Why are some animals moving north?

I've noticed that more and more animals seem to be moving north these days. This is not the same as the migration (traveling) that some animals do every year when the seasons change, so I asked Henrietta what's going on.

She explained to me that the weather all over the world is quickly changing. This is called global warming or climate change. This means that pollution in the air is trapping heat, and causing the planet to warm up.

Because of this, many species (types of living things) are moving north to find colder places to live. Scientists have noticed that in England, the silometopus spider and the comma butterfly have moved their homes 200-300 km north. In Canada, we can now see over 70 species of tropical fish (like triggerfish and flying fish) in Nova Scotia's waters!

The Altantic White Fish is unimpressed with his new neighbour

"What's wrong with that?" I asked Henrietta. I thought it would be neat to see tropical fish up north! Henrietta told me that this is not a good thing at all, because the species normally living in the north could disappear as more species from the south move in.

For example, as temperatures get warmer, red foxes are moving north into areas where Arctic foxes usually live. Since red foxes are bigger than their Arctic cousins, and the two don't normally live side-by-side, it could be more difficult for Arctic foxes to survive while the bigger red foxes take over.

Arctic fox was never pleased when her cousin red fox came to call

Grizzly bears are also moving north, into areas where there used to be just polar bears. Because of this, we are seeing baby bear cubs that are half grizzly and half polar bear, which could mean that both the grizzly and the polar bear could disappear.

Scientists are continuing to study how changing temperatures are affecting plants and animals all over the world, so hopefully we can find ways to protect species that are at risk.

What happens to leaves during the winter?

As the snow begins to melt, I'm starting to wonder what happened to all the leaves that were on the ground. In fall, leaves turn all kinds of beautiful colours, then fall off the trees and get buried under the snow all winter. Now, they're gone - where did they all go?

Henrietta told me that what happens under the snow is similar to what happens in your compost bin - the leaves decompose.

When leaves die and fall on the ground, they get broken down into tiny pieces by tiny organisms (living things) called decomposers, like earthworms, bacteria, and fungi.

Earthworms in fall

First, the larger decomposers like earthworms use their bodies to break down the leaves into smaller pieces and mix them into the soil. They also eat bits of the leaves. The small pieces of leaves that are left behind can then get broken down by other decomposers like bacteria or fungi.

When the bacteria and fungi feed on the bits of broken leaves, they release the nutrients that were in leaves into the soil. This is very important, because in spring, new plants will use these soil nutrients to grow. It's nature's way of recycling!

But in winter, if it's too cold for me to stay outside, isn't it too cold for the decomposers too? Nope! Even though the air might be very cold, it's actually warmer under the snow (often about +1 to -3 °C). The snow acts like a blanket, keeping the soil warm so that the decomposers can stay active.

Bacteria and fungi, decomposing leaves all winter

That's why, in spring, many of the dead leaves have disappeared - it's nature's way of cleaning up and recycling!

How do animals survive in winter?

Part 3: Nap time

Henrietta and I already talked about how animals survive winter by migrating or adapting, but what else do they do?

Hibernation

Many animals stay active in winter, either by leaving or adapting, but some survive winter by hibernating. Hibernation is like a very deep sleep.

The black bear is a "champion" hibernator - it can sleep 100 days without eating or drinking. How's that for sleeping in? Bears prepare for hibernation by putting on a lot of fat in summer and fall. In winter, a bear stays in its den, rolled up in a tight ball to keep out the cold. Mother bears hibernate tightly curled up with their cubs. A hibernating bear lowers its body temperature and heart rate to conserve energy.

Checking in to the hibernation hotel

Chipmunks also hibernate, but instead of storing fat for the winter, they occasionally wake up to eat nuts and seeds from the reserves they built up in fall.

Frogs and turtles also hibernate. Aquatic frogs (that live in water), hibernate at the bottom of their pond, just on top of the mud or partly buried. Terrestrial (land) frogs hibernate in soil, or in cracks in logs or rocks. Hibernating turtles bury themselves in the mud. Both frogs and turtles slow down their metabolism (everything in their body slows down) so much that they stop breathing and their heart stops beating. Ice crystals even form in their bodies, and these frosty frogsicles and turtlesicles can appear to be dead! However special "antifreeze" proteins prevent their lungs, heart, and other organs from freezing, so they can successfully come back from the dead in spring!

Turtles preparing to hibernate

Many insects go into a sort of hibernation called "diapause" in winter. This is like putting their bodies on "pause" for the winter, and starting again in spring.

All this talk of hibernation is making me sleepy, since hedgehogs also hibernate in winter. We wake up once in a while though, so I'll still be able to update the blog!

How do animals survive in winter?

Part 2: Getting a winter makeover

Last time I visited Henrietta, we chatted about migration. Today I popped over to learn a bit more about a different way animals can survive winter.

Adaptation

Not all animals leave in winter - some adapt. This means they make changes that allow them to survive and stay active in the winter.

Some birds, such as the black-capped chickadee, stick around in winter. To stay warm, chickadees "fluff" themselves up. This traps more air between their feathers, and keeps them warm just like a down-filled blanket may keep you warm. At night, they drop their body temperature - this allows them to use less energy trying to stay warm (it's like turning down a thermostat!).

Chickadees fluffing themselves up for the winter

In winter, deer keep warm by growing special hollow hairs which trap air. They also grow a dense wool-like under-fur and store fat in fall to keep them warm. The fat gives them energy too, since food is harder to find in winter.

Squirrels also grow thicker fur to stay warm in winter. However, unlike deer, they don't search for food in winter. Instead, they feed on large reserves of nuts and seeds that they hid away in fall.

Beavers do the same thing - in fall, they gather branches and store them at the bottom of their pond. When the pond freezes, they don't leave the pond all winter - they bring their food reserves into their lodge (where they live).

Beavers spending winter in their lodge

Look around when you're outside - you may spot some more animals that stay active in winter! More winter survival strategies coming up next time...

How do animals survive in winter?

Part 1: Which way to the beach?

Brrr! When it gets cold outside, people bundle up in big coats and often stay inside their warm, cozy houses... But I've often wondered:  How do animals survive the long, cold winter?

Over a cup of hot chocolate, Henrietta helped me discover one of the things animals can do to survive winter.


Migration

Do your grandparents go to Florida when the weather gets cold? Many different types of animals do the same thing, and "migrate" (travel) somewhere warmer in winter.

Some birds migrate - either in flocks (groups) or alone. Birds can travel great distances, for example, every fall, the Arctic Tern travels all the way to the Antarctic, and every spring, it travels back up to the Arctic again!

Arctic Terns preparing to go south for the winter

How do birds know when to leave and where to go? A combination of changes in the weather, the amount of daylight and the food available helps the birds decide when to leave. Birds amazingly find their way using the sun, moon, stars and even smell to guide them. They also seem to have a "compass" in their brain that allows them use the Earth's magnetic field.

Modern goose migration

Some insects migrate too - Monarch butterflies spend summer in Canada and the Northern US, and in winter, they go to Mexico. (Even though they don't need to, many people in Canada do the same thing!)

Other insects, such as termites and ants, migrate short distances by moving deeper into their underground colonies to escape the frosty world above.

Some fish do the same thing, and move to deeper water in winter. Other fish may swim south.

Finally, a few mammals (such as elk, caribou and bats) migrate in winter to search for food.

Caribou deciding it's time to migrate for the winter

Not all animals migrate, so stay tuned for more frosty animal facts! I think I need another sweater...