Predator Control

TRAP SITE SELECTION

Landscape level
Should reflect the distribution of the species you are looking to protect e.g. pateke vs
kiwi
Trapping densities typically have been 1 trap to 10 ha for mustelids, but varies with
habitat contours, e.g. could be lower density (1/15 -1/20 ha) in areas with large areas
of grassland where trapping unproductive, or could be higher density in areas with
continuous forest or mosaic habitat where there are many contours that mustelids
could be active along.
Local level
Select sites where predators are likely to hunt, ideally where two of the below lineal feature meet i.e.
stream edges (good for mustelids),
bushland edge,
fencelines,
animal runs,
crossings over water courses,
fallen trees,
ridges (mainly for cats), etc especially saddles
along tracks/roads
warm sunny sites for cats
Best sites are where there are converging features like a stream crossing a track at
the edge of bush.
A change in features is also a good site – eg pasture:bush interface
Select sites that are beneath canopy cover where possible (mustelids especially are
likely to be less concerned about overhead predators under canopy and therefore
more likely to enter a trap set).
At the trap site
A focal point for predators helps, e.g. pampas/flax/log
Dig ground over at trap site
If the site is in long grass, keep access open by providing a run, e.g. log over grass
to trap site, or weed/spray around the site
Make an effort to keep site under cover (especially for mustelid traps).
If a trap is in a good place (as per details above) – only consider moving it if it hasn’t
caught for 2 years!!!
In a ‘hot spot’ area you may want to place several traps within a relatively small area.

BAITS

Mustelid baits
DOC Whangarei have recently published the results of a series of statistically robust
stoat trials to determine the relative attractiveness of fresh rabbit meat in relation to a
variety of potential “long-life” baits, followed by a comparison between the best
performing long-life baits (in prep)
The trial concluded that:
rabbit meat is more effective in catching stoats than pilchards and eggs
that there was no significant statistical difference in catch between fresh (replaced
twice weekly) and salted rabbit meat (replaced fortnightly) although fresh rabbit still
caught more stoats.
Other points to note:
  • Bait needs to be attractive at all times. Rotten bait wont catch.
  • Keeping baits off the ground on wires will delay it going rotten
  • With hanging baits (eg in a wooden tunnel) watch bait doesn’t interfere with trap when it is sprung
  • Look to maximise air flow through the tunnel to spread the scent as much as possible.
  • Placement of bait under the trap is not recommended, as the predator may not cross the trap cleanly which will result in miss catches. Bait also degrades faster on the ground.
  • Alternate baits occasionally, e.g. during period of low/nil captures can use eggs to attract the occasional bait shy animals.
  • Salted bait is not papatable so it is important to remove old salted baits completely (carry out or bury) so target animals do not get the chance to taste it and be deterred.
  • Long life rabbit bait pastes and blocks have been developed by Connovations, but capture efficacy has not been field-tested.
  • Recent reviews of data suggests that salted rabbit is just statistically significantly better than freeze dried rabbit over 2 weeks – that may change with a monthly checking regime.
  • Eggs are the least preferred bait – and note that pen trials suggest better performance when eggs are holed.
Cat baits
Fresh bait is required – never use salted or preserved bait in traps in which the
animal must actually fire the trap by coming into contact with the bait (eg SA Cat
trap).
Minced rabbit best for Conibears/SA Cat Traps
A mixture of cat nuts and peanut butter is a good longer lasting alternative (although
the peanut butter will increase the possum bycatch/interference.)
Salted bait (e.g. pilchards) is good for legholds and treadle operated cage traps but
alternating with rabbit is recommended Canned fish is OK for coni-bears,
Alternate baits
Cage traps – cages need to be stable; also block off rear end of cage to stop pawing,
Treadle operated traps are best.
Timms traps – fish heads are good.
Remove old baits from the trap site, but it is OK to use fresh bait as enticement.

TRAP SETTING

Keep all kill and leghold traps 70 cm off the ground or in a tunnel in areas where kiwi or
other birds can access.
Mustelid Traps
Wear gloves when handling trapped animals (many target species carry leptospirosis among other things!)
Take every trap check seriously!
Keep to a strict routine of what is done to minimise mistakes like leaving safety
catches on or obstructions to Fenn bars closing
Clean out tunnels – keep free of cobwebs/obstructions etc – make it look like the
tunnel is being used by animals.
Use your boot to clear a path from the tunnel entrance back about half a metre – to
look like an animal track
Free and oil the treadle
Don’t put bait under plate
Single sets – keep fine setting and place bait not too close to blocked off end with
mesh.
‘Hazing’ of trap is important to direct animal over treadle.
Record captures and bait etc
Fenn traps
Fenn traps are still effective and legal
Ensure that the treadle plate is level or angled slightly up – and moves freely
There is value in having a variation in trap type – ie mixture of Fenn and DOC 200
Fenn Mk IV are easier to set for community members with weaker hands – but wont
catch or kill most ferrets!
Where funding allows – double fenns are preferable to singles (stoats prefer tunnels
they can access at both ends).
Often a rat in one trap will lure a stoat into the other.
DOC Series of Traps
The DOC 150 and 200 are the only traps in the world that target and humanely kill 3 pest predators – stoats, rats and hedgehogs
The DOC 250 is the only trap in the world that targets and humanely kills 4 pest predators – ferrets, stoats, rats and hedgehogs
The DOC 250 is the only trap on the new zealand market that humanely kills ferrets
In 2004 the doc series of traps won the technology section of the Bearing Point Awards for Innovation by the public sector therefore being recognized by independent agencies as truly innovative in design see www.innovationawards.co.nz

