Pest inquiry #2

Report for pest inquiry

Introduction:

New Zealand is home to a total of six wallaby species that first were brought to New Zealand about 150 years ago. However, there are only two species of wallabies that are actually affecting New Zealand's native bush and farmer's land, the Dama wallaby (North island) and Bennet’s wallaby (South island). We are going to investigate the Dama wallaby which is currently threatening the Bay of Plenty’s precious ecosystem. Since the wallabies have no natural predators, the population of the wallabies has skyrocketed and something must be done so that our native bush can be saved. In this report, we will be trying to answer the fertile question “What should be done to mitigate the deleterious effect of wallabies in the Bay of Plenty?”.

What pest are we looking at?

The pest that we have chosen to explore and try to find ways to get rid of, is the wallaby. Wallabies are native to Australia and New Guinea, and have been introduced to Hawaii, the United Kingdom and, of course, New Zealand. Wallabies have flat teeth to munch through shrubs, and they mostly consume leaves, grasses, flowers, ferns and moss . Wallabies are, for the most part, nocturnal, which makes them much harder to catch and hunt. The wallaby problem was quite unanticipated since they are nocturnal and are not seen so often in the light. Wallabies are very adorable even though they are a pest, that is why they are sometimes kept as pets but that has been for quite some time against the law. This is important because knowing what the species eat, where else they have been introduced, and why they are hard to catch can help us find a better way to eliminate the wallabies in New Zealand.

What impact does the wallaby have in the Bay of Plenty?

The estimated area covered by wallabies is already in the hundreds of thousands (hectares). They are doing more and more damage to our environment, the reasoning for this is that they are eating leaves, grass and native tussock. This is not good for the Bay of Plenty's native ecosystem as they eat far too much to let the bush grow back as quickly as they eat it. Wallabies also compete with sheep, cows and horses for food. The understanding for this is wallabies like to graze on large flat pieces of land that the farmers use for grazing their cattle. Most of the time they don't have enough food to go around all the animals. So the farmers that own the cattle are forced to hunt them or starve their cattle. The wallabies mainly live in the Rotorua area, and they are posing a significant risk to the survival of the native bush and wildlife. They damage fences, crops and seedlings so you can understand why a lot of farmers and even people that live rurally want to get rid of them.

Why were the wallabies brought to NZ?

The wallaby that poses the biggest threat to our ecosystem is called the Dama wallaby. It was brought to NZ by Sir George Gray, the governor of NZ. He had them brought over in 1870 for his tropical garden along with tropical birds and plants. They stayed on Kawau island until around 1900 when some were brought to a small island on the lake Okareka. It is situated in the Rotorua lake district but only 12 years later in 1912 when a hunter decided he wanted the easier game/animals to catch, he took them off the island and released them into the bush around the lake, but very soon they had spread very fast with no signs of stopping. Sadly this was not the end because when people saw them around the bush and their skins in shops, they immediately wanted them so more were brought over from Australia. There were 4 more species came that came over, the Parma, Swamp, Black-striped, and Brush-tailed rock wallabies were also brought over, but thankfully they died or stayed on small islands in Auckland. Meanwhile, the Tama wallaby did not stop spreading very soon, there were a hundred thousands.

What are other countries around the world doing to eliminate these pests?

In Australia, the wallaby is not a pest as it has many natural predators like dingoes, domestic dogs, red foxes and feral cats. These native animals help keep the population down to reasonable numbers. Unfortunately, NZ does not have most of these predators and if we did have them they would go for much easier prey like our native birds. As history has proven, bringing over another species to prey on our pest in New Zealand does not end well. Wallabies in Australia sometimes feed close to roads and urban areas, this means that they are often involved in car accidents. This point is important because observing what others are doing to control these species may help us find a better way to get rid of the wallaby.

What methods are we currently using to stop them, what methods are out there that we are not using and is there a new possible solution that we create?

Bait and hand-laid poisons.

Are methods such as using cyanide and 1080 good and reliable? Using bait and hand-laid poisons are methods that have their advantages and disadvantages on the Dama wallabies. Using Feratox cyanide is a good and effective method as it kills quickly (under 14 minutes) and has proved highly humane. The cyanide “strikers” each containing 1-2 capsules are placed 10-20 metres apart depending on the number of wallabies and 20 cm high on stakes or trees. The results of this method were pretty good and approximately 150 wallabies were killed.

