Northwestern Hawaiian Islands

The Northwestern Hawaiian Islands or the Leeward Islands are the small islands and atolls in the Hawaiian island chain located northwest (in some cases, far to the northwest) of the islands of Kauai and Niihau. Politically, they are all part of Honolulu County in the U.S. state of Hawaii, except Midway Atoll, which is a territory distinct from Hawaii and grouped as one of the United States Minor Outlying Islands. The United States Census Bureau defines this area, except Midway, as Census Tract 114.98 of Honolulu County. Its total land area is 3.1075 square miles (8.048 km2). All the islands except Nihoa are north of the Tropic of Cancer, making them the only islands in Hawaii that lie outside the tropics.

The Northwestern or Leeward Hawaiian Islands include:

NW Hawaiian Islands is located in Pacific Ocean
NW Hawaiian Islands
NW Hawaiian Islands
Location of the Northwestern Hawaiian Islands in the Pacific Ocean

The islands

Laysan Island Interior
The interior of Laysan, showing the hypersaline lake.
  • 156-acre (0.63 km2) Nihoa is the youngest of the NWHI, and the tallest, with 900-foot (270 m) vertical cliffs. It represents the southwestern part of the island's former volcanic cone. Ancient Hawaiians might have stayed here long-term.
  • 40-acre (160,000 m2) Necker Island is hook shaped and 270 feet (82 m) tall at its summit. Barren of vegetation, it was used by Ancient Hawaiians for religious purposes, but not for long-term habitation.
  • French Frigate Shoals is an atoll, the largest region of coral reefs in Hawaii, at 200 square miles (520 km2). The atoll is composed of a dozen or so small islands, Tern Island housing an airport and human habitations.
  • Gardner Pinnacles is made up of two small basalt peaks, the last rocky island in Hawaii. While the island itself is tiny, the surrounding reef is expansive and diverse.
  • 166-square-mile (430 km2) Maro Reef is an extremely fertile reef system that has been described as a "coral garden".
  • Laysan is a 913-acre (3.69 km2), low, sandy island with a natural lake in its interior, one of only five such lakes in Hawaii. It has arguably the most diverse ecosystem in the NWHI, and hosts about two million seabirds of seventeen species.[1]
  • Lisianski Island, only 400 acres (1.6 km2), is geologically akin to Laysan, without the lake. Though the island is slightly less biodiverse, the surrounding reef is very fertile.
  • Pearl and Hermes Atoll is an atoll very similar to French Frigate Shoals, but with much less dry land. For this reason, it was mostly ignored by guano miners and feather hunters.
  • Midway Atoll is the most commonly known of the NWHI, and is also the largest. The Battle of Midway was fought here and in its surrounding waters, and the island remains permanently inhabited, albeit by persons who are there in consequence of their service with the United States Government, not an indigenous population.
  • Circular Kure Atoll contains the 236-acre (0.96 km2) Green Island, which used to host a LORAN station and a runway, but these have since been demolished. In terms of biodiversity, Kure is one of the less impressive of the NWHI.


The Northwestern Hawaiian Islands were formed, approximately 7 to 30 million years ago, as shield volcanoes over the same volcanic hotspot that formed the Emperor Seamounts to the north and the Main Hawaiian Islands to the south.[2] As the Pacific Plate moved north and later northwest over the hot spot, volcanic eruptions built up islands in a linear chain. The isolated land masses gradually eroded and subsided, evolving from high islands in the south, much like the Main Islands of Hawaii, to atolls (or seamounts) north of the Darwin Point. Each of the NWHI are in various stages of erosion. Nihoa, Necker, and Gardner Pinnacles are rocky, basalt islands that have not eroded enough to form an atoll, or lack a substantial coral reef. Laysan and Lisianski are low, sandy islands that have been eroded longer. French Frigate Shoals, Pearl and Hermes, Midway, and Kure are atolls.

