The results of a new study suggest that jackdaws, a relative of the crow, can learn which humans are 'safe' and which are 'dangerous'.
The birds use cues from their fellows to learn which humans are to be seen as a threat, reports a team from the University of Exeter. Furthermore, they are able to recognize individual people and react to them based on their perceived threat level.
"One of the big challenges for a lot of animals is how to live alongside humans," said lead author Victoria Lee, a Ph.D. researcher at the Centre for Ecology and Conservation on Exeter's Penryn Campus in Cornwall.
"People can provide some benefits, such as the food at bird feeders, but in some cases humans are also a threat.
The crow family of birds, to which the jackdaw (Coloeus monedula) belongs, is known for its intelligence. Crows can make and use tools, recognize our faces, and are quite good with puzzles. According to the Cornell Lab of Ornithology’s allaboutbirds, “crows have more than 20 calls,” with the most common being “a harsh caw” which can take many different meanings depending on its quality or length.
Jackdaws themselves resemble crows but have distinctive gray neck plumage and irises. There are four subspecies of Jackdaw. All are loud, boisterous and live in relatively small groups but are very social. They're also able to learn from the group which humans to hide from, the findings suggest.
Lee's team worked on three sites in Cornwall (34 Jackdaw nest boxes) during the 2017 breeding season. One of the researchers put on a mask and came close to their nests while the rest of the team played recordings of either 'scold calls' or 'contact calls' (the latter of which suggests no threat).
"Scold calls are antipredator vocalizations given by jackdaws to recruit others to mob a predator," the paper notes.
The second phase of the experiment had the researcher (with the mask) return to the nests after some time, and see if there was a difference in their behavior. There was. The birds that had heard scold calls returned more quickly to their nests than the others.
Jackdaws that were played scold calls when first seeing the masked researcher returned to their nest quicker (in 53% of the initial time), while birds that heard contact calls took relatively longer (63% of the initial time) on average. The team notes that the calls did not appear to influence how long birds took to enter their nest box, or how long they spent inside, only how quickly they returned to them.
"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," Lee explains.
The paper "Social learning about dangerous people by wild jackdaws" has been published in the journal Royal Society Open Science.