1080-baits for fox control: Is everything all that it seems?
Authors: Twigg Laurie E 
Published: May 2016

The Red Fox (Vulpes vulpes), wild
Dog (Canis lupus familiaris), Rabbit
(Oryctolagus cuniculus), and feral Pig
(Sus scrofa) can have a significant and
profound impact on biodiversity and/
or agricultural production in Australia
(Saunders et al. 1995; Williams et al.
1995; Choquenot et al. 1996; Fleming
et al. 2001). Baiting programmes with
1080 (sodium fluoroacetate) form an
integral and, in some cases, the only
means by which the impacts of these
invasive species can be managed over
a large-scale (Saunders et al. 1995;
Williams et al. 1995; Choquenot et al.
1996; Fleming et al. 2001). However,
in recent times, there has been
growing concern among some
Australian rural communities that
some 1080 products are not as
effective as they once were,
particularly those used for baiting
foxes. Although such reports are often
anecdotal, their increasing frequency
is of concern. Recently, the Malleefowl
Preservation Group in Western
Australia conducted a semi-formal
survey of their Newsletter readers
regarding the effectiveness of 1080
products against Foxes, wild Dogs,
and Rabbits. Over 40 responses were
received from 15 different postcode
regions with up to 50% of these
respondents believing some 1080
products were no longer effective
(Malleefowl Preservation Group
unpublished data). Similarly, participants
in coordinated community
1080-baiting programmes in Victoria
surveyed during 2004/05 suggested
that poor bait take, loss of efficacy,
risk to farm dogs, and the high
associated costs were the main
reasons for less than ideal control
programmes (McPhee 2005). This
suggests that questions regarding the
effectiveness of 1080 products are not
unique to Western Australia. More
recently, in NSW, the effectiveness of
some 1080-baiting programmes was
shown to be less than ideal, even
when a coordinated approach was
used (Gentle 2007a; Bengsen In
Press). In one instance, such a
programme with 3 mg 1080 baits
reduced fox abundance by only 30%
(Bengsen In Press).
There are a number of reasons why
baiting programmes may have, or are
perceived to have failed (see below),
including the loss of effectiveness of
the active ingredient against the target
species. With respect to foxes, the only
assessment of their sensitivity to 1080
was a provisional study undertaken in
the late 1980s when the sensitivity to
1080 of 11 foxes was determined: 3
from the Australian Capital Territory
(ACT) and 8 from Western Australia
(WA) (McIlroy and King 1990). The
provisional nature of this study
precluded a detailed estimate of the
sensitivity of these foxes to 1080.
Moreover, it is also possible, and
probably highly likely, that the
sensitivity of Australian foxes to 1080
has changed since the assessment
undertaken in the 1980s.
This Forum Essay raises some of the
possible reasons for any decreased
baiting effectiveness, particularly the
impact of any decrease in the
sensitivity of foxes to 1080. The
original data of McIlroy and King
(1990) are reworked so as to gain
estimates of the Lethal Dose 50 and
Lethal Dose 99 values and their
associated 95% Confidence Limits.
The implications of these findings for
pest management and conservation
programmes, and some suggestions
for future research, are also discussed.