Caroline Island is an important breeding site for a number of species of seabirds, most notably the sooty tern ("Onychoprion fuscata"), numbering around 500,000—a colony of sooty terns dominates the eastern islets—and the great frigatebird ("Fregata minor"), numbering over 10,000, according to estimations made in 1980. Caroline Island and Flint Island host one of the world's largest populations of the coconut crab ("Birgus latro"). Other native animals include the "Tridacna" clam, which is abundant in the central lagoon, hermit crabs, and multiple species of lizards.