Human Impact
Starting around 2,000 years ago, the natural process of island colonization and evolution went through a radical change. Humans added themselves to the ecosystem and artificially altered the environment in numerous ways. Fields were cleared for living space and cultivation. Birds were hunted for food and feathers, until many of the species (especially those that were flightless) became extinct. In the great chain of life, the elimination of one species often has an effect on many others as the balance of nature is changed and readjusted. Some species become more dominant, while others may be wiped out.
FAST FACT
There is a popular opinion that human beings have been the major cause of disruptions in the natural environment only in the last few centuries of industrialization. In fact, this is not so. Human cultures have been exploiting and damaging their world for thousands of years. In New Zealand, for example, humans hunted a large ostrich-like bird, known as a moa, to extinction. Some scientists believe that humans may have even been partially responsible for the demise of many of the large prehistoric creatures (mammoths, for example).
Along for the Ride
Along with altering the landscape, the early Hawaiians also intentionally introduced a lot of plants and even a few animals. The early Polynesian colonists are believed to have brought about two dozen plants with them on their journey to the islands. These are often referred to as “canoe plants” and include edible species such as bananas, sugarcane, taro, breadfruit, and yams, along with utilitarian plants such as bamboo and the paper mulberry. With the unnatural advantage provided by their human attendants, these plants could easily overwhelm some of the more vulnerable native species.
The colonists also brought pigs, dogs, and chickens. Another creature probably arrived as a stowaway: the Polynesian rat, which is found throughout the Pacific.
More Drastic Changes
The impact that the Polynesian colonists had on Hawaii's ecosystems was relatively small in comparison to what happened after Captain Cook discovered the islands in 1778. It was as if a biological floodgate had been opened. Cattle, horses, donkeys, and goats were introduced and lots of insects, birds, and even amphibians appeared. Within decades, large parts of the islands had permanently changed, and not necessarily for the better. A number of both plant and animal species went extinct.
The trees and shrubs that were introduced had an especially transformative effect. Species such as eucalyptus, ironwood, and banyan can easily take over an area. Take the mesquite, or kiawe, as an example. This prolific shrub produces sweet seed pods that are a favorite with donkeys. As the donkeys' dung is deposited in the cracks torn in the lava with their hooves, the kiawe sprouts like a weed. In Hawaii, the kiawe is considered a bit of a menace. It can lead to the destruction of archaeological sites in coastal areas and has hindered access to some beaches.
While the early Hawaiians planted their canoe crops and cultivated their fields of taro and other staples, the Europeans that followed Captain Cook built big cattle ranches and plantations to grow and export such popular treats as sugar and pineapples. Add the whalers, military bases, the hotel industry, and here we are today!