The disadvantage of using this poison is that wallabies do not always eat/lick the bait and you must have a licence to use the poison. 1080 is a way to kill wallabies, but it is very cruel and it kills just about everything else that digests the poison so it doesn't kill only wallabies. All other baiting methods are not completely accurate and do not always work. Researching all these poisons is vital to finding the best possible way to eradicate the wallaby problem.

Trapping methods.

There are no completely reliable trapping methods for the Dama wallaby, but can this be changed? What about using a similar design to the possum trap using compressed air to shoot a pin through their head? The A12 possum trap is the most humane way currently to kill a possum it was made by a company called Good-natured. The trap also only targets possums and does not use any toxins. Using that would be good because it offers a quick, clean kill although it would have to be enlarged for the wallaby. If the Bay of Plenty government made a bigger version of the A12 trap, they would be able to control and maybe even diminish the established wallaby population.

After contacting Thomas Rillstone, an expert from the company Goodnature, the idea of enlarging the possum trap and using it for wallabies was thought to be “Not good and not humane”. Thomas Rillstone explained that the problem would be getting the wallaby to stick its head in the trap as they are smarter than possums. Thomas Rillstone concluded it is not the most effective trap as it was only designed for rodents and possums. Even though this is obviously not going to work, there still is a way to automatically detect wallabies by using thermal imaging, but buying one of these comes at a hefty price.

Hunting and night shooting.

Night shooting has proven to be quite effective. The government ran some tests and night shooting with three professional hunters resulted in 71 wallabies shot. The hunters hunted for a total of six nights, two of them shooting and the other using a thermal imaging scope. The disadvantage to paying hunters to hunt the wallabies is that it would be very costly and the hunters would have to walk many kilometres. Another way is to advertise wallaby hunting and perhaps pay money for them (8-$10). This idea could be expanded into farming them for their meat and fur. That would be much cheaper but would take a longer period of time. This is the easiest and cheapest method as if we just promoted hunting wallabies and maybe even put their meat on the market then the government would not have to spend much money on poisoning, baits and traps. Although if this was to be really fast, efficient and effective professionals could be paid to go hunting with thermal cameras and dogs.

Which method is the best and why is this method the best.

Our thesis is that the best, most effective way to control the wallabies is putting up fences to isolate movement of the wallaby, then poisoning them with cyanide to kill them. Cyanide kills wallabies in massive numbers and it does not cause much damage to the wallaby because it kills so quickly. The other thing is that with poison is that you can't guarantee that all wallabies were killed, so the second best method is to hunt them, but hunting is very hard to kill wallaby in mass, so that is why poisoning and hunting is our choice for the best way to kill wallabies. So this is how it works: some fences are put up in a square in an area that needs wallabies killed, then people go into that area of bush/forest that has the wallaby in it and lay the bait all over the bush, then they wait for a couple of days. This will kill the majority of the wallaby population. Then DOC lets the advertising begin for 8 to 10 dollars per wallaby killed in the area that had been just poisoned. So once you bring the wallaby to the DOC pest control centers they would pay anyone who brought them evidence that they killed the wallaby such as a tail or a leg but most likely the whole wallaby.

Conclusion:

Throughout our inquiry we have searched high and low for possible ways to mitigate all wallabies in our beloved country New Zealand. Some of those methods are poisoning with 1080 or cyanide, trapping, hunting, night shooting, and we even considered the possibility of making a bigger version of the well-known A12 possum trap. After much deliberation we came up with an ingenious plan that would certainly make it harder for wallabies to continue their destruction. We could use fences to stop the movement of the wallabies, cyanide for killing most of them, and then night hunting/shooting to clean up the very little left that has not eaten the poison. This method will be costly but with 27 million dollars out of New Zealand's 1.3 billion operation, getting rid of the wallabies should be much easier. The government operation is called MPI which stands for Ministry of Primary Industries. We think that the Bay of Plenty Regional Council should take the collaboration of 3 methods into consideration to tackle our serious wallaby problem. The quicker the wallabies are out of our native bush and farm land, the better for our ecosystem and us.

Works Cited

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Industries, Ministry for Primary. “Wallabies in NZ: Controlling Their Numbers.” Ministry for Primary Industries, Ministry for Primary Industries, 16 Nov. 2020, www.mpi.govt.nz/biosecurity/long-term-biosecurity-management-programmes/wallabies-controlling-their-numbers/.

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