PATTERNS OF LOSS ACROSS ISLAND TAXA 307Extinctions of island vertebrates since AD 1600
have affected all the major oceans, but have been
particularly concentrated in three nuclei: the
Mascarenes in the Indian Ocean, the Caribbean
arch (the Antilles), in the Atlantic Ocean, and
Polynesia (Table 11.6). The lack of extinctions of
mammals from some remote islands (e.g. Hawaii,
St Helena) is simply a reflection of the failure of ter-
restrial mammals to colonize them in the first place.
Pacific Ocean birds and the Easter Island enigma
Birds are typically the most species-rich vertebrates
on remote islands. They leave good fossil or sub-
fossil evidence, and have been relatively well stud-
ied, often from sites associated with human
settlement (i.e. middens). The picture that has
emerged of their demise in prehistoric times can
thus be more closely related to human activities
than is the case for any other taxon—and the
oceanic region where the most dramatic and con-
vincing evidence of human involvement has been
found is the Pacific. Not only has the Pacific lost
large numbers of bird species in the past, but today
it holds more threatened bird species than any
other oceanic region: approximately 110 species, of
which 31 are classified as endangered and 29
vulnerable (the two highest Red Data Bookcate-
gories; Johnson and Stattersfield 1990).
It is believed that the Australian and New Guinea
land masses on the Sahul shelf were colonized by
people at least 50 000 and 40 000BPrespectively.
Voyagers reached New Ireland and the Solomons
by 29 000BP, but then paused for over
25 000 years—islands beyond this zone quite possi-
bly were undetectable to these people (Keast and
Miller 1996). Then the ancestors of the Polynesians
became the first wave of human colonists to spread
across the Pacific, and they did so very rapidly,
between about 1200BC andAD1200 (Diamond
2005). So extensive were their explorations that
nearly all islands in Oceania (Melanesia,
Micronesia, and Polynesia) were inhabited by
humans within the prehistoric period (Fig. 11.4;
Pimmet al. 1995; Steadman 1997a). The human
colonists cleared forests, cultivated crops, and
raised domesticated animals. Birds provided
sources of fat, protein, bones, and feathers for peo-
ple and so were hunted as well as being indirectly
affected by the changes that followed human
arrival. European exploration began in the six-
teenth century, but their phase of colonization
started much later, such that, for instance, the first
missionaries arrived in Hawaii in AD1779 and in
Tahiti in AD1795 (Pimm et al. 1995).
In the Hawaiian islands, at least 62 endemic
species of birds have gone extinct since Polynesian
colonization began some 1600 yearsBP, and most of
these were lost before European contact began
(Steadman 1997a). The processes involved are man-
ifold, including habitat alteration, hunting, dis-
eases, and exotic species. The commensals
introduced by the Polynesians, especially the Maori
rat (Rattus exulans) and the feral pig (Sus scofra),
have been supplemented since European arrival by
many other exotic species, which have had a pow-
erful impact on the native biota, including black
rats, feral dogs, cats, sheep, horses, cattle, goats,
mongooses, and an estimated 3200 arthropod
species (Primack 1993). The extinctions have
included flightless geese, ducks, ibises, and rails,
and the major part of the radiation of Hawaiian
honeycreepers (Olson and James 1982, 1991; JamesTable 11.6Islands or archipelagoes that have lost at least five
terrestrial vertebrate species after AD1600 as a result of
anthropogenic activities (Source: Groombridge and Jenkins 2002)
Island or
archipelago Mammals Birds Reptiles Total
Hawaii 0 21 0 21
Mauritius 1 10 5 16
New Zealand 1 13 1 15
Hispaniola 11 1 0 12
Rodrigues 0 8 3 11
Réunion 1 7 2 10
Cuba 8 1 0 9
St Helena 0 7 0 7
Society Islands 0 6 0 6
Cayman 5 1 0 6
Jamaica 2 2 1 5
Madagascar 4 1 0 5
Martinique 1 2 2 5
Total 34 80 14 128