Traffic noise makes birds aggressive, study finds

Birds change their behaviour and become more aggressive when exposed to traffic noise, research suggests.

Experts at Anglia Ruskin University (ARU) in Cambridge examined the impact of vehicle noise pollution on yellow warblers in the Galapagos Islands.

They found songbirds living in roadside territories showed increased aggression compared with those in quieter areas as excessive sound interfered with their communication.

ARU senior lecturer Dr Caglar Akcay said the results highlighted the "significant impact" humans had on wildlife and hoped it would help improve conservation efforts.

Researchers simulated an intruder by playing birdsong from a speaker at 38 locations populated by the birds.

Twenty sites were within 50m (164ft) of the nearest road and 18 were more than 100m (328ft) away.

They then measured song - typically used to ward off intruders - and physical, aggressive behaviours such as approaching the speaker closely and making repeated flights across it.

Researchers found if external noise such as traffic interfered with the birdsong, it blocked their communication channel, increasing their aggression.

It was found even minimal levels of traffic affected responses to noise.

The birds also increased the minimum frequencies of their songs during the noise experiments, regardless of their territory's proximity to the road, helping to reduce any overlap of their songs with the low-frequency traffic noise.

"Our study shows the importance of considering behavioural plasticity in conservation efforts and developing strategies to mitigate the effects of noise pollution on wildlife," Dr Akcay said.

"It also highlights the significant impact of human activities on wildlife behaviour, even in relatively remote locations such as the Galapagos Islands."

The study also included experts from the Konrad Lorenz Research Centre at the University of Vienna, Austria.

The Galapagos Islands are located more than 500 miles (805km) off the coast of Ecuador in South America, and helped inspire Charles Darwin to develop the theory of evolution by natural selection.

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