HAWAIIAN INVERTEBRATES

Hawaii supports more species of plants and animals than any other U.S. state. Like most of the Pacific Islands, however, it has suffered a wave of extinctions unparalleled on the mainland. More than one hundred species of birds, mammals, plants, and insects have been driven to extinction by hunting, habitat loss, and exotic species introductions. The Center's Pacific islands and marine programs are working to stem the tide of extinction and protect and restore habitat for rare and endangered Hawaiian species and ecosystems. The Center’s efforts since 1999 have resulted in Endangered Species Act protections for 16 Hawaiian invertebrate species.

HAWAIIAN PICTURE-WINGS

Few of Hawaii’s unique species are as amazing as the 111 species of picture-wing flies that have evolved from a single female that migrated from the mainland some five million years ago. Hawaiian picture-wings represent one of the most remarkable cases of specific adaptation to local conditions that has been found in any group of animals on Earth. The study of Hawaiian picture-wings has contributed greatly to humanity’s understanding of biology and evolution: Scientists have recently discovered that the picture-wings may possess auto-immune system characteristics previously unknown to medical science that may unlock cures for AIDS, cancer, or the West Nile virus.


Hawaiian picture-wing. U.S.G.S. photo by David Foote.

Small insects in the Drosophilidae family, picture-wings are often called the "birds of paradise" of the insect world because of their intricate mating rituals and dances. The species Nalo Kihikihi (Drosophila heteroneura) is also known as the "hammerhead" because the males have evolved a long, narrow head much like that of the hammerhead shark to attract females and butt heads with male competitors. Like some birds and mammals, but few other insects, picture-wings defend special mating areas called "leks" where males dance, wrestle, sing, or butt heads in a performance designed to impress females.

THREATS TO THE PICTURE-WINGS

Unfortunately, Hawaiian picture-wings are gravely threatened. Seventeen or more species may already be extinct and as many as 50 may be in serious decline. The hammerhead, for example, formerly occurred at 16 sites on four of the island of Hawaii’s five volcanoes. It disappeared from every site and was feared extinct until rediscovered at a single site on the Hualalai volcano in 1993.

Hawaii picture-wings have declined because of habitat destruction and the loss of their host plants. Remaining picture-wing species are threatened by degradation of their habitat by feral animals and invasive plants, loss of host plants, predation by introduced yellow jackets and ants, cattle grazing, and fire.

CENTER ACTIONS TO PROTECT PICTURE-WINGS

Scientists sounded warning bells in 1995 that a dozen species of Hawaiian picture-wings were on the precipice of extinction, but the U.S. Fish and Wildlife Service failed to take action to protect them. The Center and the Conservation Council for Hawaii, represented by Earthjustice, filed a lawsuit against the Service. A subsequent legal agreement and court order resulted in an announcement in May of 2006 that the Service will protect the 12 most imperiled species of picture-wings by listing them as endangered under the Endangered Species Act. The Service must also protect critical habitat for these picture-wings by April 2007, and the Center will ensure that a comprehensive recovery strategy for the picture-wings is put in place.

CENTER ACTIONS FOR OTHER HAWAIIAN INVERTEBRATES

The Center, represented by Earthjustice, filed a lawsuit in 1999 against the Fish and Wildlife Service that resulted in Endangered Species Act protection for four other rare Hawaiian invertebrate species: the Blackburn's Sphinx Moth, Newcomb's Snail, Kaua`i Cave Wolf Spider, and Kaua`i Cave Amphipod.

BLACKBURN'S SPHINX MOTH

With a wingspan of five inches, Blackburn's sphinx moth (Manduca blackburni) is one of the largest of Hawaii's 10,000 native insects. When this moth species was discovered in 1880, it was abundant across the 2 million acres of dry and mesic forests on the main Hawaiian Islands. After massive forest loss and degradation, it was declared extinct in the 1970s and considered extinct until rediscovered on Maui in 1984.

The sphinx moth formerly occurred on the Hawaiian islands of Kauai, Oahu, Molokai, Maui, Kahoolawe and Hawaii. It now survives in just a few populations on Maui, Kahoolawe and Hawaii. Remaining populations are closely associated with large stands of `aiea (Nothocestrum sp.) trees. Two of the four `aiea species are themselves listed as endangered.


Blackburn's sphynx moth. Photo courtesy of W.P. Mull.

The Blackburn's sphinx moth is threatened by urban sprawl, introduction of exotic species, agricultural expansion, livestock grazing, wildfire, and military training activities. Its numbers are currently so low that it could be driven extinct by extreme weather fluctuations.

Blackburn's sphinx moth was put on the federal "candidate" list for protection in 1984, and was finally listed as an endangered species in 2000, after two lawsuits by the Center. In June 2002, the Fish and Wildlife Service proposed designating 99,433 acres of critical habitat for the Blackburn's sphinx moth. The designation includes native dryland forest on Maui, Hawaii, Molokai, and Kahoolawe. These are among the rarest remaining habitats on the heavily developed, logged, and grazed Hawaiian Islands. Seventy percent of these forests have been destroyed or degraded.

NEWCOMB'S SNAIL

The Newcomb's snail (Erinna newcombi) is a freshwater species that exists in only five or six streams on Kaua`i, where 6,000 to 7,000 of these snails inhabit fast-flowing streams and associated springs, seeps and vertical-to-overhanging waterfalls. Each stream supports a single snail population, and approximately 90 percent of the surviving snails are concentrated in two populations.

Hawaiian river systems have been degraded and destroyed by plantation irrigation systems that divert hundreds of millions of gallons of water per day, often leaving streams entirely dry. Hydropower dams divert over 90 million gallons a day. As a whole, Newcomb's snail has declined by 60 percent since 1925.


Newcomb's snail. Photo courtesy of U.S. Fish and Wildlife Service.

In response to the Center’s lawsuit, the Fish and Wildlife Service listed Newcomb's snail as an endangered species in 2000, and designated almost 4,500 acres of critical habitat for the species along 12.3 stream miles in August of 2002.

KAUAI CAVE WOLF SPIDER AND KAUAI CAVE AMPHIPOD

The Kauai Cave wolf spider (Adelocosa anops) and the Kauai Cave amphipod (Spelaeorchestia koloana) are cave-dwelling invertebrates found only in a four-square-mile area of the Hawaiian island of Kauai. The wolf spider has been reduced to just three populations, the amphipod to just five. At least 75 percent of these species’ historic habitat has already been rendered uninhabitable by development projects.


Kauai cave wolf spider. Photo courtesy of William Mull, U.S. Fish and Wildlife Service.

In response to the Center’s lawsuit, the Fish and Wildlife Service listed the wolf spider and the amphipod as endangered species in 2000.

 

April 25, 2007
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