Our Window on Nature

If you can’t beat them, trick them instead.

Possums are famous for “playing dead” when threatened, but they aren’t playing. Scientists say that the opossum actually goes into shock when overly stressed. So if you see a ‘possum lying on the ground, limp and unconscious, stand back. It has only fainted. Give it time, and it will revive and go on its way.

Several other animals are known to feign death – some of them my surprise you. At least 21 snake species are known to use this survival technique – here’s one example. When a hognose snake feels threatened by a predator, it flips over, belly up, with a gaping mouth that may ooze drops of blood.

Several other animals are known to play dead when they see no escape. Fledgling birds instinctively play dead to confuse predators. Pipistrelle bats are well known to feign death. So do some lizards. We’ve recently heard about an entire clutch of owlets playing dead, but they too got up and began moving when the threat passed. But here’s the biggest surprise – even spiders are known to play possum in order to prevent being eaten!

Here’s a shocker. The Sooty Shearwater, an 18” long seabird, migrates up to 40,000 miles a year, along a route that crosses the Pacific Ocean.

Working down in New Zealand, a crew of UC Santa Cruz biologists electronically tagged the legs of 33 shearwaters in early 2005. They recovered working tags when over half of them returned, carrying a record of where each bird flew.

Leaving in April, the Shearwaters crossed the Pacific Ocean (about 500 miles), pausing long enough to grab enough fish, squid, and krill to keep them alive. Part of their food they could gather from the ocean surface – to get the rest, they had to dive up to 200 feet into the water!

Sooner or later all the tagged birds landed to spend their winter in one of three areas - off the coast of Japan, Alaska, or California.

There was no traveling from place to place – each bird started south from its own wintering area. And all the tagged Shearwaters crossed the equator within a 10-day period in October. Is that impressive, or what!