Biology Reference
In-Depth Information
sence of predators such as rats had left them defenseless. The birds weren't able to migrate
or to evolve quickly enough ways to protect their nests. So the rats ate the eggs and nestlings,
reproduction plummeted, and many species passed into oblivion.
Steadman's current focus is across the South Pacific, where he spends his days in bird
graveyards reassembling the rich faunas that were clubbed to death by hungry Polynesians
and exploring lavaisolated pockets where the fossils are the result of natural mortality. His
observations illustrated the importance of an ecohistorical approach to understanding con-
temporary rarity and extinction. For example, his research sheds light on the extent and tim-
ing of the start of the biodiversity crisis on Pacific islands by showing us that a steep decline
in species occurred nearly 1,000 years ago. It also offers clear evidence that natural rarity was
exacerbated by invasion of humans and the fauna they brought with them.
After Steadman's talk, I asked Thane Pratt about the list of obituaries and the percentage of
those species that were flightless. He listed 5 species of geese (plus 1 not yet described by sci-
ence), 2 ibises, 1 hawk (possibly 1 undescribed), 1 eagle, 5 rails (plus around 5 undescribed),
4 owls, 2 crows (plus 2 undescribed), 18 honeycreepers, and more recently a flightless duck
from Kauai that went extinct, for a total of nearly 40 extinctions. Of these described extinct
species, 13 were flightless, to which could be added 6 undescribed flightless species, for a
total of 19. Add the historical Hawaiian and Laysan rails and you have 21 species that had
lost their ability to fly to safer ground when faced with a new threat and that had perished as
a result. That's only a short list of what was lost before the arrival of Europeans, based on the
species paleontologists have identified from several excavations scattered among the islands.
The true number of extinctions remains a guess.
Sitting in a darkened auditorium listening to one scientific talk after another can induce slum-
ber. So much talk about extinction also rekindled my desire to get out and see these rarities
before they disappeared. Later that morning, our bird-seeking group returned to the upland
forest along the Saddle Road, where Liba once again was our guide. A tip steered us to the
Pu'u 'Ō'ō Trail for spotting 'akis. “
Pu'u
” means hill, and “
'ō'ō
” is the name of an extinct
Hawaiian bird that represented an endemic family, closest to the silky flycatchers and wax-
wings. The 'ō'ō must have been a dashing bird, a jet-black honeyeater more than thirty cen-
timeters long with yellow epaulets and undertail coverts. So coveted was its plumage that
many were slaughtered for the feather trade, reportedly as many as 1,000 individuals around
1898 just outside of Hilo. By 1987 the 'ō'ō had been wiped out, the victim of habitat loss,
hunting, and disease, illustrating once again that there are usually multiple causes, not just
one, for such an ultimate fate.
