JUSTIN BINFET, A BIOLOGIST with the Wyoming Game and Fish Department, strode down a sagebrush-covered hill in the Deer Creek Range of central Wyoming, his phone in his hand. The mid-June sun beat down as the wind picked up. Binfet hopped across a clear, rocky creek and climbed hundreds of feet up the opposite ridge. He stopped occasionally to course-correct after checking his phone, which showed dozens of dots on a map, indicating that a mountain lion had been hanging out near the area. A female lion usually sticks around for one of two reasons: She’s made a den and has kittens, or she killed something big and is taking her time dining.
Binfet hoped for the latter. Wind and hot sun can make quick work of a carcass, so he didn’t dawdle.
He and a few other biologists had fitted the wild cat with a GPS collar 18 months earlier so they could track her movements. Her collar collected her location every three hours, and the data was sent to a satellite daily. A complicated algorithm analyzed those pings and alerted the scientists if the lion had likely killed something.
Binfet reached the top of the ridge, where sagebrush flowed into a few robust junipers that abutted the limestone bluffs above him. His truck sat far below along the vague two-track we’d driven in on, the only sign of humans for miles.
“I’m looking for a kill in some pretty open stuff,” Binfet said.
Minutes later, he found it: the remains of an elk calf, baking in the sun a few feet away from a juniper as tall as a house. Binfet wanted to know whether a lion had killed this calf, and if so, whether the calf was infected with chronic wasting disease, or CWD, when it died.
Tufts of fur were buried in a bed of needles and duff beneath the tree — signs of a lion cache. The only way to tell if the calf had been infected was to examine its lymph nodes, which Binfet hoped hadn’t yet decomposed into slime. He turned to the calf, stretched blue surgical gloves over his hands and set to work, using a scalpel to dissect the several-day-old carcass that was already melting into the earth.
Any information gleaned from it would provide one small piece of a much greater puzzle — the question of
