Do you remember those small white birds you would often see flying at a particular time of every year? Well, those small white birds are Arctic Terns, and they are in the middle of what is called Arctic Tern migration.
Arctic Terns are migratory birds that travel along the longest route around the globe annually. These birds undergo the longest bird migration. Their scientific name is Sterna paradisaea and belongs to the family Laridae of the Kingdom Aves, which consists of only birds. These Arctic terns are commonly known as “The Swallow of the Sea” or “The Champion of Migration.”
About Arctic Terns
Arctic Terns have a circumpolar breeding distribution around the whole world which means that they are always flying towards and from the poles of the globe. They fly around the Arctic and Antarctic poles all around the year back and forth.
This is the longest migratory route ever recorded in animal history spanning around 30,000 kilometers which is 18,641 miles from the North pole also known as the Arctic Circle to the South Pole which is the Antarctic Circle.
They fly around Europe, Asia, North America, Africa, South America, inferring that it is seen around all continents but at different times of the year based on their migration stage.
What is Migration?
Migration is a seasonal activity where the animals or birds move from the breeding grounds to the wintering grounds and back to the breeding grounds over the span of a whole year.
Typically the breeding grounds are where these birds mate, lay eggs, incubate, and eventually, they hatch from the eggs. In the wintering grounds, they escape from the winter of their breeding grounds. They also molt their feathers over here. It directs us to say that these Arctic Terns enjoy summer all year long, making them the animals which view major daytime all year.
The Arctic Tern migration begins with their journey from the Arctic Circle, which is their breeding ground. The Arctic Terns breed, lay their eggs, incubate them and wait till they hatch here. After hatching, the young fledglings have about a month or so to develop, after which they would migrate. They travel in groups or flocks together, as they are social animals. The Arctic Tern migration path has them fly down towards the Antarctic Circle.
We estimate them to be in a lot of hustle to move to the South pole. But in contrast to that, these incredible little birds take a lot of small breaks while moving down to their wintering grounds. Especially around the Caribbean islands, they take small breaks as this is their primary feeding zone.
This is a primary feeding zone for a lot of migratory birds and not only Arctic Terns. This indicates that there is a lot of competition here as well for food. They feed on the fishes in the warm waters of the Arctic sea and take small breaks.
At this moment, they slowly approach the Equator. The birds take a different migratory path at the Equator, a strange one to put it in words specifically. They diverge as they are approaching the Equator where they initially traveled as one congregation now half of the birds traverse along a path lining the continent of Africa. The other half of the birds traverse along the continent of South America.
It has been observed that the Eastern terns fly towards the west coast or along the coast of Europe and Africa. The Arctic Terns, which are flying initially along the west coast, fly around the Eastern coast or along the African coast.
They follow their respective paths but reach the same point on the South pole at around the same time earlier or later. All of these birds meet here in their wintering grounds, flock around the Weddell Sea in Antarctica.
In fact, bird lovers come around to this lake at the tip of Antarctica, where they can see all of these birds on ice caps. What a wonderful sight to see and relish! They again begin their route to the Arctic Circle in the month of November.
Contrary to the path they flew from the North Pole to the South Pole, they take a shorter route and fly quite faster compared to their arrival flight. It seems as if they are in a hurry to be back to their breeding grounds, isn’t it? They take direct paths and cross over the Equator, the Arctic Sea, etc., and then return back to the Arctic Circle in the month of April.
These small birds, which fit in approximately the size of an adult hand, fly past all temperature zones, including the Tropical and Temperate Zones, and dwell in the Polar zones.
Their bodies are well equipped for all of these weather and temperature conditions. They live in all of these areas and fly at extreme heights, making them the longest animal migration.
Understanding Their Migration Routes
Now that we have learned their migratory route, we might get perplexed on how this is known to humans, along with the fundamental question, what is migration. It does make you wonder how humans acquired knowledge and intricate details about these birds and their patterns. Well, speaking of learning their migratory route, it was quite a bit of a hassle. Researchers conducted experiments to learn this migratory route of the Arctic Tern migration. They located traps for the birds in Greenland, which is a part of the Arctic Circle.
A lot of the birds were intelligent enough not to fall into these traps laid by researchers. But a few birds were trapped, and geolocators were tagged to the feet of these birds. These can be seen as tiny sticks to their red feet. However, these devices do not cause harm to the birds on their journey. They do not cause any sort of inconvenience. Geolocator, which is abbreviated as GLS, is an electronic tracking device typically used in research studies of migratory routes of birds or animals. These small instruments are tagged to the birds’ feet, after which they begin their journey together in flocks.
However, these geolocators need to be removed after the birds arrive on their journey route. Back in April, when the birds return, the exact same birds should be trapped, and the geolocator is removed.
