Black-tailed prairie dogs (Cynomys ludovicianus) spend most of their time looking for one of two things: food or predators. But occasionally, a group of the highly social rodents will do something strange. Out of nowhere, a prairie dog, like the one pictured above, will stand up on its hind legs and leap into the air while shouting “wee-oo!” Then, one by one, each of its nearby friends will do the same. Watching this “jump-yip” behavior spread through a group of prairie dogs is like watching the crowd at a football game do the wave, as you can see in this video, but the reason behind the contagious displays remained mysterious. Now, a new study provides a possible explanation for the jump-yip waves. After observing 16 prairie dog towns for months on end, researchers found that the more group members joined a jump-yip wave, the more time the wave’s instigator spent looking for food immediately afterward. The scientists think that kicking off a jump-yip wave is a way for a prairie dog to test how well its immediate neighbors are paying attention to their environment—and, therefore, how helpful they are likely to be at spotting predators, the team reports online today in the Proceedings of the Royal Society B. If a prairie dog knows its neighbors are on the lookout for surprises like sudden jump-yips, lurking coyotes, or circling falcons, the more comfortable it feels concentrating on foraging and eating. This decision-making process, the team argues, suggests that prairie dogs may have at least a rudimentary “theory of mind,” and that this basic awareness of the mental states of their companions may be crucial to their survival.