Biology Reference
In-Depth Information
absence of rare vertebrates over the landscape—that is, until you hit pockets that turn out to
be sacred areas where deities reside and humans dare not tread. The only reason the nēnē is
still on the Big Island is that a remnant population of about thirty to fifty lived in the saddle
between Mauna Kea and Mauna Loa, an area deemed kapu (taboo) and avoided by supersti-
tious Hawaiians. Nevertheless, a concerted effort was required to coax the nēnē away from
the gaping crater of extinction.
Today's stable population of almost 2,000 was achieved through captive breeding and re-
lease, the success of which depends on two factors: reintroduction into appropriate habitat
and protection from predators. Adult nēnēs can fly, but they nest on the ground and the gos-
lings are vulnerable for a long time. Soon after the recovery program began, it became clear
that many birds released into marginal highland habitat that lacked abundant food plants sub-
sequently perished. The nēnē's odds of survival in the wild picked up when mongooses, feral
cats, and feral dogs were removed from the area. Now, with a better understanding of the
habitat and protection needs of this species, releases are targeted more effectively. On Kauai,
where mongooses never entered, predation is less severe and the nēnēs are finally doing well.
Ironically, like Canada geese on the mainland, the nēnē is fond of golf courses, demonstrat-
ing an ecological flexibility to exploit and eventually rebound in humanaltered habitats.
All approaches to recovering rare avian species and rare plants and insects on islands have
similar requirements: remove nonnative plants and exotic mammalian herbivores and predat-
ors; fence off, if necessary, the critical habitat that can support the rare species; and let nature
take its course. The idea is that rare native birds will respond to the positive changes under
these management actions. In fact, Jack Jeffrey and his colleagues have shown that native
bird numbers have increased at Hakalau Forest National Wildlife Refuge since forest restor-
ation began twenty years ago. For example, 'i'iwis, 'apapanes, and Hawaii 'amakihis have
more than doubled in density. The number of breeding birds in Hakalau's open forests has in-
creased, as shown by the Hawaii 'elepaio (31 percent), 'aki (125 percent), and Hawaii creeper
(39 percent).
In certain cases in which a species' population has fallen below one hundred individuals,
captive breeding, reintroduction, and translocation have become important tools. But all of
these interventions are very expensive, and conservation in Hawaii is underfunded. The
Hawaiian Islands contain about 45 percent of the endangered species in the United States but
receive less than 5 percent of federal funding.
Climate change has emerged as a long-term threat to the persistence of rarities in many
places we have visited, and Hawaii is no different. Besides the issue of birds moving upslope
to find the microclimates they prefer, their parasites might tag along with them in a warming
climate. In the 1990s, the fear was the introduction and establishment of a species of
Culex
mosquito that could survive the cool temperatures of the montane forests and spread deadly
disease in the presently malaria-free zone. However, Peter Vitousek informed me, “it's too
