Aldabra giant tortoises were introduced to Cousin Island as part of the conservation management programme, and they now wander freely across the reserve. These are the world's largest tortoises — adults can reach 250 kilograms and live well over 100 years. On Cousin they are unhurried and entirely unafraid of visitors, making for close encounters impossible in the wild.
Cousin also has exceptional reptile diversity beyond the tortoises. Four endemic skink species live here, along with native geckos, giving the island one of the highest lizard densities per hectare anywhere in the world. The geckos in particular are active during guided walks and easy to spot on tree trunks and rocks.