List of mammals of Nauru

This is a list of the mammal species recorded in Nauru. All four of the mammal species in Nauru are marine mammals of the order Cetacea.
None of the four species have been assessed by the International Union for Conservation of Nature, as there is inadequate information to make an assessment of the risks to these species, so all are marked DD (data deficient).
Order: Cetacea (whales).
The order Cetacea includes whales, dolphins and porpoises. They are the mammals most fully adapted to aquatic life with a spindle-shaped nearly hairless body, protected by a thick layer of blubber, and forelimbs and tail modified to provide propulsion underwater.