The others most likely disappeared due to habitat loss. The Polynesians cleared most of the lowland dry forests on the islands they inhabited, so any birds living in these areas either adapted and moved somewhere else or died off along with many plants and invertebrates that we will never know about (Wilcove 1999).
While the Polynesians did have a significant impact on Hawaii's wildlife, the Europeans that colonized the islands began changing the face of Hawaii at a much more rapid pace, starting with Cook. He introduced three goats to one island when he first visited, and from then on the scale of the invasion kept increasing. Before 1820 Europeans had introduced cattle, sheep, horses, donkeys, turkeys, and cats. Eventually, exotic wild animals such as mouflon sheep, axis deer, mule deer, and pronghorn were all introduced so the new colonists could have large mammals to hunt. Exotic birds were also introduced from around the world to replace the many native species that were being wiped out. One ornithologist estimates that at least 170 alien bird species from all over the world were introduced to the islands (Wilcove 1999). Most did not form stable populations and died off, but some became naturalized. These previous examples have only highlighted the intentional introductions by Europeans. Many smaller organisms hitched rides on the ships and planes going to Hawaii, including centipedes, cockroaches, scorpions, and most disastrously of all, mosquitoes and ants (Wilcove 1999). Exotic plants also came in great numbers with Europeans. Many were easily able to replace native species, and today almost half of the free-living flowering plant species in Hawaii are non-native (Wilson 2002). The leis involved in the famous custom of placing flowers around tourist's necks are the flowers of a foreign plant species (Royte 1995), a sad symbol of Hawaii's current plight. .
The alien organisms mentioned above had a wide range of negative effects on native wildlife.
