Wildlife & Habitat
James Campbell NWR provides habitat for approximately 117 species of birds and contains one of the largest concentrations of wetland birds in Hawai‘i, including four of Hawai‘i’s six endangered waterbirds. The refuge also serves as a strategic landfall for such migratory birds as the kioea (bristle-thighed curlew) and ‘akekeke (ruddy turnstone) from as far away as Alaska and Siberia. Unusual vagrant birds include the northern harrier, peregrine falcon, black-tailed godwit, Hudsonian godwit, curlew sandpiper, solitary sandpiper, and snowy egret, making James Campbell NWR one of the top lowland birding sites in Hawai‘i.
During spring and early summer, ae‘o begin scraping shallow depressions for their nests as wetland waterlines recede and mudflats dry. The ‘alae ke‘oke‘o and ‘alae ‘ula explore stands of bulrush and cattail searching for insects and aquatic plants to eat. Amid the reeds, floating platforms comprised of various plants serve as nesting sites for both species. ‘Alae ke‘oke‘o especially can be spotted grazing on the short grass atop impoundment dikes. Young of all species, including the gangly ae‘o, can be found throughout the summer. Migrating shorebirds and waterfowl begin arriving in the fall and stay throughout the winter on wetland edges and open water areas.
The greatest threats to wetland birds at James Campbell NWR are predation by nonnative animals, invasive alien plants, outbreaks of avian botulism, and, for the koloa, hybridization with feral mallards. Predation by feral dogs, feral cats, mongooses, and rats is a serious threat to all waterbirds on O‘ahu, and especially to their nests. Nonnative bullfrogs may be the worst predator on small waterbird chicks. These predators are controlled on the refuge to protect waterbirds. Invasive alien plants, particularly California grass and marsh fleabane, can degrade habitat quality by encroaching and choking wetlands. Plant growth requires regular control through prescribed burning, water level fluctuation, and mechanical clearing. The number of feral mallards on O‘ahu has increased since koloa were reintroduced to the island in the 1960s, and hybridization between koloa and feral mallards is now common and widespread. Recent changes in regulations have made it illegal to import mallards into Hawai‘i, but already there may be no pure koloa left on O‘ahu.
Saving Hawai‘i's Native Duck