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.

Species of the Month

We're still in Old Man Winter's icy grip for at least another month, so it's the perfect time to feature another critter that thrives in cold, snowy weather. This month we'll take a look at the elusive Canada lynx.

Canada lynx slinking among the vine maples

Scientific name: Lynx canadensis

Kingdom: Animalia (animals)

Class: Mammalia (mammals)

Order: Carnivora (carnivores)

Range: Circumpolar- Canada, northern US 

Habitat: Forest and tundra

Lifespan: Up to 14.5 years

Diet: Snowshoe hares, rodents, birds, fish, carrion

Predators: None known though bears and wolves may prey on kittens

Conservation Status: Listed as threatened under the US Endangered Species Act and endangered by the state of Michigan

The giant feet are visible in this shot (USFWS)

Other Information: The lynx is known for its intricate relationship with the snowshoe hare. The lynx population fluctuates in response to that of the snowshoe hare, with the lynx lagging by about a year in a nine year cycle of boom and crash. The lynx may as well be known as a snowshoe bobcat, as they are similar in appearance. The lynx has large feet that work as snowshoes, allowing it to hunt in the deepest snow. Another difference between the cats is the longer tufts of ear hair on the lynx. Litters are commonly two or three kittens, born April to June. They stay with the mother until the following mating season, almost a year later. Lynxes are solitary creatures, and are mainly nocturnal hunters. While smaller animals are their main prey, they will take a sick or injured deer if the opportunity presents itself.

This shot offers a better view of the ear hair (USFS)

This week's information comes from the University of Michigan's Animal Diversity Web.

Winter Adaptations

As I deal with a pair of winter storms over the course of writing this blog, I am sitting cozy and warm inside my house. How do animals, who don’t live in houses with central heating or furnaces make it through the winter? Some migrate to warmer areas, but those that stay behind have special adaptations that help them cope with the cold and snowy weather.

Many animals go into mega energy conservation mode during the winter because not only do they lack heating systems for their homes, they also lack supermarkets that carry a reliable food source. For herbivores, their plant-based food supply is either dormant (and not producing the nutritious shoots they crave), or buried under snow and ice. Whether warm-blooded or cold-blooded, both need to keep warm to survive. Cold-blooded critters rely on the sun’s radiant heat to stay warm, and this is a challenge when it’s cold outside and the sun isn’t reliable. Warm-blooded critters metabolize food to stay warm- they eat much more than cold-blooded ones. One option to keep up metabolism is to spend energy to search for scarce food. But there are other ways to get by.

Hibernation is probably the first coping mechanism you think of, and it’s quite common in the mammal world. Bears do it, bats do it. What is it, compared to normal sleep? When you go to sleep your body slows down. Breathing and heart rate go down and metabolism slows, and your body temperature cools a bit. Hibernation is an extreme version of this. But to be asleep for weeks or months on end requires quite a bit of sustaining energy, even if bodily functions slow to the point of nearly stopping. That’s why bears go on a feed frenzy each fall, gorging themselves on spawning salmon or high-energy moths if they live in the right place.

NPS graphic of a hibernating bear

For those that don’t hibernate, finding food is a priority. Arctic foxes and snowshoe hares both grow a white coat for snow camouflage. The fox uses its camo to hunt; the hare uses its to avoid being eaten. The bison uses its large head as a snowplow to uncover buried vegetation. Ever wonder what that large hump at its shoulder is? Extra muscles to support all that head.

Snowshoe hare (Montana Fish, Wildlife, and Parks)

Bison plowing for food (NPS)

Preserving body heat is a great way to maximize caloric efficiency. The thick fur coat of a muskox traps body heat. Blubber insulates whales, seals, and walruses. Polar bears have black skin that absorbs heat, and their fur traps heat, including body heat that they radiate.

Walruses (US Fish and Wildlife Service)

Ease of mobility is also an efficiency adaptation. Lynxes and caribou both have large feet that act as snowshoes, making it easier to get around so they burn fewer calories doing so.

Check out the foot on that lynx! (Natural Resources Research Institute)

These are just a few of the many adaptations that make survival possible for warm-blooded mammals. There are others, and there are also adaptations for cold-blooded animals (like a frog with antifreeze in its blood) and plants too! Enjoy your heater for the rest of the winter!