When I looked at the classification of the ducks, I was horrified because it was based on purely superficial things like… ducks that would dive and ducks that would not dive, ducks that would eat fish and so… ducks that would not eat fish, and it was a totally artificial classification. And I knew the work of two European ornithologists who had studied the habits and displays of ducks and had come to very different conclusions. One was Heinroth, the director of the zoological… of the aquarium and the zoological garden in Berlin, and the other one was the well-known Konrad Lorenz, and so I decided to produce a… for American readers who were not familiar with this literature, a modern classification of ducks. And, fortunately, by that time, the French ornithologist, Jean Delacour, had arrived at the museum, and Delacour, who was a wealthy fancier of birds, had had practically all the species of ducks of the world bred at his… in his animal park in France, and so I got him to help. And between the two of us we wrote a paper on the classification of ducks which was probably the most widely printed paper of mine, because not only was it reprinted several times in ornithological literature, but in the literature of the hunting… clan, hunting papers, sports papers, animal breeders, bird breeders, and so in… in lots of these journals this paper was reprinted. Now, the findings that Delacour and I made… were not always correct, but it was the basis and the… the changes were rather… rather minimal. But later on when molecular data were added and some other things it turned out that a few of our decisions were incorrect. But it certainly started an absolutely new era in the study of ducks, even though based on a… a lot of the European literature.