Kauai History and Adaptation

Hawaii boasts an astounding degree of biodiversity containing 21 of the world’s 22 climatic zones – from deserts, to tropical rainforests, to alpine, to snow-capped summits. The tropical climate of the Hawaiian Islands is quite hospitable, making the area particularly rich in flora. There were also no large animals to eat plants, therefore defenses weren’t needed and over time were lost. For example, many different mints evolved here, but their ‘minty-ness’ is a defense against animals, and all of the Hawaiian mints lost the chemical and became mint-less mints. Along with these we have greenbriars without briars, raspberries without barbs, nettle-less nettles, sumac-less sumac, and spine-less hollys. Some plants started out as bushes growing in dry climate, then their seeds traveled inland to wetter climates and they became taller trees. ‘Ohi’a is a good example of this adaptation. It is found from sea level to high on the mountain slopes. Depending on its habitat, it can be scraggly and short, or tall and straight, and its bright-red blossoms make it one of the most attractive native trees. One kind of silversword that grows in dry regions slowly changed over the years by growing gray hairs on its leaves to protect it from the hot sun. The hairs also helped to hold water on the leaves so it could survive in its new dry climate. The silverswords living in wet areas have different adaptations.

The Hawaiian honeycreepers are the most spectacular example of adaptation anywhere in the world. Through diversity, bill variation, feather coloring, foraging patterns, and diet, the honeycreeper boasts twenty-three different variations all evolving from a single ancestor. Nectar-feeding honeycreepers evolved long, curved bills designed for probing flowers. Insectivorous honeycreepers developed thin, warbler-like bills for picking insects from the foliage. Bark-picking honeycreepers relied on their bills to pick, pry, peck, and probe. Seed-eaters developed stouter, stronger bills for cracking tough husks. And some multi-tasking honeycreepers developed mis-matched upper and lower beaks, each with a specific purpose. Some of these amazing birds even developed tubular tongues to better sip the floral nectar. Of the many species of endemic honeycreepers, several are presently endangered, and others are already extinct.

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