5 July 2016 Do possums howl at the moon?

Knowing if nocturnal pest mammals are more affected by the phases of the moon or by illumination could bring New Zealand one step closer to being pest free and save control agencies significant sums of money.

Lincoln University Ecology Master’s student Shannon Gilmore’s research into the effect lunar phases and illumination have on activity levels in possums, stoats, rats and mice is aimed at finding more effective and efficient means of targeting and managing these pests.

“It costs millions every year to control their populations,” says Shannon. “We’re waging a kind of war on pests. We need to discover their weaknesses. What trait do all four have in common that we can take advantage of? They are all nocturnal, and many nocturnal animals dramatically reduce their activity with the full moon, while others can become more active.

“If I can discover their preferences and am able to predict whether a full moon would make a pest more active, increasing the likelihood of it encountering bait or a trap, then we could decide when it is worth deploying controls. It’s a fine tuning of our battle plan. ”

Shannon’s research follows on from similar studies, but past researchers were unable to accurately measure illumination levels, a significant drawback as they couldn’t determine whether the animals were responding to the moon’s cycle or the change in light levels. The recent availability of low cost, portable, weather-resistant and highly sensitive Sky Quality Meters (SQM’s) used by astronomers could be a game changer.

“I’ll be able to calculate an illumination level throughout a night and this may give some insight. Conditions such as cloud cover, season, weather and urban light pollution will also be considered.”

Shannon is conducting her fieldwork on Banks Peninsula in Canterbury, which provides a variety of habitats and easy access to possums. Camera traps and bite marks on non-toxic wax tags at each field site record the activity levels of the pests. 

While the broad objective is to discover how the activity levels of possums, rats, stoats and mice change with moon phase or illumination levels, testing new equipment a better way to measure illumination levels, Shannon says discovering the lunar phase and illumination preferences of pest animals has the potential to provide organisations such as the Department of Conservation, regional councils and other agencies with practical information they can use.

“Streamlining pest control operations means less material assets wasted and reduced labour intensity. Conservation work has a reputation for a general lack of cash and any savings tend to be warmly welcomed.” Shannon says the study would not have been as successful without funding from the Brian Mason Trust, whose mission is to advance scientific objectives in Canterbury and has facilitated efforts to make New Zealand pest free.