You’d think it would be easy to persuade people to protect prairie dogs: Not only are they a keystone species, with nine other species directly dependent on them for survival, but they’re also irresistibly cute, with big eyes and big personalities. Yet the personable little rodents often find...

India leaps into his pool, pouncing on a purple plastic egg—his favorite toy, according to his caregivers. After a few minutes, the tiger ambles over to his watering tub. Instead of taking a drink, he plops in and closes his eyes in contentment. Although he’s young—roughly 10 months old on this June...