Download the instructions for setting the DOC series traps 150/200/250.

Download 150 instructions
– Download 200 instructions
– Download 250 instructions

Housed in Wooden tunnels baffles were made from 20 mm mesh and the entrance hole size was 60 mm square
The entrance hole should be no larger than 60mm otherwise cats can enter the tunnel and pull out of the trap as it doesn’t kill them. A larger entrance hole may
produce trap shy cats (unless using a DOC 250.)
A hole larger than 60mm will also allow possums in which will reduce stoat catch.
DOC 200s are not approved for cats.
Wooden tunnels with larger mesh ends are likely to allow more air movement
through them therefore increasing the volume of scent for predators to be able to find
traps
Tilt your tunnel so that salty liquid from the bait runs out of the tunnel and not around
the trap in order to avoid corrosion
For more information on DOC 200 best practice sets, contact DOC.
Note that ferrets have been shown to pull out of DOC 200 traps – and a trap shy
ferret can be as dangerous to a kiwi as a wandering dog!
Cat Traps – SA Cat Traps / ConiBear Traps
These are very effective traps when set correctly – but near enough is not good enough.
If not set correctly they wont catch or worse, will produce trap shy animals !
Ramp:
 Angle of the ramp should not exceed 35 degrees.
Ramp should not be more than 100 mm wide (wider ramp gives more room for rats
and target species to go around the side of the ramp and remove the bait without
being caught.) Fence battens make good ramps.
Make sure it is wide enough for a large cat to get up
Mounting plate:
Secure the trap plate firmly to the tree using screws.
Choose a straight tree that will let the trap sit as close to the trunk as possible.
Nail the chain higher up than the trap so that caught animals will hang down.
The holding plate for the trap should be hard against the top of the ramp – not above
it. Push the trap firmly into the plate so it sits at the back and doesn’t wobble.
Ensure the lip of the plate faces upwards slightly– just press down and pull up on the
two bottom lips on the plates to realign them.
Trap set:
Have the trigger wires splayed so they section the trap into thirds.
The trigger pins should be level with or slightly forward of the front of the trap. The
spring should be on a 45 degree angle down once set.
Oil the trigger system (drop of engine oil) at each check – especially if a possum or
rat has been caught in the trap.
Sometimes need to use a chainsaw file in the groove if they become too sensitive –
but don’t over file! Don’t file the back of the washer as it is critical to making the trap
go off.
If the trap will not set try setting the trap with the dog set outside the washer. If the
dog is the problem then the trap will keep going off set this way. If the washer is the
problem then the trap will stay set.
Bait placement:
The bait should be placed on the plate and going up the tree above the plate. Bait
can also be spread on the ramp as a lure.The bait must be behind the trigger
mechanism.

Cage Traps

For cats meat is attached to the rear hook and when the cat pulls on the meat the cage door closes. Most commercially available cage traps need to have fine chicken wire attached to the rear end and rear sides of the cage; otherwise harrier hawks will pull the meat through the bars.

Cage traps should be bated with small pieces of meat and traps should be set along fence lines, along the edge of water and in vegetation free areas under trees. They should be moved to a new site every three months.

Fresh meat should be added every two weeks, each cage should be checked daily for content and at the same time the door should be checked to ensure that no vegetation is going to prevent it from closing.

Cage traps are very successful on feral cats, but their disadvantage is that you have to kill the feral cat once you’ve caught one.

Cage traps are virtually maintenance free and will last for an indefinite period of time.

 The Timms Kill Trap
The New Zealand designed and manufactured ‘Timms’ kill trap was initially designed to kill possums, but the trap can also be used very successfully on feral cat control, and is very effective when used in conjunction with cage traps.

The powerful execution arm in the ‘Timms’ trap is set be pulling on the external cocking cord. Great care must be exercised when cocking the trap and in its placement – which must be well away from children and family pets

The trap has an internal stake to which meat is attached; the meat must be attached before the trap is cocked.