North of the Darwin Point, the coral reef grows more slowly than the island's subsidence, and as the Pacific Plate moves northwest, the island becomes a seamount when it crosses this line. Kure Atoll straddles the Darwin Point, and will sink beneath the ocean when its coral reef cannot keep up with the rate of subsidence, a destiny that awaits every Hawaiian island.[3]

Biodiversity and endemism

The Hawaiian Islands are about 2,500 miles (4,000 km) from North America and 3,800 miles (6,100 km) from Asia, and it is because of this isolation that the Hawaiian Islands have extraordinary numbers of unique species.[4] Only a species that could fly or swim immense distances could reach the archipelago. But whereas Polynesians, and later, Europeans, have largely altered the ecosystem of the Main Hawaiian islands by introducing alien species, the ecosystems of the NWHI remain, for the most part, intact. The extensive coral reefs found in Papahānaumokuākea are home to over 7,000 marine species.[5] Of the many species that live here, over 1,700 species of organisms are endemic to the Hawaiian Islands (i.e., they are found nowhere else). For this reason, the region has been dubbed "America's Galápagos".

Though not subject to nearly as much extinction as the main islands, the Leeward Islands have had their share of abuse. From the late 19th to the early 20th centuries, fishermen, guano miners, and feather hunters killed most of the birds and sea life living in the NWHI. Rabbits were introduced to Laysan and Lisianksi, where they multiplied and devoured most of the vegetation, permanently extinguishing several species. However, most of the damage was reversed, and the islands were restored largely to their pre-exploitation state.

Some of the endemic species of the NWHI include the Nihoa and Laysan finch, the Laysan duck (the "rarest native waterfowl in the United States"),[6] and the Nihoa fan palm. Other notable species are the Laysan albatross, the highly endangered Hawaiian monk seal, and the green sea turtle. The only native trapdoor spiders in the Hawaiian archipelago (Nihoa spp.), recently discovered, are found only here. Most endemic species are highly vulnerable to extinction as one major catastrophic event could wipe out all of the vegetation on each small island. Additionally, seventy percent of all coral reefs in the United States are found here.


Lisianski Island Reserve Sign
The reserve sign on Lisianski

It is known that the Ancient Hawaiians ventured from the main islands as far as Mokumanamana (Necker), but they might have gone further to French Frigate Shoals. However, they must have been gone by the 18th century, when Europeans discovered the islands, because the islands were deserted upon discovery. Many agricultural terraces have been found on Nihoa, proving that Hawaiians lived there long-term, but Mokumanamana, much barer of vegetation, was probably not able to support many people for long. It is thought that the early Hawaiians only came to Mokumanamana for religious purposes.

The first of the Leeward Isles to be discovered by Europeans was Nihoa. James Colnett discovered it in 1786, although historically the credit has gone to William Douglas. Later that year, La Pérouse discovered Necker, and named it for Jacques Necker, the French Minister of Finance. La Pérouse then went on to discover French Frigate Shoals. The last of the NWHI to be discovered was Midway Atoll, which was found by N.C. Middlebrooks in 1859. In 1925, the Tanager Expedition travelled to many of the NWHI. The islands were mapped, new species were discovered and described, and the archeological sites on Nihoa and Necker were found.

Naming system

Most of the islands have two names; one in English and one in Hawaiian (indicated in parentheses above). The majority of the Hawaiian names used as alternative to the English ones were created in modern times, the original names that ancient Hawaiians gave to all of these islands that they encountered prior to Western contact are found in various oli (chants) and moʻolelo (stories).

National Monument

On June 15, 2006, American President George W. Bush issued a public proclamation creating Papahānaumokuākea Marine National Monument under the Antiquities Act of 1906. The Monument encompasses the islands and surrounding waters, forming the largest marine wildlife reserve in the world. President Theodore Roosevelt had declared the Northwestern Hawaiian chain a bird sanctuary in 1909 and the islands had been protected since 2000 with a designation as an 'ecosystem reserve' by President Bill Clinton, but increasing it to national monument status provides unprecedented control. 139,000 square miles (360,000 km2) of ocean was at that time set aside for protection, about the size of the U.S. state of California.

In August 2016, President Barack Obama expanded the area of the monument by roughly four times. The expanded monument was at that time the world's largest marine protected area.[7][8]

Entry to the Monument is limited through a permit system, jointly administered by the state of Hawaii, NOAA, and FWS. Anyone who comes to the islands must follow stringent procedures designed to prevent any stray species from entering and disrupting the ecosystem. All clothes must be bought new, and kept wrapped until before arrival. In fact, all "soft" items (camera strap, blanket) must be bought new, and all "hard" items (camera, binoculars) must be cleaned thoroughly. Then, every item must be frozen for 48 hours. A new set of equipment must be prepared for each island one is going to, to prevent inter-island species introduction. However, French Frigate Shoals and Midway Atoll are exempted from these rules, as they are deemed too altered by humans already to worry about introducing new species.

