The 917-acre (371-hectare) Hanalei National Wildlife Refuge was established in 1972 to conserve four species of endangered waterbirds, and is located in Hanalei Valley on the north shore of the island of Kauai. The refuge consists of 300 acres (121 hectares) of the flat floor of Hanalei Valley, a portion of the Hanalei River, which is a designated American Heritage River, and adjacent steep slopes and ridges. The floor of Hanalei Valley is approximately 0.5 miles (0.8 km) wide and was formed by erosion and alluvial deposits from the Hanalei River, which meanders through the valley. The valley floor ranges in elevation from 10 feet (3 meters) near the Hanalei Bridge to 40 feet (12 meters) at the refuge's southern boundary, and the refuge extends up to 400 (121 meters) feet on adjacent ridges.
The Hanalei area has been used by people to cultivate taro and rice for about 1,000 years. The USFWS allows several farmers to cultivate taro on the refuge under a special use permit. Water from the river is diverted through a system of ditches, channels, and pipelines to irrigate 186 acres of taro fields and 62 acres of wildlife impoundments before returning to the river.
Average monthly temperature at the refuge ranges from the lower to upper 70s (?F) throughout the year, and the median annual rainfall is about 80 inches (2 meters). Vegetation on the refuge is dominated by naturalized alien species. A paved county road passes through the refuge, providing viewing access to some areas, but the wetland portions of Hanalei NWR are not open to the public.
Hanalei National Wildlife Refuge contains one of the largest concentrations of wetland birds in Hawai`i. It is an important breeding, feeding, and resting area for five bird species listed under the U.S. Endangered Species Act; the Koloa or Hawaiian Duck, Hawaiian Stilt, Hawaiian Coot, Hawaiian Common Moorhen, and Nene or Hawaiian Goose. The vast majority of Hawaiian Ducks occurs on Kaua`i, and Hanalei supports the largest concentration, with a maximum of 251 birds observed in August 1994. Nene were reintroduced to Kauai beginning in 1985 and are increasing rapidly. About 50 Nene were present in the Hanalei area in 2007, one of few locations where this upland goose is regularly seen in wetland habitat.
Hanalei also supports a variety of migratory waterfowl, shorebirds, and other wetland birds from August-April. Some species occur primarily during migration, but others are present throughout the winter months. At least 23 species of waterfowl and 19 species of shorebirds have been observed at the refuge, and several unusual visitors are now seen regularly at Hanalei, including White-faced Ibis, Brant, and Osprey. Numerous vagrants have appeared over the years, including Baikal Teal and Golden Eagle, making Hanalei one of the top sites for wetland birds in Hawai`i.
Habitat and land use
Habitats at Hanalei National Wildlife Refuge include a section of the Hanalei River, various types of wetlands including open water, emergent wetlands, and taro fields, and upland forest on adjacent slopes and ridges. Vegetation in the lowland river bottom areas on the refuge consists primarily of alien species such as California grass (Brachiaria mutica) and Java plum (Eugenia cumini), and also the indigenous hau (Hibiscus tiliaceus). Taro (Colocasia esculenta) is cultivated in irrigated fields. Upland forested slopes are also dominated by alien vegetation, such as guava (Psidium spp.), Java plum, monkey-pod (Samanea saman), and mango (Mangifera indica). A few native trees, such as ohia (Metrosideros polymorpha), koa (Acacia koa), and hala (Pandanus tectorius), can be found in upland forests.
Hanalei National Wildlife Refuge was established for the conservation of four species of endangered waterbirds, and 62 acres (25 hectares) on the refuge are used as water impoundments to provide wetland habitat specifically for waterbirds. A larger portion of the wetland area on the refuge, 186 acres (75 hectares), is farmed for taro under a special use permit, which provides marginal habitat for some waterbirds. The refuge itself is not open to the public, but a road runs through the refuge to provide access to private land and state land and the Okolehao hiking trail above the refuge. The refuge can be viewed from an overlook located at a pullout on the eastbound side of the Kuhio Highway, where there are interpretive and educational display panels. Boating and fishing are permitted on portions of the Hanalei River. The Ho`opulapula Haraguchi Rice Mill organization conducts historic and environmental education activities for local school groups and limited commercial tours on the refuge under a special use permit.
Pressure/threats to key biodiversity
The greatest threats to wetland birds at Hanalei are predation by non-native mammals, outbreaks of avian botulism, invasive alien plants, limitations on amount of suitable habitat due to agricultural uses, sea level rise, and, for the Hawaiian Duck, hybridization with feral Mallards. Predation by feral cats and rats is a serious threat to all waterbirds on Kaua`i, especially their nests. Predators are controlled on portions of the refuge to protect waterbirds. Outbreaks of avian botulism occur occasionally as a result of nutrient-rich sediments, high water temperature, low dissolved oxygen, and fish mortalities. Dead fish provide a mechanism (maggots) to transmit botulism to waterbirds. Invasive alien plant species, particularly California grass, can degrade habitat quality by encroaching and choking wetlands, and require regular control. The amount of high-quality habitat available to waterbirds on the refuge is limited by the amount of land under permit for taro cultivation. Taro fields are used to some degree by some waterbirds, particularly Hawaiian moorhens, but waterbird abundance is generally lower in taro fields and repeated human disturbance may lower nesting success. There are few feral Mallards on Kaua`i currently and this island serves as the last stronghold for pure Hawaiian Ducks, but the number of feral Mallards may be growing and must be controlled as soon as possible to prevent genetic introgression into the Hawaiian Duck population. Global sea level rise could inundate freshwater and brackish coastal wetlands needed by waterbirds.
All of the 917 acres (371 hectares) comprising Hanalei National Wildlife Refuge is owned by the U.S. Fish and Wildlife Service. A portion of the refuge, 186 acres (75 hectares), is farmed for taro under a special use permit.