Although the Galapagos remained untouched by man until fairly recently, the effects of man’s short presence in the islands have been disastrous upon their fragile ecosystem. First, the pirates of the seventeenth and eighteenth centuries, and then the whalers and sealers of the nineteenth, carried off hundreds of thousands of giant tortoises to store as a source of fresh meat aboard ship. At the same time they introduced various types of mammals that established themselves on a number of islands. Some, such as rats, disembarked involuntarily from the sailing ships, while others, like goats, were intentionally set free in order to provide these early sailors with meat.
In 1832 the islands were claimed by Ecuador, and with their annexation came the first permanent settlers. It was only natural that these colonists, as well as later settlers, would bring with them a thorough stock of domestic animals, as well as many other living organisms that they transported unknowingly. As a result, the majority of the islands today carry an assortment of these relics, including cattle, horses, donkeys, pigs, goats, dogs, cats, rats, mice, and many introduced insects and plants. In many places these have caused severe damage to the native flora and fauna. Most gravely affected by predation from pigs and dogs were the tortoises, land iguanas, and dark-rumped (or Hawaiian) petrels. Unable to resist pressure from the introduced black rats, four out of six species of endemic rice rats have become extinct. Also, on a number of islands goats and other herbivores have seriously altered the native vegetation. Among the major islands only Tower and Fernandina have completely escaped such introductions so far.
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