dominated by forest species. The high rate of
extinction in the avifauna prior to European settle-
ment must have been related to the characteristics
of the forest areas removed by the Polynesians:
these being shown by palaeoecological data to have
been mainly the drier, eastern forests, or those
inland areas where drought or severe climate
restricted regeneration after clearance. In pre-human
times, it was the drier, more structurally diverse
forests on more fertile soils which supported the
greatest diversities of New Zealand’s birds.
Pacific seabird populations have also suffered, as
Steadman (1997a) points out; petrels and shearwa-
ters have seen the greatest loss of species, and many
other seabird species have had their distribution
and population sizes diminished, including alba-
trosses, storm-petrels, frigatebirds, and boobies.
Abbott’s booby (Papasula abbotti) is a classic exam-
ple: once widespread in the South Pacific, it now
breeds only on Christmas Island in the eastern
Indian Ocean.
Easter Island (27 9 S, 109 26 W) was, until the
colonization of Tristan da Cunha, just two centuries
ago, the most isolated piece of inhabited land in the
world. When first contacted by Europeans on
Easter Day AD1722, it presented a fascinating
enigma: how could this impoverished treeless
island, with its impoverished people, have
supported the construction of the remarkable giant
statues (moai), and how and why had it all gone
wrong? The flora of Easter Island consists today of
over 200 vascular species, of which only 46 are
native. However, formerly the flora was richer, con-
taining several native tree and shrub species.
Evidence for a forest cover is provided not just by
pollen records, and by the discovery of palm nuts,
but also by the discovery of extinct endemic
achatinellid land snails, and by the identification to
species or genus of over 2000 fragments of charcoal
(Diamond 2005). The forests are now known to
have contained a giant palm tree (Paschalococos dis-
perta) and a number of other trees (e.g. Sophora
toromiro), some reaching over 30 m in height.
Palynological studies by Flenley and colleagues
demonstrate that the forests of Easter Island per-
sisted for at least 33 000 years (as far back as the
record goes), during the major climatic shifts of the
late Pleistocene and early Holocene. We can thus be
clear that deforestation by humans was responsible
for the treeless state of the island (Flenley et al. 1991;
Bahn and Flenley 1992; Diamond 2005).
Dated archaeological evidence indicates that
Easter Island was settled by the Polynesians from
the Marquesas or Gambier archipelagos (Oliver
2003) some time between AD300 and AD900, with
the more recent date preferred by Diamond (2005)
as the most reliable earliest date of occupation. Their
effect on the forest was soon detectable in the pollen
record (Bahn and Flenley 1992) and it was entirely
eliminated some time between the early 1400s and
the 1600sAD(Diamond 2005). The human popula-
tion reached its peak of about 10 000 (or possibly as
high as 15 000) around AD1600, but subsequently
collapsed along with the megalithic culture that had
sustained the quarrying, sculpting, transport, and
erection of the moai. Figure 11.5 sets out a model of
the sequence of events which may have led to this
collapse, within which a pattern of overpopulation
and continuing overexploitation and thus resource
depletion was central. This depletion involved not
just the loss of a forest cover, but through it the loss
of the raw materials (large trees in particular)
needed to make ocean-going canoes, further dimin-
ishing resource availability. The pattern of decline
may have also been influenced by the introduction
of rats by the Polynesians, which could have had a
key role in limiting tree recruitment (Fig 11.5). The
loss of trees and other plant species is matched by a
more complete loss of native birds than on any com-
parable island in Oceania (Steadman 1997a).
Examination of bird bones associated with artefacts
600–900 years old has revealed that Easter Island
once had at least 25 species of nesting seabirds, only
7 of which now occur on one or two offshore islets,
and just one of which still nests on the main island.
Native land birds are known to have included a
heron, two rails, two parrots, and an owl. None
survive.
The Easter Island story holds some interesting
twists and turns that remain the subject of some
debate amongst archaeologists. When the Dutch
captain Jacob Roggeveen and his three vessels
arrived in AD1772, the overthrow of the statue-
building culture and its chiefs and priests had310 ANTHROPOGENIC LOSSES AND THREATS TO ISLAND ECOSYSTEMS