When Admiral Roggeveen arrived, there were two main tribes on the island. The first was the Ha-nau-aa-epe, tall and white red haired people recognized by their long ears. The other tribe was the smaller built people of Ha-nau-mo-moko, well known for their short ears.
A conflict between the two tribes resulted in a massacre of the first tribe, leaving the island in a state of civil disorder. At least 21 species of trees and all species of land birds were extinct because of the overharvesting and overhunting. The island was largely deforested and it did not have any trees more than 10 feet tall.
No animals besides rats inhabited the island. Loss of large trees meant that residents lacked canoes, without which fishing was no longer an option. By the 18th century, residents of the island were largely sustained by farming with domestic chickens as the primary source of food.
The Easter Island had a vast number of seabird colonies containing over 30 resident species, perhaps the world's richest biological fund. Such colonies have all disappeared from the main island. Fossil evidence indicates that at least five species of landbirds (two rails, two parrots and a heron) have become extinct.
Also leading to the collapse of island society were some other human factors. In December 1862, Peruvian slave raiders struck the Easter Island for several months. Abductions were common and some sources claim that half of the island's population, more than 1500 people was captured.
When the slave raiders were forced to repatriate the people they had kidnapped, they also left carriers of smallpox causing an epidemic which killed large numbers of population. In conclusion, the Easter Islands are the real example of our dependence to the nature. Similar events that happened all those years ago are happening again in tropical rainforests. The changes to come are difficult to observe and forecast, but will surely affect the global climate and biodiversity.