Manuae is among the most significant seabird nesting sites in the southern Cook Islands. Red-tailed tropicbirds, brown boobies, great frigatebirds, white terns, and noddy terns all breed here in substantial numbers, with the frigatebirds particularly spectacular — large colonies gather in the pisonia trees on the two islets, and the birds are entirely unafraid of the rare human visitor.
The nesting season peaks between October and February, when the colonies are at their most active. Even outside nesting season, the concentration of seabirds over and around the atoll is remarkable. For birdwatchers, this alone justifies the considerable effort of getting here.