Heating up hotspots: Biodiversity restoration on New Zealand islands
About 40% of the indigenous avifauna of New Zealand is now extinct, prompting some to describe the country as a biological disaster. The distinctiveness of the remaining biota and threats from invasive species, have led to New Zealand being listed as a biodiversity hotspot. Conservation successes on island biodiversity hotspots are here reviewed. At least 60 islands have been cleared of 14 species of exotic mammals, increasing the area from 2162 ha naturally free of pests to over 30 000 ha in 2007. Three examples are used to illustrate the various goals for the islands. The first dual species eradication was of Pacific rats and rabbits from Korapuki Island (18 ha) in 1986-1987. The largest pest eradication campaign ever undertaken was the eradication of Norway rats from Campbell Island (11 300 ha)and the most controversial was the removal of Pacific rats from Little Barrier Island (3 083 ha). Numerous species of plants, invertebrates, reptiles, and birds have benefited from the eradications. Studies on small islands have revealed additional components of ecosystem recovery including reinvasion by seabirds and renewal of scale insect-honeydew-gecko interactions. Benefits of these restoration initiatives go beyond biodiversity to renewed nutrient cycling and changes to carbon sequestration. Challenges range from the pragmatic; such as how to measure the success of restoration projects, to the political; such as how to apply the benefits of ecosystem restoration on a large scale.