Arctic Terns’ Marathon Migration Always Follow The Same Routes

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Arctic Terns have one of the longest migrations among bird species. In fact, they even set records because of the distance. The birds are quite small. But every year they migrate to Antarctica all the way from the Arctic. The round-trip measures approximately 18,600 miles, or 30,000 kilometers.

You would think the trip would become boring after generations. But that doesn’t happen to the arctic terns. They do not mix up the routes or experiment with them. The latest research has discovered that the far-flying, slender birds fly through some particular routes. And they always stick to those.

Arctic Terns Are The Marathon Runners Of Seabirds

Joanna Wong, the lead author, is a British Columbia University graduate from the IOF (Fisheries and Oceans Institute). She says that these birds’ migration is the world record holder when it comes to the length of animal migrations. The immense distance also means the arctic terns have interaction with numerous ecosystems that fall on the path.

Their breeding season takes place in the cold Arctic region. Then, the remainder of the year when they are not breeding, they spend in the frigid regions of Antarctica. Wong is particularly impressed by the fact that the grand journey (which is a round-trip) happens every year, without fail. Arctic terns are also known to have a lifespan of about 30 years. So, a massive distance gets covered by the birds in the span of their entire lives. What is more interesting is that they have a small size too.

Sadly, Arctic terns numbers are decreasing, as reported by the IUCN. Predators like minks are currently threatening them. Of course, there are also the factors brought about by climate change: loss of key prey as well as habitats.

Read: Shrinking Animals: An Ornithologist Reveal That Birds Are Shrinking

Wong explains that presently humans do not know of any animals who have a further range. Arctic terns also act as indicators, conveying a lot of information about the various ecosystems on the path of their grand annual marathon journey. If, in a year, they fail to reach their destination. Then it is almost certain that some ecosystem on their route is facing an environmental problem.

Tracking Them Is A Difficult Task

However, the arctic terns have a wide range geographically. As a result, studying colonies poses a challenge for researchers, particularly when the migratory routes have bottlenecks. Wong explains that these birds are either on the move or at polar ice caps. Both of these environments are not easily accessible for humans.

arctic terns

In Europe, there have been efforts to track the arctic terns. However, the birds’ routes remain uncharted in Canada, which is an important breeding spot for the terns.

To study them, Wong’s team fitted 53 birds with light-level geolocators. The birds were selected from 5 breeding colonies spread across North America. The devices record the intensity of ambient light. Wong explains that the device can estimate the location of the birds using daylight and solar noontime. The birds also come back to the colonies where they left. So finding them once more was not difficult.

Read: Migratory Birds: Their Flights Charted Through Northwest Mexico

The research concluded that the majority of tracked Arctic terns have common routes of migration. This means that Terns who were born in Canada, Greenland, the US, or Norway, all follow similar routes when going on the annual journey. There were 3 common routes found while going south, and 2 for returning north. Some other species of seabirds also have the same routes.

Wong explains that this means that conserving Arctic Terns can be adapted on the fly to the areas and periods when the birds use certain parts of the routes. As a result, conservation efforts for a bird such as this would be much easier.  

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