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Nihoa (0.8 km2, 280 m) is the youngest of the North-western Hawaiian Islands (see EBA 216; also for map), and is an uninhabited volcanic remnant of a once-high island with very little level ground, and sheer cliffs which drop to the ocean on three sides. Several well-developed valleys are densely vegetated with low shrubs, and grasses are common on most ridges. For its size, Nihoa supports a remarkable endemic flora and fauna, including two restricted-range species, Millerbird Acrocephalus familiaris and Nihoa Finch Telespiza cantans. The island is treated as a Secondary Area rather than as an EBA because A. familiaris is also known from Laysan Island (EBA 216), though it became extinct there some time during 1912-1923; the two races-familiaris from Nihoa and kingi from Laysan-are, however, sometimes regarded as full species. Both Nihoa's endemics are numerically quite strong (389-1,031 A. familiaris and 1,350-3,810 T. cantans in 1993) but are treated as threatened (classified Vulnerable) because of their tiny ranges. Although Nihoa is part of the Hawaiian Islands National Wildlife Refuge, the accidental introduction of rats or other predators to the island would doom its endemic species, and would be a serious threat to nesting seabirds.
Important Bird Areas (IBAs)
Threat and conservation
BirdLife International (2021) Endemic Bird Areas factsheet: Nihoa. Downloaded from
http://www.birdlife.org on 04/12/2021.