Native plants form a variety of community types, including shrubland, forest, and areas of bog and moss-lichen. Most shrubland lies in coastal lowlands on the lee sides of the mountains, extending to considerable altitudes where rainfall is slight. Forests grow above the shrubland on the lee sides of mountains, extending to sea level on the windward sides. There are at least four kinds of native forest, reflecting differences in availability of moisture. Shrubs mixed with scattered trees grow on the upper slopes of the high mountains, above the forest zone.
Bogs are common in areas of heavy rainfall.
Mosses and lichens grow above timberline, where rainfall is low and frost is frequent. Introduced mammals include the axis deer, Hawaiian wild boar, feral sheep, and goats. There are large populations of such water birds as terns, tropicbirds, boobies, shearwaters, and petrels. Native land birds include hawks, owls, crows, warblers, and thrushes. Several species, including the crested honeycreeper and ou, are near extinction.