The World’s Greatest Migrator: the Arctic tern flies over 45,000 kilometres each year

The last Au Naturel column looked at the sudden appearance of birds during spring migration. Today, when you walk along the Millennium Trail, look out for a white bird with pointed wings and a forked tail. It should be flying buoyantly over the river. At first glance you may think it’s a gull, but look closer to see that it is slimmer, with a dark head and sharp orange bill. What makes this bird, which some call the sea swallow, so special?

Consider where it spends its time during our winter — as far south as the Antarctic, which has the daylight hours we have during summer. Upon arrival here in June it spends most of its hours in daylight.

It’s likely no other species on the planet spends as much time in daylight as the arctic tern. This amazing bird travels up to 45,000 km (the circumference of the earth at the equator) during migration alone. It likely travels well over one million miles during its approximately 25-year lifespan.

Most of this time is spent in the air and far out at sea, which makes it special when it comes close enough to be easily observed. So why here, and why now? Like so many species it’s all about sustenance and love.

If you’ve ever cast a fishing line towards a point where a fish has surfaced, how often will you actually land that fish? If you answered 1 in 12 times, that’s about the same rate of return the tern has when it spots ripples on the water and dives headfirst for a meal. If they have young to feed they do this hundreds of times a day — it should be easy to watch for.

Last year I noticed they were diving towards me on the Millennium Trail close to Robert Service Way. Upon further examination I surmised they had their nest in the gravel at the edge of the embankment. If you get near their nests they are very aggressive, so watch your back if they set up shop in the same area this year.

Arctic terns mate for life, and often return to the same nesting areas. Most often this shouldn’t be a concern; they commonly nest on gravel bars in braided river channels.

These birds are quite vocal. If you were a bird, what would you most want to say?

I’d say, “Hey, watch your back.”

That’s their alarm call.

The other call is, “Hey, check me out, I look pretty good”, or something to that effect when preparing to mate.

Listen for a harsh “kip”, or a “keeeerr” over the river.

Migrating species are affected by alterations in both summer and winter habitats. The arctic tern utilizes each pole of the planet, and these areas are seeing the greatest change in climate variation. Few other species deal with the reality of climate change more than the one who experiences it at both poles.

Let’s enjoy this bird while it’s visiting and recognize it for what it is — the world’s greatest migrator.

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