How To Trap and Monitor Pests

Placing and baiting traps

Finding the best location for your trap(s) will depend on the type of trap you have and the predators you want to target.

When placing traps, if children might come onto your property, make sure that they cannot reach the trigger mechanism, either by placing the trap out of reach e.g. mounted high enough on a tree, or by making sure it is inside a secure trap box which is designed so that children cannot reach inside.

To identify the best place to put traps, a good way to start is to place some chew cards around your property. These are cards impregnated with a lure which encourage pests to chew on them. The bite marks left behind can then be used to identify the pest animal. That way you can see which pests are a problem and where they are the most prevalent. Your Local Co-ordinator should be able to supply you with some chew cards and can give you some advice on how to use them.

Chew and wax cards (Pest Control Research)

Chew cards showing typical chew marks, from left to right: possum gnaw marks, stoat/hedgehog/cat puncture marks, rats chew entire sections of card, mice chew small sections of card (Halo)

To place traps, some tips to keep in mind are:

  • Consider where pests might be in your backyard and why. Many predators can be found near water and food sources such as fruit/nut trees, roses, compost bins, and chicken houses. Rats and mice often enjoy the warmth of your house during the colder months.
  • Predators will often use regular pathways in the grass, along fence lines and ridges, down the side of the house, near compost bins, waterways and culverts – basically, the easiest path to travel along.
  • Look for ‘sign’, such as faecal pellets, bite marks, scratch marks, bark with urine stain, and partially eaten leaves.
  • Possums and other mammals like to be warm and dry. Rather than get their feet wet walking through long wet grass, they will use tracks and roads to move around, unless there is a food source that draws them away from these main thoroughfares. They tend to be more active on clear moonlight nights and stay closer to home when the weather is bad. This also means that they tend to nest in sheltered spots including thick vegetation, such as in riparian plantings, and in trees covered in vines.
  • Mustelids will be attracted to locations where mice, rats and chickens are present, as well as rabbits.

Placing Traps

Place traps on a flat surface and make sure that the entrance and exit are clear of obstructions including long grass, other vegetation or sticks etc. If setting traps off the ground for possums, set them 350-400mm above ground so they can reach the bait while sitting on the ground. If you are concerned about by-catch or small children, it is possible to place the trap higher off the ground and to provide a ramp (a broken branch can be used) or ladder for possums to climb, though this will probably mean that the trap catches fewer possums.

Bait

Choosing the right baits and pre-feeding, especially for mustelids and rats, are also important. To pre-feed, just bait the trap and leave it unset. If possible, if using a trap which is encased in a box, remove the trap itself so the pest animal doesn’t have to step on it, to get them used to going into the trap box to get food, before introducing the trap and setting it.

There are lots of options for baits/lures. These include several commercial lures that you can buy, or using your own. Commercial lures are normally easy to handle and designed to last longer than fresh bait. Some examples of lures for each pest include:

  • Mustelids: fresh baits are preferred and include hen eggs or fresh meat e.g. rabbit, beef, chicken, possum, fish-based cat food, dead mice or rats, or you might want to try salted or freeze-dried meat. Eggs can also be hard boiled. Bright coloured trap boxes, or placing reflectors near your trap, can also help attract them.
  • Possums: a flour and icing sugar mix of five parts flour to one of icing sugar with the option of adding a spice such as cinnamon; or try peanut butter, jam, or pieces of fruit. If using the flour-icing sugar mix, put it in a soft drink bottle with holes drilled into the lid and spray the lure on the trap and around the trap in order to lure the possum in to the trap. For raised traps, always place lure below traps to encourage animals to move up to the trap. The white colour of the flour-sugar mix also acts as a visual lure. Reflectors can also be used to attract possums to the trap.
  • Rats and mice: peanut butter

Also, some pests have a clear season of trap-ability. For example, ferrets, especially females, are relatively easy to catch in summer and autumn but more difficult to catch in late winter and spring.

