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This food tastes disgusting! This is what great tit and blue tit can learn from one another by watching video recordings, researchers report. The birds therefore recognize disgusting reactions of others across species boundaries and can use the observation to avoid certain food objects. This social learning means that they do not need to have potentially dangerous experiences themselves. In addition, the effect could have shaped the evolution of warning signs in insects, the researchers say.
One gets wise from one’s own experience, it is said – but sometimes, as is well known, observation is enough: Humans have a particularly strong talent for drawing lessons from the reactions and actions of their fellow human beings. This form of social learning is also known from various animal species. In previous studies, scientists have shown that great tits can learn to avoid inedible prey by observing other species. Some insects even make targeted use of their enemies’ recognition capabilities: they use colors or drawings to signal that they are poisonous or taste unpleasant.
“In our previous work with great tits, we found that when one bird sees another being repelled by a new species of prey, both birds will avoid it in the future,” said Rose Thorogood of the University of Cambridge. In the current study, she and her colleagues have now investigated whether birds of different species can learn from each other in this way. The focus was again on the great tit (Parus major) and another prominent songbird in our gardens: the blue tit (Cyanistes caeruleus).
Instructional videos with disgusted tits
For their study, the researchers first accustomed the birds to small white bags as “prey”: they contained delicious pieces of almond. For the later experiments, the biologists then filmed individual great tits and blue tits, which picked up and opened a special bag. It was marked by a striking black square and contained pieces of almond that had been dipped in a bitter substance. After the respective bird had tried the contents, he showed a corresponding disgust reaction: he threw the sachet away and cleaned his beak intensively.
The researchers then used these recordings as “instructional videos”, which were presented to some birds on screens: some of the great tits observed a fellow species in the disgust reaction, while others a blue tit and vice versa. Then these test animals were then confronted with an offer of different food bags. Some were plain white as usual, others had a cross and the third variant was the one with the square from the instructional video.
The observation of the choice of feed of the titmouse showed: In contrast to birds from control groups, all titmice from the instructional video group clearly avoided the sachets with the squares. Accordingly, they had learned socially through the example of a conspecific as well as an alien bird. As the researchers continue to report, there was only a slight difference between the species of tit: blue tits learned best from their fellows, while blue tits acted as teachers for great tits as did their fellows.
Important for hunters and prey
With other combinations of bird species, there is probably also social learning across species boundaries, the researchers say. According to them, this may be one of the reasons why some species like to socialize with others – as is the case with cabbage and blue tit. In this way, the animals can access a broader information base. “By learning from others, you can save time and energy trying different prey and avoid possible negative effects of eating toxic objects,” says co-author Liisa Hämäläinen.
Social learning may also have had a major impact on the development of warning colors and markings for inedible prey, the scientists say: “Anomalies can be an effective anti-predator defense against insects. But only after predators have learned to associate the warning signal with an unpleasant effect, ”says Hämäläinen. As the study now shows, it obviously does not always require a victim to do so: birds can learn to avoid certain insects by observing the damage done by others, and are therefore likely to contribute to the evolution of the warning symbols, the scientists explain.
Source: University of Cambridge, professional article: Journal of Animal Ecology, doi: 10.1111 / 1365-2656.13180