The first time it happened, it was over so quickly that John Hoogland almost missed it. It was a spring day in 2007. Hoogland was sitting in a two-meter-tall observation tower near Walden, Colorado, watching a colony of white-tailed prairie dogs. During his stakeout, he saw one of the small, burrowing rodents—a female called “Head 6”—jump on something. She grabbed it, shook it for a few minutes, and then walked away.
Hoogland assumed he had just seen a case of infanticide, that the female had killed a neighbor’s baby. But when he walked over to investigate, he realized he was wrong. The victim was actually a baby ground squirrel—a completely different species of burrowing rodent, about half the size of a prairie dog.
“We had never seen anything like this,” he says. Not in 35 years of observing wild prairie dogs, and not in four years of watching the white-tailed species specifically. “But once we knew what to look for, it seemed like it was going on everywhere. The next day, I saw another kill. And then more.”
Between 2007 and 2012, Hoogland and his assistants witnessed 101 instances of prairie dogs dispatching ground squirrels. “It’s so quick and subtle,” he says. Brutal, too. The prairie dog would grab the smaller animal by the neck or chest and violently shake it for a few minutes, either breaking its neck or puncturing its heart. Most attacks happened after a ground squirrel entered the prairie dog’s territory. But in rare cases, the killer waited in ambush outside the victim’s home-burrow, or actively dug it out. In six occasions, “the female actually stalked a baby almost like a tiger coming in for a kill,” says Hoogland.