The Hanalei River system is one of the longest streams in Hawaii, and runs through habitats from the summit bogs of Waialeale to the coral reefs in Hanalei Bay.

Prehistorically, most of the Hanalei River Valley was a low elevation wet forest composed of native trees such as ohia lehua (Metrosideros polymorpha and loulu palm (Pritchardia sp.) But the valley has been intensively modified by humans for over 1000 years and little native vegetation remains in the lower sections of the valley. One can still find find a few native plants on the lower slopes, such as koaia (Acacia koaia) sandalwood (Santalum freycinetianum) and hala (Pandanus tectorius). But even these hangers-on are threatened by aggressive alien weeds such rose myrtle (Rhodomyrtus tomentosa) and bush beard grass (Schizacrium condensatum). The upper sections of the valley still retain some of the native riparian plants including papala kepau (Pisonia umbellifera) and mamaki (Pipturus albidus).

The frequent overbank flooding of the river and the ground water seepage from the surrounding hills has created extensive wetlands along the valley floor. These wetlands are a very productive ecosystem and important to the hydrological and ecological functions of the Hanalei River Valley. Hawaiians long ago converted almost all these fertile wetlands to taro cultivation which can still be seen today. Prior to taro cultivation much of these wetlands would have been hala and loulu palm forest and sedge marshlands. In wet fallow taro patches one can still find a few native sedges such as kaluha (Schoenoplectus juncoides). Those wetlands not in taro are now completely dominated by alien weeds, particularly California grass (Brachiaria mutica). Even the river bank has become overgrown with hau bush (Hibiscus tiliaceus), one of the few Polynesian plants to have become a weed.

It is important that these wetland weeds be managed, because left unchecked, they eliminate the wetland habitat for Hawaii’s endangered waterbirds. Four species of unique Hawaiian waterbirds live and breed in the Hanalei Valley. The Hawaiian stilt or ae'o (Himantopus mexicanus knudseni), the Hawaiian coot or 'alae ke'oke'o (Fulica alai) and Hawaiian Hawaiian moorhen or 'alae 'ula (Gallinula chlorops sandvicensis) can all be seen and heard around the managed wetlands in Hanalei. The Hawaiian duck or koloa maoli (Anas wyvilliana) frequents the long stretches of the Hanalei River itself, but can be seen flying around the wetlands in the morning or evening.

Recently several endangered Hawaiian goose or nene (Branta sandwicensis), were released on the Hanalei National Wildlife Refuge as part of the recovery program for this species. Another common but infrequently seen endangered species in these wetlands is the Hawaiian hoary bat or ape'ape'a (Lasiurus cinereus). Just at dusk this bat forages for insects over the river, the wetlands and even the estuary.

STREAM SPECIES

ALIEN SPECIES