When a species reaches very low numbers or its habitat becomes critically endangered the decision may be taken to remove some or all individuals from the wild and attempt to conserve them in captivity. This chapter explores the rationale for the strategy as well as the methods and effectiveness. The ultimate goal must be to reunite species and habitat through reintroduction and we also explore the methods used to achieve this through examples of recent efforts.

By reading this chapter students will gain an understanding of the circumstances in which ex situ conservation and reintroduction have been undertaken; the range of methods used in plant and animal breeding; and the advantages and disadvantages of opting for ex situ conservation strategies. Additionally, students should gain a knowledge of some of the current ex situ programmes and reintroduction projects taking place.

What is ex situ conservation and when is it necessary?

The practice of ex situ conservation involves the removal of individuals or groups from their natural habitat into captivity, either to breed or to maintain a genetic stock. This is usually done by zoos and aquaria for animals and botanic gardens and herbaria for plants. Such places are increasingly moving from simply exhibitions of species that satisfy public curiosity to organisations with an active role in conservation.

In the previous chapter we have seen how populations can decline to a size where the odds are stacked against their survival, and the probability of extinction is greater than the probability of survival.