Abstract
Animal behavioural variation has gained a lot of attention in recent years. Behavioural variation can influence many aspects of animal research, so it is surprising that this behavioural variation is relatively neglected when planning wildlife management strategies and predator control operations. My study explored the variation in behaviour displayed by the common brushtail possum (Trichosurus vulpecula) in the presence of predator control and detection devices. I asked whether possum behaviour varied depending on; (1) the level of predator control a site had been exposed to previously, (2) the device type, and (3) whether the site was located in an urban or rural setting. This study was carried out at ten locations representing a range of high and low predator control sites in urban and rural settings in East Otago, New Zealand between July 2020 and January 2021. Motion activated cameras were set up at each location to record the behavioural response of possums to three different types of control/detection devices; a A12 kill trap, a cage trap, and a chew card. From the images, I recorded the amount of time it took a possum to approach a device, how long it interacted with the device and explored the area around the device, and whether it ate the bait.
Possums in areas with higher exposure to predator control spent less time interacting with control/detection devices than those that had little or no exposure to predator control. This shows that possums exposed to high predator control are shyer and hesitant of novel objects, and less likely to interact with a trap or detection device. Possums were faster to approach the chew card but spent less time interacting with it and exploring in its vicinity compared to the other devices. Alternatively, possums were more hesitant and slower to approach the A12 trap but spent more time interacting with it and exploring the area around it than either of the other control devices. Finally, possums from urban locations were more likely to interact with control devices in a way that would have led to their capture/detection/death (depending on the device type) than possums from rural locations. This is likely due to urban possums being bolder, adaptable to change and more accustomed to novel objects than rural possums.
Overall, this study demonstrates that possums from different locations display differences in behaviour that correspond with the level of predator control experienced at that location. It also shows that a possum’s behavioural responses to detection and control devices depend on whether the site is urban or rural, and the device type. This research supports the idea that individual behavioural variation in populations could be a major factor in the difficulty we are having in trying to eradicate every individual possum from New Zealand and offers a reason why we often have numerous residual populations remaining after a control operation. It also provides evidence that more insight into behavioural differences in individuals within populations is needed to better wildlife management strategies and improve predator control in New Zealand.