Monday, November 23, 2009
Wrangling penguins at the south pole
Somewhat like rabbits, Adelie penguins avoid capture by sharp turns. Once I had a chance to play predator, and learn how penguins give predators the slip.
When I was at the south pole working for some ornithologists, my job was to recapture the penguins after they had been released, during a study of how they navigate. I used a snowmobile to chase them across the ice cap at South Pole Station. The surface was very rough, somewhat like frozen, breaking waves. I'd go over the crest of a wave, and bam!, I'd slam down two or three feet. The penguin I was chasing was hidden from time to time behind the frozen waves--then I'd see a head pop up.
As I closed in on a penguin, they'd start to spiral inward to the right or left, turning more tightly than I could with the snowmobile.
At this point, I'd jump off the snowmobile, with my fish landing net in hand, and chase the bird on foot, sprinting as fast as I could. They would zigzag this way and that on all fours. Since they were down on the ground, I'd have to bend over to catch them, and at this point, they would sometimes run back between my legs. Usually I'd just try to tackle them--leaping and landing on my belly, with arms outstretched.
The altitude was 10,000 feet--effectively higher, since air is thinner at the poles. I was wearing 70 pounds of polar gear, running in slippery snow. So if I missed, as I usually did, I'd just lie there panting tilll I caught my breath. When I recovered, I'd climb back on the snowmobile and chase the wily bird all over again, until I finally caught him. If I didn't catch him, he'd starve on his way to the coast, 800 miles away. (I did catch all of them.)
The real predators of penguins
Penguins have no land predators. Usually, they are pretty "tame," unless you actually try to lay a hand on one, at which point, they flee or fight, depending on their personality.
Predators of adult penguins are normally in the water--leopard seals or orca whales. Both are much larger than penguins, and so the penguins must be able to turn more sharply.
That explains why the penguins always spiraled as I approached them on the snowmobile. They were just using the instinctive defense they probably use in the water. Still, it worked quite well against a snowmobile--a snowmobile that was actually chasing them.
It would be different if penguins had to cross highways. When the vehicle isn't pursuing the animal, or even trying to avoid the animal, then zigzagging has the wrong effect. It makes it harder to avoid the animal, and then you have... roadkill.
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