Over the years, 26 gorillas have been born at the Bronx Zoo, whose parent organization, the Wildlife Conservation Society, runs one of the most successful gorilla breeding programs in the country. The society, which also operates wildlife centers in Manhattan, Queens and Brooklyn, trades gorillas periodically with 51 participating North American zoos. Its first objective is to increase the genetic diversity of an endangered species, but a second, related goal is to create happier gorillas by finding mates and establishing compatible groups. "These are very intelligent, sensitive animals," said James Doherty, curator of the Bronx Zoo. The zoo's current population of gorillas numbers 19. Only the Lincoln Park Zoo in Chicago has more, with 22. Interactive Habitat.