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Nihoa Island (23° 04' N - 161° 55' W)
Nihoa Island (23° 04' N - 161° 55' W)
The island closest to the Main Hawaiian Islands (MHI) is Nihoa.
This small basalt island lies 160 nautical miles (296 km) east southeast
of Necker Island and 155 nautical miles (287 km) west northwest of
Kauai and 250 nautical miles (463 km) from Honolulu.
Nihoa is the largest volcanic
island in the northwestern chain, with approximately 171 acres (0.7 km2) of
land. It is about a mile long and a quarter mile wide, and
it is the tallest of the Northwestern Hawaiian Islands (NWHI) at 903 feet (275 m) on its easternend.
IKONOS satellite image of Nihoa (Photo: NOAA)
Nihoa's submergent coral reef habitat totals approximately 570 km² (140,554 acres).
It was designated a wildlife refuge by President Theodore Roosevelt in
1906. Nihoa is also called "Bird Island", which translates from its ancient name, Mokumanu.
Map of Nihoa Island.
Nihoa Island (23° 04' N - 161° 55' W) is the
highest island in the Northwestern Hawaiian Island chain
with Miller's Peak reaching to an elevation of 910' (277
meters) (Photo: NOAA/ George H. Balazs)
Although seemingly inhospitable,
between 1000 and 1700 A.D this remote and rugged island was
visited and inhabited by Hawaiians. More than 80 cultural
sites have been discovered, including religious shrines,
habitation terraces and bluff shelters, agricultural terraces,
and burial caves. Artifacts found included fishhooks, sinkers,
cowry shell lures, hammerstones, grindstones, and adzes (ax - like tools).
NOAA vessel approaching Nihoa Island (Photo: NOAA)
Nihoa Island - Tanager Peak (852ft) (Photo: NOAA)
Terrestrial plants and animals
The terrestrial fauna include monk seals (Monachus schauinslandi),
72 species of arthropods including giant crickets and earwigs,
two species of endemic land birds, the endangered Nihoa finch
and the endangered Nihoa millerbird (Acrocephalus familiaris kingi),
and several species of seabirds, such as terns, shearwaters,
petrels, boobies, albatrosses, tropic birds, and frigate
birds. Endemic endangered plants include the Nihoa fan palm
the only species of tree on the island, and the leguminous
'ohai shrub (Sesbania tomentosa). Most of the ridges are
covered with two species of grass and the valleys are densely covered
with shrubs and bushes.
The endangered Nihoa Finch (Telespyza ultima ) is an endemic
that lives only on the island of Nihoa. It prefers open but
vegetated habitat, nesting in small holes in rock outcrops
100 to 800 feet (30.5 to 244 meters) above sea level (Photo: USFWS/Craig Rowland)
The endangered Nihoa Millerbird
kingi ) is an endemic bird found only on Nihoa. The
population size of the Nihoa Millerbird has fluctuated
between 300 and 700 individuals in the last 30 years. Threats
to the Millerbird include introduced plants and animals,
and fire. The Nihoa Millerbird got its name because
of its appetite for the miller moth (Photo: USFWS/Craig
The Nihoa fan palm (Pritchardia remota), is an endemic endangered
plant. It is the only species of tree on Nihoa (Photo: Botany
Dept., U. Hawaii/Sheila Conant)
Shallow water habitats
Basalt underlies most shallow water habitats surrounding Nihoa. These basaltic habitats consist of submerged portions of sea cliffs close to shore, caves and lava tubes, ledges, overhangs, basalt pinnacles, boulders, cobbles, sand deposits, basalt benches and slopes, trenches, and shelves which are constantly punished by swells and currents. Consequently, there are few suitable habitats for strong and extensive coral colonies to grow and flourish.
Corals and algae
Coral cover is not greater than 25 percent in any habitat. Around Nihoa and the next island in the NWHI chain, Necker Island, there are only submerged reefs, no emergent ones. Most of the reefs are found at 40 ft or deeper. On the North side of Nihoa, few corals were found at depths shallower than 70 feet. Most of the corals observed are low growing encrusting species (Maragos and Gulko, 2002). Seventeen species of scleractinian (stony) coral were found at Nihoa. Small encrusting forms of the lobe coral, Porites lobata, and rose
coral colonies (Pocillopora meandrina) were the most
common. Encrusting pink coralline algae covered many rocky
surfaces in very shallow water. Some red, brown and green
algae were common around the island. The red alga, Asparagopsis
taxiformis, is an edible species that is no longer common
in the Main Hawaiian Islands (MHI).
The cauliflower coral, Pocillopora meandrina. (Photo: National Park Service/ Eva DiDonato)
The edible marine red alga, Asparagopsis taxiformis, while
common in Nihoa, has become uncommon in the main Hawaiian
islands (Photo: R. Cavaliere, Biology Department, Gettysburg
The spotted linckia, Linckia multifora (photo: www.edge-of-sea.com/Alberto
Other invertebrates and fishes
The most common invertebrates found (excluding
corals and other cnidarians) are the smaller encrusting
species, such as sponges, ectoprocts (bryozoans), and tunicates.
Large invertebrates were uncommon, except for a couple
of species of rock-boring sea urchins and a starfish, the
spotted linckia (Linckia multifora).
Sharks, jacks, monk seals, and other apex predators (predatory animals which are at the top of their food chain and are not normally preyed upon by other predators) are common
to the island. However, due to the limited number of habitat
types, species diversity of reef fishes is low when compared
to other atolls and islands in the NWHI. Fishes uncommon
or rare in the MHI but typical of the NWHI,
such as the spotted knifejaw, Oplegnathus punctatus, are
often found. Nihoa supports a small population of endangered
Hawaiian monk seals with limited reproduction, probably maintained
by immigration from other breeding colonies.
A list of NWHI coral species (pdf,30kb) adapted from: Maragos, J., G. Aeby, D. Gulko, J. Kenyon, D. Potts, D. Siciliano, and D. VanRavensway. 2004. The 2000-2002 Rapid Ecological Assessment of Corals in the Northwestern Hawaiian Islands, Part I: Species and Distribution. Pacific Science 58(2):211-230.
Fishes uncommon or rare in the Main Hawaiian Islands, but
typical of the NWHI, such as the spotted knifejaw, Oplegnathus
punctatus, are often found in Nihoa (Photo: NOWRAMP)
In order to protect the island's fragile ecosystem, few
visitors are allowed on Nihoa and strict protocols are required.
Approval must be given by the U.S. Fish and Wildlife Service
and is mostly granted to those doing cultural and scientific
Link to metadata and data held by CoRIS
Click on the following URL to locate metadata and data in the CoRIS holdings on Nihoa Island. When the query screen comes up, enter Nihoa in the window, and then click on Search.