We Vaccinate Animals More Than Ourselves

Every year, at the end of August, Travis Livieri drives into the grasslands of South Dakota’s Conata Basin, where, armed with spotlights and syringes, he spends his nights scooping up subjects for a grand experiment they could not hope to understand. His quarry are the region’s black-footed ferrets, considered by many to be North America’s most endangered mammal. His goal is to save the animals from the existential bind that we have put them in.

Black-footed ferrets once dotted the landscapes of a dozen western U.S. states, plus portions of southern Canada and northern Mexico. But decades of habitat destruction and culling of their prairie-dog prey have sent ferret populations plummeting. The greatest threat to their survival now is also one of our own making: plague, a bacterial scourge that Asian trading ships imported into the U.S. more than a century ago. To mitigate that human disturbance, Livieri, a wildlife biologist, has turned to another—a plague vaccine, developed for the military, that protects animals too. Just 200 black-footed ferrets, more than half of the world’s remaining population, are left in Conata Basin and the surrounding Badlands National Park. One by one, Livieri and his team aim to catch and immunize them all. “I’m like an alien-abduction machine,” Livieri told me.

People have been vaccinating domesticated animals for centuries, but only two reasons justify immunizing wildlife, says Tonie Rocke, a research scientist at the U.S. Geological Survey: “to prevent spillover to domestics and humans of a zoonotic disease, and for conservation purposes.” But although human vaccines function primarily as preventives, offering immunity to animals such as black-footed ferrets can be a conservation strategy of last resort. “The fact that we’re looking