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Last
month a bunch of bird people were in Hilo. They attended
the 67th Annual Meeting of the Coopers Society. The Coopers
Society publishes The Condor, one of the prestigious journals
for ornithological research. Professional researchers,
government officials, land managers, and conservationists
all came to network, hear presentations on new research,
and do some birdwatching. For the general public these
meetings and presentations were generally of little interest.
The talks were loaded with feathery techno-speak and genetic
jargon. There was no local press or media to capture the
deliberate and painstaking news that came from behind
the lecterns at the Hilo Hawaiian. Nevertheless, amidst
the slides, overhead transparencies, and statistical graphs
were some bone rattling ideas of Hawaii's natural world.
Two
participants at the meeting were Helen James and Storrs
Olson. Among other things, they study bird fossils from
Hawaii. Now these are not petrified fossils like the romantic
dinosaur digs. These are primarily bird bones found in
archeological middens, beach areas, and lava tubes. Both
of these scientists, associated with the Smithsonian Institution's
National Museum of Natural History, construct a dismal
view of Hawaii's ecological past with their bones. "Hawaiian
ecological communities have undergone dramatic changes
since the arrival of humans," James writes. She argues
that at least half of Hawaii's land birds are extinct.
Storrs Olson thinks that the extinction rate for our birds
may approach 80%. This paleontological perspective, according
to Olson, takes some fundamental ideas down the drain.
Hawaiian
Forest |
Lava
Tube |
Hawaiian
Beach |
One
idea down the tubes is the idea of the eco-friendly Polynesians.
Fossil evidence suggests a significant Hawaiian impact.
Once the Polynesians arrived in Hawaii, they began to
do two things to the birds here. First off, they ate an
awful lot them. In the archeological garbage pits of Hawaiians
past are numerous bird bones. Native bird bones dominate
the earliest sites. As time progresses there are less
and less native bird bones in the middens and more and
more Polynesian introduced food sources such as dog, pig,
and chicken. These pits show several extinct species of
flightless land birds and numerous species of seabirds.
Secondly, the Hawaiians cleared vast areas of lowland
forest habitat with agricultural plantings, firewood gathering,
and burning for grassland cultivation. This loss of habitat
drove certain birds to extinction and many others were
forced into marginal areas.
While
the fossils reveal a remarkable number of extinct land
birds, there seems to be only one extinction at the species
level for seabirds. However, the numbers of seabirds has
been reduced dramatically, with entire populations disappearing,
not just in Hawaii but throughout Polynesia. The seabirds
in the Pacific at one time numbered in the many millions
and they migrated great distances. Olson argues that an
intimate connection between human culture and the seabirds
existed. The huge columns of migrating seabirds from archipelago
to archipelago in the Pacific, a literal stream of birds,
provided the Polynesians with an automatic guidance system
of navigation. Following the birds, they discovered the
islands. As they ate the birds, their navigation system
was lost. The dramatic decline of seabird populations
in the fossil record coincides with the end of Polynesian
back and forth migration. At about the time the Hawaiians
lost touch with other Polynesian cultures, vast amounts
of seabird fossils disappear throughout the Pacific.
Another
idea shaken by the bones is the makeup of the pristine,
native Hawaiian ecological communities. All of the common
forest birds found today in Hawaii are nearly absent in
the fossil record. Notably rare are the nectar eating
honeycreepers such as Iiwi, Apapane, and Amakihi that
dominate the native forests today. Instead, the fossils
show an abundance of birds that currently are exceedingly
scarce or extinct like the Kioea, which is found commonly
in the lava tube fossils of Kona. Another cave find was
the herbivorous, giant, flightless goose, the Moa Nalo,
found in Umii Manu, or bird trap. This lava tube, discovered
in 1992 by biologist Jon Giffen on the slopes of Hualalai,
contained hundreds of bird skeletons including the oval-billed
Nukupuu, specialized at excavating insects from tree limbs
and trunks and, the giant akialoa, the largest honeycreeper
yet discovered. According to the fossil evidence, the
Hawaiian forests were dominated by seedeaters, herbivores,
specialized insect eaters, and predators like the sea
eagle, harrier, and long-legged owl. The Nihoa Millerbird
and the Laysan Finch though now restricted to Nihoa and
Laysan respectively, were found in fossils throughout
the main islands. Likewise, the Laysan Duck and the Gallinule,
coastal wetland birds today, were found at high elevations
on Maui and Hawaii Island. Many species in historic times
that are known from specific locales, habitats, and islands
have been discovered in many different areas. So far over
three dozen new species of Hawaiian birds have been found
in the fossil aviary. The bird bones tell of a dramatic
transformation in Hawaii's forests.
The
fossil evidence begs the point, Olson says, as to what
plant species composed the forest communities? If there
were different bird population communities eating different
food sources, where did that resource come from? Perhaps,
the nectar producing Ohia-lehua tree did not dominate
our forests as it does today? Perhaps, the pre-human Hawaiian
forests were altogether different communities than we
know at present? If so, then a forest that today is completely
made up of native plant species and appears to be "pristine,"
is really a forest that has been fundamentally altered
by the arrival of humans. Among Hawaiian biologists, conservationists,
and environmentalists, you can be sure amidst that pile
of thought, they have a bone to pick with Olson and James.
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