Testing the attractiveness of olfactory and acoustic cues to mammalian predators in a wetland environment

Invasive mammalian predators have detrimental impacts on native wildlife both globally and in New Zealand. These impacts in New Zealand have led to the initiative for New Zealand to become predator-free by 2050. To achieve this ambitious goal, more effective control technologies need to be adopted. One avenue of doing this is improving lure effectiveness to draw target animals into control devices more readily, and to develop lures that are more cost-effective, and last longer in the field. While animal trials in captivity can be used to test lure effectiveness, it is not always clear if the same animal responses will be observed on animals in the wild. I tested the presence, approach and entry response of Possums (Trichosurus vulpecula), mice (Mus musculus) and ship rats (Rattus rattus) to three different scent cues and three different sound cues at Wairio Wetland, Wairarapa using trail cameras. One of the scent cues being tested was a traditional peanut butter bait for comparison, while the others are considered novel cues. Results of the field trial were compared against a captive trial of ship rats in pens to the same cues conducted by Manaaki Whenua Landcare Research (MWLR) to see if captive trials can be used to reliably inform pest control management choices in the field. Peanut butter was approached significantly more than the control by possums and possums were observed around peanut butter more than any other lure. Mice approached and entered traps containing cat scent more than any other lure, but this result was not statistically significant. Possums displayed a similar ranking of attractiveness to cues as captive ship rats, but mice did not. There was a lack of ship rats observed in the field, thus direct comparisons between the captive and field trial were unable to be made. Despite this, the data yielded some valuable results about the influence of covariates on animal activity. Overall, more studies are required to ascertain whether the ship rat captive trials can reliably inform management strategies in the field. There is also more study required to test the true value of a novel cue, particularly in terms of cue longevity.