Kauai History and Isolation

Now, go back in time, and imagine a newly formed Kauai isolated in the middle of the North Pacific Ocean some 2400 miles from the nearest land mass. It is time to fill the island with life.

Wind… this is one of the ways life came to the Hawaiian Islands. A spore from a plant somewhere far, far away is released into the wind and carried by a rising current high into the jet stream. Eventually it drifts down and settles on a barren lava field. Lucky spore.

Wing… imagine migrating birds carrying seeds either in their digestive tracts or stuck to their feathers. After visiting a distant island in the South Pacific, the bird heads back to the north and lets go a seed in the form of a dropping. If it hits an island, and if it lands in a suitable area, in the right type of soil, in the right climate, at the right elevation, maybe it will grow.

Wave… ocean currents transporting salt-resistant seeds, rafted plants, or insects on floating debris. Picture a seed with its own built-in flotation device, bobbing along for miles and miles until it is washed up on shore in hopes that it will take root.

Of the millions of organisms that embarked on this chance voyage, very few arrived here, and then actually survived here. Seventy-five percent of the survivors came by wing; hitchhikers of new life barbed to feathers, stuck in mud on a foot, or traveling cargo in a digestive track.

Owing to its isolation, the Hawaiian Islands are biologically unique, and the percentage of endemic species (species found nowhere in the world except Hawaii) is very high. Plants and animals colonizing Hawaii gradually changed with time, evolving into new forms that were better adapted to island life. With the absence of predators and competitors found in their former homelands, their survival no longer depended on elaborate defense mechanisms. Those qualities that once protected them proved unnecessary and were eventually lost. The island’s 100 endemic land birds evolved from as few as 20 original ancestors. One thousand kinds of flowering plants evolved from 280 original plants. And about 10,000 insect and spider species evolved from about 400 colonists. The astounding diversity of life that flourished on these isolated, and once barren islands bears witness to the force of evolution and the tenacity of life.

previous – Kauai History and Volcano Islands
next – Kauai History and Adaptation