Squirrels eavesdrop on the chatter of songbirds to work out whether the appearance of a predator is cause for alarm, researchers have found.

Animals including squirrels have previously been found to tune in to cries of alarm from other creatures, while some take note of “all-clear” signals from another species with which they co-exist to assess danger.

But the latest study suggests animals may also keep an ear out for everyday chitchat among other species as a way to gauge whether there is trouble afoot.

“This study suggests that eavesdropping on public information about safety is more widespread and broader than we originally thought,” said Prof Keith Tarvin, co-author of the study from Oberlin College, Ohio.

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“It may not require tight ecological relationships that allow individuals to carefully learn the cues provided by other species,” he added, noting that the grey squirrels and songbirds in the study moved from place to place without regard for the other.

Writing in the journal Plos One, Tarvin and colleagues reported on how they made their discovery by observing 67 grey squirrels as they pottered about different areas in the parks and residential regions of Oberlin.

After 30 seconds of observing a squirrel, researchers played it a recording of the call of a red-tailed hawk, which lasted a couple of seconds – and their behaviour in the next 30 seconds was monitored.

The results revealed that in the 30 seconds after hearing the hawk call the squirrels increased the percentage of their time spent “vigilant” – showing behaviour such as freezing, fleeing or standing – compared with before the call, while they also looked up more often to scan the environment.

The squirrels were then played either a three-minute recording of several different species of songbird chattering on a feeder, or ambient noise.

The team noted that these songbirds were often wary of red-tailed hawks and were known to make alarm calls in response to these hawks, as well as to predators that prey on them as well as squirrels. However, they chatter when there is little sign of a threat.

Results from 28 squirrels that were played bird chatter and 26 squirrels that were played ambient noise were analysed – the others having scampered out of view before data could be collected.

Taking into account the animals’ responses to the hawk call and whether they were in a tree or on the ground, the team found squirrels that were played bird chatter raised their heads less often during the recording than those played ambient noise, and the number of these “lookups” dropped off faster over time.

Squirrels showed similar levels of vigilant behaviour during both types of recording but those exposed to bird chatter seemed to reduce this behaviour more rapidly than those exposed to ambient noise.

“Recognition of bird chatter as a sign of safety is likely adaptive, as squirrels that can safely reduce their vigilance level in the presence of bird chatter presumably are able to increase foraging success,” the authors wrote.

However, they noted there was more work to be done to unpick whether the squirrels were listening to particular species, and whether they were focusing on the chatter or rather the general foraging and jostling of birds – sounds that were also present on the recording.

The team suggested that with levels of human-made noise increasing, squirrels may find it harder to eavesdrop on birds, meaning they may have to spend more time being alert and less time foraging.

Dr Jakob Bro-Jorgensen, an evolutionary ecologist from the University of Liverpool who was not involved in the study, said the research shows that animals can assess predation risk not only from alarm calls but also from non-alarm signals, even from species that they do not usually hang out with.

“The study calls attention to how animals can gather information from their environment by using cues that may at first glance seem irrelevant,” he said. “And it makes you wonder how the more and more pervasive impact of human activities on natural soundscapes may compromise survival of wildlife in ways we haven’t thought of.”