Jackdaws can learn to recognise a potential human threat without warning if they hear the alarm calls of their fellow birds the first time round, according to new research.
A small study involving 34 jackdaw pairs suggests the birds use social learning – the ability to learn from each other through observation and imitation – to identify individual humans that pose a risk to them.
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Previous experiments have shown jackdaws can recognise human faces.
To see if they could tell the difference between the humans who pose a threat and those who do not, the scientists played recordings of two types of jackdaw calls when an unknown person approached their nest.
These were either alarm or “scold” calls, which the birds use to alert others to a potential threat, and contact calls, which are used in a range of different contexts but are not associated with any specific event.
Victoria Lee, a PhD researcher at the University of Exeter’s Centre for Ecology and Conservation and lead study author, told the PA news agency: “Jackdaw contact calls and alarm calls sound very different from each other, and previous research and our own observations demonstrate that these calls are used in different contexts and serve different functions.”
When jackdaws saw the same person for the second time, the birds that had heard the alarm call the first time reacted defensively by returning more quickly to their nests.
Results from the 102 trials carried out across three sites in Cornwall showed the birds from the scold call group returned to their nests more than twice as quickly (53 per cent on average) when seeing that human again. On the other hand, the birds that heard contact calls took longer to return to their nest (63 per cent on average).
Though jackdaws returned to their nests more quickly after seeing a human associated with scold calls, the researchers said the calls did not appear to influence how long birds took to enter their nest box or how long they spent inside.
Ms Lee added: “Being able to discriminate between dangerous and harmless people is likely to be beneficial, and in this case we see jackdaws can learn to identify dangerous people without having had a bad experience themselves.”
The research is published in the journal Royal Society Open Science.