An Island Within an Island
Year listed: 1967
Feeding habits: Finicky
Paul banko walks along the arid slopes of the 13,796-foot-high Mauna Kea volcano on Hawaii’s Big Island. He’s searching for a yellow-crowned songbird called the palila. He hears the trilled warble that gives the bird its onomatopoeic name, but he doesn’t actually see one. “Typical Hawaii birding experience,” Banko deadpans. For nearly two decades, Banko, a U.S. Geological Survey wildlife biologist, has sought to reverse the palila’s decline by working to restore its habitat and coaxing the birds to colonize another territory. The bird, a type of Hawaiian honeycreeper, lives almost exclusively on seeds from the increasingly scarce mamane tree.
The state’s flora and fauna have long been vulnerable to habitat loss, invasive species, overharvesting and disease. In deed, Hawaii is home to a quarter of all the United States’ animals and plants listed under the ESA, with more than 300 threatened or endangered species, more than 100 candidate species and more than 1,000 species of concern. Almost half of Hawaii’s native bird species have become extinct.
Human activity has devastated Hawaiian birds and other wildlife since Polynesians first settled the islands some 1,600 years ago. Stowaway rats that leapt from their canoes preyed on birds’ nests. Several species of flightless geese, prized as food, were extinguished. Other birds were culled for their plumage, and Hawaiian kings cleared forests for agriculture. Europeans, arriving in the late 18th century, brought mosquitoes that later transmitted avian pox and malaria, against which native songbirds had little resistance. Introduced sheep, pigs, cats and cattle compacted soils, ate mamane seedlings or devoured nestlings. Ranchers cleared forests for cattle pastures. Mongooses were imported to control the rats, but because mongooses hunt during the day, when rats hide, the mongooses ate ground-nesting birds instead. The palila vanished from the islands of Kauai and Oahu probably before 1800.
Hawaii’s endangered species experience is instructive, Banko says, because the destruction and fragmentation of habitats as well as the domination of native species by invaders are the root causes of many species’ decline. “We see this as a microcosm of what’s happening on the continent in terms of watching ecological processes unravel,” he says. The process is just more obvious on a real island than on one of the ecological islands that increasingly occur on the mainland— isolated habitats surrounded by highways, strip malls and housing developments.
The palila was one of the first species to be protected under the ESA when an early version of the law passed in 1966. Still, state authorities did little until 1978, when the palila did what any red-blooded American bird would do: it sued. In Palila v. Hawaii Department of Land and Natural Resources (the first time a bird was a plaintiff in a lawsuit, which was brought by the Sierra Club Legal Defense Fund), a federal court ruled that under the ESA, the state had to prevent further damage to the bird’s habitat. In the 1990s, when the U.S. Army proposed building a road through critical palila habitat, the ESA dictated that the military pay nearly $14.6 million to fund palila restoration projects.
By then, most palila were confined to a 12-square-mile forest on the west slope of Mauna Kea, between 7,000 and 9,000 feet. This lone population of about 3,000 birds easily could have been wiped out by fire, storms or a disease that strikes mamane trees. With the military’s mitigation money,
Banko and co-workers set out to expand the palila’s existing forest and establish a new palila population On Mauna Kea’s north side. Banko and others netted palila on the west slope, equipped them with tiny radio transmitters and moved them to the north slope. Most of the birds simply flew the 12 miles home. This past March, however, the researchers relocated another 75 wild palila, and some appear to have stayed put. At the same time, Alan Lieberman, of the Zoological Society of San Diego’s Center for Reproduction of Endangered Species, along with his colleagues at Hawaii’s KeauhouBird ConservationCenter, have bred palila in captivity and released 15 of the birds in the northern habitat. Though some died or disappeared, Lieberman says, the survivors appear to be acting like wild palila, and at least one pair is mating. On Mauna Kea’s north side, Banko walks around a forest of 20-foot-high mamane mixed with an occasional koa and sandalwood tree. Over a hand-held radio, he receives a report from one of his field researchers: there are five palila in a tree half a mile away. The tree stands in the middle of what the researchers have dubbed “palila paradise,” where they’ve spotted 20 of the birds. “I think the palila will colonize this area,” Banko says, but he acknowledges it might take decades to build a community that won’t need to be supplemented with captive-bred or relocated birds. He spots a female palila flitting in and out of the mamane tree. Everybody spies her activity through binoculars. After a few minutes, it’s obvious what she is doing: building a nest.