Wild Things: Life As We Know It
Tail-waving squirrels, black-footed ferrets and tool-using crows
- By Jess Blumberg, T.A. Frail, Megan Gambino, Laura Helmuth and Sarah Zielinski
- Smithsonian magazine, October 2007, Subscribe
Trees Thrive on Fear
Aspen are particularly tasty to elk and have long suffered from over-browsing in Yellowstone National Park. But now aspen in some areas are making a comeback—thanks to wolves. Though eradicated from Yellowstone in the 1920s, wolves were reintroduced in 1995 and have been multiplying ever since. The result? Elk avoid riversides, where they're particularly exposed to the predator, and there's a whole new crop of young aspen in such areas, according to Oregon State University researchers, who credit the arboreal rebound to the "ecology of fear."
Back From the Brink
Black-footed ferrets were declared extinct in 1979, victims of disease, loss of their prairie habitat, and the poisoning and shooting of their prey, prairie dogs. A few years later, a group of 18 was found in Wyoming. Thanks to captive breeding, hundreds now live in the wild. Bonus insight: many endangered species reproduce late in life and rarely, so the populations depend on individuals reaching old age. University of Wyoming biologists report that the key to success for the ferrets, which typically live only three or four years but have large litters, is ensuring they reach their first birthday—the start of their prime breeding age.
Thinking Ahead
New Caledonian crows can plan ahead to solve a problem, say New Zealand researchers, who put meat behind bars and gave the birds access to a stick too short to reach the food. Six of seven birds tested used the short stick to reach a longer one, which they then used to get their treat. The crows make and use tools in the wild, but in this case they extended the idea "tools get food" to "tools get tools get food." Such complex reasoning had been seen only in primates before.
What Ravages of Time?
Frozen microbes found in samples of eight-million-year-old Antarctic ice, the oldest ice on earth, are alive—alive!—according to a study led by Rutgers University. True, once the microbes (mostly bacteria) were thawed, they grew and reproduced more slowly than microbes extracted from younger ice. Still, the finding pushes back the age of the oldest living organisms by about 7.5 million years. The researchers say the microbial DNA encased in ice "is essentially a 'gene popsicle.'"
Observed
Name: Spermophilus beecheyi, or the California ground squirrel.
Obvious Defensive Weapon: Tail waving. Ground squirrels wave their tails to appear larger to, and thus intimidate, hungry snakes.
Secret Defensive Weapon: Tail heating. When confronting rattlesnakes, ground squirrels wave their tails and transfer body heat to them, emitting infrared radiation, say University of California at Davis researchers.
What's with the heat?: Because rattlesnakes can sense infrared radiation, a hot tail makes the ground squirrel look even bigger.
And squirrels know this?: Precisely. What's more, when threatened by a gopher snake, which doesn't sense heat, ground squirrels shake but don't heat their tails. Animal communication, the researchers say, includes much more than meets the human eye.
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