Fireworks are important elements of celebrations globally, but little is known about their effects on wildlife. In new research, scientists at the University of Amsterdam used weather radar and systematic bird counts to quantify how flight responses differed across habitats and corresponding bird communities, and determined the distance-dependence of this relationship. On average, approximately 1,000 times as many birds were in flight on New Year’s Eve than on other nights. They found that fireworks-related disturbance decreased with distance, most strongly in the first 5 km, but overall flight activity remained elevated tenfold at distances up to about 10 km. Communities of large-bodied species displayed a stronger response than communities of small-bodied species.
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Hoekstra et al. analyzed the instantaneous flight response of birds across habitats and distances to the synchronized discharging of fireworks throughout the Netherlands on New Year’s Eve. Image credit: Nick.
“We already knew that many water birds react strongly, but now we also see the effect on other birds throughout the Netherlands,” said lead author Dr. Bart Hoekstra, an ecologist at the University of Amsterdam.
“Birds take off as a result of an acute flight response due to sudden noise and light. In a country like the Netherlands, with many wintering birds, we are talking about millions of birds being affected by the lighting of fireworks.”
In 2022, scientists discovered that geese are so affected by fireworks that they spend an average of 10% longer looking for food than normal during at least the next 11 days.
They apparently need that time to replenish the lost energy or to compensate for the unknown foraging area in which they have ended up, after fleeing from the fireworks.
In the new study, Dr. Hoekstra and colleagues looked at which species take off after fireworks and when this occurs.
They used information from Royal Netherlands Meteorological Institute weather radars during both a clear New Year’s Eve and on other normal nights.
They combined this with distribution data from Sovon, the Dutch Centre for Field Ornithology, based on bird counts by hundreds of volunteers.
“We already knew that many water birds react strongly, but it was still unclear how birds outside these water bodies react to fireworks,” Dr. Hoekstra said.
“Through the counts we know exactly where which birds are and using the radar images we can see where they actually take off because of fireworks.”
The authors were able to calculate how many birds take off immediately after the start of the fireworks, at what distance from fireworks this happens, and which species groups mainly react.
The analysis makes it clear that in the study areas around the radars in Den Helder and Herwijnen alone, almost 400,000 birds take off immediately at the start of the fireworks during New Year’s Eve.
Moreover, it appears that larger birds in open areas in particular fly around for hours after and at remarkable altitudes.
“Larger birds such as geese, ducks and gulls fly to a height of hundreds of meters due to the large-scale discharge of fireworks and remain in the air for up to an hour,” Dr. Hoekstra said.
“There is a risk that they will end up in bad winter weather, or that they will not know where they are flying due to panic and accidents could occur.”
Because 62% of all birds in the Netherlands live within a radius of 2.5 km of inhabited areas, the consequences of fireworks are high for all birds throughout the country.
“Flying requires a lot of energy, so ideally birds should be disturbed as little as possible during the cold winter months,” Dr. Hoekstra said.
“Measures to ensure this are especially important in open areas such as grasslands, where many larger birds spend the winter.”
“The effects of fireworks on birds are less pronounced near forests and semi-open habitats.”
“In addition, smaller birds such as tits and finches live there, which are less likely to fly away from disturbance.”
The team argues for fireworks-free zones in areas where large birds live.
“These buffer zones could be smaller in areas where light and sound travel less far, such as near forests,” Dr. Hoekstra said.
“Furthermore, fireworks should mainly be lit at central locations in built-up areas, as far away from birds as possible.”
“It would be best for birds if we moved towards light shows without sound, such as drone shows or decorative fireworks without very loud bangs.”
The study was published in the journal Frontiers in Ecology and the Environment.
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Bart Hoekstra et al. Fireworks disturbance across bird communities. Frontiers in Ecology and the Environment, published online December 7, 2023; doi: 10.1002/fee.2694
