New Zealand Journal of Zoology abstracts
Forest invertebrates found on baits used in pest mammal control and the impact
of sodium monofluoroacetate ("1080") on their numbers at Ohakune, North Island,
New Zealand
GREG SHERLEY*
MICHAEL WAKELIN
Science and Research Division,
Department of Conservation
P. O. Box 10420, Wellington
New Zealand
JAY MCCARTNEY
Freidrich Alexander Üniversität
Institut für Zoologie II
Staudt strasse 5
D-91058, Erlangen, Germany
*Present address: South Pacific Regional Environmental Programme, P.
O. Box 240, Apia, Samoa.
Abstract We listed all invertebrate taxa found in contact
with non-toxic carrot and pollard baits commonly used for poisoning pest
mammals with sodium monofluoroacetate ("1080") over two winters (1995 and 1996)
at 12 sites in mixed podocarp and hardwood forest near Ohakune, central North
Island, New Zealand. Invertebrates were found on 12% and 23% respectively of
the 11 000 carrot and 6000 pollard baits observed. The usage of baits
varied with time, peaking in October, and for pollard baits usage also varied
between sites. Of the 113 taxa identified, ten taxa contributed >=1% each of
the total number of invertebrates, and three made up 66% of the total. The
numbers of three of the four species most commonly found on baits did not
correlate with the numbers of those species caught in nearby pitfall traps. The
results suggest that at any time only a small proportion of baits have
invertebrates on them, and the few individuals per bait represent a small
section of the fauna present in the litter.
Observations of the impact of 1080 on invertebrates were made at the same
Ohakune site over two winters (1996 and 1997). Invertebrates were found on 43%
of over 22 000 toxic and non-toxic pollard baits examined. A total of 133
taxa was identified, of which only 13 taxa each comprised >1% each, and
three taxa together accounted for 67% of the total number of invertebrates
visiting baits. The proportion of baits with invertebrates on them, and the
number of invertebrates per available bait, were both significantly lower when
1080 was present in a bait. Recovery of invertebrate numbers started within six
days of toxic bait removal, but subsequent application of toxic baits further
reduced the number of invertebrates observed. We did not determine whether the
reductions in invertebrate numbers were due to poisoning or aversion to 1080.
There was no reduction in invertebrate numbers on non-toxic baits placed at
20 cm or more from a toxic bait.
These results are relevant to assessments of the risk to non-target species
from primary and secondary poisoning while controlling pest mammals by aerially
broadcasting baits laced with 1080.
Keywords Sodium monofluoroacetate; 1080; pest management;
poisoning; baits; non-target species; forest invertebrates; risk assessment
Z98034/35
Received 16 September 1998; accepted 31 May 1999
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