With the help of genetic specialists at the San Diego Zoo's Center for Reproduction of Endangered Species, the orangutan SSP was able to establish, through chromosome and pedigree analyses, the subspecies of each animal in the population. The orangutan SSP then developed the breeding programs separately for animals of Bornean and Sumatran origins. Because the subspecies distinction was not known clearly until the early 1980s, there was, and is, a sizable captive population of hybrid orangutans in North America. Since the genetic identity of each animal was established, the SSP has controlled breeding to prevent any future inbreeding. Females not intended to breed are prevented from reproducing by means of hormonal inplants similar to those used by human females for long-term contraception.
Males generally remain intact, though many hybrid males have been vasectomized.
Sometimes males not currently recommended for breeding are kept in all-male groups. It is important to point out that it is not now, nor has it ever been, the policy of the orangutan SSP to castrate any animal, regardless of subspecies. With the advent of safe, effective contraception, subspecific hybrid orangutans can be, and are, maintained in the same enriched, stimulating captive habitats as their purebred cousins. The SSP is charged with maintaining three separate, genetically healthy populations of orangutans. The science of small population management has grown tremendously over the past two decades, largely driven by the necessity of managing captive animal populations.