We might think of eavesdropping an important survival technique for many species. By listening in on what other species are communicating to one another, valuable information can be learned.
On the grasslands of North America, for example, black-tailed prairie dogs make alarm calls when they spot predators.
The reason they call is to warn other prairie dogs of danger, so that they can take cover and therefore escape being eaten. But it’s not only other prairie dogs who listen out for these alarm calls. Recently, researchers discovered that long-billed curlew pay attention to prairie dog calls too.
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The researchers set up an experiment where a predator (in this case, a stuffed badger) moved towards incubating curlews. In half the cases, the researchers played prairie dog alarm calls while the predator moved toward the curlews, while in the other half no sounds were made.
Incubating curlews adopted a nest defence posture more quickly when prairie dog alarm calls were made than when they were not. This suggests that curlews both listen to prairie dog’s alarm calls, and act on this information by engaging in faster nest defence.
This is a classic example of eavesdropping: the prairie dogs are only trying to communicate to their own kind, but the information is useful for curlews, and they therefore listen out for it and use it for their own (and their offspring’s) survival advantage.
Burrowing owls are known to do the same: they listen for prairie dog alarms and become more alert when they hear a prairie dog shout about danger.
Interestingly, many species seem to like living near prairie dog ‘towns’, even though there tend to be more predators in these areas. Researchers think this might be because of the perks of having such noisy neighbours. By telling one another about predators, prairie dogs inadvertently protect far more than they bargain for.
Such loud information sharers are known as keystone information producers.
Other keystone information producers include chickadees and titmice, both North American bird species. The loud alarm calls of chickadees and titmice not only give other species an early warning of danger, therefore decreasing predation risk, but their calls also mean that eavesdropping species can spend less time scanning for danger and more time eating – good news all round.
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Top image: Black-tailed prairie dogs © Getty
