Bengaluru: A new study has found that human noises can prevent birds from reproducing or even developing normal social behaviour.
Conducted by researchers of Queen’s University Belfast, UK, the study was published in the journal Biology Letters Wednesday. Researchers said the study has also established for the first time a link between human-induced noise pollution and decline of bird population.
To understand the effect of human noises in birds, researchers studied bird songs and their responses. Birds use their songs for various reasons. The most well-known reason is, of course, for attracting mates. But, the ability to compose sounds with structural complexity allows birds to use songs to give other signals as well such as for claiming new territories for nesting or breeding purposes.
Birds also communicate aggression through songs, and often settle disputes by effectively arguing melodiously with each other.
One way to understand bird songs is by recording a song, then playing it back in a controlled environment and then observing behaviour of other birds.
The researchers had first recorded songs of European robins. Then they played the songs back to the birds in a controlled environment and checked their reactions.
They first discovered that complexities of the songs signalled a level of aggressive intent of the birds and affected the response of other birds. The more complex a song was, the more aggressive the reaction was from other birds.
When the researchers introduced human noises in the environment, they noticed that the birds’ responses were dampened and they did not react with the kind of urgency required despite increasingly complex and aggressive songs being played in the environment. At times, the birds even misjudged the complexities and reacted more aggressively than was required.
“The birds receive incomplete information on their opponents’ intent and do not appropriately adjust their response,” said Gareth Arnott, principal investigator of the study, in a statement.
“Where song is disguised by background noise, in some cases the male ends up fighting more vigorously than he should, but at other times gives in too easily,” he added.
‘Human-made noise impacts both animals and birds’
The new study raises concerns over birds’ ability to develop social behaviour, compete for resources, breed and live safely, and most importantly, reproduce.
Birds, like most other life on Earth, have already been affected by human activities such as habitat loss to farming, climate change and residential and commercial development, expansion of cities, among others.
This is also the first time that a link between noise produced by humans and decline of bird population has been established by a study.
“The study shows that human-made noise pollution impacts animal habitats and directly influences their ability to communicate properly, which may have implications for their survival, and on population of birds,” said Arnott.