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...

Danielle Tepper had always loved dolphins. When she went on vacation to Hawai'i, she knew she had to see them firsthand. Tepper—now a senior editor at the Humane Society of the United States—wanted to do it ethically, so she avoided captive dolphin attractions. Instead, she booked an excursion to...