Home > Endemism in the Hawaiian Islands

The relatively short time that the existing main islands of the archipelago have been above the surface of the ocean (less than 10 million years) is not the time period available for biological colonization and evolution in the archipelago. High, volcanic islands have existed in these waters far longer, extending in a chain to the northwest, once mountanous islands now reduced to submerged banks and coral atolls. Midway Atoll, for example, formed as a volcanic island some 28 million years ago. Kure Atoll, a little further to the northwest, is near the Darwin Point—defined as waters of a temperature that allows coral reef development to just keep up with isostatic sinking. And extending back in time before Kure, an even older chain of islands spreads northward nearly to the Aleutian Islands; these former islands, all north of the Darwin Point, are now completely submerged as the Emperor Seamounts.

There are other factors as well. The islands are well known for the remarkable diversity of environments that occur on a high mountain in a trade winds field. On a single island, the climate can differ around the coast from dry tropical (< 20 in or 50 cm annual rainfall) to wet tropical; and up the slopes from tropical rainforest (> 200 in or 500 cm per annum) through a temperate climate into alpine conditions of coldness and dryness. And the rain climate impacts on soil development, which largely determines ground permeability, which effects the distribution of streams, wetlands, and wet places—and on and on and on.

Distance—remoteness—is a filter. And of those germs of life that occasionally made it through, how many found their way into a suitable microclimate? Whether a seed or spore attached to a lost migrating bird's feather or an insect falling out of the high winds, put there by a storm in its homeland—of these, how many found a place to survive and whatever else was needed to reproduce? This narrowing of the gene pool meant that at the very beginning the population of a colonizing species was a bit different from that of the far away contributing population. And now, in these islands, the rules for survival are not the same. There are different competitors, or maybe none; perhaps no predators either. Distances are compressed, and yet over those distances: a great variety of suitable and unsuitable conditions. Natural selection—different environmental factors working on a skewed gene pool—leading each founding population slowly away from clear identity with that in the old homeland, enhancing characters that contribute to survival, dropping those that do not.

And what of the neighboring island? Another filter; another separating divide.

1 Arrival of Humans

Human contact, first by Polynesians and later by Europeans, has had a significant impact. Both the Polynesians and Europeans cleared native forests and introduced non-indigenous species for agriculture (or by accident), driving many endemic species to extinction. Fossil finds in caveAlternate meanings: Cave (disambiguation A cave is a natural underground void. Cave types and formation Caves are formed by geologic processes. These may involve a combination of chemical processes, tectonic forces and atmospheric influences. Primary caves, lava tubeLava tubes are natural conduits through which lava travels beneath the surface of a lava flow. They can be actively draining lava from a source, or can be extinct, meaning the lava flow has ceased and the rock has cooled and left a long, cave-like channels, and sand dunes have revealed an avifauna that once had an endemic eagleAquila ''Haliaeetus ''Pithecophaga ''Circaetus Scientists argue whether Accipitriformes are a separate order,or belong to the Falconiformes. Eagles are large birds of prey, which are found mainly in the Old World, with only two species ( Bald Eagle and Go, two raven-size crowSee text The true crows are in the genus Corvus they are large Passerine birds. As a group they show remarkable examples of intelligence; it would not be at all an exaggeration to characterize crows as being to birds what higher primates (including humanss, several bird-eating owlStrigidae Tytonidae An owl is any of some 200+ species of solitary nocturnal birds of prey in the order Strigiformes . Owls mostly hunt small mammals, insects, and other birds, though a few species specialize in hunting fish. They are found on all the Ears, and giant ducks known as moa-nalosMoa-nalos : Animalia : Chordata : Aves : Anseriformes : Anatidae Subfamily†: Anatinae Genera Chelychelynechen ''Thambetochen ''Ptaiochen † See also Diving duck, Dabbling duck The Moa-nalos are an extinct group of aberrant ducks that used to.

Today, many of the remaining endemic species of plants and animals in the Hawaiian Islands are considered endangered, and some critically so.