More than onethird of the countrys endangered bird species call Hawaii home. Three of themthe Hawaiian stilt, the Hawaiian coot and the Hawaiian moorhenare thriving at Pearl Harbor and James Campbell National Wildlife Refuges on Oahu, where careful management for more than 30 years has increased and stabilized their numbers.
In a yearround balancing act, vegetation is controlled and water levels are manipulated to serve the different foraging and breeding habits of each species, while their predatorsdogs, cats, mongoose and rats (all exotic to Hawaii)are discouraged with fences and traps. Sometimes were pumping water in to suit loafing coots or nesting moorhens, says David Ellis, project leader at Oahu National Wildlife Refuge Complex, which includes the two wetland refuges. At other times, we have to let water out to create the saturated mudflats where stilts like to nest.
That makes the process sound far simpler than it is. But the result is that the waterbirds populations on the refuges are stable at a very high level of productivityin some cases, still rising slightly. Theyre not declining anymore, so thats a very big step for any endangered species, Ellis says. We dont expect dramatic increases on the refuges now, because we may have reached our peak.
In addition, some of the birds are venturing beyond refuge boundaries. Through banding, weve discovered that chicks do leave, says wildlife biologist Mike Silbernagle, for 19 years a driving force behind the recovery effort.
The coastal refuges were created in the 1970s, shortly after passage of the Endangered Species Act. James Campbell Refuge, on Oahus northern coast, includes two wetlands covering more than 160 acres. On the southern coast, Pearl Harbor Refuge was established on the famed naval base when airport construction threatened crucial stilt habitat. It totals 98 acres. Though small by mainland standards, these wetlands are just as crucial, Ellis says.
The first step was to cut back invasive plants that choked the wetlands. The next was to facilitate water management by building dikes, creating ditches and installing wells and pumps. The third was finding defenses against predators. Plants, water and predators are continuously monitored and managed to get the correct mosaic of vegetation for each species.
Similar efforts are under way on other Hawaiian refuges, notably Hanalei Refuge on Kauai and the Kealia Pond Refuge on Maui. Theres a bigger picture in the recovery of these species, and were part of that, Ellis says.
He and Silbernagle use the birds Hawaiian names, and Silbernagle admits to having a favorite. It isnt the aeo (stilt), a chattering attentiongrabber with its showy looks and fussy habitat demands. Nor is it the more tolerant, more visible alae keokeo (coot). Its the elusive alae ula, the moorhen.
Theyre so funny, Silbernagle says. Theyre built like a chicken. They have a whole repertoire of vocalizations. And theyre so secretive. He has seen a moorhen hide behind a few stems of sedge, like a child who covers his eyes and believes hes invisible. Then it will sort of melt back into the vegetation, making it the hardest to count.
Surveys in 200406 estimated an average of 1,810 stilts statewide, up from 951 in 198991 surveys; 1,648 coots, up from 1,238; and 372 moorhens, up from 155. Of those, the two Oahu refuges contributed 225 stilts in 200406, up from 147; 361 coots, up from 246; and 49 moorhens, up from 25. Ellis says the recovery goal is an average of 2,500 of each species statewide over five years.
Even if the birds are eventually delisted, the job wont be done. The two refuges are core areas that must continue to be highly managed into the future, and unknown challenges await, Ellis says. Sealevel rise will be a huge wild card.
And then, Silbernagle says, there are the birds themselves: The birds make sure you never learn all there is to know about them.
Alison Howard is a Virginiabased freelance writereditor.