Glossary Terms
The Hawaiian word for the land, ‘āina, embodies the union of Hawaiian culture and identity with the land and the forces that shape it. Because of its importance in the Hawaiian culture and of the biological uniqueness that has evolved in Hawai‘i, the value of the remaining native habitats and the preservation of ‘āina cannot be overstated.
The native biota of Hawai‘i exhibit several unique characteristics that make them vulnerable to a variety of stresses they did not evolve with:
These traits make endemic organisms more likely to succumb to threats from nonnative plants and animals. Many introduced organisms developed in their natural environments to have high rates of reproduction, disperse widely, and tolerate some level of stress or harm, and these traits give them an evolutionary advantage over the native biota.
Some threats to native ecosystems are widespread across the islands, while others may be island- or habitat-restricted. Threats to the fragile native ecosystems of the Wai‘anae moku include the following:
|
Threat |
Damaging Effects |
|---|---|
|
Feral pigs, goats |
Destroy young shoots of native plants, disturb ground, promote spread of invasive plant seeds, degrade stream quality |
|
Rats and mice |
Predators of native snails, eat seeds of native plants |
|
Invasive plants |
Crowd out native plants and compete for water and sunlight |
|
Mosquitoes |
Spread diseases like avian malaria, viruses, fungus to native plants |
|
Nonnative aquatic species |
Competition for food and resources present in streams, alteration of stream habitat, predators of native aquatic species |
Feral Pigs and Goats. Feral ungulates like pigs and goats damage habitats by browsing the young shoots and lower branches of defenseless plants. These animals also bring seeds of aggressive nonnative species from other areas into native forests, carrying them in mud on their hooves and by ingesting and excreting them. By disturbing stream beds and banks, these species increase erosion and sedimentation, which degrades stream habitats.
Wild pigs also have an indirect but devastating impact on native birds. By making wallows in the forest floor and by eating the tuberous centers of tree ferns, pigs create pools of stagnant water throughout the rainforest. Mosquitoes, not native to Hawai‘i, breed within these pools. The mosquitoes then spread avian blood diseases such as pox and malaria by biting the birds. Lacking genetic defenses against these diseases, the native birds weaken and die. Research has drawn direct correlations between the number of pigs in a forest and the level of disease in the forest bird population (Pacheco and Pacheco 2004).
The endangered lo‘ulu palm, Pritchardia kaalae.
Source: U.S. Geological SurveyRats and Mice. Rats and mice eat the seeds of native plants like the lo‘ulu palm (Pritchardia kaalae) and the tree snails (Achatinella spp.) that were once plentiful. This opportunistic snacking lowers the total number of individuals that can survive to bear fruit or breed to grow the next generation.
Invasive Plants. Invasive plants compete for resources like water and sunlight and can prevent other native plants from growing.
Insects. Insect predators such as the black twig borer (Xylosandrus compactus) spread disease to native plants, while mosquitoes spread avian malaria to native birds.
Nonnative Aquatic Species. Nonnative aquatic species often eat native species and can disturb the balance of the stream itself.
Conversion of native forest to ranch and agricultural land can change the characteristics of the watershed, leading to a greater potential for fire damage from both planned and accidental fires. Fire is not a naturally occurring component of native ecosystems and encourages the spread of nonnative grasses that out-compete native plants for space and nutrients. Even the most routine fires can cause damage if they get out of control. In 2003, a planned fire in Mākua valley escaped the firebreak road and burned 2,100 acres, which included critical habitat of the O‘ahu ‘elepaio (Chasiempis sandwichensis ibidis), native dry forest, native grassland, and 71 individual native, endangered plants (Kakesako and Leone 2003).
The effects of the 2003 fire in Mākua Valley.
