Sensitivity of audio-lured versus silent chew-track-cards and WaxTags to the presence of brushtail possums (Trichosurus vulpecula)

Abstract

Accurately identifying the changes in relative abundance (performance-based monitoring) or distribution (surveillance-based monitoring) of the brushtail possum (Trichosurus vulpecula) within the landscape, is a fundamental component of possum control programmes. For surveillance-based monitoring, sensitive monitoring tools are required. Interference-based detection devices, including chew-track-cards (CTCs) and WaxTags (WTs), are considered more sensitive than leg-hold traps as they are smaller and lighter, allowing for a greater number of devices to be deployed over large areas. Our study indicated that CTCs were more sensitive to possum presence than WTs over the time frame of the study, which was attributed to the stimuli of the peanut-butter lure incorporated into the CTCs thus encouraging the possums to interact with detection devices. The addition of audio lures increased the sensitivity of both detection devices and made WTs equally as sensitive as CTCs with 75% of noisy monitoring sites detecting possum presence. As possum populations are reduced to increasingly lower densities in an attempt to locally eradicate bovine tuberculosis, the use of audio lures may become a greater part of possum surveillance monitoring in New Zealand.