Arctic Wildlife Primer #2 - Marine Mammals and Land Lovers
As their name suggests, marine mammals depend on the ocean environment for survival. They actually have it a little easier cold-wise than true land animals like Arctic foxes, who battle terrestrial temps as low as -50 C versus the -2 C maximum low in the ocean where seals swim. The biggest issue for marine mammals is their need for fresh air. They need tough skulls and thick skin for breaking through the ice to suck a little O2!
Though many whales visit the Arctic, only a few species stay for the duration. Bowhead, beluga and the narwhal are the only true, year-round Arctic whales. You can recognize them by their lack of dorsal fins, which evolution decided would get in the way while skimming under the ice and popping up for air. Other whales you might see in Arctic waters include fin, humpback, minke, pilot, and even blue whales in coastal Greenland. Killer whales, which are really big dolphins, are also known to prowl the ice pack.
Ringed, bearded, harp and hooded seals all live in the Arctic. Seals use their blubber and a highly specialized blood-warming system to stay cozy in near-freezing water. Polar bears, killer whales and killer humans are their natural predators.
Walruses are Arctic ice dwellers. They live on floes in the moving ice pack and at the ice edge, though they’ve been known to haul onto land when ice is scarce. These animals are bottom-feeders that like shallow waters, where they use their whiskers and tusks to feel around for food. The Atlantic walrus hangs out in the northern Davis Strait, the north coasts of Greenland, Svaldbard, Novaya Zemlya, the Laptev Sea, as well as in the Bering and Chukchi seas.
Polar bears are considered more marine mammals than land mammals. Though they live on both land and sea, they spend most of their time on ice floes and in the water, and they depend mostly on seals for food.
Though the Arctic is made up of ice, tundra and permafrost – where only the surface thaws in the summer – plants bloom and insects swarm during the brief and sunny summer. The nearly continuous daylight from May to July gives land mammals and migratory birds the opportunity to feast, breed and make merry before the polar night sets in again.
Around 40 species live there, but only 12 or so species live in the far north year-round. With air temperatures colder than water temperatures and 24 hours of winter darkness, land mammals must be extremely well adapted to survive the Arctic.
One of the cold-weather strategies is: Be big. To help reduce heat loss, polar versions of animals are bigger and they have shorter limbs, more fur and blubber. Bigger animals have a greater body surface to mass ratio, which helps retain heat. Only big animals roam in the Arctic winter, and they often huddle in groups or herds to keep warm.
Small animals go underground – or at least under the snow – and live on plant roots and other things that keep them from surfacing. Food is hard to find in the winter. Except for the Arctic Ground Squirrel, who snuggles in communal burrows, none of these little guys actually hibernate.
Terrestrial critters can be divided into the following categories: hunters, grazers and browsers.
Hunters range from small predators like Arctic fox to big hunters like the Gray wolf, which is the biggest and baddest wolf anywhere at 80 kg (175 lb). Grizzly, or brown, bears and polar bears are the largest predators in the Arctic, and grizzlies in particular are not very social. Grizzly bears roam open areas like tundra, and their diet varies depending on the available seasonal menu.
Besides their white fur and black skin, polar bears differ from Grizzlies in that they are as much a marine mammal as a land mammal. They’re Olympic-worthy swimmers and travel from tundra, fast ice and pack ice in search of food like ringed and bearded seals, as well as an occasional whale calf. They’re not too picky – they also eat fish, plants, small animals and birds.
Grazers and browsers are vegetarians. They travel huge distances to find enough forage to survive the Arctic winter. Caribou (reindeer), moose and musk ox are the primary herd animals. The North American Caribou is the only truly Arctic species of grazer/browser, and they migrate in huge groups of 50,000 to 500,000! Musk ox gather in herds of 12 or more, and they like the tundra. Moose prefer marshy areas with a little tree cover.
Don’t forget the little fellows, like lemmings, who are common in the far north of Canada and Greenland. They eat grass and Arctic willow leaves, and they look like rat-sized hamsters. They’re well-adapted to living under the snow – their big claws are all the better for digging, plus their short tails, blunt snout, small ears hidden in fur and tiny eyes do great in the cold. Can't We All Just Get Along?
That’s a wonderful sentiment, but it depends on your perspective. The Arctic food chain includes predators and prey – meaning, some must sacrifice so that others may live.
An even bigger issue than who’s for dinner is the role of humans in the Arctic. With human interaction resulting in: oil reserves being mined from places like Prudhoe Bay; a huge pipeline that sits precariously on permafrost and slices through grazing territory of caribou; prospective drilling in the Arctic National Wildlife Refuge; the hunting of ‘at risk’ animal populations by indigenous peoples; and polar ice melting at an alarming rate… the Arctic is a sensitive and controversial place. For such a cold place, its future stirs up some heated discussions!