Wild Things: Life as We Know It
Flying mammals, Galápagos iguanas and sidewalk songbirds
- By Smithsonian magazine
- Smithsonian magazine, February 2007, Subscribe
Mammals have been flying as long as birds, according to research on a newfound fossil. Chuang Zhao and Lida Xing / Nature
Roads to Ruin
When pastures and roads carve up a forest, even trees that aren't chopped down suffer. That's one finding from the world's longest (22 years) and largest (32,000 trees) study of forest fragmentation, conducted in the Amazon by the Smithsonian Tropical Research Institute. Trees that grow slowly or prefer shade are especially weakened; many that were once surrounded by dense rain forest are felled by windstorms.
Mammals Catch Birds in Flight
Mammals have been flying as long as birds, according to research on a newfound fossil. A flying squirrel-like glider called Volaticotherium antiquus (ancient gliding beast, illustrated above) from Inner Mongolia lived 125 million years ago—about 70 million years before any other mammal is known to have taken flight, bats included. Gliding, says paleontologist Jin Meng of the American Museum of Natural History in New York City, saves having to climb up and down to move from tree to tree.
Keeping Cool
Why did scientists chase dozens of marine iguanas on the Galápagos Islands? To learn why island animals with no predators tend to be so calm. After subjecting the three-foot-long reptiles to 15 minutes each of “experimental harassment,” the researchers, from Princeton and other universities, captured the animals and took blood samples. On predator-free islands, hassled iguanas had levels of the stress hormone corticosterone that were similar to those in unchased animals. But on islands where cats and dogs had been introduced, researcher-chased iguanas released more of the hormone. That finding suggests that the reptiles are able to learn fear.
Street Music
More evidence that life in the big city can change a creature's tune: researchers from Leiden University in the Netherlands analyzed the songs of great tits, birds related to chickadees, in ten European cities, including London, Berlin and Paris. Compared with great tits in nearby forest sites, the urban birds sang faster and at a higher pitch—presumably to make their voices heard over the low-frequency din. The study suggests not only that these songbirds are surprisingly adaptable but also that there's a good reason city dwellers can be shrill.
Observed
Name: Gymnothorax javanicus, the giant moray eel, and Plectropomus pessuliferus, a grouper
Formerly seen as: Crevice lurker and bottom dweller, respectively
Now seen as: Huntin' buddies. A new study has found that they seek prey jointly, a behavior rarely seen among mammals and never among fish. They have complementary skills, with the grouper preying in open water and the moray within coral reefs; working together, they leave their targets no place to run or hide.
Isn't it just a coincidence?: No. The grouper, when hungry, gives the moray a special head shake, according to Redouan Bshary of the University of Neuchâtel in Switzerland. More often than not, the moray responds by joining forces with the grouper.
Do they share?: No. When either partner catches a fish, it swallows the prey whole. This prevents the predators from fighting over the spoils and may be the key to the evolution of such coordinated hunting.
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