STOAT CONTROL
KILL TRAPPING (CURRENT BEST PRACTICE)
www.predatortraps.com CREATED: 27 April 2005
TECHNIQUE
Trap layout
 Trap lines should follow habitat perimeter, ridges, tracks, altitudinal contours and
waterways. Stoats will come to us.
 Broad-scale control, trap lines up to 1 km apart and trap stations placed between 100
and 200m (maximum) apart on the lines. A typical intensive trapping operation (Moehau
kiwi recovery zone) has traps spaced 100-180 metres apart. Trap spacing should be
established as precisely as possible measured on the ground (not GPS).
Trap lines will protect a strip approximately 400m either side of the line. Traps set 100200 m apart should ensure that female stoats are put at risk of being caught. While stoats
have large (49-256ha), often over-lapping home ranges, the core range is often quite
small.
 Localised control (patches of forest within pasture) of threatened species protection
requires an intensive trap layout: Set trap stations about 50 metres apart around the area
being protected.
There must be enough traps available to be confident a stoat will encounter a trap.
 A good track infrastructure is important, and each trap station numbered for ease of
relocation and data collection.
Reduces the risk of missing a trap during checking and allows capture data to be related
to each trap site.
Timing of operations
 Timing is critical and depends on the species being protected and the biology of stoats
and their prey at the site.
e.g. To protect kiwi chicks, control stoats for most of the year i.e., kiwi chicks are
vulnerable until they are >1000g
e.g. To protect kaka, control while the females are on the nest until the chicks fledge
e.g. Increased control and checking of traps will be required during stoat eruptions
Effective use of traps
Trap checking regimes need to consider:
 Trap occupancy rate (of both target and non-target species),
 Field life of the bait used.
Timing of inspection regimes vary from weekly (or more frequently) during high stoat and/or
rat numbers; to monthly in winters with low stoat numbers and when bait is not rotting.
Localised site protection inspections may need to take place on a more frequent basis (i.e.
daily).
EQUIPMENT
Trap type
Key elements are: catch effectively, kill humanely, easy to use and maintain, light weight,
portable and cheap.
 The DOC 150 and 200 is recommended.
This traps has passed the National Animal Welfare Advisory Committee (NAWAC)
guidelines for use as stoat kill traps.
Maintenance of traps
Traps
The DOC 200 traps are galvanised or made of stainless steel so does not require initial
treatment.
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Any coating applied to maintain traps should not repel stoats or attract non-targets, and be
user friendly. Examples of protective coatings are:
 Dipping the traps in melted preserving wax,
 Nothing (in dry conditions),
Traps in use
 Traps should be regularly cleaned with a wire brush.
Removes mould, fur and bits of dead animals and allows for identifying what has escaped
from an empty sprung trap.
 Un-sprung traps should be set off at 4-6 weekly intervals.
 A formalised maintenance regime is important. Traps should be regularly maintained,
including checking for worn pivots, weakened springs.
Tunnel/Cover
Kill traps must be set in a tunnel or under a cover. A tunnel has three functions: i) orientate
the animal relative to the trap, ii) protect the trap and iii) keep out non-target species. It must
have the following:
 Be made of solid material.
Kiwi can poke their beaks through tunnels made of wire mesh.
 Minimum of 600mm long. Where weka are present the tunnels need to be at least 950mm
long to prevent weka accessing the traps.
This provides space for two traps with double baffles on each end.
 Tunnel width must match the trap being used.
 Double baffles at each end.
Restrict kiwi beaks & other non-target species.
 Entry holes of 50mm x 50mm cut into baffles.
Allows stoats to enter but restricts non-targets. Correctly positioned, the holes help make
the animal step onto the trigger plate.
 Solid anchorable design.
Prevent traps being disturbed by pigs and possums.
 Removable roof.
Ease of access to check/set traps.
 Bait is secured between the traps.
Ensures bait doesn’t move or get removed.
Bait and lures
Key elements are: high palatability, a field life aligned with frequency of field checking, doesn’t
attract non-targets, easy to use and cheap.
 The most effective baits may differ with location and the natural diet of stoats in the
location.
Stoats are flexible and opportunist in their diet.
 Effective baits include rabbit and fresh, white, un-cracked hen eggs.
Fresh baits such as rabbit may be highly attractive to stoats but will need replacing at
frequent intervals.
Hen eggs are often the most practical bait because they are readily accessible, easy to
store and handle in the field, and can last up to one month in cool climates.
 Baits should be changed regularly (timing depends on environmental conditions) and
disposed of away from the trap.
SKILLS REQUIRED
 Managers need a good working knowledge of stoat ecology and the prey ecology to
manage operations effectively.
 Trappers should have a good working knowledge of stoat behaviour. Specific on job
training in the use of traps is essential.
 A consistently high standard of setting traps is essential – trappers must be dedicated to
the work.
 Trappers need sound bush navigational skills involving compass and map reading.
