In the wild, many species are becoming extinct for a variety of reasons, including poaching, human encroachment, deforestation, and others. The only means to avoid this fate is through preservation of the natural environment, establishment of national parks, embryonic zoos, and correct breeding programs within zoological facilities.
Upon reaching maturity, every animal of every species is genetically programmed to try and pass on its DNA. With each new season, wild animals hatch or are born here at the zoo, but this is not as simple as it may seem. Non-related, compatible pairs of the proper age must be established, the proper environment has to be provided, and daily nutrition needs to be balanced and appropriate for each animal. By providing these necessities, we increase the chances for successful breeding and rearing of offspring; the rest is left up to the animals.
In the end, if we are lucky, there will be a new generation for the public to see, and a new addition to the genetic bank.