 This is the Natural History Museum in Rotterdam, the Netherlands, where I work as a curator. An ordinary day at work can pass without much excitement, but on June 5, 1995, a loud bang against the window changed my life and ended that of a duck. When I heard this bang, I looked out of the window and I saw this. This was the duck. It died because of the collision with the glass, but next to it was a live duck, and please pay attention, both are of the male sex. Then this happened. The live duck mounted the dead duck and started to copulate. Well, I'm a biologist, I'm an ornithologist, I said to myself, this is something wrong. One is live, one is dead, and must be necrophilia. And remember, both are of the male sex, homosexual necrophilia. So I sat down, took my notes, took pictures, and I could do so for about 75 minutes. Then I got hungry, I wanted to go home, but before I did that, I really had to collect the duck for the collection of the museum. And of course, I checked the sex of the dead duck, and here's a rare slide of a duck's penis. So it was indeed of the male sex. So what do you do when you see something new to science? You publish it. Well, it took me about six years to decide to do that, because I couldn't explain this behavior. I could tell the story in a bar at the birthday party at the coffee machine, but I couldn't share it with my peers. In the end, I did it. The first case of homosexual necrophilia and the male duck. So here's the situation again. A is my office from where I heard the bang. B is where the duck hit the glass. C is from where I watched it. About six people read my paper. But then I got a message from Mark Abrams from Harvard University telling me, you've won a prize. You've won the Ig Nobel Prize. I said, the Ig Nobel Prize? Shouldn't these messages come from Stockholm? No, it came from Cambridge, Massachusetts. And the Ig Nobel Prizes, they honor achievements that first make people laugh and then make them think. And the goal is to make more people interested in science. So I said, yes, that's a nice prize. So I went to the ceremony and the ceremony is very special because real Nobel laureates, and you see about 12 Nobel laureates here, give the prizes to the Ig Nobel Prize winners. And you get 60 seconds to say something. And here's the duck. There you go. Winning this Ig Nobel Prize changed my life. People started sending me all kinds of duck related things. I have a huge collection. But more importantly, I became a kind of specialist in remarkable animal behavior. And if somewhere on this planet a bird or a mammal behaves badly, I know of it. First, there are the mistakes. This is a moose trying to mate with a bronze statue of a bison. This is in Minnesota, 2004. This is in the Netherlands last year, April, a frog trying to copulate with a goldfish. And now this is serious science. This is the first ever victim of homosexual necrophilia in a ground squirrel. The specimen was collected in 1959 and still kept in the Bell Museum in Minnesota. Here are barn swallows, a roadkill in Hong Kong, 2004. Turkeys in Wisconsin. And if you take a look at the other pictures, you see the famous turkeys of the experiments they did in the 50s in the U.S. Which concluded that turkeys copulate with almost everything, including a detached head. But look here. What's wrong with this picture? The position. These are cane toads in Australia, by the way. And these came in just a month ago from the Netherlands. Take a good look. You see the position of the female is lying on its back. And the missionary position is not done in birds. Besides, the duck was dead for two days. So there was my theory. I thought, well, death has to be sudden and in the copulatory position to have necrophilia possible. I don't know where this will end. Well, to end this now, a more serious matter. You're all invited to join me at June 5th, 5 to 6 for Dead Duck Day. We do it every year. We congregate at the Natural History Museum in Rotterdam to remember the bird that hit the window. And to discuss new ways to prevent birds from colliding with glass. Because that is one of the major causes of death in birds worldwide. When that's over, we go to a local Chinese restaurant. We have a six course duck dinnered. I hope to see you next year on June 5th. Thank you.