Vampire Bats Make Apt Runners
Bats are four-legged mammals like mice, dogs and cows. But with their front legs so specialized for flight, most bats can barely walk. The vampire bat is a rare exception, often sneaking up on its prey on all fours. Now, in a novel experiment involving a specialized bat treadmill, scientists have shown that these blood-sucking spooks are excellent runners, too.
John W. Hermanson of Cornell University's College of Veterinary Medicine and graduate student Daniel K. Riskin had seen vampire bats hop -- a feat in which the furry fliers attained speeds of more than 6 feet per second almost instantly from a dead stop on all fours. To see whether the bats could break into a true running gait, they tested five of them on a variable-speed treadmill housed in a clear plastic box small enough to prevent the animals from launching into flight.
A Sumatran tiger prowls toward a "camera trap" in the Indonesian jungle.
(World Wildlife Fund)
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At slow speeds the bats walked their usual stealthy walk, alternating left and right limbs. "It's almost like watching a cat on the prowl," Hermanson said. But at high speeds they broke into a "bounding gate." Video analyses showed that the strong, wing-like front legs did most of the work, reaching forward in unison and hitting the ground on their wrists while the rear legs lifted up and moved forward together. "We classify this novel gait as a run because it includes a significant aerial phase," they wrote March 17 in the journal Nature.
Equally surprising, the researchers said in interviews, was how clever the animals proved to be. When placed in a new cage, the bats would instantly figure out where the hidden door was and casually lurk nearby -- then leap out when it was opened. And all the scientists had to do was move their hand toward the switch that turned the treadmill on and the bats would start walking.
"They look straight at you, in the eye," Riskin said. "They're brilliant animals."
-- Rick Weiss
Mountain Living Has Its Benefits
Is mountain living healthier? Apparently so, at least if you're a farmer or herder.
A 15-year study has found that Greek villagers living in the mountains had lower mortality rates, and even lower death rates from heart disease, than comparable villagers living in the lowlands.
In the study of three villages about 130 miles from Athens, Greek researchers found that the effect of living in the mountains was especially pronounced for men, who were almost half as likely to die from heart disease as men living in the valleys. The mountain village was about 3,500 feet above sea level, whereas the lowland villages were near sea level.
Reporting in the Journal of Epidemiology and Community Health, the researchers concluded that the benefit was most likely the result of the increased physical activity of the mountain villagers, as well as their physical adaptation to the lower oxygen levels of mountain air. They came to those conclusions because the villagers at higher elevations did not have either lower blood pressure or lower cholesterol levels -- two common predictors of longevity and cardiac health.
The study followed 1,150 people and took into account factors including age, weight, smoking, alcohol consumption and education. In all three villages, the men were farmers and animal herders and the women were homemakers.
Although overall mortality rates were lower for the mountain villagers, they were not substantially so. Death rates from heart disease, however, were significantly lower in the mountains, especially for men -- who spent much of their days walking up and down the hills as they plowed the fields and tended the flocks. It was that activity, the researchers concluded, that provided a "protective effect" for the men.
-- Marc Kaufman
Rare Tiger Not Camera Friendly
All great performers hate to be bothered by a camera flash, but few of them end up swatting the photographer and taking a bite out of the lens.
But that is exactly how a rare Sumatran tiger decided to enforce its own "no flash photography" rule, deep in an Indonesian jungle.
The camera in question was part of a series of 30 "camera traps" set up by the World Wildlife Federation to monitor wildlife. No human photographer would have lived to tell the tale, but the film survived, and a series of images of the encounter have been posted on the Internet.
The first shows the tiger walking across the frame, oblivious to the camera. The second is where things get interesting. The tiger has whirled and is prowling toward the camera. A human photographer would have beat an exit at this point, but the camera kept clicking.
The third and fourth images are blurred and overexposed, but the camera's excuse is solid: It was being mauled. The fourth image is actually a picture of the inside of the tiger's mouth.
Subsequent images show various parts of the tiger's anatomy close up as the beast sniffed around the camera trap. The predator no doubt meant to make a dignified exit, but WWF described the last image as "a close up view of its backside."
The images can be seen at www.worldwildlife.org/cameratrap/.
-- Shankar Vedantam