See also


  1. ^ Rauzon, 100
  2. ^ Clague, D. A. and Dalrymple, G. B. (1989) Tectonics, geochronology, and origin of the Hawaiian-Emperor Chain in Winterer, E. L. et al. (editors) (1989) The Eastern Pacific Ocean and Hawaii, Boulder, Geological Society of America.
  3. ^ Rauzon, 3
  4. ^ Rauzon, 4
  5. ^ "Papahānaumokuākea Marine National Monument". official web site, National Oceanic and Atmospheric Administration. Retrieved 2009-07-28.
  6. ^ FWS (2009). "Laysan Duck - Midway Atoll National Wildlife Refuge". U.S. Fish & Wildlife Service.
  7. ^ Eagle, Nathan (August 26, 2016). "Obama To Create World's Largest Protected Marine Area Off Hawaii". Retrieved August 26, 2016.
  8. ^ "Fact Sheet: President Obama to Create the World's Largest Marine Protected Area". August 26, 2016. Retrieved September 3, 2016.


External links

Achyranthes atollensis

Achyranthes atollensis (also called atoll achyranthes or Hawaiʻi chaff flower) was a species of plant in the family Amaranthaceae. It was endemic to the Northwestern Hawaiian Islands of Kure, Midway, Laysan and the Pearl and Hermes Atoll. Its natural habitat was sandy shores. It became extinct due to habitat loss (residential, commercial and military installation development) and the introduction of non-native species, and was last seen in 1964. It was a perennial shrub living in dry shrublands on calcareous sand and atolls.

French Frigate Shoals

The French Frigate Shoals (Hawaiian: Kānemilohaʻi) is the largest atoll in the Northwestern Hawaiian Islands. Its name commemorates French explorer Jean-François de La Pérouse, who nearly lost two frigates when attempting to navigate the shoals. It consists of a 20-mile (32 km) long crescent-shaped reef, twelve sandbars, and the 120-foot (37 m) high La Perouse Pinnacle, the only remnant of its volcanic origins. The total land area of the islets is 61.508 acres (24.891 ha). Total coral reef area of the shoals is over 232,000 acres (94,000 ha). Tern Island, with an area of 26.014 acres (10.527 ha), has a landing strip and permanent habitations for a small number of people. It is maintained as a field station in the Hawaiian Islands National Wildlife Refuge by the United States Fish and Wildlife Service. The French Frigate Shoals are about 487 nautical miles (902 km; 560 mi) northwest of Honolulu.

Gardner Pinnacles

The Gardner Pinnacles (Hawaiian: Pūhāhonu) are two barren rock outcrops surrounded by a reef and located in the Northwestern Hawaiian Islands at 24°59′56″N 167°59′58″W.

It is 511 nautical miles (946 km; 588 mi) northwest of Honolulu and 108 miles (94 nmi; 174 km) from French Frigate Shoals. The total area of the two small islets—remnants of an ancient volcano—is 5.939 acres (24,030 m2). The highest peak is 170 feet (52 meters). The surrounding reef has an area in excess of 600,000 acres (2,400 km2; 940 sq mi).

Gardner Pinnacles was first discovered on June 2, 1820, by the American whaler Maro commanded by Captain Joseph Allen.

The Gardner Pinnacles are home to some species of fish not found anywhere else in the Northwestern Hawaiian Islands, and have more species of coral than two rocky neighbors to the south, Necker Island and Nihoa. Numerous insects live on the island, and a researcher claims to have found two new species of spiders here.

Since this is part of a wildlife refuge, Gardner Pinnacles is off limits to even the military, although they made an unauthorized landing in 1961 or 1962 and blew off the tip of the outcrop to create an emergency helicopter landing spot for the Hawaiian HIRAN project, an effort to determine location of area islands with great precision for navigational purposes. To this day the tip has not been replaced, and debris from the blast can be found scattered throughout the island. In the Hawaiian Archipelago, adjacent islands/reefs are French Frigate Shoals to the southeast, and Maro Reef to the northwest.

