Biology Reference
In-Depth Information
Scanning the trees, Jack and Liba spotted a honeycreeper we hadn't yet seen that day. The
'ākepa
dazzles beholders with its burnt-orange plumage and slightly crossed bill, which en-
ables it to pry open leaf buds for prey. Suddenly the sounds of the native birds were drowned
out by the exotic red-billed leiothrix and a flock of Japanese white-eyes. One person asked,
“If you erected a mist net to capture birds, would you catch more native or exotic species?”
The ratio, Jack replied, would be about ten individuals of native bird species for every intro-
duced one. We were relieved to hear that, in an archipelago full of things from everywhere
else, native Hawaiians still reign in Hakalau Forest.
When our party stopped for lunch, a native fruit fly landed on a bush near David, perhaps
attracted by his fruit salad. In Hawaii, fruit flies form new species like an out-of-control ex-
periment. Since any individual fly could be new to science, it was tempting to thrust it into al-
cohol and send it on to a fly taxonomist. Identified so far are five hundred species of fruit flies
that swarm wildflowers all over Hawaii, but some experts estimate that the number of known
species will increase. Fruit flies are not particularly endangered, as are many honeycreepers,
but like them some are quite beautiful and ornate, far more compelling than the red-eyed,
vestigial-winged mutants of genetics class. Other insects were about, but if we looked closer,
we would find only introduced ant species grubbing for our lunch spoils. Ants never made it
to Hawaii before human introduction, and many of the arthropods that did arrive, like many
birds, shed their wings to become flightless versions of their mainland ancestors. Hawaii has
a depauperate collection of insects in terms of number, but those that do occur on the islands
are highly endemic and often have narrow ranges. Remarkably, the Hawaiian Islands have
more species of fruit flies than are found in the rest of the world combined. “First in Fruit
Flies”—not a slogan that will appear anytime soon on automobile license plates in Hawaii,
but of profound interest to biologists.
First honeycreepers, then silverswords, and now fruit flies are showing us how rare species
persist in a compressed space and how adaptive radiation results in many new species that
themselves are rare. Adaptive radiations have occurred in many places—in South America
and Australia and even in Mexico's Chihuahuan Desert, home to a great radiation of prickly
pear cacti, evening primroses, and desert fish (cichlids), wherever the necessary conditions
have prevailed. But it is easier to study radiations on island archipelagoes. The Galápagos
Islands are home to radiations of finches, mockingbirds, tortoises, and giant dandelions.
The fruit fly kept hovering about; evolutionary marvel or not, I would have traded encoun-
tering ten new species of fruit fly for a single 'akiapōlā'au. We resumed our walk, hoping
to catch sight of the faux woodpecker. Liba showed us the nest, to which the male typically
returned about every forty-five minutes to feed the female. Our plan was to sit silently under
the tree and wait. A half hour into the vigil, Liba stood up and pointed to her left. She had
heard an 'aki calling in the distance. We heard nothing except red-billed leiothrixes, house
finches, and white-eyes, all imported singers.
