In truth, bird migration is a much more incredible feat than we might have thought! That is why it is commemorated on 8 May, on Migratory Bird Day. Here are five incredible things that migratory birds do that make migration even cooler.

Does this migration make me look fat?

Birds get fat before migrating! Well, no wonder, they need the extra calories and energy for the long trip they’re about to undertake. But what’s most surprising is probably just how much bigger they get. Warblers can weigh up to twice their regular weight before setting off. Holy cow! Er, warbler we mean. They don’t only bulk up by overeating. Insect-eaters switch over to fruit, converting sugars into fatty acids in the liver and storing them as fats.

Warblers can weigh up to twice their regular weight before setting off.

Taking the night shift.

A lot of birds like cuckoos, warblers, flycatchers, orioles, sparrows, vireos and thrushes are night owls, er… birds. It means they migrate at night because it has certain advantages. Nighttime is cooler, yes, but so is the air! And when they’re on the move, birds produce a lot of excess heat. The air is also much less turbulent and, probably most importantly, their predators like falcons or hawks are sound asleep.

Swimming and walking also count!

Would you ever say penguins are migratory birds? Probably not. But migration doesn’t necessarily mean it needs to be done flying! Most species of penguin migrate by swimming and they can cover distances of up to 1,000 kilometers or 620 miles. Take that, Olympic swim team! Walking counts, too. During droughts, emus in Australia also hit the road in search of greener pastures.

Migration doesn’t necessarily mean it needs to be done flying!

Something's fishy...

Back in the day, people didn’t know why birds suddenly disappeared at certain times of year, and the explanations they came up with were delightful! In Ancient Greece for example they thought they turned into fish. One other common belief was transmutation or metamorphosis. Aristotle was convinced redstarts turned into robins in the winder and then back into redstarts!

Taking the strait route.

Turns out, like people, birds also find themselves taking the same routes and possibly running into some traffic jams! That’s because large soaring birds can soar because of rising hot air – that is something that only occurs over land, so they are unable to soar past large bodies of water like the Mediterranean. That’s why, during migration, raptors and storks pass through straits like Bosphorus, Messina and Gibraltar.