Maintenance of Traps

To maintain your traps you will need to:

  • Check and rebait traps at least once a month, and ideally more frequently if using fresh bait as it needs to be palatable for the pest to interact with the trap enough to be caught in it e.g every four to five days for fresh meat, and every two to three weeks for eggs.
  • The more pests there are in your area the more frequently you should check your traps.
  • Make sure the trap is still working – to test a trap use a stick to trigger it.
  • Some traps will need a bit of maintenance to keep them working. It’s a good idea to lubricate the working parts of the trap once or twice a year.

The Predator Free NZ website has trapping guides targeting each pest species (http://predatorfreenz.org/tools-resources/trapping-best-practice/).

Recording Your Traps and Catches

An important aspect of achieving a predator free port hills is to coordinate our trapping efforts. We can do this by recording trap locations, the number and type of pests being caught, and whether people are actively maintaining their traps. Predator Free Port Hills is using Trap.NZ to do this.

Predator Free Port Hills Projects Trap.NZ (Trap.NZ)

 

Recording catches also means that we can see how much progress has been made, which helps with publicity and funding, but also keeps everyone informed and enthusiastic as we can see the collective results of the group. Even if your trap isn’t catching anything, it’s still important to record that you are baiting and maintaining your trap. If you decide to host a pest monitoring or tracking tunnel, this is also where tracking tunnel results should be recorded.

Trap.NZ is free, and is for individuals and groups to actively manage their pest control projects. Predator Free Port Hills has set up a project on Trap.NZ for each active area. If your area is not covered, get in touch with a Local Co-ordinator or the secretary of the Summit Road Society.

To access Trap.NZ, you can either use their website (www.trap.nz) or the Trap.NZ app.

The Trap.NZ app is a simple to use tool that allows you to plot traps and bait stations in the field and collect records while you are out checking your traps.   It works offline and syncs data with the Trap.NZ website when back in coverage.

Via the Trap.NZ website you can capture and understand your pest control results, view other pest control activities in your area, and link up with other groups. A suite of reports, graphs, and interactive maps are available to help see where hotspots are showing up for different pests, report results, and to keep everyone informed of the successes of our hard work.

Trap.NZ has been developed with the support of WWF and Groundtruth Limited.  It has been operating since 2014 and is used by over 380 groups throughout New Zealand.

Pest Monitoring

Pest monitoring can be done to identify the types of pests that are present and to get a measure of pest activity. It can be done using tracking tunnels or you can simply look for animal scats i.e. poo, or toothmarks on fruit and nuts. Tracking tunnels will give a measure of changes in relative abundance over time.

A tracking tunnel is a run-through tunnel containing a pad that shows the footprints of animals that travel through the tunnel. A tracking pad can be made by placing two pieces of paper either side of a sponge soaked with a tracking medium like food colouring. As an animal passes through the tunnel it picks up the tracking medium on its feet, then, as it departs from the tunnel, it leaves a set of footprints on the papers. It is a non-destructive sampling technique so it does not impact the target species or, any non-target species.

Homemade tracking tunnel (DOC)

 

Footprints left on the tracking papers can then be compared to pictures of tracks from different types of pests.

Examples of pest footprints as well as native Rainbow Skink footprints (Pest Detective).

 

One thing to consider when monitoring is that some predators will peak in numbers and/or activity at certain times of the year. For example, stoat numbers peak in summer, but that peak is only for a very brief time and this is when many species of native birds appear to be most vulnerable.

Another thing to look for are animal scats. For example, stoat scats are black, long and thin, and usually are full of bones, feathers or fur, and 40-80mm long. Scats are often deposited as a ‘marker’ in prominent positions such as on top of logs or stones along travelling routes. The scats of ferrets and weasels are very similar, only differing in relative size. However, take care not to confuse these scats with blackish bird droppings – the contents of the droppings should identify the owner.

Possum scats top, and stoat scat bottom left (Jaqui-nz, Nature Watch), mouse and rat droppings bottom right (Goddamn Bowtie, doctorwhogeneral.wikia.com).

The Pest Detective is a great website for identifying pest poo if you aren’t too sure (http://www.doc.govt.nz/get-involved/conservation-activities/become-a-pest-detective/).

Monitoring gives us some information, but it’s very difficult to know how many pests you haven’t tracked or caught. These are the ones that are important.