Transcript:

ambience: Coyote howl

The howling of a coyote is an increasingly common sound, as this once-Western animal has spread into suburbs and even cities throughout the United States. In some places, the flourishing coyote population is considered a menace, but efforts to reduce it are backfiring. I'm Jim Metzner and this is the Pulse of the Planet, presented by DuPont. Suburban and city dwellers may not exactly welcome the influx of coyotes, which rarely attack humans but are known to kill small pets. But the coyote problem is more serious in the Western ranching states.

"There's no doubt that livestock ranchers will suffer economically if they don't attempt to locally reduce coyote populations."

Matt Gompper is a coyote expert at Columbia University.

"Coyotes can do very significant damage to livestock operations, especially sheep operations. Sheep are very susceptible to coyotes."

But programs to control livestock predators have run into a paradox: killing coyotes only seems to increase the coyote population. Gompper says this may be because only the larger, older coyotes are seen and killed.

"The easiest animals to see and kill are the territorial individuals, the breeding individuals. As you remove individuals, those open territories are now taken up by younger individuals and younger individuals tend to have larger litters. So if you have larger litters, well you have a potential for a rapid rebound in the population."

In fact, experts estimate that at least seventy per cent of the coyotes in a given area would have to be killed every year to actually reduce the population. Pulse of the Planet is presented by DuPont, bringing you the miracles of science, with additional support provided by the National Science Foundation. I'm Jim Metzner.