January 7, 2014 | 2
Prairie dogs have the most sophisticated vocal language ever decoded. Even better than chimps, dolphins and orcas. This could change with further research into chimp, dolphin and orca language, but right now, prairie dogs are where it’s at.
Last year, animal behaviourist from Northern Arizona University and founder of the Animal Language Institute, Con Slobodchikoff, discussed his research on the vocalisations of the Gunnison’s prairie dog (Cynomys gunnisoni) from Arizona and New Mexico. He discovered that this species’ communication system is so advanced, not only do they have different warning calls depending on the type of predator – coyote, domestic dog, human, hawk – they also construct sentences describing what a particular predator looks like. So, “a medium, rectangle-shaped dog with yellow fur (we call them German shepherds) is approaching”, or “Here comes a tall human being wearing a green t-shirt who is also fat.” (I’m teasing, prairie dogs, I’m sure your sentences sound much more elegant.)
By showing captive prairie dogs a number of simple silhouetted shapes such as triangles, circles and squares, Slobodchikoff also determined that they can come up with new calls to communicate to each other about things they’ve never seen before.
Here’s a video of Slobodchikoff explaining exactly how it works:
And that’s just the warning calls. Slobodchikoff mentions two other aspects of prairie dog communication that appear to be just as important, but have proved much more difficult to decode. Social chatter between colony mates doesn’t lead to any perceivable change in behaviour, so it’s almost impossible to extract a meaning from it. And then there’s the jump-yips.
Performed by the black-tailed prairie dogs (Cynomys ludovicianus) of North America, and the Mexican prairie dogs (Cynomys mexicanus) jump-yips are exactly what it’d look like if you stuffed a chubby rodent full of popcorn seeds and remotely popped them, one by one. To perform a jump-yip, a black-tailed prairie dog will abruptly raise its chest up to at least an erect posture, sometimes bending so far back that it propels itself off the ground (the “jump” part), and lands on its butt. It will also raise its little arms up in the air for emphasis while emitting a high-pitched “wee-oo” call (the “yip” part). It’s all over in a second, and the best part is, unlike all other prairie dog vocalisations and displays, this behaviour is 100% contagious. Just like a Mexican wave through a stadium, once a jump-yip is instigated, it will travel through an entire colony, each prairie dog jumping and yipping after its closest colony mate has jumped and yipped.
Here are some great jump-yips:
The function of this very conspicuous behaviour has for years remained elusive. Various studies have suggested it could have to do with territorial disputes, or perhaps it’s an “all clear” signal to let the colony know that a predator has moved on. Perhaps it’s a way of promoting social bonds within a colony, or does it allow an individual to collect information from its colony mates about their levels of watchfulness when its own awareness of its surroundings is compromised, say by a brood of pups that need close attention? All of these appeared to make sense, and the “all clear” explanation gained the most traction, but for James Hare, Associate Head of the Biological Sciences Department at the University of Manitoba in Canada, something didn’t add up.
“I was aware of what had become the broadly accepted explanation for these displays from reading John Hoogland’s book, The Black-tailed Prairie Dog: Social Life of a Burrowing Mammal, where they are said to act as an “all-clear” signal, but noted that the captive group at the zoo would jump-yip even when predators were present, and thus thought this notion must be incorrect.”
Watch the jump-yip Mexican wave, shot by another of the researchers on the team, Robert Senkiw:
Reminded of the emergency broadcast signals that would appear routinely on TV during the cold war years of his youth, as a way to train the population in case of an actual emergency, Hare supposed that the jump-yips could be performing a similar function. Publishing in Proceedings of the Royal Society B: Biological Sciences today, Hare and his colleagues suggest that the jump-yips serve to probe neighbouring individuals for information regarding their current state of watchfulness, or ‘vigilance’. And this, they supposed, allowed the jump-yip instigator to spend more time foraging for food instead of keeping watch for predators.
The team video recorded 173 jump-yip bouts within 16 black-tailed prairie dog towns – very large colonies – spread across four naturally occurring populations in South and North Dakota and two introduced populations in Winnipeg, Canada. They found that the more individuals that participated in a jump-yip bout, and the longer a jump-yip bout lasted, the more time the instigator would allocate to foraging. This finding ties in with one of the hypotheses mentioned above that suggested the jump-yips served as a way to collect up-to-date information from colony mates on their current level of watchfulness.
Just as group-living insects mimic each other’s evasive movements and schooling fish avoid predators by copying their neighbours’ behaviour, and emperor penguins behave like a Mexican wave to stay warm, the collective waves of jump-yip behaviour in black-tailed prairie dogs appears to optimise foraging time because the instigator knows his colony mates are being watchful, and also reduces the risk of any one individual getting picked on by a predator, because they’re all displaying conspicuously at the same time.
What Hare and his colleagues aren’t sure about, and what they hope to figure out next, is what drives a particular individual to probe the watchfulness of their colony mates, and whether this instigating behaviour has consequences for its survival and reproductive success. One would guess, offers Hare, that various factors such as sensory impairment due to old age; preoccupation while caring for young; living in a dangerous location i.e. the edge of a colony; or environmental conditions such as wind or loud noises could prompt an individual to instigate a jump-yip bout more frequently than others. “Even personality differences, such that some individuals are more ‘fearful’ than others, could contribute to such variation,” he adds. “Indeed, there’s a lifetime of research necessary to address the cost-benefit trade-offs in exploring variation in the tendency to use public information.”
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