The trap must then be staked to the ground or tied to a fence post or tree.
The ‘Timms’ trap is a brilliant design and, whilst some people believe they are unsuitable for cats, over 350 feral cats were killed at one New Zealand site using the Timms trap.
The only modification some people recommend to the Timms trap is the enlargment of the width of the entrance hole, by 10mm each side.

Misc:
Spraying the trap with black enamel paint can improve the catch rate.
The trap must be set at least 700mm off the ground.
Frequency of trap checking
Varies seasonally, and depending on what you are trying to protect
Brown Teal require year round trapping because of their vulnerablility to predation.
Fortnightly trap checks from November to June, and monthly checks from July – Oct
appears to be sufficient for kiwi protection.
Brown Teal  may require more frequent trap checks.
Beware of autumn stoats which will be strong and intelligent and account for a lot of
birds at this time of year especially patake and late kiwi chicks.
If there are high capture rates of rats, consideration could be given to more frequent
checks primarily to remove rats from traps, especially in single-set regimes.
Eliminating Rats

Rats are also very susceptible to entering tunnels and being killed by Fenn traps, and rats can be added to the Fenn trap ‘target’ list. In one small remnant native bush area in the Wairarapa region of New Zealand nearly 250 rats were killed in Fenn traps over a seven year period, and in the same area today it is quite rare to trap a rat. But like all predator programmes they must be ongoing indefinitely if our bird life is to experience long term benefit.
Careful placement of commercially available rat poisons also helps keep rat populations under control, but it is essential to ensure that rats cannot carry the poison bait await from the bait station and also ensure that birds cannot get into the bait station; otherwise birds will eat the bait and, in most cases, die.

Try to avoid trap site contamination

Always use a pair of gloves when handling predator traps and try to ensure that human scent is kept to a minimum – no smoking, no solvents, etc.

Poisoning Rats

There are a variety of commercially available rat poison bait and bait stations, but as already mentioned, great care is needed to ensure that the rats cannot carry the poison away from the bait station. The poison must be ‘captive’ at the bait station.

Other traps

Another trap which specifically targets rats is the Victor Professional Snap Trap, which are placed in small rate sized tunnels. This trap will also kill weasels and stoats, but for all-round use the Fenn has the edge.

Eels

Commercial eel fishermen will be only too pleased to assist.

Paradise Shelduck & Pukeko

In Brown Teal areas they must be kept under control and this can be easily done by shooting them – during duck shooting season these birds can be shot as a game speices if you have a hunting license, or having obtained the necessary permit.

Hedgehog (Erinaceus europeus)

Fortunately they are easily eliminated by the Fenn trap, although they are at time a nuisance to extract from a Fenn trap, and easily caught in cage trap. Good numbers have also been killed in the Timms trap.

MAINTENANCE AND PREPARATION OF NEWLY PURCHASED TRAPS

Currently no simple solution to prolonging the life of traps.
Anodising helps prolong the life of the trap (but not if in a tunnel made from tanalised
wood). Done by Metal Protection Ltd, Auckland.
If not anodised, each trap should be dipped in engine/vegetable oil mix before being
set in the field (catch rates don’t seem to be affected by the use of engine oil).
At each check the trap should be checked to ensure the treadle plate drops freely.
Apply a few drops of engine oil around the dog hinge, and/or tweak the treadle from
side to side to free it.
Bring traps in every 1-2 years and clean – Water blast them and use a wire brush to
remove any scale rust. Once dry, dip them into engine oil or a mix of 4ltrs penetrol to
8ltrs of vegetable oil. (Penetrol is available from paint shops)

WHAT IS EATING YOUR CATCH?

Mustelids will often make an entry hole in the groin area of possums and work their
way into muscle.
Cats will rip the guts out.

RECORD KEEPING

Keep good data!
Map where animals are caught
Use these data to refine your trapping, e.g. in following years you can be better
prepared for focussing on sites and times of year when captures have been high in
the past.
Good data is crucial to maintaining the support of both funders – and others within
your project.
Remember to use your data! Eg monitor what is the rat by-catch from year to year
and do the species change in relative abundance?

RIPPLE EFFECTS – OTHER THINGS RESPONDING

Besides blue penguin, kaka, quail and pheasants etc benefiting from predator
control, pests might benefit in some years also e.g. rabbits, rats, mice and weasels
If other sensitive or threatened fauna are present, appropriate contingencies might
be needed, e.g. control of rats and rabbits – integrated pest management.

HEALTH AND SAFETY

Leptospirosis, camplobactor and numerous other nasties are out there and can take
the fun out of living (leptospirosis is carried by both rats and hedgehogs)
Wear disposable gloves for all handling of traps
Use water-proof bandaids over cuts and wash your hands before eating or smoking
Alcohol based anti-bacterial wipes in sachets are a good way to sterilize your hands
before eating in the field.
Pateke Partners Area

Pateke Partners Area