Environmental Engineering Reference
In-Depth Information
(Rainbolt and Coblentz 1997). If resources are not limited, the upper boundary
for a decision on feasibility would be where eradication was no longer the most
cost-eff ective option. h e assessment of eradication feasibility cannot be divorced
from the hazard posed by the pest, with more eff ort being justifi ed by pests with
greater threats (Panetta and Timmins 2004).
A key lesson learnt in feasibility planning since 2001 is that it is an essential part
of eradication but cannot be produced as a mere recipe because every case has a
unique mix of issues that have to be considered and managed (Towns and Broome
2003).
Assuming the feasibility plan is accepted and the operation funded, the next
phase requires a detailed operational plan to describe when, how, and who will
conduct the eradication operations, and include how the outcomes and conse-
quences of the attempt will be measured (e.g. Cromarty
et al
. 2002). h is entire
planning process is critical if the inevitable failures when aiming higher are not
to prove fatal to ongoing eradication attempts. Just as important are funded
and planned reviews of progress towards eradication, especially for weeds where
projects commonly extend over many years (Mack and Lonsdale 2002) and for
animals where eradication is achieved by successive culling events. Such reviews
are necessary to determine whether or not the project is on track, or if it is likely to
become a
de facto
sustained control project (Bomford and O'Brien 1995; Panetta
and Lawes 2007).
Eradication of some alien terrestrial vertebrates from islands was a well-established
practice before 2001. For example, there were 282 successful eradications (and
25 failures) of rodents reported between 1951 and 2000, and 66 successes (and
nine failures) reported since 2001 (Howald
et al
. 2007). The failure rate has not
changed (r
2
0.46) but the size of islands on which rodent eradication
has been achieved has increased (Table 4.1). Reviews of other vertebrate eradica-
tions have been published for feral goats (Campbell and Donlan 2005) and feral
cats (Nogales
et al
. 2004) (Table 4.1).
Other terrestrial vertebrate species that have been routinely eradicated before and
after 2001 include feral pigs (
Sus scrofa
) from at least 20 islands with the largest being
Santiago, Galapagos (58,465 ha) in 2000 (Cruz
et al
. 2005); rabbits (
Oryctolagus
cuniculus
) from at least 20 islands with the largest being St Paul, Kerguelens at
800 ha in 1996 (Lorvelec and Pascal 2005); brushtail possums (
Trichosurus
vulpecula
, Fig. 4.1) from 16 islands in New Zealand with the largest being Kapiti
at 1970 ha (Cowan 2005); and red (
Vulpes vulpes
) and arctic foxes (
Alopex lagopus
)
from 39 Aleutian islands including 93,000 ha Attu Island (Ebbert 2000) and red
foxes from many smaller islands in Western Australia (Burbidge and Morris 2002)
mostly before 2001. Less routinely, several other vertebrate species occurring on
many islands have been eradicated from only a few—sometimes because no one has
=
0.54, P
=
