Published: 6 December 2022 at 22:00
Research finds that additional noise increases levels of physical aggression
Researchers have found that human-made noise pollution causes robins living in rural areas to become more physically aggressive.
The study, published in the journal Behavioral Ecology and Sociobiology and funded by the British Ornithologists’ Union, investigated the behaviour of male European robins (Erithacus rubecula) living in both urban and rural areas.
Robins are fiercely territorial and the scientists, from Anglia Ruskin University (ARU) in the UK and Koç University in Turkey, measured aggression towards an intruder by using a 3D model of a robin. The model was accompanied by recordings of robin songs, while additional traffic noise was added through a separate speaker nearby.
Robins rely on signals – both visual and acoustic – to indicate their territory and keep out other individuals, and they change their behaviour when threatened.
As well as adapting their songs to ward off intruders, robins adopt specific visual displays during territorial interactions. These include swaying and displaying the red feathers on their neck, as well as moving closer to their opponent and attempting to chase it away.
By recording the birds’ behaviour during interactions with the simulated intruder, researchers found that urban robins typically displayed more physical aggression than rural robins. However, rural robins became more aggressive with the addition of traffic noise. The scientists believe that physical displays of territoriality increase because traffic noise interferes with robins’ signalling behaviour using song.
During tests on urban robins, which are already living in noisier habitats, the simulated traffic noise did not affect levels of physical aggression, but they adapted to the additional noise by reducing their call rate.
The researchers suspect that urban robins have learned to “sit out” temporary increases in noise whereas rural robins have not, and rural robins instead compensate with increased physical aggression.
Dr Caglar Akcay, Senior Lecturer in Behavioural Ecology at Anglia Ruskin University (ARU) and the senior author of the study, said:
Lead author Çağla Önsal, who carried out the research during her studies at Koç University, added:
Caglar Akcay teaches on our undergraduate Animal Behaviour and Zoology degrees, as well as the MSc Animal Behaviour Applications for Conservation. Find out more about these courses at an Open Day.