Well, at that time, it was only a few hundred thousand, the population grew since that time, and about two to 300,000 zebras. And so he captured wildebeest and zebras, put the animals collars and followed these animals with the plane. And so he could show how the migration takes part in the Serengeti ecosystem and that about half of the times, migration is outside of Serengeti National Park. But in the ecosystem in Ngorogoro Crater area and in the north and Southern Kenya and Mara Reserve. So that was a very important thing for Grzimek and a very sad thing because in an airplane crash, he lost his son, Michael, with whom he worked very closely together. But Bernhard Grzimek finished their work, the famous film, “Serengeti Shall Not Die”, that got an Oscar. And I think that was one of the biggest success in conservation education, because it was really, if you ask in Europe, elder people, everybody say, oh, we have seen “Serengeti Shall Not Die”. And Serengeti became known and the problems of conservation and, at that time, Tanganyika National Park became known in Europe.