In 1995, the Natural History Museum Rotterdam got a new wing made of glass. It was beautiful for humans — but not so much for birds. Many of them lost their lives flying into the invisible walls.

Photo: James Duncan Davidson

“I developed an ear for identifying birds just by the sound of the bang they made on the glass,” says Kees Moeliker in Session 9 of TED2013. “It was on June 5, 1995, that I heard a loud bang that changed my life and ended that of a duck.”

When Moeliker rounded the building, he saw two male ducks, one living and one dead. He watched confused as the live one mounted the dead one and started to copulate with it. As far as he knew, this was the first observed case of homosexual necrophilia in ducks. But Moeliker, a researcher who didn’t want to kill his career, was worried about sharing this finding. “It was a nice thing to discuss at birthday parties,” he says, “but not a nice thing to discuss with your peers.”

It took him 6 years to decide to publish, but eventually he submitted the paper. At first, nothing much happened. But then he got a call from a prestigious committee: The Ig Nobel Prize committee. He’d won. Soon, his email was flooded with duck paraphernalia and images of other animals’ strange sexual habits — a moose trying to copulate with a statue, a frog trying to copulate with a goldfish, and necrophiliac pigeons.

“If there’s an animal misbehaving on this planet, I know about it,” says Moeliker. He notes one pattern about these images: “Missionary position is very uncommon in the animal kingdom.”

Moeliker wonders if we might be somehow to blame for this strange animal behavior. He gives the example of a bird called Mad Max that continually flew into a glass windowpane over and over again, from 2004 to 2008, because it sees its own reflection and tries to fight it. Could it be that our morphing of their environments is changing animal behavior?

Every year on June 5, Moeliker now holds Dead Duck day, a holiday dedicated to finding new ways to keep birds from colliding with windows. He invites us to celebrate with him, and walks offstage.

Kees Moeliker’s talk is now available for viewing. Watch it on TED.com»