I saw that some swallows were classified on basis… primarily I guess their color. If they were dull-colored they were put together and the glossy ones were put in another group, and I discovered or I knew that among the dull-colored one were some that built mud nests, just like the barn swallow does and like the… the cliff swallows and things that. And so I reorganized the swallows on this basis and I got the help of a worker on American birds, and South America in particular, James Bond – incidentally, he gave the name to the famous James Bond – and between James Bond and myself we worked out a classification of the swallows primarily based on the nesting habits, but also on some other things. And this classification based on behavior has now been almost completely confirmed. There's only one species which they change by the molecular people, and that has always been something that I've been rather pleased with, that behavior has, in this case, been such an important clue to relationship.