Human activities often have negative effects on animals, whether intentional or not. Fireworks are an especially loud and jarring disturbance with consequences for companion and wild animals. Many of the immediate effects of fireworks are already known — for example, companion animals and wild birds show increased anxiety. However, the potential longer-term effects on wild birds are not fully understood. 

This study looks at what happens to wild migratory geese in the short- and long-term after New Year’s Eve (NY) fireworks displays disturb their roosts. It is typical for geese to stay at a roosting site all night and return to the same site for several nights in a row when undisturbed. Researchers wanted to know how human population density and fireworks intensity would affect their roosting and feeding behavior. They also looked at differences in areas (and years) with fireworks bans.  

To carry out the study, the authors used GPS tracking data to compare night movement and foraging behavior in four different wild goose species (totaling 347 individuals) in the 12 days before and after NY in Western Europe. They looked at greater white-fronted geese, bean geese, barnacle geese, and pink-footed geese.

The results show that fireworks have long-lasting effects on geese, beyond the event itself. Two major behavior changes were noted during and after fireworks activity: increased foraging behavior and changing roost sites. Specifically, geese flew higher and further in response to NY fireworks. Geese were also likely to switch roosting sites more frequently after NY fireworks. 

The authors note that preserving energy is crucial for surviving the winter in Western Europe. Frequently changing roost sites is a problem because it uses up more energy, meaning geese must find extra food to compensate. According to the authors, this can lead to conflicts with farmers when geese forage on farmland. Geese spent up to 10% in additional energy because of their increased flight activity. 

Even with fireworks bans in some locations during the COVID-19 pandemic, the researchers found that the bans were not completely effective. For example, bean geese and greater white-fronted geese continued to show increased flight activity (as well as increased altitude and distance flown). According to the authors, the unpredictable nature of fireworks likely makes it difficult for geese to adapt. 

There were minor variations by species, which the authors believe is explained by differences in location. Geese in roosts further from dense human populations were less affected than those in more populated areas. The authors also believe that migratory geese are more reactive than other birds in general, even during fireworks bans, because people in Western Europe are known to hunt them. 

The study’s scope was limited to wild geese in Western Europe. Further research could explore the effects of fireworks on other wild animals, for longer periods, and in other locations where fireworks are common on New Year’s Eve and other holidays. 

The authors conclude that there needs to be greater awareness of not only the immediate effects of fireworks on animals, but also the aftereffects, particularly near protected areas. Animal advocates can use this information to push for policies limiting fireworks activity around vulnerable areas.