People are constantly bombarded with new information. We receive it on our phones, from our friends and while eavesdropping on a conversation in line for coffee.
It's easy for misinformation to spread, especially when people don't take the time to check out the accuracy of that information for themselves before sharing it with others. Fortunately, many people make it a habit to check something out before passing it along.
Humans aren't the only fact-checkers in the animal kingdom, according to recently published research by Christopher Templeton, a biology professor at Pacific University.
In a new study, published in the journal Nature Communications last month, Templeton and his colleagues from the University of Montana and the Max Planck Institute for Ornithology showed how a songbird found across the United States, the red-breasted nuthatch, fact-checks the "predator warning" calls of another common songbird, the black-capped chickadee.
Nuthatches and chickadees are "co-occurring," meaning they are found together in many of the same places, although the two species are not closely related. They have similar diets and occupy similar places in the ecosystem — including being prey for common predators, like hawks and owls.
In a 2007 study, Templeton and co-author Erick Greene concluded that nuthatches pick up on the calls of chickadees as a form of what they described as "interceptive eavesdropping."
In his latest study, Templeton delves further into the subject. The study suggests that when nuthatches hear warning calls from chickadees about dangerous owls, they do recognize them, but they will often go to the source to assess the threat level themselves instead of immediately warning other nearby nuthatches.
Templeton says the research reveals a type of communication in a bird that isn't so different from that of humans.
"There's a lot of really nice analogies with news cycle stuff," Templeton said. "So many people will just push a button to send on this Tweet or this Facebook post or whatever without actually reading it or checking the sources."
Templeton studied the birds in Missoula, Montana, where they're particularly common — eating seeds off birdfeeders in people's gardens and in parks.
"We would always get people's permission, of course," Templeton said.
Both chickadees and nuthatches use "mobbing calls" — calls that tell other nearby members of their species that they've observed a predator and want help to scare it away by mobbing it.
The chickadee mobbing call is the call for which it's named: "chick-a-dee-dee-dee-dee."
The birds vary their calls, producing more frequent, urgent-sounding calls if the predator is more dangerous, Templeton said — something he and Greene found in a 2005 study.
Counterintuitively, larger great horned owls are less dangerous than northern pygmy owls, Templeton said.
Templeton and his colleagues wanted to test whether or not nuthatches, in essence, believe the credibility of chickadee calls and pass on information about the threat level of a predator to other nuthatches.
Templeton would find a pair of nuthatches and place a speaker in a nearby bush or tree. He would then play either the call of a great horned owl or a northern pygmy owl to make nuthatches respond to directly observing their predators.
He also played the mobbing calls of chickadees to see if nuthatches passed on that indirect information about predators to other nuthatches by voicing their own call, which Templeton was ready to record and then later analyze in the lab.
"What we found is that the nuthatches change their call between little owl and big owl, but when they hear chickadee calls reflecting those two things, they produce a more generic alarm call that says, 'Hey, the chickadees are really upset about something over here, everybody be wary, but I'm not going to tell you exactly what it is before I figure it out myself,'" Templeton said.
Nuthatches' ability to use information about chickadee calls, but reserve judgment about potential danger until they've observed the danger directly is evolutionarily advantageous, he said.
"Nuthatches live in long-term pairs, so there's kind of a lot at stake," Templeton said. "They don't want to tell their mate that there's something really dangerous if it's not so dangerous, because then their mate is going to waste a lot of time trying to deal with a predator when it could be foraging."
He said the next step in the research is to study whether or not nuthatches have a call that tells their partner the results of their fact-checking.
There's a lot more to discover about animal communication, Templeton said.
"That's one of the neat things about studying animal communication is the more you look, then the more you see that's going on out there," he said.
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