New Zealand Journal of Zoology abstracts
Comparison of the capture efficiency of a kill-trap set for brushtail possums
that excludes ground-birds, and ground set leg-hold traps
G. A. MORRISS
B. WARBURTON
W. A. RUSCOE
Landcare Research
P.O. Box 69
Lincoln, New Zealand
email: MorrissG@landcare.cri.nz
Abstract Ground-set leg-hold traps are commonly used in New
Zealand to catch possums (
Trichosurus vulpecula), both for control, and
to monitor success of control operations. These sets have occasionally caught
kiwi (
Apteryx spp.) and weka (
Gallirallus australis), so the
Department of Conservation now requires that all traps set on conservation land
be placed 70 cm above the ground in areas inhabited by these species. To
set leg-hold traps at this height requires the use of platforms or boards,
which reduce trapper efficiency, and longer trap chains, which increase the
chance of the captured possums injuring themselves. An alternative approach,
which has the potential to improve trapper efficiency and address the animal
welfare concerns, is to use kill traps set at least 70 cm above the
ground. Tree-trunk-set kill traps (BMI 160) were compared with ground-set
Victor No 1 unpadded leg-hold traps. In the first two trials, BMI traps set
with plastic cubbies (161 possums/432 trap nights) recorded capture
efficiencies significantly less than those achieved using the Victor traps (215
possums/432 trap nights). In trials with more rigid wooden cubbies, the capture
efficiency of BMI (218 possums/480 trap nights) and Victor traps (224
possums/480 trap nights) were not significantly different. Of the 379 possums
caught in the BMI traps, 367 (97%) were struck in the head or neck (the desired
target location for a humane kill), and 98% were killed. Results from these
trials indicate that if BMI traps are left for three or more nights between
checks, their capture efficiency will be greater than that achieved for Victor
leg-hold traps that must be checked every day. We conclude that there are kill
traps that can be used effectively for killing possums, which eliminate the
risk of traps to ground-dwelling birds, and will thus help reduce our reliance
on the use of leg-hold traps.
Keywords Trichosurus vulpecula; leg-hold traps; BMI
kill traps; non-target species
Z99040
Received 27 September 1999; accepted 4 April 2000
PDF file of entire paper: medium quality (936K); (scanned from paper original: notes about this process)
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