It is about 2,512 hectares (6,207 acres) in size and was declared a nature reserve in the 1960s. The monkeys were once an endangered species but numbers have increased in recent years thanks to conservationists working closely with the local people. It is estimated that there are now between 2,000-2,500 monkeys on the island and while they are wild, it is possible to get near to them. The elusive Zanzibar leopard (last seen several years ago) is said to feed here at night – perhaps this is why the reserve is only open during the day.