Hawaiʻi has the dubious distinction as the endangered species capital of the world, with more imperiled species per square mile than any other place on the planet. While Hawaiʻi makes up less than 0.2% of the land area of the United States, it’s home to over 400 threatened or endangered species, nearly one of every three domestic species listed under the Endangered Species Act (ESA).

Hawaiʻi’s native species are so vulnerable because they evolved in isolation. Due to Hawaiʻi’s remote location in the middle of the Pacific, before humans arrived, new species reached the islands only by wind, wave or wing. New plant species successfully colonized the islands only about every 100,000 years.

Once in Hawaiʻi, these pioneers encountered little competition and evolved into a multitude of new forms, filling empty ecological niches. Scientists believe a single seed, likely carried from North America stuck to a bird’s feather, evolved into a family of 28 entirely new plant species, occupying diverse habitats from wet to dry forests and from near sea level to alpine shrublands.

When humans came on the scene—first Polynesian voyagers, who arrived about 2,000 years ago, followed by European explorers in the late 18th century—the ecological calculus radically changed. By design and by accident, people brought with them a host of threats that assaulted Hawai‘i’s native species, including sheep, pigs, goats, cows, rats, aggressive weeds, mosquitos and mosquito-born diseases.

The endangered palila, a small bird in the honeycreeper family, depends on the native Hawaiian dry land forest for food, shelter, and breeding. (U.S. FWS)

The ESA’s enactment in 1973 gave Hawaiʻi’s unique natural heritage the ability to survive these new threats. Particularly important was Congress’ realization that, for the new law to work, citizens needed to be able to go to court to enforce its provisions.

But species don’t benefit from the ESA’s protections unless they first get listed as endangered or threatened. Sixteen years after the ESA’s passage, the Fish and Wildlife Service had identified hundreds of Hawaiian plants as listing candidates, but had listed only 19. In 1989, Earthjustice went to court to challenge the Service’s foot-dragging, winning ESA protection for nearly 200 plants unique to Hawaiʻi.

Later, Earthjustice returned to court to secure ESA protection for a variety of native Hawaiian species, from the Oʻahu ʻelepaio (a native bird) to the Kauaʻi cave wolf spider and Kauaʻi cave amphipod to the Blackburn’s sphinx moth on Maui and Hawaiʻi Island.

Once on the list, Hawaiʻi species have benefited from the ESA’s strong protections. Earthjustice has used the law to protect the palila, an endangered bird found only on Hawaiʻi Island’s Mauna Kea, from sheep and goats that destroy the native trees that provide the bird’s sole food source. Earthjustice secured a series of court orders holding that the State of Hawaiʻi, which managed the sheep and goats for hunting, violated the ESA’s ban on harming endangered species. As a result, the state must remove the animals from the mountain. Earthjustice has also successfully challenged the Army’s failure to protect imperiled plants and animals—many found only at Mākua on Oʻahu—from training-related fires that were pushing 30 species toward extinction.

An endangered Hawaiian Monk Seal suns itself on the beach in Kauai, Hawaiʻi. (Trudy Simmons / Shutterstock)

The ESA’s reach also extends to the oceans surrounding the Hawaiian Islands. Earthjustice has brought a series of ESA lawsuits to protect listed sea turtles, including the endangered leatherback turtle, from drowning on hooks in the longline fishery. Earthjustice also shut down fisheries in the Northwestern Hawaiian Islands that were depriving endangered Hawaiian monk seals—one of the rarest marine mammals in the world—of food.

For decades, Earthjustice has successfully taken action to protect hundreds of imperiled Hawaiian plants and animals. While serious challenges remain, thanks to the ESA, we have a fighting chance of continuing to preserve Hawaiʻi’s unique flora and fauna for future generations.

Learn more about Earthjustice and the ESA at earthjustice.org/esa.