Hakalau Forest National Wildlife Refuge is a protected area on the Big Island of Hawaii. It is one of two units, along with the Kona Forest National Wildlife Refuge that is managed as part of the Big Island National Wildlife Refuge Complex. Access to the Kona Forest is restricted since it contains several endangered species.

Description

Hakalau Forest NWR contains some of the finest remaining stands of native montane wet forest in Hawaii. The slopes below 4000 ft feet receive very high rainfall - 250 in annually. Bogs, fern patches, and scrubby forest dominate this area, which is dissected by numerous deep gulches. Rainfall decreases to about 150 in at elevations above 4500 ft, where majestic koa (Acacia koa) and red-blossomed ōhia lehua (Metrosideros polymorpha) trees form a closed-canopy forest. Further upslope, above 6000 ft, rainfall decreases to 100 in or less and native forest merges into abandoned pastureland where alien grasses and weeds, introduced as forage for cattle, are the dominant vegetation. Since 1989, over 400,000 koa, ōhia, and other native plants have been planted in this area as part of the refuge's reforestation program. The Pua Akala Cabin, located within the refuge, was nominated to the National Register of Historic Places in August 2008. In 1985, 32733 acre on the eastern slope of Mauna Kea were established as the Hakalau Forest Unit. In 1997, the Fish and Wildlife Service purchased an additional 5300 acre of land to create the Kona Forest Unit of Hakalau Forest NWR. The Kona Forest Unit includes lands within the Hookena and Kalahiki land divisions on the western slopes of Mauna Loa, at elevations of 2000 - 6000 ft. One of the primary purposes for the creation of this unit was to protect the habitat of the alalā (Corvus hawaiiensis), which is now extinct in the wild. The Kona Forest Unit is located about 23 mi south of Kailua-Kona, coordinates 19.38278°N, -155.85139°W. The Kona Forest district is somewhat drier than the Hakalau Unit.

Wildlife and habitat

Much of Hawaii's native lowland habitat was first degraded following the Polynesians’ arrival over a thousand years ago. In the late 18th century, cattle, goats, and European pigs were additionally 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. Introduced animals such as mosquitoes, wasps, small Asian mongooses, cats, and rats have also harmed 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, blackberry (Rubus spp.), banana poka (Passiflora tarminiana), and English holly (Ilex aquifolium). The replacement process may have been accelerated by efforts to create more pasture land through bulldozing and burning, and by logging mature trees for timber and fence posts. Eight of the 14 native bird species occurring at Hakalau are endangered. Thirteen migratory bird species and 20 introduced species, including eight game birds, as well as the endangered opeapea (Hawaiian hoary bat, Lasiurus cinereus semotus) also frequent the refuge. Twenty-nine rare plant species are known from the refuge and adjacent lands. Twelve are currently listed as endangered. Two endangered lobelias have fewer than five plants known to exist in the wild.

Climate

According to the Köppen Climate Classification system, Hakalau has an oceanic climate, abbreviated "Cfb" on climate maps. The hottest temperature recorded in Hakalau was 81 F on July 17, 2002, while the coldest temperature recorded was 30 F on February 10, 2021.

Recreation

To prevent spread of Rapid ʻŌhiʻa Death, the refuge is closed to self-guided visits. Guided visits on a commercial tour can be arranged for hiking and birdwatching.