7 Things You Didn’t Know About North American Mammals
About 500 species of North American mammals share the same ancestor as all other mammals on the planet, including humans. It took millions of years for the distinct species to evolve separately, but they arrived on this continent in different ways. Some traveled over the Bering Land Bridge, walking into what is now Alaska and migrating south. These creatures crossed over from Russia during a period of low sea levels some 2,588,000 to 11,700 years ago. Others traveled north along the Isthmus of Panama. Here are some facts you may not have known:
1) Cats were among the first to arrive.
During the Pleistocene Era, some of the first mammals to prowl through the great North American grasslands were early felines, such as the saber-toothed tiger and the jaguar.
2) North America had elephants.
There were at least two types of elephants living in North America during those early years of migration. These included the woolly mammoths, who left so many remains that some are still discovered in many areas of the continent even to this day.
3) Porcupines waddled north from Mexico.
It is not a surprise that armadillos came from the south, but so did the ancestor of the northern-dwelling porcupine, who thrives in the colder climate of the northern hemisphere.
4) Climate change has already killed over half of North American mammal species.
About 11,000 years ago, there was a wave of mass extinction as climate change created an inhospitable environment for many species. We are now beginning to see threats of another wave of extinction, and many species of animals are already diminishing in numbers, such as the polar bear and the Mexican wolf.
5) Geography has an enormous effect on the diversity of North American mammals.
Due to the great variation in the geography of the continent, various species have evolved to survive in different areas. The grasslands support the bison and the prairie dog, while the coniferous forests are home to the whitetail deer and the chipmunk. The position of the continent on the planet has a lot to do with its seasonal changes, and the animals have adapted accordingly. The Arctic fox changes its coat from dark to almost completely white in the winter. The snowshoe hare and the long-tailed weasel do the same.
6) Animals developed different body features to survive.
Mammals have developed in all different shapes and sizes to best adapt to their environments. The Canadian lynx can walk across the surface of snow thanks to its over-sized feet. River otters are streamlined so they can swim and maneuver through water. Fawns are spotted like the sun-dappled forest floor where they lie to hide, and the spots vanish later when the deer grow up, rendering them inconspicuous as they stand against a backdrop of trees.
7) Mammals have an impact on their environment.
The yin and yang of the predator-prey relationship is a very important factor in maintaining a balance in nature. An overabundance of plant-eating prey animals can eat themselves right out of a home. They need predators to keep their numbers in check, to control disease, and keep the population strong and hardy. This is no more evident than in the balance of wolves and moose on Isle Royale, Michigan. For decades, scientists have studied the generations of mammals on the remote island in Lake Superior. In 2018, the wolf pack had dwindled down to a mere two individuals. The cause was due to a lack of diversity in the pack. Because of global warming, outside wolves can no longer migrate across the lake ice. Scientists have begun to replace the pack with wolves moved from Minnesota and other areas to help control the island’s burgeoning herd of moose.