Noise creates stress, and this connection has been known to humans for some time. But loud noises don’t just bother people. According to a team led by the prospective cognitive psychologist Çağla Önsal from Koç University in Istanbul, birds also react to city noise: like the scientists now in the magazine Behavioral Ecology and Sociobiology to reportrobins behave more physically aggressively in the city than in the country – and rural robins also become more irritable when under the influence of city noise.
Robins have a strong territorial social behavior. If a rival invades their own territory, they immediately start singing to scare them away. If that doesn’t help, the robin becomes physical: it fluffs up to show its red chest or approaches the opponent to chase them away. If he doesn’t react, it’s on him.
Urban robins sit out street noise
To test the behavior of the birds experimentally, researchers from Britain’s Anglia Ruskin University (ARU) and Koç University built a model of a robin and confronted 21 real birds living in Istanbul and rural areas around the metropolis. In order to make the dummy look as real as possible, they also played the song of a robin over a loudspeaker. Later they played additional recordings of city noise. And they found: Urban robins responded more aggressively to the simulated intruders than rural birds. And robins from rural areas also became more aggressive when traffic noise was also played to them. With urban robins, this extra amplified background noise showed no such effect. They only reacted by singing less themselves.
The scientists suspect that urban birds are probably used to the noise pollution and know that it will pass again. Until then, they would, so to speak, sit out the additional noise. Rural robins, on the other hand, are less familiar with road noise, which is why they become aggressive more quickly.
“The chronically high level of noise pollution that prevails day and night in urban living spaces, for example from traffic or construction machinery, can permanently disrupt the efficient transmission of acoustic signals,” says Çağlar Akçay, behavioral ecologist at the ARU in a press release from the university. “This is probably the main reason why urban robins tend to be more aggressive than rural birds.” And he warns: robins are quite small birds. And for such, not only stress but also aggressive behavior are rather unhealthy.