HALEAKALA NATIONAL PARK, Hawaii — Much of native Hawaii--its lush rain forests and the noisy, colorful birds that inhabit them--is gone forever, and its remnants are hurtling toward the same oblivion in the worst extinction crisis in the nation.

Ravaged by species brought into the islands from other lands, Hawaii's native birds and plants are succumbing at a rate that has made the 50th state the endangered-species capital of the nation.

A deceivingly lovely passion flower introduced as an ornamental vine is smothering the rain forests. A mongoose imported to kill rats that were damaging the sugar cane is preying instead on birds. A snail introduced to eradicate a farm pest has decimated the islands' highly prized array of ornate-shelled native snails.

Although Hawaii comprises only 0.2% of the U.S. land area, the state accounts for more than 70% of extinctions in the nation and harbors more than 25% of the nation's rare and endangered birds and plants. Almost half of Hawaii's native birds are endangered and at least nine species have dwindled to fewer than 100 birds. Less than a quarter of the state's native forests remain.

"The species loss here, compared to the mainland, is just fantastic," said Charles P. Stone, a National Park Service research scientist based at Hawaii Volcanoes National Park on the big island of Hawaii. "Two-thirds of the native birds are already extinct."

The losses of native species have been mounting for decades, but the crisis until recently has failed to attract much interest or concern. Lulled by a hospitable climate and oriented toward the islands' stunning array of beaches, residents paid little heed to what was happening in the rain forests.

"Hawaii is such a beautiful place that it's hard to think anything is wrong," said Mark White, Maui project director for the Nature Conservancy.

Alien species frequently turn on native plants and animals, but Hawaii's wildlife is particularly vulnerable to their scourges. Having evolved on the most isolated archipelago in the world, the native plants and animals did not have to fight for survival and therefore lack many of the defenses of their mainland relatives. When exotic species are introduced, the natives quickly succumb.

On the road to this volcano-crowned national park on Maui, rolling hills are carpeted with deep green grass and sprinkled with clusters of lanky eucalyptus trees. It is a pastoral scene, interrupted only by an occasional old plantation home. Closer to the park stands a small grove of stately pine trees, alive with birds and shading a needle-cushioned path below.