Oddly, cougars aren't David Choate's biggest worry during his long stretches in the Desert National Wildlife Refuge. The post-doctoral scholar is the lead field researcher for a multi-agency project trying to find out why the desert bighorn sheep population there hasn't rebounded since a die-off in 1980s. Could the area's cougars be eating more than their expected share of our state animal?

To find out, Choate hikes into the vast land with roadkill on his back and sets his cages. He tranquilizes the cougars, fits a radio frequency transmitter collar on them, and releases them unharmed back into the wilderness. The solitary predators can be very dangerous but an injury can lead to starvation, so they're wary of tangling with unfamiliar or larger creatures. "I suspect that by the way their tracks cross mine that sometimes they're observing me, but they tend to avoid confrontations with humans," he says.

The real danger comes from the land itself. The former African safari guide sets up camp far off rudimentary roads, often enduring nasty windstorms, freezing temperatures and the occasional scorpion guest, so he can immediately reach a caught animal. Because cougars move primarily at night, so does he. During a bad snowstorm last winter, he hiked over a steep ridge in the dark, only to find that the snow itself had set off the trap. "Collaring takes patience," he says.

Then comes the dirty work. Choate tracks their movements. A cougar will return to its kill site over several days to feed on a stashed carcass. "I go looking for evidence; it's analogous to doing crime scene forensics." A fresh kill can be gruesome; a decaying one might be covered in maggots. He also bags up droppings from cougars, sheep, and deer for lab analysis.

"Most people have this Disney-esque or National Geographic view of wildlife work," Choate says. "We often have little direct contact with (live) animals. Most of the time we're tracking bleeps and blips from a radio signal or we're elbow-deep in a carcass or collecting scat."