Is moonlight the ultimate weapon?

Being terrorised by house mice was a challenge I faced growing up through my primary school years. Forgetting to empty half eaten lunch from my school bag in the evening could result in large rat holes by the morning. This was a lesson that I had to learn the hard way and the cost of numerous school bags. My guilt at being forgetful, being scolded by mum and the shame of having to take the mouse attacked bags’ to school are vivid memories from my childhood that still makes me laugh.

It is amazing how many introduced pests compete with humans causing massive destruction to our food, our precious belongings, the environment and wildlife that we so cherish.

Stoat attacking Mallard, image by cc Michael Sveikutis


“The truth is, the natural world is changing and we are totally dependent on that world. It provides our food, water and air. It is the most precious thing we have and we need to defend it.” David Attenborough

Animals that compete with us for food, space and the other natural resource, damage our crops and native forests, cause nuisance and loss of wildlife, generally are hard to control and have overcome pest control measures. These species, pose a great risk to our environment and survival. History has seen many countries introduce animals without understanding their impact.

Introduced animals are often classified as ecological pests (pests having an impact on the environment) because they have a huge impact on the structure, function or composition of indigenous plant communities.

Mammals were introduced in New Zealand through European ships during the late 18th century with over 23 introduced mammal pests now existing in  New Zealand. Over the years, as the human population grew, so did the introduced pest populations across the North and South islands. Mammal pests of concern in New Zealand include rabbits, birds, eight different species of deer, fish, insects, mustelids (ferrets, stoats and weasels), rats, cats, mice and possums which are all intruders that have caused the disappearance of a number of populations (and species) of native birds and lizards.

Stating that we have a pest problem is an understatement (Gilmore, 2016). Three of these most damaging pests i.e. rats, possums and stoats are now considered to be the top priority for New Zealand and the government has announced the Predator-free NZ  2050 goal to remove these pests from NZ soil.

To me reducing pest levels to zero seems unrealistic. As an agriculturalist working in the biosecurity sector in Fiji, I have always been exposed to the idea of controlling population rathers than reducing populations to zero. With the growing exposure to the environmental problems caused by these pests, it is clear why NZ is eager to remove the pest population. Current control of these pests involves baiting using toxins such as 1080 and trapping using cages.

So what is Predator free by 2050 goal all about?

Through its predator free 2050 commitment the NZ government has agreed to pay an additional $7 million dollars, as well as attracting in at least as much commercial/private money. This will be on top of the already $70 million budget that NZ is spending yearly in pest control. These pests are really expensive!!


Where will the funds go?

  • predator control projects
  • scientific research concerning control and complete removal of the pest
  • increased support for community pest control projects
  • improving current pest control tools and technology

Predator Free 2050 expected outcomes:

  1. Remove the major threats to our native wildlife
  2. Enhance economic returns from agriculture and forestry and reduce risk of disease
  3. Create new opportunities for regional development
  4. Reinforce New Zealand’s trade and tourism brand
  5. Provide a legacy for future generations

An example of current research that provides hope for meeting the predator-free goal

The Pacific lifestyle is full of myths and legends and the story of a village in Fiji thought to be affected by moon phases has always made me wonder about this effect. Human lunacy due to moon phase has been studied widely with little evidence suggesting that it exists. Fijians tend to accept it with a mischievous mind. We might have failed to prove the impact of Moon on humans but a recent research study carried out at Lincoln University has proved that moonlights can be used in control of mammal pests in New Zealand.

We might have failed to prove the impact of moon phase on humans but a recent research study carried out at Lincoln University has suggested that moon phase can be used in control of mammal pests in New Zealand.

Moonlight can be used in pest control, image by cc Robert Koehler

 Lincoln University student Shannon E. R Gilmore (2016)  focused on identifying the effect of moon phase and moonlight illumination levels on nocturnal (night dwelling) mammal pests such as rats, stoats, possum and feral cats. The study used information from three New Zealand locations i.e. Blue Mountains (Otago), Hawkes Bay and Banks Peninsula (Canterbury).  According to Gilmore (2016), little is known about the impact of the moon on the nocturnal pests in New Zealand. Past studies mentioned that moon phase might have an impact but failed to determine how.

The study concluded that increasing moonlight illumination reduced the nocturnal pest activity. Baiting and monitoring of nocturnal pests were identified to be more effective on darker nights and in shaded parts of the forests.  Sky Quality Meter was identified as an effective tool for detecting moonlight under very dark conditions. Apart from this, Sky Quality Meter could also detect significant differences in illumination (light) between moon phases and under different canopy covers. Gilmore (2006) recommended using Sky Quality Meter for future nocturnal pest studies.

Using moon phases to lay out baits for controlling and monitoring nocturnal pests could improve the efficiency of the current pest management system. In order to achieve predator-free NZ 2050 goal,  more effort needs to be put into research to identify better and effective control methods.

The author Ashika Prasad is a postgraduate student in the Master of Science taught at Lincoln University. She wrote this article as part of her assessment for ECOL 608 Research Methods in Ecology.

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