Source: CZM Hawai‘iPaving of low-elevation streambeds, along with man-made pollution, dumping, and runoff from developed land, has made streams in the moku very inhospitable to native aquatic species. These aquatic species are amphidromous, which means they must spend a part of their life cycle in salt or brackish water before returning to the less disturbed freshwater streams farther mauka. Many of the nonnative species that are established in streams were intentionally introduced for various reasons, such as to provide game fish or to control aquatic weeds or mosquitoes. Some of these species, including nonnative catfish and crayfish, burrow into stream banks and increase siltation and erosion. Other species are predators of native stream biota. Still others carry parasites that impact native species (Yamamoto 2004).
The Wai‘anae Mountains are truly unique, and many government, community, and research organizations recognize their tremendous ecological value. The mountains provide habitat for over 50 species of endangered plants, host rare breeding populations of the O‘ahu ‘elepaio, and provide some of the last remnants of dry cliff habitat in the islands.
These mountains also contain the last populations of Achatinella mustelina, the once abundant O‘ahu tree snail. Initially, the nonnative snail Euglandina rosea was brought to Hawai‘i as a biological control method for African snails, which are also nonnative. However, the Euglandina became a predator of the native Hawaiian tree snails, helping to push 300 species to the brink of extinction. Fortunately, action was taken, and after years of careful study and management, the native tree snails in the Wai‘anae Mountain Range are slowly increasing their populations (Hadfield and others 1993).
Much attention has been paid to the threats to terrestrial and aquatic resources in Hawai‘i. The news channels extensively covered the invasion of water fern (Salvinia molesta) in Wahiawa Reservoir on O‘ahu, and there are ongoing battles with the coqui frog (Eleutherdactylus coqui) in Waipahu, Waimanalo, and the neighbor islands. The State of Hawai‘i has provided funding for an All-Island Invasive Species Committee to combat these threats. But despite efforts such as quarantine and eradication, many new plant, insect, and aquatic species become established each year. Other island ecosystems can be looked to as examples of potential threats to guard against. For example, the brown tree snake (Boiga irregularis) has devastated Guam’s native bird population, and in Tahiti, native forests have been swallowed up by dense stands of miconia (Miconia calvescens). Hawai‘i is currently one of only a few states that do not have West Nile Virus. (Hawai‘i Ecosystems at Risk 2004). Despite the many threats facing terrestrial and aquatic ecosystems, the efforts of the community and informed decision-making can preserve the uniqueness that remains.
‘Olelo No’eau
He lokomaika’i ka manu o Kaiona.
Kind is the bird of Kaiona.
Said of one who helps a lost person find his way home. The goddess Kaiona, who lived in the Wai’anae Mountains of O’ahu, was said to have pet birds who could guide anyone lost in the forest back to his companions."
– Hawaiian saying
Hadfield, M.G., S.E. Miller, and A.H. Carwile. 1993. "Decimation of endemic Hawaiian tree snails by alien predators." American Zoology 33: 610-622.
Hawaii Ecosystems at Risk. 2004. Miconia calvescens: An Invasive Weed in Hawaii. Hawaiian Ecosystems at Risk Project. http://www.hear.org/MiconiaInHawaii/
Kakesako, G.K., and D. Leone. 2003. Fire scars key habitats: A Makua military burn gone awry chars homes of rare species. Honolulu Star-Bulletin. July 24, 2003.
Pacheco, R., and C. Pacheco. 2004. Conservation in Hawaii. Hawaii Forest and Trail. http://www.hawaii-forest.com/conservation.html
Yamamoto, M. 2004. Alien Species in Hawaiian Streams. State of Hawaii Department of Land and Natural Resources (DLNR). Division of Aquatic Resources. http://www.hawaii.gov/dlnr/dar/streams/stream_aliens.htm
Juvik, S.P. and J.O. Juvik. 1998. Atlas of Hawaii. University of Hawaii Press.
Pukui, M.K. 1983. ‘Olelo No‘eau, Hawaiian Proverbs & Poetical Sayings. Bishop Museum Press. Honolulu, HI.
