It’s not easy being a rodent in the U.S. Great Plains.
Animals like black-tailed prairie dogs (Cynomys ludovicianus) are under constant threat of being preyed upon from land and air by predators that include hawks, eagles, and coyotes.A black-tailed prairie dog peeks out of its den. Photograph by DLILLC/Corbis
To cope with this danger, the social animals are in constant communication, including via so-called “contagious” displays, in which an action by one creature is mimicked by others in its group.
In a new study, published January 7 in the Proceedings of the Royal Society B, researchers examined one such maneuver, known as a “jump-yip” display, in which a prairie dog rears on its hind legs and emits a high-pitched yelp. This is usually followed by identical behavior from its kin—producing an effect similar to “the wave” that’s popular in sports stadiums worldwide.
This curious behavior has long been observed among groups of wild prairie dogs, and can even be observed in prairie dogs living in captivity in small numbers, according to study co-author James Hare, associate head of the Department of Biological Sciences at the University of Manitoba in Winnipeg.
Watch prairie dogs “do the wave.”
Photograph courtesy Darlene Stack
The question is why they do it: And now Hare thinks he has an answer.
Explaining the Wave
Some scientists had theorized that the prairie dog jump-yip serves as an “all-clear signal” that tells the colony the predator threat is gone.
However, the team’s video observations showed that the behavior occurs regardless of whether a predator is present—suggesting it has a broader purpose.
“This work reveals that black-tailed prairie dogs use contagious ‘jump-yip’ displays to probe the responsiveness of their neighbors, effectively testing their level of vigilance, and adjusting their behavior according to how much they can rely on their neighbor’s awareness of potential risks in their environment,” Hare said.
In other words, the wave-like response of nearby colony members indicates that everyone in the group is paying attention and on their guard against potential threats.
Prairie Dog Crowd-Sourcing
Working together pays off for prairie dogs: The bigger the group, the less each individual has to pay attention, freeing up more time to forage for food and so forth. (Watch a video of a prairie dog alarm call.)
Indeed, Hare’s team found that the more fellow prairie dogs responded to a jump-yip display, and the longer their response lasted, the more time the initial “jump-yipper,” if you will, devoted to foraging instead of keeping a lookout.
So a jump-yip appears to function as a quick way to check both collective alertness and group size before deciding on an individual action, a calculus the paper refers to as a “foraging-vigilance trade-off.”
Call it the original form of crowd-sourcing: By surveying the awareness of their compatriots, the prairie dogs are in effect taking a quick survey and using the results of that query to make more informed decisions.
Giant Leap for Communication
Humans engage in contagious displays as well, from yawning to laughter. This manner of “emotional contagion” serves to improve social cohesion, and as Hare’s study notes, has often been considered a precursor to more advanced cognitive abilities. (Read “Animal Minds” in National Geographic magazine.)
“Our findings also fit beautifully with work on primates, including humans, which suggest that contagious displays [like yawning or emotional expressions] provide a window into the mind of others,” said Hare, “suggesting of course, that species probing the minds of others are [consciously] aware that they are distinct from those others.”
One small jump-yip for prairie dogs perhaps, but a potential giant leap for our understanding of social communication and animal cognition.
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