The Arctic Tern’s Record-Breaking Global Journey

At True Investigator, we know all about the amazing journeys that animals make in order to find food, avoid harsh weather, or sojourn to the breeding grounds with the rest of their wayfaring brethren. Most recently, we discussed the incredible migrational behavior of the Arctic reindeer, but today, we go a bit farther afield, up into the skies where our avian neighbors rule the roost.

There are many incredible migrations in the animal kingdom. Animals travel by land and by sea, sometimes many thousands of miles over the course of a year, but none is quite as astonishing as the annual journey of another Arctic denizen; the Arctic tern. This small, unassuming seabird weighs little more than a baseball but is known to travel farther in a single year than any other known animal on Earth.

In this article we will travel with the tern as it makes its astonishing migration from the Arctic to the Antarctic and back again; a round-trip annual journey of 40,000 miles or more! So strap yourselves in, explorers, as we travel together on a trek that will take us roughly the circumference of the globe.

The Tiny Arctic Tern

It is possible that many readers will be unfamiliar with the Arctic tern (Sterna paradisaea). It’s no wonder really, of all the seabirds that you might have encountered in your life: penguins, seagulls, or even pelicans, chances are good you’ve never had the pleasure of seeing an Arctic tern up close. Nevertheless, this graceful little bird has found a way to make a name for itself.

The Arctic tern is fairly unassuming by seabird standards, though it can be identified by its sleek body, pointed wings, and distinctive forked tail. During breeding season, adult terns get a bit more color than the usual pale grey of their bodies. At these times, they display a black cap on their heads and bright red-orange beaks and legs.

Arctic terns breed in northern regions around the Arctic Ocean, including parts of Alaska, Russia, Northern Canada, Greenland, and Scandinavia. Their preferred breeding grounds are open coastal areas, tundra areas, or on small, rocky islands where predators rarely venture.

A Journey Between Two Poles

The Arctic tern’s most remarkable feature has to do with the sheer scale of its annual migration. Each year, these birds move between the Arctic, where they breed, and the Antarctic. In essence, they are following the seasonal cycle of summer. On this long journey, there are many stages. The first begins in the Northern Hemisphere.

Spring and Summer
Arctic terns arrive in the far north to breed during the Arctic summer. In this brief period, daylight lasts nearly 24 hours. Insects hatch and fish swim in great shoals near the breeding grounds, and so, food is abundant.

Autumn Migration
After breeding, hatching, and raising their chicks, the terns begin their long journey south. They travel across the Atlantic Ocean toward the Southern Hemisphere.

Southern Summer (Antarctic Waters)
Once they have arrived in the far-flung southern reaches of the world, the Arctic terns will spend several months enjoying the so-called “summer” in Antarctica. Even here, there is a period of long daylight and robust feeding grounds full of prey that will give them the energy they need for the journey back to the north.

Return Migration
At the end of the southern summer, the birds begin the long journey back to their Arctic breeding grounds; thus beginning the cycle anew.

Interestingly enough, by following the sun between the North and South poles, it believed that Arctic terns experience more daylight than any other animal on Earth.

Why Migrate So Far?

The answer is found in the journey itself. When the sun is shining and the world is warm, food is plentiful. This not only allows the terns the opportunity to become amorous but to feed their ensuing hatchlings easily. The great migration allows the birds to take advantage of the most productive feeding conditions available in either of their given territories.

This is partly due to the fact that Arctic and Antarctic regions experience seasonal bursts of marine productivity. Cold ocean currents bring nutrients to the surface, fueling plankton growth, which then supports fish populations. The seabirds feast upon the small fish, crustaceans, and marine invertebrates, as do their hungry young.

Built for Endless Flight

So how are Arctic terns able to make this journey, you may ask? the main reasons have to do with certain physical and navigational adaptations that make such an astonishing migration possible. Tern wings are long and narrow, designed for efficient gliding and shaped so that they can ride ocean winds and air currents while conserving the greatest amount of energy possible. The birds are also incredibly small, weighting only about 3 to 4 ounces at the most. Their lightweight, streamlined forms allow them to glide and stay aloft like little, maneuverable, intelligent paper airplanes.

A Life Spent in Motion

Arctic terns are not what most of us would consider “homebodies.” These rolling stones spend most of their lives traveling. Our current scientific understanding is that terns can live for 30 years or more, which means that, in its lifetime, a single bird may travel well over a million miles. By comparison, that is like one of us making multiple round trips to the moon!

Navigation Across the Globe

One of the most fascinating mysteries surrounding Arctic terns is how they manage to find their way across such a wide stretch of ocean. How does a teensy bird like this navigate such vast distances with remarkable accuracy? Well, researchers believe the birds rely on several cues such as Earth’s magnetic field, the wind and ocean currents, and like the human sailors of old, the position of the sun and stars in the heavens.

They have fairly good eyesight and brainpower as well, so they might just as easily remember coastal landmarks along the way. Interestingly enough, young terns often make their first migration without a lick of guidance from experienced adults, which suggests that some navigation abilities are instinctive.

Challenges Along the Way

Despite their incredible endurance, Arctic terns face numerous challenges during migration. They often face severe storms on the way. They must fly for long periods without rest, often becoming exhausted if the journey becomes too rough. They face marine predators along the way as well, including other birds, and will often have to compete with other animals for food at pitstops. Sadly, climate change and other human-derived alterations in ocean ecosystems have affected fish populations along the way, thus making their journey that much more difficult.

True Investigator Says…

As you can see, though the Arctic tern might be tiny, it’s record-breaking global journey is among the most extraordinary of its kind. In the history of this planet, few creatures have shown the tenacity and navigational skills to fly across the poles. The Arctic tern’s biological adaptations have helped it evolve in such a way that it can make this journey, year after year. It might not be easy but it is proof that size does not limit the potential for achievement. And that is a lesson that we can all take to heart.