to be effective predators of bighorn sheep due to the escape plan that the sheep have in the rugged terrain.

How Do Bighorn Sheep Deal With Cougars?

Cougars appear to be the only predators that can decimate a sheeps population even if the sheep are in habitats with escape terrain.  The prey is usually determined and selected by the size. 

The less experienced, smaller cougars select the smaller lambs, with the larger, more experienced adults killing larger sheep.  Rams tired from rutting are also preyed upon by the Cougars. 

Cougars will kill both rams and ewes and can kill any age class.  Cougars are much more likely to prey on bighorn sheep when they live alongside mule deer as this is a great food source for the cougar.

How Do Bighorn Sheep Deal With Golden Eagles?

Golden eagles can be problematic to young lambs with many being killed because of the bird.

Do Bighorn Sheep Have Good Eyesight?

The bighorn sheep have horizontal pupils that help them to look for predators.  The sheep need to be able to see panoramically to detect predators that could approach from different directions.  They also need to be able to see forward clearly so that they can run over rough terrain. 

The horizontal pupils create a panoramic view, wider and shorter than what a round or vertical pupil would be able to see.  Consequently, this will allow the animal to see almost nearly in every direction.  The image quality would also be much better ahead of and behind the sheep. 

The flat shape of the pupil also captures less overhead light and capturing more light from the ground.  Bighorn sheep rotate their eyes so that they stay horizontal to the ground when their heads are up or down. 

The horizontal eyes help to keep the sheep alive by cutting out extra dazzling lights from the sky, giving them a panoramic view and a better image quality.  The bighorn sheep have very wide spaced eyes helping the panorama effect.

For more information on bighorn sheep, here I have written 101 facts you may not know.

Bighorn sheep photo
The horns…The magnificent horns

What Do Bighorn Sheep Use Their Horns For?

To get the attention of a ewe, the rams butt head to compete for their love rival.  This takes the form of butting horns in contests that can take up to 24 hours.  The rams can run at each other at speeds of 40 km/h and can withstand forces up to 800 pounds.

Due to the geometry of the horns, the impact causes side to side vibration at the horn tips.  This allows the horns to draw away the kinetic energy from the brain cavity and dissipate it as heat.  Because of this the bones have been adapted through evolution to suffer little or no injury or structural damage. 

The horn is made from keratin, and a portion of the horn is filled with a thin cortical bone shell containing a foam-like tubular bone.

Female ewes have longer straighter horns as they do not use these in the rut.  The ewes can use their horns to get into spiky cacti to get the nutrients and liquid out of the center.

How Have Bighorn Sheep Adapted To Eating And Drinking?

The bighorn sheep have adapted well to living in the desert heat and the mountainous snow.  Their temperatures can fluctuate several degrees safely, unlike most mammals, for instance. 

In the desert, they will rest in the shade of caves and trees.  Desert bighorn can go for several weeks or months without visiting water in the winter, but in the summer they will usually go to a watering hole every three to five days. 

Bighorn sheep recover from dehydration quickly and can lose up to 30% of their body weight due to dehydration.  This allows the desert bighorn to survive in areas away from predators.

The bighorn sheep has a complex stomach to extract all the essential nutrients out that it needs.  The foliage they eat provides the moisture required. 

The stomach is very complex, having four chambers.  The bighorn does not chew their food much before swallowing it, however.  The plants go into the first chamber of their stomach, which is full of bacteria and other organisms that help break down the plant material as a result. 

The sheep spit up the food before chewing it again.  This then goes into the second, third, or fourth chamber where the water and nutrients are taken out of the food.

For more information on bighorn sheep, here I have written 101 facts you may not know.

Conclusion

Bighorn sheep have some great adaptations to allow them protection from predators and to live in conditions that most animals could not.  Their eyesight is fantastic, and their adapted hooves are perfect for the many environments they live in.

Ever wondered why sheep baa? Find out here in an article I have written.

Bryan Harding

Bryan has spent his whole life around animals. While loving all animals, Bryan is especially fond of mammals and has studied and worked with them around the world. Not only does Bryan share his knowledge and experience with our readers, but he also serves as owner, editor, and publisher of North American Mammals.

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