Millions of birds take flight in the Netherlands at midnight on New Year's, according to BirdLife Netherlands. They are startled by the Dutch tradition of New Year's fireworks, the organization sad on the website Nature Today on Tuesday.

The bird protection agency used new radar techniques to keep an eye on birds' behavior. Around midnight on New Year's, millions of birds take flight and are in the air throughout the Netherlands. "In some places, more than a thousand birds are flying per square kilometer. Completely disturbed, they fly an average of 500 meters. Sometimes they stay in the air for half an hour or longer", the agency said.

According to the agency, the effect fireworks have on these animals are "very clear and not positive". The birds experience a lot of stress due to the startle response and consume more energy than usual due to the unexpected flight. It can also be dangerous as some birds can't navigate in the dark. "In blind panic they collide with buildings and power lines."