Great tits ‘update traditions’ to more efficient behaviours when new birds join group, scientists say

‘Immigration is a powerful driver of cultural change’ for these birds, say study authors

Birds such as great tits can rapidly adopt more efficient behaviours when new members join their groups, new research suggests.

Scientists in Germany who studied populations of great tits saw that the garden birds were able to switch from one behaviour to a better alternative when their group members were slowly replaced with new birds.

They said the research “reveals immigration as a powerful driver of “cultural change” in animal groups”, and said this could help species adapt to rapidly changing environments.

Though it sounds strange to speak about animals’ “culture”, the scientists said the term refers to any behaviour that is learned from others, shared by members of the group, and persistent over generations.

With this understanding, cultural traditions are known to exist in many animal groups, including primates, dolphins and whales, rodents, and birds.

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Great tits provide a classic example of animal culture: in the 1920s, birds in a Swaythling on the edge of Southampton in the UK were observed to open the foil tops of milk bottles to steal cream.

This behaviour then spread over the subsequent 20 years, until birds throughout the country were doing the same.

In 2015 scientists said they had sufficient evidence to say that great tits were able to maintain cultural traditions. A new way of feeding - what scientists refer to as an innovation - could be taught to a single bird, and that solution would be learned by other birds and gradually spread throughout populations.

The new study builds on this research as it was still not known if groups can change their behaviour altogether - once a tradition has taken root, are animals condemned to repeating the same behaviours or can they pivot to more efficient ones?

The research demonstrated that more efficient behaviors can outcompete an established inefficient behaviour, but only if there were demographic changes in the group.

The researchers said they had pinpointed a fundamental process - population turnover - which they said was crucial for the ability of animals to change their traditions.

The study involved teaching wild-caught great tits to solve puzzles and used fine-scale tracking of their behaviour.

“Experimental evidence of cultural change in animals is pretty rare, so we were surprised and excited by the outcome,” said first author Michael Chimento, a doctoral student in the Research Group of Cognitive and Cultural Ecology at the Max Planck Institute of Animal Behavior.

The research team was led by senior author Lucy Aplin, who is a Max Planck Research Group Leader and also a principal investigator in this field at the University of Konstanz. She studied populations of great tits caught from forests around Konstanz.

Because wild great tits form changeable social groups during winter, when conditions are harshest, the scientists thought that immigration could play a part in cultural evolution.

“These fluid groups could influence how their culture changes, as new group members might see solutions to problems with clearer eyes, because of their lack of experience,” said Mr Chimento.

The researchers used captive populations of wild-caught great tits to examine how fluid social groups might change a socially learned feeding tradition.

They created 18 groups of birds, each with an automated puzzle-box that gave a reward. When a bird solved the puzzle, the type of solution, time of solution, and identity were recorded using automated technology.

Each group had a tutor that was trained on a relatively inefficient puzzle solution, which then spread through the group. Then, half of the groups were kept static, and in the other half, group members were gradually replaced with new birds from the wild over the course of four weeks.

Despite both types of groups innovating a more efficient solution, fluid groups were much more likely to adopt it as their preferred behaviour, the researchers said.

The original residents, who were experienced with the puzzle, were generally the ones who innovated the efficient solution, but didn’t adopt it as their preferred behaviour.

The inexperienced immigrants, on the other hand, picked up on this innovation and did adopt it, amplifying the available social information. Birds in fluid groups were able to solve the puzzle-box faster than in static groups, despite having less overall experience.

“Great tits seem to do well in and among human-made habitats, compared to other species,” said Mr Chimento.

“Our study shows how their fluid social dynamics might be part of their secret to success and contribute to their flexibility.”

The research is published in the journal Current Biology.