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Resurrecting island ghosts
Island habitats have endured rampant extinctions at the hands of humans during the past
few hundred years. Their unique arrays of flora and fauna evolved in isolation from mainland
populations, and as a result predators were rare or absent. When people arrived on islands,
they were confronted by a range of naive animals, unused to fight or flight, which were easy
prey and soon extinguished. Essential ecological services were lost with them, but islands
remained haunted by their ghosts: trees with elaborate herbivore defences and seeds that are
too big to be dispersed, and flowers with no pollinators (Bond et  al. 2004, Nicholls 2006,
Hansen and Galetti 2009). Being particularly hard hit by megafaunal extinctions in the recent
past, islands deserve special attention when it comes to re-wilding, and ecologists are now
grappling with the problem of how to restore ecological functions that depend on extinct spe-
cies (Hansen 2010, Kaiser-Bunbury et al. 2010).
Oceanic islands are home to an array of unique species, isolated from their mainland rela-
tives, they have evolved distinct traits and adaptations. Islands are particularly vulnerable to
anthropogenic degradation; deforestation and loss of species have commonly followed the
arrival of people. Naïve animals, unused to predators are easily hunted to extinction, while
introductions such as rats and domestic cats have had devastating consequences. Despite
these challenges, island restoration is an important conservation focus, because island
endemic species are irreplaceable and represent unique evolutionary and ecological poten-
tial. Although islands are vulnerable ecosystems, their isolation also makes them more amen-
able to risky reintroduction experiments; often with a simplified flora and fauna, the effects of
reintroductions can be more easily monitored and rectified, if need be (Kaiser-Bunbury et al.
2010). Island taxa tend to be smaller than their mainland counterparts, facilitating transport
and logistics (Hansen 2010). Furthermore, because many island extinctions occurred rela-
tively recently and were caused by humans, it is likely that suitable environmental and cli-
matic conditions still prevail, and there is much to be gained from restoring lost evolutionary
linkages.
On the island of Kaua'i, Hawaii, interdisciplinary projects combining insights from palaeo-
ecology, ethnography, historical ecology, palaeontology, and archaeology are informing
ambitious restoration and re-wilding projects that are not only ecologically intelligent but
also culturally sensitive and economically viable. Colonized by people over 1,000 years ago,
Kaua'i has suffered an extinction crisis of catastrophic proportions, caused by the introduc-
tion of alien species, over-harvesting of edible animals and birds, and vegetation clearance
for agriculture and intensive plantations of sugar cane and other cash crops. Though natural
variations in climate may have exacerbated some of these effects, the impacts are overwhelm-
ingly anthropogenic. Waves of extinction of flightless birds, land snails, finches, and various
plants coincided with Polynesian and European arrival, and continue to the present (Burney
et al. 2001, Athens et al. 2002, Burney and Burney 2003, 2007).
On Kaua'i, today's fragmented and impoverished landscapes do not provide a realistic eco-
logical template for restoration, and the palaeoecological record has provided insights for re-
wilding projects that are based on past, natural distributions, and which restore genetic
 
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