Swiss study shows birds continue to suffer for days after fireworks

Study shows: Birds continue to suffer for days after the fireworks Keystone-SDA

Birds flee, find it hard to rest and avoid their roosts for days afterwards, a new study carried out in Basel shows.

“After a fireworks display, you often see lots of birds sleeping during the day. With their heads buried in their feathers, they try to catch up on the sleep they’ve missed,” explained biologist Valentin Moser in an interview with the Keystone-SDA news agency.

For the study, published in the journal Animal Behaviour, the researcher – who was then working at the Swiss Federal Institute for Forest, Snow and Landscape (WSL), studied the behaviour of birds at a roosting site in the Basel border triangle over three winters (2020/2021 to 2022/2023). The focus was on black-headed gulls, but other waterbirds and songbirds were also recorded.

On New Year’s Eve nights, the flight time of black-headed gulls increased dramatically around midnight. The birds reacted immediately to nearby fireworks, soaring to great heights and displaying clear signs of stress.

Other waterbirds, such as ducks and swans, left the area as soon as the first bang was heard and, in most cases, did not return until the following day. According to the study, even songbirds – which are normally diurnal – were seen flying around in a panic at midnight.

Exhaustion in the days that followed

The disturbance did not end after a single night. In the days following New Year’s Eve, the number of black-headed gulls at the roost fell dramatically. In the winter of 2022/2023, there were over 60% fewer birds on January 1 than there had been on December 27. It took several days for the population to recover and for the stress-related behaviour to return to normal levels.

The least behavioural disturbance among the birds was recorded in the winter of 2020/2021 during the Covid-19 pandemic. At that time, the use of fireworks was at its lowest due to the restrictions.

“Birds are able to cope with this level of disturbance,” said Moser. “The problem with fireworks, however, is that they are often set off over a very wide area, leaving birds with no chance to avoid them.” Nor is there often any time restriction – fireworks are set off throughout the night.

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Translated from German, reviewed by an English Department journalist.