The arctic tern holds the record for the longest migration of any bird in the world. This incredible seabird travels over 25,000 miles round-trip every year as it migrates between its breeding grounds in the Arctic and wintering grounds in the Antarctic. That’s like flying all the way around the planet!
The arctic tern’s epic journey is a feat of endurance that leaves other migratory birds in the dust. But why does this small bird undertake such a monumental migration each year? And how does it manage to travel thousands of miles between the polar extremes of our planet?
Why Does the Arctic Tern Migrate So Far?
The arctic tern migrates tremendous distances each year for one key reason: to take advantage of the bountiful marine food resources found in the far north and far south polar regions.
During the northern summer, arctic terns breed and raise chicks in the high Arctic. This region provides prime feeding grounds, with 24 hours of daylight in which to hunt fish, shrimp, and other seafood to feed their young.
As winter approaches, however, the supply of food becomes scarce in the freezing Arctic. So the terns undertake their marathon migration to Antarctica, where a rich buffet of seafood awaits them in the southern summer. By moving between the poles each year, the birds enjoy an endless feast!
Unique Adaptations for Extreme Migration
The arctic tern is specially adapted to handle its extreme migratory lifestyle. Here are some of its unique features:
- Extremely long, pointed wings optimized for swift, buoyant flight over huge distances.
- Long-lasting stamina to fly hundreds or even thousands of miles at a time.
- Ability to sustain flight speeds up to 40 mph for days on end during migration.
- Specialized digestive and metabolic systems that allow them to quickly stock up on fat reserves for the long journey.
- Impressive navigational skills and memory to return to the same breeding and wintering sites each year.
The Route of the Arctic Tern’s Migration
The arctic tern’s migration route spans vast distances across the globe. Here is an overview of their marathon international journey each year:
Fall Migration
Having raised their chicks through the short Arctic summer, adult terns and juveniles head south in late August or September. Their journey begins at Arctic breeding colonies distributed around the northern coasts of Alaska, Canada, Greenland, Scandinavia, and Russia.
The birds fan out across the North Atlantic, flying down the coasts of North America and Western Europe. Some birds fly down the center of the Atlantic Ocean, traveling thousands of miles over open water between stopovers on scattered islands like the Faroe Islands and Azores.
Most arctic terns stage briefly along the Atlantic coast to rest and feed. But they don’t stay long before resuming their southbound odyssey.
By late October, most arctic terns have reached the limits of the Southern Ocean encircling Antarctica. Their journey has carried them over 25,000 miles from their starting point in the high Arctic.
Wintering in Antarctica
For the southern summer, arctic terns disperse widely along the Antarctic coastline and offshore waters. Here they enjoy 24 hours of daylight and plentiful seafood once again.
Some migrate as far south as the Antarctic Peninsula and surrounding islands. Others spread out along the coasts of continental Antarctica. They avoid areas with thick sea ice, frequent storms, and freezing temperatures.
Arctic terns remain in Antarctica from November through February. They fatten up on a bounty of fish, krill, and squid throughout the region’s long sunny days.
Return Northward Journey
As autumn approaches in Antarctica around late February, the terns begin their northern migration back to the Arctic breeding grounds. This leg covers a similar distance of approximately 15,000 to 25,000 miles.
However, arctic terns follow a more direct route flying northwest across the Atlantic rather than hugging the coasts. Their nonstop transoceanic flight can take 2 to 3 weeks of exhausting flight.
Most birds reach the waters around Iceland, Greenland, and Norway by late March or April. From here, they disperse out to Arctic colonies across the northern hemisphere.
By May, the terns are back on their summer breeding territories, preparing to mate and lay eggs. Their navigational skills have guided them back thousands of miles to within just a few hundred yards of where they nested the previous year!
Incredible Facts About the Arctic Tern’s Migration
The arctic tern’s annual odyssey is an unrivaled feat of endurance. Here are some mind-blowing facts about their marathon migration:
- The total round trip distance covered is around 25,000 to 31,000 miles.
- Their nonstop transatlantic flight segment can cover over 4,000 miles without stopping.
- Arctic terns travel further than any other migratory bird species each year.
- Their lifespan is over 30 years, meaning they will fly over 650,000 miles in their lifetime, equivalent to 3 round trips to the moon!
- They travel from one extreme polar environment to another, experiencing 6 months of daylight and 6 months of darkness.
- Some individuals migrate slightly shorter distances by hopping between ships while crossing oceans.
Fast Facts on Arctic Tern Migration
Total annual migration distance | 25,000 – 31,000 miles |
---|---|
Longest nonstop flight segment | 4,000+ miles across Atlantic Ocean |
Travel speed | Up to 40 mph sustained |
Time spent flying each year | Around 5 months in migration |
Breeding grounds | High Arctic coasts |
Wintering grounds | Coastal Antarctica |
Total lifetime flight distance | 650,000+ miles |
Tracking the Arctic Tern’s Migration
Ornithologists have employed various methods to track arctic terns and gain insights into their spectacular migratory journey each year. Here are some of the techniques used:
Banding
Attaching numbered metal bands onto terns’ legs provides information when birds are recaptured in subsequent years. Results reveal their ages, migration routes, and lifespan.
Geolocators
Tiny electronic data loggers attached to the birds record light levels. When recaptured, this reveals their migration routes and stopover locations based on time and length of daylight.
Satellite Tags
Advanced satellite transmitters can now relay near real-time tracking data on the bird’s precise location during migration. However, these are still limited by the tags’ small size and battery life.
Threats Facing Migrating Arctic Terns
Although arctic terns are champion migrants, their extreme lifestyle faces some growing challenges:
- Climate change – warming oceans may affect marine food supply and breeding habitat.
- Offshore energy development – risk of collision with turbines and disturbance.
- Overfishing – depletion of food fish stocks en route.
- Oil spills – can contaminate birds and food sources.
- Extreme weather – storms and strong winds can blow migrating terns off course.
- Predators – gulls, skua, falcons prey on adults and eggs.
Protecting key breeding colonies, migration stop sites, and wintering areas will be crucial to maintaining healthy arctic tern populations into the future.
Conclusion
The epic migration of the arctic tern is one of the natural world’s most incredible feats of endurance. By traveling up to 31,000 miles or more annually between the Arctic and Antarctic, this seabird experiences polar summers and endless daylight.Specialized adaptations allow arctic terns to complete such distant journeys year after year across oceans and continents. As climate change and other threats mount, protecting these champion migrants throughout their range will ensure this epic polar odyssey continues for generations to come.