NatureToday | Fireworks cause long-term disturbance to wild birds

Anyone with a pet knows that the combination of loud bangs, bright flashes of light and smoke can cause fear and disorientation in animals. In recent years, a European team of researchers has tracked hundreds of tagged birds during the three weeks around New Year. This now provides the first detailed insight into the response of individual wild birds to fireworks.

Fly away and get stronger

“We see a strong response in most of the animals we followed,” says animal ecologist Bart Nolet. “We show that a large proportion of the birds fly away from their roosts during the fireworks, end up in other roosts further away from human habitations and forage longer in the following days – presumably to regain strength.”

The disturbed birds rested two hours less than on nights without fireworks. In addition, they flew 40 to 150 meters higher and also much further than the previous nights: on average about 10 kilometers but up to 500 kilometers non-stop. The latter they usually only do during migration. The unusual behavior did not stop with the New Year’s celebration. During all studied days after the New Year, they changed roosts more often and the geese spent more time eating.

Don’t fall out of the blue

These conclusions do not come completely out of the blue. Earlier research in the Netherlands with radar showed large-scale disturbance with thousands of birds flying up at the start of the fireworks at midnight. And also a small study with a few tagged geese around a fireworks display in Ireland showed that the birds briefly flew up from their roost. But now this new study shows that the disruptive effect lasts longer than the fireworks themselves.

“We measured the response of nearly 350 tagged birds across four species of geese over eight consecutive years,” explains Nolet. “On average, this gave about two years of data per bird and thus a total of about 700 tracks of their movements before and after the turn of the year.” This research took place in Germany, Denmark and the Netherlands. In the Western European countries, the disturbance is probably great because people are allowed to set off fireworks themselves in all sorts of places instead of a smaller number of firework shows in central places.

Energy loss

The four bird species studied are all migratory birds that breed in the far north and spend the winter in the three western European countries. These are white-fronted geese, brambles, pink-billed geese and pygmy geese. However, their hibernation changed abruptly as soon as the fireworks started.

Under normal circumstances, geese return to the same body of water several nights in a row to rest. On New Year’s Eve, the birds flew away to places further away from people and with a lower concentration of particles in the air. This further indicates that they are most likely trying to escape the effects of the fireworks.

Once fledging, they foraged 10 percent longer and moved less during the week and a half after New Year’s that was studied. “The animals compensate enough for the extra energy that the New Year’s flight cost them,” says Nolet. “In the dark days around the turn of the year, the geese have the hardest time getting enough food. They mainly eat during the day. The disturbance therefore comes at an unfortunate time for the birds, especially if it coincides with a cold period with a lot of snow.”

No more fireworks at the picnic area

In the last year of the study (from 2020 to 2021), the corona pandemic led to a widespread ban on fireworks. Corona gave the team a unique opportunity to compare the results. But already then, fireworks effects were detectable: In two of the four species of geese, there was still more activity among the birds due to flying further and higher.

“This shows that even small amounts of fireworks affect the behavior of geese,” Nolet said. “To create a safe place for birds, fireworks should no longer be fired near protected bird areas and other important bird roosts.”

Resting grounds (dots) and night flights (lines) of tagged geese during a) the night of 22-23 December and b) during the New Year

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Text: NIOO-KNAW
Pictures: Helmut Kruckenberg; Gerard Muskens; Conservation letters

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