Hawaiian tropical low shrublands

The Hawaiian tropical low shrublands are a tropical savanna ecoregion in the Hawaiian Islands. These shrublands cover an area of 1,500 km2 (580 sq mi) in the leeward lowlands of the main islands and most of the smaller islands, including the Northwestern Hawaiian Islands. The ecoregion includes both grasslands and mixed shrublands. Kāwelu (Eragrostis variabilis), mauʻu ʻakiʻaki (Fimbristylis cymosa), ʻakiʻaki (Sporobolus virginicus), and Lepturus repens are common grassland plants. Shrublands are dominated by ʻilima (Sida fallax), ʻaʻaliʻi (Dodonaea viscosa), naupaka (Scaevola spp.), hinahina kū kahakai (Heliotropium anomalum var. argenteum), kīpūkai (Heliotropium curassavicum), maʻo (Gossypium tomentosum), ʻakoko (Euphorbia spp.), ʻāheahea (Chenopodium oahuense), naio (Myoporum sandwicense), kolokolo kahakai (Vitex rotundifolia), and pūkiawe (Styphelia tameiameiae). More than 90% of the plant species found in this ecoregion are endemic, including ʻōhai (Sesbania tomentosa), ʻāwiwi (Schenkia sebaeoides), and wahine noho kula (Isodendrion pyrifolium).

Kure Atoll

Kure Atoll (; Hawaiian: Mokupāpapa) or Ocean Island is an atoll in the Pacific Ocean 48 nautical miles (89 km; 55 mi) beyond Midway Atoll in the Northwestern Hawaiian Islands at 28°25′N 178°20′W. The only land of significant size is called Green Island and is a habitat for hundreds of thousands of seabirds. A short, unused and unmaintained runway and a portion of one building, both from a former United States Coast Guard LORAN station, are located on the island. Politically it is part of Hawaii, although separated from the rest of the state by Midway, which is a separate unorganized territory. Green Island, in addition to being the nesting grounds of tens of thousands of seabirds, has recorded several vagrant terrestrial birds including snow bunting, eyebrowed thrush, brambling, olive-backed pipit, black kite, Steller's sea eagle and Chinese sparrowhawk.


Laysan (; Hawaiian: Kauō [kɐwˈoː]), located 808 nautical miles (1,496 km; 930 mi) northwest of Honolulu at N25° 42' 14" W171° 44' 04", is one of the Northwestern Hawaiian Islands. It comprises one land mass of 1,016 acres (4.11 km2), about 1 by 1 1⁄2 miles (1.6 by 2.4 km) in size. It is an atoll of sorts, although the land completely surrounds a shallow central lake some 8 feet (2.4 m) above sea level that has a salinity approximately three times greater than the ocean. Laysan's Hawaiian name of Kauō means egg.

Laysan albatross

The Laysan albatross (Phoebastria immutabilis) is a large seabird that ranges across the North Pacific. The Northwestern Hawaiian Islands are home to 99.7% of the population. This small (for its family) gull-like albatross is the second-most common seabird in the Hawaiian Islands, with an estimated population of 2.5 million birds, and is currently expanding (or possibly re-expanding) its range to new islands. The Laysan albatross was first described as Diomedea immutabilis by Lionel Walter Rothschild, in 1893, on the basis of a specimen from Laysan Island.

Laysan finch

The Laysan finch (Telespiza cantans) is a species of Hawaiian honeycreeper, that is endemic to the Northwestern Hawaiian Islands. It is one of four remaining finch-billed Hawaiian honeycreepers, and is closely related to the smaller Nihoa finch. The Laysan finch is named for Laysan, the island to which it was endemic on its discovery. It was subsequently introduced to a few other atolls, and its historical range included some of the main islands.

Laysan honeycreeper

The Laysan honeycreeper or Laysan ʻapapane (Himatione fraithii) was an extinct bird species that was endemic to the island of Laysan in the Northwestern Hawaiian Islands.

Laysan noctuid moth

The Laysan noctuid moth (Agrotis laysanensis) was a species of moth in the family Noctuidae. This species is now extinct.

It was endemic to Laysan, in the Northwestern Hawaiian Islands.

