Wildlife & Habitat


Learning from the Past to Protect the Future.

Much of Hawai‘i’s native lowland habitat was degraded following the Polynesians’ arrival over a thousand years ago. In the late 1700s, cattle, goats, and European pigs were released into the forests, and hundreds of additional alien plants, animals, and insects have subsequently been introduced. Most lowland plants seen today like the orchid, ginger, and plumeria are aliens or nonnative. Mosquitoes, wasps, mongooses, cats, and rats are other examples of animal introductions that have had detrimental impacts on Hawaiian habitat and native species.

Grazing pressure by cattle and pigs has resulted in the replacement of Hawaiian plants by more competitive alien grasses and shrubs within the upper portions of Hakalau Forest. Below this pasture area, the native tree canopy is still intact, but the native understory has been replaced by alien grasses, banana poka, and English holly. The replacement process may have been accelerated by efforts to create more pasture land through bulldozing and burning, and by logging mature koa and ‘ōhi‘a trees for timber and fence posts.

  • Birds

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    Common native birds, as well as endangered birds, have been sighted at Hakalau Forest. The ‘ō‘ū, a finch-billed honeycreeper with a yellow head, was last sighted in 1977. This extremely rare bird feeds on forest and aids in the dispersal of native seeds.

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  • Mammals

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    The endangered ‘ōpe‘a pe‘a (Hawaiian hoary bat), Hawai‘i’s only native terrestrial mammal, is a common resident at the refuge but is seldom seen because its nocturnal behavior makes it difficult to see. The bat is an insect feeder and forages in forest openings searching for flying insects which it takes in flight.

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  • Plants

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    Native Hawaiian plants arrived on the islands by natural means - wind, ocean currents and birds. Native plants are either indigenous (occurring naturally in Hawai‘i and other locations) or endemic (found only in the Hawaiian Islands). The majority of native Hawaiian plants are endemic.  

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  • Arthropods

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    Native Hawaiian invertebrates encompass over 5,000 endemic insect species that are known to occur in Hawaii. Invertebrate populations play an integral role in native Hawaiian ecosystems serving as critical food resources for ‘ōpe’ape’a and native birds. Hawaiian invertebrates are essential pollinators of native trees and the biotrophic mediators of the forest.   

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  • Geology and Soils

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    The Hawaiian Islands were formed by a series of volcanic eruptions that occurred at various hotspots beneath the Earth’s crust. Hawai‘i Island is the largest and youngest island in the Hawaiian chain and encompasses a total land area of 4,028.2 mi2. The landmass was formed when five volcanoes of varying ages (Kohala, Mauna Kea, Hualālai, Mauna Loa, and Kīlauea) joined together.

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