The environmental wonder boy and mischief maker Jared Diamond, author of The Third Chimpanzee, 'Guns Germs and Steel' and 'Collapse: How societies choose to fail or survive' etc, books that caught the imagination of the Progressives and the Green Blob, turning them into best sellers, also managed to cause a lot of angst amongst a lot of people and various attempts have been made by historical based researchers to refute what he said – that the people of Easter Island soiled their own nest. Apparently, he also thought Montana was a basket case – cattle ranching country, and even that Viking settlement of Greenland was due to human mismanagement rather than the collapse of the Medieval Warm Period and the swallowing up of their farms by an increasing encroachment by the ice sheet. The theory was deliberately provocative as their is no evidence the Polynesians of Easter Island were responsible for their decline – or the Vikings for their abandonment of Greenland (or the cowboys of Montana for the praire range devoted to beef cattle rather than wild buffalo herds). Besides, if they had over populated the island they would simply have got in their boats and moved somewhere else. After all, that is how they got to Easter Island.
It was pointed out rats could have killed ground nesting birds on Easter Island, stowing away on boats and multiplying in what was a virgin territory with little competition. Others simply pointed to the arrival of Europeans in the 18th century, bringing with them diseases the Polynesians had no resistance to, or by exploiting them by shipping them to other islands to work as slave labour on plantations. One could easily envisage a drastic fall in population numbers in the circumstances, although in the early 20th century the thinking was that islanders had been fighting amongst themselves in competition for resources. This may even have fueled the manpower involved in transferring people to other islands to work on those plantations mentioned previously.
At http://phys.org/print379329684.html … some researchers have taken the view there might be some truth in all the theories and have set out to see what role weather played (as anything to do with climate is sure to attract funds). It turns out that Easter Island has a cycle of alternating wet and dry periods. Sometimes one part of the island is wetter than the other giving some of the inhabitants an advantage. This is all to do with the track of the tropical rain belt, a well known phenomenon that is known to affect the Galapagos Islands off South America, and certain South American societies (as well as lands in the Old World too). We are told these drought episodes challenge 'collapse' theories, a direct reference to the environmentalist clique. See als0o www.eurekalert.org/pub_releases/2016-04/f-wrh040716.php