This moth was one, if not the main species, eaten by the likewise extinct Laysan millerbird. Agrotis moths are commonly known as "millers", and the bird was named after its favorite food.

Lisianski Island

Lisianski Island (Hawaiian: Papa‘āpoho) is one of the Northwestern Hawaiian Islands, with a land area of 384.425 acres (155.571 ha) and a maximum elevation of 40 feet (12 m) above sea level. It is a low, flat sand and coral island about 905 nautical miles (1,676 km) northwest of Honolulu. The island is surrounded by reefs and shoals, including the extensive Neva Shoals. Access to the island is limited by helicopter or by boat to a narrow sandy inlet on the southeastern side of the island.

List of species of the Northwestern Hawaiian Islands

This is a list of the species that inhabit the Northwestern Hawaiian Islands. Except for researchers and volunteers living on Midway Atoll, Kure Atoll, and Tern Island, the leeward islands are uninhabited by people but home to at least 7000 species ranging from marine mammals, fish, sea turtles, birds and invertebrates. Many of these species are rare or endangered and at least 25% are endemic to the Northwestern Hawaiian Islands. This list identifies which islands the species lives on, and whether the species is endemic to the NWHI.

Maro Reef

Maro Reef (Hawaiian: Nalukākala - "surf that arrives in combers") is a largely submerged coral atoll located in the Northwestern Hawaiian Islands. It was discovered in 1820 by Captain Joseph Allen of the ship Maro, after whose ship the reef was named. With a total area of 747 square miles (1,935 km2), it is the largest coral reef in the Northwestern Hawaiian Islands. It contains 37 species of stony coral. Unlike most atolls, the coral extends out from the center like spokes on a wheel. Located about 850 miles (740 nmi; 1,370 km) northwest of Honolulu, Hawaii, Maro Reef contains about 1 acre (4,000 m2) of dry land which itself can be submerged depending on the tides. Some scientists believe that it "may be on the verge of drowning" because the reefs are detached and are vulnerable to strong storm waves.USNS Mission San Miguel (T-AO-129) ran aground on the reef, while running at full speed and in ballast, and sank on October 8, 1957.

National Register of Historic Places listings in Hawaii

This is a list of properties and historic districts in Hawaii listed on the National Register of Historic Places. More than 340 listings appear on all but one of Hawaii's main islands (Niihau being the exception) and the Northwestern Islands, and in all of its five counties. Included are houses, schools, archeological sites, ships, shipwrecks and various other types of listings. These properties and districts are listed by island, beginning at the northwestern end of the chain.

This National Park Service list is complete through NPS recent listings posted October 11, 2019.

Necker Island (Hawaii)

Necker Island (Hawaiian: Mokumanamana) is a small island in the Northwestern Hawaiian Islands. It is located at 23°34′30″N 164°42′01″W in the Pacific Ocean, 155 miles (135 nmi; 249 km) northwest of Nihoa and 8 miles (7.0 nmi; 13 km) north of the Tropic of Cancer. It contains important prehistoric archaeological sites of the Hawaiian culture and is part of the Hawaiian Islands National Wildlife Refuge within the Northwestern Hawaiian Islands National Monument.

The United States Census Bureau reports its land area as 45.193 acres (182,890 m2). The island is rocky with steep sides and has very little soil. Its highest elevation is 277 feet (84 m). The island is named after Jacques Necker, a finance minister of Louis XVI.


Nihoa (; Hawaiian: [niˈhowə]), also known as Bird Island or Moku Manu, is the tallest of ten islands and atolls in the uninhabited Northwestern Hawaiian Islands (NWHI). The island is located at the southern end of the NWHI chain, 296 km (160 nmi) southeast of Necker Island. Nihoa is the closest NWHI in proximity to the eight main windward Hawaiian Islands at approximately 240 km (130 nmi) northwest of the island of Kauaʻi. The island has two peaks, 272 m (892 ft) Miller's Peak in the west, and 259 m (850 ft) Tanager Peak in the east. Nihoa's area is about 171 acres (0.69 km2) and is surrounded by a 142,000-acre (57,000 ha) coral reef. Its jagged outline gives the island its name, Nihoa, which means "tooth" in the Hawaiian language.The island is home to 25 species of plants and several animals, making it the most diverse island in the entire NWHI. Endemic birds like the Nihoa finch and Nihoa millerbird, and endemic plants like Pritchardia remota, Schiedea verticillata, and Amaranthus brownii are found only on Nihoa. The plant communities and rocky outcrops provide nesting and perching areas for 18 species of seabirds, such as red-footed boobies and brown noddies, terns, shearwaters, and petrels. Prehistoric evidence indicates Native Hawaiians lived on or visited the island around AD 1000, but over time the location of Nihoa was mostly forgotten, with only an oral legend preserving its name. Captain James Colnett rediscovered the island in 1788, and Queen Kaʻahumanu visited it in 1822. It was made part of the Kingdom of Hawaii by King Kamehameha IV.

