Environmental Engineering Reference
In-Depth Information
2003), and so this risk should at least not get any larger. Illegal importation into the
pet trade and smuggling of wildlife and plants remains a concern.
h e good news is that on islands managers have aimed higher, although largely
for vertebrate pests and mostly for mammals. Rodent and ungulate eradication is
becoming routine and is being planned for increasingly larger areas. h is is import-
ant if eradication is to make a substantial contribution to the conservation of native
biota and ecosystems. New Zealand is often regarded as a testing ground for eradi-
cation but despite its successes only 0.008% of the total land area of its 710 islands
have never had exotic mammals (the main animal threat) and only 0.15% of the
area has been rendered free of exotic mammals by eradication (Parkes and Murphy
2003). Eradication is thus a vital pest management strategy, but insu cient by
itself. It must be planned along with border biosecurity and sustained control.
Prevention of reinvasion of areas that have been cleared of invasive plants or ani-
mals is, of course, also vitally important.
Further good news is that there is substantial research to develop new control
techniques or to modify older techniques, often developed for sustained control
strategies to suit eradication aims. As examples, species-selective toxins or con-
trol devices (e.g. Marks 2001) may allow pests to be targeted without the expense
of managing non-target animals at risk to the broad spectrum toxins now used.
Modern genetic tools allow better understanding of the source-sink dynamics
of populations (e.g. Robertson and Gemmell 2004), and can identify and man-
age reinvasion risks and pathways (Abdelkrim
et al
. 2007). Finally, the wheel has
turned full circle and the ability to achieve 100% population reductions learnt
on islands are being applied to mainland problems, either to achieve eradication
(Parkes and Murphy 2003) or to reduce sustained control intervention frequencies
by limiting rates of recovery of pest populations (Morgan
et al
. 2006).
We thank D. Morgan and P. Cowan for comments on drafts of this chapter, and
J. Hone and M. Bomford for earlier discussions on the essential conditions for past
eradication.
