Optimising management strategies for invasive predator control: a
modelling approach
Abstract
(1) Invasive predators pose a serious threat to native biodiversity,
with trapping being one of several methods developed to manage and
monitor their populations. Many individuals in these predator
populations have been found to display trap-shyness, which hinders
eradication and results in inaccurate estimates of population size.
Lures are used to help overcome trap-shyness by increasing the
probability of interaction with the device but the extent of this
behavioural trait in wild populations, and the best timing for the
introduction of a new lure or combination of lures, are uncertain. A key
challenge for wildlife managers is maximising the efficacy of invasive
predator control, particularly in relation to baiting and trapping, so
that pests are extirpated, or survivors are reduced to a minimum. (2) We
first use a Bayesian estimation method to quantify the trap-shyness
trait in a population of brushtail possum in a New Zealand forest; the
resulting estimated parameters are then used to calibrate a stochastic,
individual-based model simulating the outcomes of different luring
scenarios. (3) We show that the brushtail possum (Trichosurus
vulpecula) population analysed was likely split into a smaller, very
trappable group, and a larger trap-shy group, with low mean nightly
probability of interaction with traps of 28% [14%-56%]. (4)
Synthesis and applications: Our results show that using multiple lures
can result in a greater population knock-down than using a single lure,
and that it is more efficient to use a combination of lures for the
entire duration of a kill-trap operation than to switch from one lure to
another.