PROTECTING  WILDLIFE ON YOUR PROPERTY FROM RATS.

In order to protect wildlife on your property it is necessary to control and if possible eradicate rats.  Rats are enormously destructive animals. We have two main species of rat in New Zealand and both species were introduced in the early days of settlement. There is the Norway rat which can be very large, 400 gm plus, and is a brownish colour. This rat is not a climber but will feed on anything available to it and lizards, eggs, insects, seeds, all form a part of the animal’s diet. My good friend and very wise bushman William Ducre has remarked that rats are often on the brink of starvation so will eat almost anything.

The most numerous species of rat which is found right across the country is Rattus rattus, also known as the black rat, or roof rat. This animal is a very adept climber and will feed on all of the life eaten by the Norway rat, along with the chicks and the eggs of tree nesting birds. These animals are extremely destructive. In some areas they remain for extended periods in trees only venturing to the ground when their arboreal water source evaporates.

Researchers estimate rat numbers per hectare in the New Zealand native forest, ranges on average, between 6 and 8 animals with the numbers increasing dramatically during the warmer breeding months and especially in times when native trees are seeding or fruiting.

We now know that rat footprints are quite individual, in that the size of the feet varies quite significantly between animals, and this variance shows as difference in foot width which is measurable in mm. We measure from toe 1 to toe 4 on the front feet [there are only 4 toes] and toe one to five on the hind foot. The extra toe is in the same position as the thumb is on a human hand; below the line of the fingers or toes as the case may be.

There may be little or no visual evidence of presence of rats in your garden. Yet it is probable that you will have them. The most likely indication of rats being present is sign that they have tunnelled into your compost bin, as they will gnaw right through the plastic body of the bin to gain entry, or dig a tunnel through soil if there is no fixed base on the bin.

My wife Lois assists monarch butterfly as the monarch eggs laid in the early summer are almost immediately taken by wasps. Lois collects the minute, newly laid eggs, then places them in a warm situation and when they hatch places swan plant leaves in trays as food for the growing caterpillars. During the winter the unit is heated. The caterpillars duly form chrysalises and when the butterflies hatch they are able to fly in an enclosed area where there are suitable plants provided for them to feed from. After 2 days the butterflies are released and last year Lois released over 1200 of these beautiful animals.

However in the middle of the year Lois found a pile of monarch wings in a corner of the butterfly house. There were 40 wings so 20 butterflies had been killed and their bodies eaten. A search of the butterfly house showed a tunnel had been dug by rats allowing them access from the outside.

Lois placed a Black Trakka monitoring tunnel within the butterfly house and when the card was tracked by a rat she placed a Kness trap within the tunnel and caught both the presumed offender and the next night his friend.

We had thought our property to be relatively free of rats so the incident with the rats and the butterfly house lead us to monitor more closely. We already had 4 permanent tracking tunnels in place but we had become too complacent, following no sign of rats for a few months. We live in an area where all of the sections are an acre; there are a significant number of both large pohutukawa and puriri trees and some dense areas of regenerating bush, along with a huge number of trees planted in the last 10 to 20 years as sections have been developed.

Another reason for our complacency was that bait stations placed primarily for possums are regularly refilled for although the possums no longer exist on our peninsular rats take the baits.

The resurgent monitoring showed the presence of rats and Lois took it upon herself to catch them.

Inside a tunnel, [and these can be made from timber or coreflute on a timber base] a monitoring card is placed. The standard operating procedure set by the Dept of Conservation calls for the inside of the tunnel to be 100mm square with a length of 500mm.

Place a small [fingernail sized] piece of peanut butter in the centre of your card. Placed directly in the centre of the ink. Slide the card into the tunnel and check daily for any footprints. You will probably record cockroach tracks, weta tracks and mice and rat tracks. Refer to our website to assist with identification.

When rat tracks show, the following night you should place a rat trap baited with peanut butter inside the tunnel.

With the Kness traps there is the advantage that the rat can enter from either end of the tunnel and it will still be caught. The trap has a kill bar that only moves through 90 degrees and there is less time for a rat to dodge out of the way. The trap has a large trigger plate which surrounds a well into which peanut butter is placed and the slightest pressure on this plate will set the trap off.

The traps are very, very easy, to set as it is a simple procedure in which a bar is pulled down to lock into a fitting. One click and they are set. Nothing near to hurt your fingers. The body is solid plastic which will not absorb fluids from a dead animal. When releasing a dead rat you do not touch the kill bar but push down on the setting bar and the animal drops free.

In the past 3 months Lois has caught 12 rats, all of them Rattus rattus and they have ranged in weight from 79 gm to 175 gm. {Lois places the freshly dead animals in a plastic bag, weighs them on a set of electronic scales and records the data.

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