Friday, February 28, 2014

Forget the Distance, It's the Navigation that's the Thing

I've been thinking more about my latest arm-chair discover, the Albatross. What initially struck me about this bird is the remarkable distances it's able to cover (it can fly thousands of miles without flapping it's wings!). But I've decided that's not really the most impressive feat, what's truly miraculous is their navigational abilities.

I can imagine how a bird, or any object, could potentially cover long distances. That's just physics. But how does an animal leave a random point on Earth, fly thousands of miles, and make its way back to that point to feed its young? Tern island is an itty bitty spec (holy smokes, there's street view! And of course, reviews), and yet birds leave there for weeks at a time, and manage to get back to feed their particular chick. That, my friend, is magic.

Ahhh, but I can hear you already. You've watched enough movies to know that birds use the Earth's magnetic core to navigate with. Not so fast. A bunch of scientists assumed the same thing:

After making foraging flights of several thousands of kilometres, wandering albatrosses (Diomedea exulans) are able to pinpoint a specific remote island where their nests are located. This impressive navigation ability is highly precise but its nature is mysterious. Here we examined whether albatrosses rely on the perception of the Earth's magnetic field to accomplish this task. We disturbed the perception of the magnetic field using mobile magnets glued to the head of nine albatrosses and compared their performances with those of 11 control birds. We then used satellite telemetry to monitor their behaviour.

The birds, it turned out, were not impressed:

We found that the ability of birds to home to specific nest sites was unimpaired by this manipulation. In particular, experimental and control birds did not show significant differences with respect to either foraging trip duration, or length, or with respect to homing straightness index. Our data suggest that wandering albatrosses do not require magnetic cues to navigate back to their nesting sites.

So there it is, a mystery waited to be teased out. In the mean time, I'm just going to stand back and be very, very impressed.

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