Despite enormous scientific breakthroughs, the bird world is still full of riddles – and perhaps none are more persistent than the mystery of migration.
How on earth do birds cover the enormous distances from their breeding sites to their winter grounds, and how do they find their way? Are those really the same robins and martins that return to you year after year, and how do they fly at night, and over the sea?
Here we’ll reveal some of the most miraculous facts about bird migration that are sure to astound even the most seasoned birders.
Vast Distances
One of the most immediately striking things about bird migration is the enormous distances that they travel. Isn’t it amazing to think that many of North America’s summer migrants fly all the way to South America to spend their winters?
Bobolinks, chimney swifts, eastern kingbirds, purple martins, and scarlet tanagers are just a few of the bird species that migrate to South America each year, and the American golden plover even travels from the Northern tips of Alaska and Canada to Patagonia each year!
The prize for the longest flights, however, goes to the Arctic tern. Traveling between its Antarctic summering grounds and its Arctic breeding grounds, the birds circumnavigate the entire globe every year! At almost 50,000 miles per year, the birds can travel a distance equal to three times to the moon and back in a lifetime.
Need for Speed
To cover the phenomenal distances that we’ve just discussed, birds need to travel fast. The speed with which each species travels varies greatly, but most birds migrate at speeds between 20-50 miles per hour – not so different from the pace at which we drive motor vehicles.
If you’ve ever seen a great snipe in flight, you probably won’t be surprised that they’re the fastest migrating bird in the world. Traveling at speeds of up to 60 mph without the help of a tailwind, the snipes often cross more than 4000 miles from their breeding grounds in Scandinavia to their winter grounds in equatorial Africa in just a couple of days.
What surprised scientists the most about studying the snipes is that they crossed all kinds of suitable terrain for feeding, drinking, and resting without once taking a break! All in all, their journey takes them between 48-92 hours, but they’re not the only birds that can fly such long hours without pausing.
Longest Non-Stop Flights
While the non-stop, 4000-mile flights of the great snipe are doubtlessly impressive, they are dwarfed by the marathon flights of their cousin, the bar-tailed godwit.
The large wading bird breeds all across the Arctic and overwinters further south. The subspecies L.l. bauri that breeds in Alaska, however, takes the arduous journey right across the Pacific Ocean to overwinter in Australia and New Zealand.
Since there is nowhere to stop on the way, the birds have been recorded flying more than 8,000 miles without a break! The journey can take up to 11 days, meaning the Godwits must establish plentiful fat reserves to fuel their journey before they set off.
Now, snipes and godwits are larger, powerful birds that are designed for long, fast flights, but what about migratory songbirds? The tiny blackpoll warbler, which weighs less than an ounce, is known to fly 80 hours nonstop from Eastern Canada to Northern South America without a break. To my mind, that seems an equally miraculous feat!
Dizzying Heights
Now that you’ve been dazzled by the distances that migratory birds fly, how about the dizzying heights that they make their journeys at? While some migratory birds can be seen and heard passing overhead at relatively low altitudes, others fly so high that they pass by without detection.
Bar-headed geese are one such example of a high-flying bird. Topping 23,000 feet, the mighty waterfowl cross some of the highest Himalayan peaks, making them the highest-flying migratory bird in the world. At only 6000 feet shy of Everest’s peak, it’s a wonder they don’t need oxygen masks to survive!
Amazingly, the geese are outdone by Ruppel’s griffon vulture, a non-migratory bird but a supreme master of the sky. Nobody knows exactly how high the species can fly, but what we do know is that in 1973, an airplane flying over the Ivory Coast ingested one into its engine at 37,000 feet. That’s over 7 miles high!
Night Flights
It wasn’t until I began spending my springs in a wooden cabin that I realized the extent to which migratory birds fly at night. Hearing the honks of various species of geese passing overhead throughout the night gave me a new appreciation for their determination and epic feats of endurance.
It’s not only geese that migrate during the night, though, and it turns out that night flights hold several advantages for migratory birds. The colder air temperatures help to prevent the birds from overheating, and the night sky also hosts fewer predators.
But how on earth do migratory birds navigate during the night? When they can’t see their familiar landmarks, surely the darkened landscape makes it very difficult for them. Let’s find out more.
Miracles in Navigation
Ever since humans began witnessing birds making their epic journeys, we have asked: How do they know their way? While memorizing landmarks may play a crucial role, how do solitary birds know where to go on their first journey, and how do birds navigate at night?
In the 1960s, a father-and-son scientist team placed caged indigo buntings in a planetarium where they could alter the direction of the night sky imitation overhead. They found that the birds did indeed change attempted flight direction according to the stars, indicating that birds do use celestial bodies to navigate.
Scientists studying other ways that birds navigate have long proposed that birds have some sort of built-in compass that can read the Earth’s magnetic field. It wasn’t until recently, though, that quantum physics provided a feasible explanation for this.
It’s now thought that birds have special cryptochrome proteins in their eyes that can detect even subtle variations in the surrounding magnetic field. Explaining this is definitely beyond the scope of this article, but for the inquisitive among you, here is a video that might help!
Returning To Place of Birth
If you’ve been wondering whether the robins or hummingbirds arriving in your yard in the spring are the same that were born there last year, the answer is that it’s highly likely indeed!
While it’s already miraculous that birds manage to migrate thousands of miles, it’s even more extraordinary when they return to their exact place of birth. Yet studies of banded birds show that many types of songbirds really do return to their previous year’s nest sites, whether they were born there or raised the last year’s brood.
It can be wonderful to anticipate and welcome the return of the same families of birds year after year. Like old friends, it can be a joy to see one another again after a long time apart. But returning to the same nest sites can cause competition within bird families, too!
If several breeding seasons are successful, the number of birds may begin to outnumber suitable nest sites, which is when you can help the birds enormously by installing more nest boxes!
You can read more about the benefits of gourd nestboxes and the types of birds they can attract, in our dedicated guide, here.