Typically there are a lot of troubles in this experiment, such as the device may stop working midway through the journey or fall off from the bird’s foot if not tied properly. Sometimes, the birds that have been tagged may not be found after returning due to their vast numbers in the region. So from the data received of these returned birds, this data is deduced.
Arctic Terns measure about 8.6-12.7 grams in weight which is about 3.5 ounces. Their length is 33 to 36 centimeters from the angle of their long beak to the tip of the tail. Their wingspan is roughly around 76 to 85 centimeters. To understand it better, the weight of Arctic Terns is about as heavy as a single banana.
Arctic Terns feed on marine animals such as small, schooling fishes, and marine and pelagic invertebrates. A few of them are believed to feed on terrestrial invertebrates and berries. Arctic Terns acquire their food by plunge-diving into the water and getting ahold of fish or insects. They also feed on sand lances, sandeels, herrings, code, and smelts.
These Arctic Terns are primarily monogamous. This implies that they mate with only one Arctic Tern for their whole life span. Pretty settled in, isn’t it? After breeding, each female Arctic Tern lays about 2 to 3 eggs during every breeding session. These eggs are typically dark brown colored with dark blackish spots in the middle.
Arctic Terns are very defensive birds. They take extreme care of their eggs during their incubation period. In fact, many birds lay their eggs near Arctic Tern nests so that the Arctic Terns would protect the eggs of the other birds while they are away from their baby eggs.
The incubation period is about 22 days, after which the eggs hatch and the birdlings or baby birds crack open the eggs and enter the world. These birds spend about a month or two with their parents learning basic life skills, after which they are left to their own by their parents.
Arctic Terns commonly live near the seas or water grounds. This is so that they stay away from their potential predators such as minks, and other sea birds, arctic foxes, and rats. Along with this, they also take their food from water sources. Henceforth, these birds are quite often found around water sources.
Their wintering grounds are the Antarctic grounds where they live on top of ice caps. These birds molt their feathers over here while standing on these ice caps.
Arctic Terns are very often confused with Common Terns. Some bird observers commonly call Arctic Terns and Common Terns, Comic Terns, which is a combination of their names.
Common Terns can be differentiated from Arctic Terns because they have an orange-red beak. Whereas Arctic Terns have a blood-red beak.
How Long do Arctic Terns Live?
Their lifespan is about three decades or thirty years. But they do not begin breeding until they reach three to four years of age. Until they reach their reproductive age, they do not mate but still, migrate from the breeding grounds to the winter grounds. The oldest Arctic Tern was found to be thirty-three years old.
How do Arctic Terns Adapt to Migration?
The body of the Arctic Terns is adapted for the longest bird migration. It has bones that are hollow and filled with air which is known as the “pneumatic bones.” This decreases the overall bodyweight of the bird, making it easier to fly. They also have long pointed wings and long pointed tails, which help in better flying.
Arctic Terns glide rather than flapping their wings on the bird migration flyways. This helps in the conservation of energy. As a matter of fact, these birds can even sleep while they are gliding. This explains how they are able to travel the longest migration time out of every type of bird.
Arctic Terns are ordinarily greyish white in color, including the tail with an astounding blood-red beak, and the top of the head has a cap of feathers in black. Doesn’t it seem so attractive and fascinating with three of the most beautiful colors that form the fantastic combination?
They travel for about 90,000 kilometers towards and back from the poles. The largest route recorded to date is 96,000 kilometers during an Arctic Tern migration. Some scientists believe that there is a longer Arctic Tern migration route that exists that has yet to be figured out yet. To perform such a feat, they take the aid of the Earth’s wind systems or wind belts. Wind belts are the direction in which wind blows. Arctic terns usually fly in the same direction to make it easier for their flight.
These tiny birds travel approximately 2.4 million kilometers in their total lifespan. This is almost three or four times the distance between the Earth and the Moon!
They have short legs and webbed feet. They seem incredibly clumsy on the ground but have the highest flight record.
A very unique feature about these birds is that they experience a maximum of daylight hours compared to any other animal species. They experience summer in both the regions that they migrate to, which helps them achieve this. Well, this could be one reason why they are so active and can fly for longer hours. It would be tough to fly during winters or monsoons, given the obvious weather conditions.
The Arctic Tern migration is the longest bird migration. They fly from the Arctic circle, their breeding ground, to the Antarctic circle, their wintering ground. They travel about ninety thousand kilometers to and fro these poles. Their migration route is from the North Pole along the continents of Europe, Africa, North America, and South America to the South Pole. It is fascinating to watch these birds travel these vast distances over their lifetime. Nature is indeed beyond words! You can set goals to bird-watch for these Cranes and record your results.