Biology Reference
In-Depth Information
more than 50 percent of Hawaii's endemic birds went extinct with the arrival of the Polynesi-
ans, another 20 percent had died off since 1825, and about 70 percent of the remaining birds
were listed as endangered or threatened. Included on this list were eleven species determined
to be basically unrecoverable or functionally extinct. Steadman summed it up to me this way:
“The past few hundred years have only made the situation worse. While the surviving species
of birds deserve our best efforts to save them from extinction, the sad truth is that there's not
that much left to save.”
Steadman is right in one sense: It is too late to safeguard most of these avian rarities be-
cause many of them are already extinct. The question that remains is how fruitful would be
any effort put into saving the remaining species. And if we were to make a concerted try,
what would be the best method? Recovery efforts now under way involve both species- and
habitat-oriented approaches to conservation. Although there are many rare species worthy of
recovery efforts, the Hawaiian bird species receiving the most attention so far, in addition to
the 'aki, are the Hawaiian crow, the Hawaiian goose, and the palila.
The endemic Hawaiian crow, the
'alalā
, was one of the rarest birds in the world when spe-
cies recovery work began several decades ago. Biologists often joke that long after humans
disappear and all the rare species before them, Earth will still be teeming with cockroaches
and grasshoppers, with crows to gobble them up. Like other species of crows on Pacific is-
lands, however, the Hawaiian crow is ecologically very different from our plentiful main-
land crows. It is a forest bird, highly frugivorous, and it shuns agricultural and urban land-
scapes. “The 'alalā has declined for many of the same reasons as have other native Hawaiian
birds—loss of habitat, hunting, disease, and introduced predators,” Liba said. Before they can
learn to fly, fledgling 'alalās are caught on the ground by cats and mongooses. Avian pox and
malaria have also taken their toll.
By 2004, the last wild 'alalās were declared gone, so it is now up to the captive population
to be the source of the recovery effort. The current 'alalā captive breeding program on the
Big Island contains more than seventy-five individuals, but releases into the wild of captive-
born young have been disappointing. Captive birds are treated for pox lesions before being
released and their release area is beyond the malaria danger zone, but released birds are of-
ten killed by
'ios
, native Hawaiian hawks. This circumstance is surprising because crows
routinely mob and drive off hawks and eagles in other parts of the world. In Hawaii, even
though the released birds seem to recognize hawks, they don't react. Experts have recommen-
ded removing Hawaiian hawks from the release sites by whatever means necessary, an ironic
twist because the 'io itself is an endangered species (although currently being considered for
delisting). Better proposals are to liberate the chicks on another island where the hawks are
absent or to free them in dense forests where 'ios would be less common.
The prospects for the Hawaiian goose, the
nēnē
, is more optimistic. The nēnē looks far too
tasty to have survived the Polynesian luau. A common phenomenon in native lands is the
