Galápagos, the Canaries, and the Bahamas.
Similarly, many other problems, such as feral ani-
mals, habitat loss, and burning, are common to
numerous islands (e.g. Cronk 1989; Vitousek et al.
1995; Rodríguez-Estrella et al. 1996). Thus, although
solutions have to be tailored to the particular cir-
cumstances of each island system, field managers
and conservationists often face the same problems.
There are thus still many benefits to be gained sim-
ply from improved information exchange between
those involved in conservation management on
islands (Adsersen 1995, Campbell and Donlan
2005).
The large catalogue of extinctions of native island
species is bound to increase. What can be done to
stem the tide? If we cannot save the remaining evo-
lutionary wonders of the showcase islands such as
Galápagos and Hawaii—and the signs are not
hugely encouraging—then the prospect for many
other less totemic islands and island endemics must
be dismal indeed. Yet, it is not a hopeless task.
Species can be saved by means of rigorous habitat
protection, pest or predator control, and transloca-
tion of endangered island species (Franklin and
Steadman 1991, Marrero-Gómezet al. 2003), given
adequate political and financial support.
Biological control—a dangerous weapon?
Biological control is the term given to pest control
not by means of chemical agents but by the intro-
duction of a species that targets the pest organism
without seriously affecting non-target species.
Cronk and Fuller (1995) state that it is the long-term
goal of conservation managers in Hawaii to achieve
the biological control of most of the introduced
weeds, but as yet only 21 are controlled biologically.
Although in many cases biological control is the
only practical approach, there are associated risks
(above; Williamson 1996). A classic example in ear-
lier times was the introduction of the mongoose as
a pest-control agent. The mongoose has shown lim-
ited success in controlling rats but has been
extremely effective in devastating many native
island bird and reptile species, particularly ground-
foraging skinks and snakes (Case et al. 1992). So, it
is vital that biological control programmes begin
with rigorous screening and testing to ensure that
the control agent’s effects are highly specific to the
target species (e.g. Causton 2005).Translocation and release programmes
Translocation and repatriation from ex situbreeding
and rearing programmes have been used as meas-
ures to rescue highly threatened species on islands,
with some success. Translocation is used to remove
a species from an overwhelming local threat or to
re-establish a population on an offshore island
where it may be safe from exotic predators. In gen-
eral, translocated wild animals have been found to
establish more successfully than captive-bred ani-
mals. Griffith et al. (1989) surveyed translocation
programmes undertaken in Australia, Canada,
Hawaii, mainland USA, and New Zealand over the
period 1973–86. They found that only about 46% of
release programmes of threatened/endangered
species were successful, a far lower percentage than
for translocations of native game species, for which
the success rate was 86%. They attempted to iden-
tify the factors influencing success for 198 bird and
mammal translocations from within their survey.
The single most important factor was the number
of animals released. They also found that herbi-
vores were significantly more likely to be success-
fully translocated than carnivores or omnivores,
that it was better to put an animal back into the cen-
tre of its historical range than the periphery, and
that wild-caught animals fared better than captive-
reared animals.
In New Zealand, a number of threatened bird
species have been translocated into small offshore
islands that either lacked or have been cleared of
introduced predators, such as the ship rat (Rattus
rattus), which are prevalent on the mainland
(Lovegrove 1996). By this means the extinction of
several species, including the South Island saddle-
back (Philesturnus carunculatus), have been averted.
The kakapo (Strigops habroptilus), a flightless, noc-
turnal parrot, was once considered to be effectively
extinct, until the discovery of a small population on
Stewart Island (Clout and Craig 1995). They contin-
ued to decline following rediscovery, to fewer than
50 individuals, as a result principally of predationSOME CONSERVATION RESPONSES 331