Coyote pee smells bad to me – mountain beavers identify and avoid urine of predators
MOUNTAIN BEAVERS LIKE TO EAT diced apples, but they are much less likely to feed, scientists have discovered, if the bowl has been laced with, say, coyote urine. The news comes from zoologist Gisela Epple of the Monell Chemical Senses Center in Philadelphia. Epple and her colleagues are looking for a humane way to keep beavers from laying waste to Douglas fir saplings (which is what the animals favor when no diced apples are available) in replanted forests in the Northwest. She thinks the urine of beaver predators- -coyotes, bobcats, and minks–would work like a charm.
Unlike regular beavers, mountain beavers are nocturnal, with tiny eyes that can hardly see. Epple thinks they navigate mainly by smell. “When you watch the animals, you see they do a lot of sniffing,” she explains. That observation gave Eppie the idea for her beaver repellent. To test the idea, she and her colleagues offered mountain beavers a couple of choices: between a bowl of diced apples whose rim was coated with predator urine and a bowl laced with the urine of the harmless prairie vole; and between undoctored apples and apples stinking of butyric add. The point of the latter experiment was to find out if mountain beavers are disgusted by any strong smell.
The results showed that the beavers had a specific aversion to predator urine: they didn’t avoid butyric acid at all, and they ate six times as much apple from the prairie-vole-urine bowl as from the coyote-urine bowl. Furthermore, the repulsion was long lasting; even after many days of exposure, the beavers always preferred the nonpredator-scented bowls. Epple thinks they can detect compounds in the urine of their carnivorous predators that are produced during the digestion of meat and fat. “It’s probably an innate response,” she says.
Once Epple pins down the active agent in the predator urine, it could be synthesized as a liquid or in granules and applied to tree saplings. The same type of repellent, she thinks, could also deter such garden pests as deer and woodchucks. (indeed, some gardeners are already in the habit of defending their turf with lion dung from the local zoo.) Epple much prefers this tactic to shooting the pests, a solution that lasts only until the next one comes along to fill the void. “You could keep the animal population that’s there,” she says, “but just keep them away from what is valuable for us and leave the other plants for them to eat.”
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