New Zealand Journal of Zoology abstracts
Trap catch as a relative index of ferret (Mustela furo) abundance in a
New Zealand pastoral habitat
M. CROSS*
A. SMALE
S. BETTANY
M. NUMATA
D. NELSON
R. KEEDWELL
J. RAGG
Department of Zoology
University of Otago
P.O. Box 56
Dunedin, New Zealand
*Present address: C/- Animal Nutrition Unit, AgResearch Invermay, Mosgiel, New
Zealand. Email: crossm@agresearch.cri.nz
Abstract The density of a ferret population in South Island
pastoral farmland was estimated by live capture, mark and release, and by
removal trapping, during March and April 1997. An estimate of 6.3 ferrets per
km
2 (5.5-8.4, 95% CI) was obtained after 8 days of mark and release,
whereas 10 days of removal trapping provided an estimate of 5.3 ferrets per
km
2 (5.3-5.9, 95% CI). There was significant variation in individual
trappability. Proportionally more unmarked ferrets were captured as population
density was reduced during removal trapping. Four person-days effort were
required to remove 50% of the ferret population from an area of 1254 ha,
while removal of 80 or 95% of the population took considerably greater effort.
Trapping provided a reliable relative index of ferret abundance. While there is
a need to replicate this study in order to confirm its validity, it confirms
the use of a relative index as a valuable tool for measuring the efficacy of
control operations and estimating ferret abundance.
Keywords Mustela furo; ferret; bovine tuberculosis;
abundance estimates; removal trapping; mark and release; relative index
Received 4 August 1997; accepted 30 September 1997
PDF file of entire paper: medium quality (598K); (scanned from paper original: notes about this process)
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