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STANDARDS
Animal Welfare Act 1999
 Under the Animal Welfare Act 1999, NAWAC developed draft guidelines for testing kill
traps. It is recommended that only traps that have passed NAWAC guidelines are used,
because other traps that have not passed may be prohibited or restricted.
SUSTAINING CONTROL OVER THE LONG TERM
 Monitoring conservation outcomes is helpful to judge effectiveness of the control
programme.
Control operations are useless unless outcomes are achieved.
 Achieving outcomes from predator control are long term and often control must take place
for 5 years+ to get results. Funding must be in place for long-term control.
Stoat populations are cyclic within and between years. This can result in years when
anticipated outcomes are not achieved.
 Baits may have to be alternated and/or combined over the duration of control programme.
Stoats are flexible and opportunist in their diet, so a change in abundance of their normal
prey can cause a rapid shift to alternative food resources.
 Good data collection helps operations to be more effective and efficient over the long
term. What is recorded depends on what the project wants to know. Typical questions
are: What trap sites catch most /least? How much trap effort is generally required to
achieve the outcome in this block?
 It is important to maximise trap efficiency by selecting the correct trap type, bait, layout,
seasonal timing, and length of operation.
LIMITATIONS
 There is no “window of opportunity” post control as stoat numbers quickly return to precontrol levels.
Stoat re-invasion is essentially constant and rapid making effective long term control
ongoing.
 Kill trapping for stoat control is labour intensive but sustainable and responsible.
INFORMATION
Recommended reading
 King, C. M. 1990. Stoat In C. M. King (Ed.) The Handbook of New Zealand Mammals, pp.
206-224-206. Oxford University Press, Auckland.
 King, C. M., Griffiths, K., Murphy, E. C. 2001. Advances in New Zealand mammalogy
1990-2000: Stoat and weasel. Journal of the Royal Society of New Zealand 31: 165-183.
 Department of Conservation 2002. What’s happening in stoat research? Fourth report on
the five-year stoat research programme. Department of Conservation, Wellington, New
Zealand.
REFERENCES (SOME REFERNECES OF INTEREST)
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Dilks, P. J.; O'Donnell, C. F. J.; Elliott, G. P.; and Phillipson, S. M. 1996. The effect of
bait type, tunnel design, and trap position on stoat control operations for conservation
management. New Zealand Journal of Zoology 23:295-306.
Rudolf, P. 2000. Mustelid control and research. in Shaw, P., editor. Northern Te
Urewera Ecosystem Restoration Project : Annual Report July 1998-June 1999. Dept.
of Conservation, Opotiki Area Office, Opotiki, N.Z.
King, C. M.; O'Donnell, C. F. J.; and Phillipson, S. M. 1994. Monitoring and control of
mustelids on conservation lands. Part 2. Field and workshop guide. Department of
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Conservation Technical Series 4, Department of Conservation, Wellington, New
Zealand.
Dilks, P.; Willans, M.; Pryde, M.; and Fraser, I. 2003. Large scale stoat control to
protect mohua (Mohoua ochrocephala) and kaka (Nestor meridionalis) in the Eglinton
Valley, Fiordland, New Zealand. New Zealand Journal of Ecology 27(1):1-10.
King, C. M. 1980. Field experiments on the trapping of stoats (Mustela erminea). New
Zealand Journal of Zoology 7:261-266.
Miller, C.; Elliot, M.; and Alterio, N. 2001. Home range of stoats (Mustela erminea) in
podocarp forest, south Westland, New Zealand: implications for a control strategy.
Wildlife Research 28:165-172.
King, C. M.; Griffiths, K.; and Murphy, E. C. 2001. Advances in New Zealand
mammalogy 1990-2000: Stoat and weasel. Journal of The Royal Society of New
Zealand 31(1):165-183.
Sim, J.; and Saunders, A., editors. 1997. National Predator Management Workshop
1997. Proceeding of a workshop held 21-24 April 1997, St Arnaud, Nelson Lakes.
Department of Conservation, Wellington.
Murphy, E. C.; Clapperton, B. K.; Bradfield, P. M. F.; and Speed, H. J. 1998. Effects
of rat poisoning operations on abundance and diet of mustelids in New Zealand
forests. New Zealand Journal of Zoology 25:315-328.
Saunders, A. 2000. A review of the Department of Conservation mainland Island
restoration projects and recommendations for further action. Department of
Conservation, Wellington.
Warburton, B. 2001. Traps and trap-testing. in Walker, A., editor. Proceedings of
Mainland Island Hui, Omapere 20-23 August 2001. Department of Conservation.
Thomas, M. D. 2001. Kill-traps for stoat (Mustela ermina) control. Research
Investigation No. 3412, Pest Control Research Ltd., Christchurch.
Department of Conservation. 2002. What's happening with stoat research? Fourth
report on the five-year stoat research programme. Department of Conservation,
Wellington.
www.predatrortraps.com created: 27 April 2005
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