Diminishing endemics at Chatham Islands and possible preservation

[First paragraph(s)...]
Chatham Islands were rich in endemic species when discovered in 1791. Centuries of Moriori habitation had no serious effect on plant and bird population.
New ecological factors, the axe and livestock, introduced by European settlers ,subsequent to 1840 to commence the farming era, took heavy toll of vegetation Animal existence depended largely on native plants and the most palatable ones probably suffered most while others were destroyed or damaged by trampling. The importation of rabbits and hares was prohibited but similar wisdom was not shown regarding opossums.
Although most of the land is cleared now, numerous good-sized patches of bush still exist on many parts of the islands.