Searching for the Sea

A red tide flows from the forest to the sea. It is fall on Christmas Island in the Pacific Ocean. That’s when millions of red crabs migrate. They skitter to the sea to release their eggs. How do they know what to do?

Their timing is linked to rain. The island’s wet season begins in October. The crabs abandon their rain forest burrows. Males travel to the ocean in great numbers. They dig deep burrows and wait for the females to arrive. They mate in or near the burrows. Then the males return to the forest.

Fast Fact:

More than 120 million red crabs transform Christmas Island into a vast moving red carpet as they move together.

The crab migration is also linked to the phases of the moon. During the last quarter of the moon, at the turn of the high tide, the females release their eggs into the ocean. This ensures that most of the eggs reach deep water. Then the females return to their homes. The young grow up in the sea and come to land as adults.

Millions of red crabs make a mad dash to the sea as part of their migration.

07/08/2024 18:06:25

Over the Ice

During winter months on Antarctica, Adelie penguins migrate north. They make their homes on large platforms of ice. Here, there is better access to food. During summer months, the penguins move south to coastal beaches. They look for ice‑free land where they can build nests.

To make these treks, the penguins must follow the sun. But in winter, the sun doesn’t rise south of the Antarctic Circle. So, the penguins chase the ice.

Fast Fact:

The longest
treks for Adelie penguins have been recorded at 17,600 kilometers (10,900 miles).

Sea ice “grows” during the winter and extends out from the shoreline. So, as long as the penguins live at the edge of this ice, they have access to open water.

Adelie penguins chase the sun on their migration.

07/08/2024 18:06:25

The Great Glide

What does an animal do when it doesn’t know its migratory path? Such was the problem for the whooping crane. Near extinction due to hunting and loss of habitat, North American whooping cranes were in danger.

Cranes are excellent navigators. They can follow well-defined paths that young cranes learn from their parents. But by 1941, there were only 15 whooping cranes left in the world. Conservation efforts have brought those numbers up to more than 400 individuals today.

Still, conservationists were faced with a challenge. How do you teach hand-reared chicks their migratory path?

A creative solution was hatched. Young birds were trained to follow ultralight aircraft that guided them along a safe route and showed the birds the “correct” stopovers to use.

These birds are so smart, they only need to be shown once. Having made the southbound trip with their guides, they were able to return on their own. Now, the cranes can pass on their knowledge to the next generation.

Whooping cranes needed a lesson on where to go when they migrated.

Migration Madness

Millions of animals migrate. They use a variety of ways to help them get where they’re going. Some rely on Earth’s magnetic field. Some rely on clues from the land.

Others use the sun, moon, and stars to help them make their way. Still others rely on physical landmarks or scents. Whatever tools animals use, their abilities to migrate help them survive.

07/07/2024 03:07:28

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