Alien Pest Invasion: The Story Native Wildlife Damage Native Plant and Watershed Damage Agricultural Damage Potential Impact Silent Invasion Home

pig damage The single greatest threat to the survival of Hawai`i's remaining native forests is the destruction caused by non-native species.

Hawai`i is home to the only tropical rain forests in the 50 states--and half of these rain forests are already gone. Hawai`i relies on its rain forests for almost all of its fresh water. As alien plants and animals deplete these forests, they put our future water supplies increasingly at risk, as well as threaten our unique native species.

miconia Hawai`i's forests and other natural areas have been and continue to be invaded by non-native weeds like banana poka and miconia that choke out and compete for sunlight with native species. Banana poka, an attractive non-native vine from South America, has smothered over 70,000 acres of prime native forest. Hardest hit have been the state's precious koa forests, which support many native species, and supply Hawai`i's most renown cabinetry wood.

Haleakala silversword Saved from feral goats and pigs by a decade of fencing and hunting, the Haleakala silversword is now threatened by the Argentine ant, which probably hitched a ride to Hawai`i in foreign cargo. In some areas, these ants are wiping out the native bees and other insects that this spectacular plant depends upon for pollination.


deer in Lana`i Because of Hawai`i's geographical isolation in the middle of the Pacific, large mammals were not found here naturally, as they could not travel the distance across the water without the aid of humans. Non-native pigs, goats, deer, and sheep have spread into virtually every watershed area in the state. Where they root and trample, they destroy vegetation, accelerate erosion, and pollute the water supply with eroded silt, feces, and foreign diseases.