In 1909, Nihoa became part of the Hawaiian Islands Reservation, a federal wildlife refuge established by U.S president Theodore Roosevelt. The Tanager Expedition surveyed the island in 1923, taking a comprehensive biological inventory of its many species. In 1940, it became part of the Northwestern Hawaiian Islands Wildlife Refuge and in 1988, it was listed on the National Register of Historic Places due to its culturally significant archaeological sites. In 2006, it became part of the Papahānaumokuākea Marine National Monument. Efforts are underway to ensure that endangered plant species are propagated beyond their limited range and represented in ex situ collections. Persons intending to visit Nihoa for cultural and scientific research purposes require a USFWS-issued special-use permit to land on the island so as to reduce the risk of introducing alien species to Nihoa's already fragile ecosystem.

Papahānaumokuākea Marine National Monument

The Papahānaumokuākea Marine National Monument (roughly ) is a World Heritage listed U.S. National Monument encompassing 583,000 square miles (1,510,000 km2) of ocean waters, including ten islands and atolls of the Northwestern Hawaiian Islands. Created in June 2006 with 140,000 square miles (360,000 km2), it was expanded in August 2016 by moving its border to the limit of the exclusive economic zone, making it one of the world's largest protected areas. It is internationally known for its cultural and natural values as follows:

"The area has deep cosmological and traditional significance for living Native Hawaiian culture, as an ancestral environment, as an embodiment of the Hawaiian concept of kinship between people and the natural world, and as the place where it is believed that life originates and to where the spirits return after death. On two of the islands, Nihoa and Makumanamana, there are archaeological remains relating to pre-European settlement and use. Much of the monument is made up of pelagic and deepwater habitats, with notable features such as seamounts and submerged banks, extensive coral reefs and lagoons."

Pearl and Hermes Atoll

The Pearl and Hermes Atoll (Hawaiian: Holoikauaua) is part of the Northwestern Hawaiian Islands, a group of small islands and atolls that form the farthest northwest portion of the Hawaiian island chain. The atoll consists of a variable number of flat and sandy islets, typically between five and seven. More were noted in historical sources but have since been lost to erosion and rising sea levels.

The atoll is named after Pearl and Hermes, a pair of English whaleships that wrecked there in 1822. It has been the site of at least eight known shipwrecks, including the Japanese Wiji Maru, SS Quartette, and most recently the M/V Casitas, which ran aground on the reef in 2005.

The atoll is an important habitat for seabirds, marine life, and invertebrate species. Twenty-two bird species nest and breed on the island, including twenty percent of the world's population of black-footed albatrosses. The atoll has historically been included with the rest of the Northwestern Hawaiian Islands in conservation efforts. It is included in the Papahānaumokuākea Marine National Monument, created in 2006. Ghost nets and other fishing debris, as well as rising sea levels, pose a significant risk to the atoll and its wildlife.

Tern Island (Hawaii)

Tern Island is a tiny coral island located in the French Frigate Shoals in the Northwestern Hawaiian Islands, at 23.870°N 166.284°W / 23.870; -166.284, approximately 490 miles (790 kilometres) west north west of Oahu. It has a land area of 105,276 m2 (26.014 acres). The island provides a breeding habitat to 18 species of seabirds, threatened Hawaiian green sea turtles, and endangered Hawaiian monk seals. It is maintained as a field station in the Hawaiian Islands National Wildlife Refuge by the United States Fish and Wildlife Service.

Northwestern Hawaiian Islands
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