Honouliuli Preserve contains a globally rare, lowland, diverse mesic forest in the Waianae mountain range on the island of Oahu. For the last four years The Nature Conservancy (TNC) planted over 12,000 plants, 4,000 of which are listed as endangered. Their planting efforts included two species which were previously extinct in the wild and endemic only to the southern Waianae mountain range.

TNC installed nine catchment tanks and irrigation systems. They now have over 4,000 gallons of water storage capacity across the preserve that allows the irrigation of thousands of out plantings in dry periods. The water also allows TNC to chemically control weeds that would otherwise continue to degrade native plant and animal habitat. Water based herbicides are also used to reduce the fuel loads posed by invasive grasses. Rodenticide, bait boxes, and snap traps are used to control rodents across more than 70 acres of rare snail habitat, and to protect naturally occurring and planted endangered plant species during reproductive periods. This method of pest control has been used on approximately 70 acres during the endangered Oahu Elepaio forest bird nesting season. For the last four years, The Nature Conservancy observed nesting success rates of between 50% and 75%. As evidenced by previous research in southeastern Oahu (E. Vanderwerf 2000), without rodent control, nesting success rates are around 30-40%, not even high enough for population replacement.

Recently, TNC completed building a 4300 ft., 25 acre fence to protect native snail, plant, and invertebrate habitat for 4 endangered and 28 rare species. This fence will also be used as a site for further diverse mesic forest restoration efforts as well as for the outplanting of 9 endangered plant species in the coming months.

During the last planting season, 150 Cyanea grimesiana plants and 10 Cyanea pinnatifida plants were planted with survival rates above 80%. Both plant species are critically endangered, with no naturally occurring C. pinnatifida plants remaining in the wild. As the total global population for C. grimesiana is less than 40 naturally occurring plants in the wild, TNC’s efforts are significant. Their road to recovery is paved with funding from our Wildlife Habitat Incentives Program.

Wildlife Habitat Incentives Program
with The Nature Conservancy