Hi, this is Emily from MinuteEarth.
Each autumn, tens of billions of birds fly from higher latitudes to the tropics, and
if they went straight - as the crow flies - their trips would be thousands of miles
long.
But instead, they often zig and zag along the way – adding an extra thousand miles
or more to their journeys, which actually helps them get to their destinations faster.
Winds on Earth regularly blow in specific directions, and when birds fly with the wind
at least partially at their backs, they can greatly increase their flying speed compared
with birds flying against the wind.
So even if, say, a swallow has to go out of its way and fly 25% farther to take advantage
of the wind, if it doubles its airspeed velocity by doing so, it can get there in less than
two thirds the time.
On top of this, many migrating birds are land-lubbers at heart.
Small birds generally avoid water because they’re too small to survive storms on the
open seas.
Larger birds, on the other hand, stay above land because their wings are big enough compared
to their bodies that they're able to get lift, without flapping, from huge columns of rising
air called thermals, which form from uneven heating of the ground.
A bird in a thermal can simply rise with the hot air and then glide down to the next thermal.
Sticking to land during their long migrations brings birds from all over the world together
at a few key straits and land bridges along their routes.
For a few weeks each year, these hot spots fill with flocks of squawking foreigners,
both in the sky and on the ground below.
This video was sponsored by W.W.
Norton and Company, the publisher of the new book “Where The Animals Go: Tracking Wildlife
with Technology in 50 Maps and Graphics”, which tells the stories of animal movements
throughout the world.
We LOVED this book, and this higher-than-birds-eye view of Israel’s avian and plane traffic
during the Fall migration actually inspired us to make this video.
If you want to learn more about bird migrations, or python invasions, or baboon commutes, check
out WhereTheAnimalsGo.com.