Detecting and protecting the threatened Kangaroo Island dunnart (Sminthopsis fuliginosus aitkeni)

Abstract

Reliable and cost‐effective monitoring methods are a critical component of conservation management practices that work to prevent the extinction of threatened species. We evaluated the best means of monitoring the threatened Kangaroo Island dunnart (Sminthopsis fuliginosus aitkeni, hereafter KI dunnart). Variation in detection probability and cost was examined between four trapping methods. We then compared the occupancy of the KI dunnart in a 2017–2018 survey to a survey from 1999 to 2001. Across the 2017–2018 survey, the KI dunnart was detected at only five sites and was detected most frequently using camera traps on drift fence lines. The taxon was estimated to occupy 27% (95% confidence interval: 7–65%) of sites in the eucalypt woodlands of western KI. Of the methods that have successfully detected KI dunnarts, cameras on fence lines were the most cost‐effective. Power analysis suggests that future monitoring surveys in spring and autumn must survey at least 55 sites to be capable of detecting a 60% decline in the KI dunnart population, and 26 sites to detect an 80% decline. Ongoing intensive monitoring is required to assess the population trajectory of the taxon and support its persistence on the island in the long term.

How do invasive predators and their native prey respond to prescribed fire?

“…This indicates that the response of these species to fire is not determined solely by fire type or severity, but rather a complex interplay of factors that likely include pre‐fire environmental conditions, prey availability, and ecosystem‐specific dynamics. For instance, cat abundance declined considerably following a severe wildfire in southern Australia (Hohnen et al., 2021 ). In contrast, a GPS study in northern Australia found that cats strongly selected for areas recently burnt by severe prescribed fires and containing high prey abundance (McGregor et al., 2014 ).…”

First you get the money, then you get the power: Comparing the cost and power of monitoring programs to detect changes in occupancy of a threatened marsupial predator

“…Thus, the likelihood of a quoll encountering a live trap (assuming quolls were present at the site), was also greater. Whilst a number of previous studies have directly compared the capacity of live and camera traps to detect species (Hohnen et al, 2019; Richardson et al, 2018; Welbourne et al, 2015), the results of these studies are mixed, likely due to a combination of varying species habits, camera models, live trap methods, intensities in trapping effort, and bait use. Comparisons with our own results are therefore unlikely to be useful.…”

“…Calculating the power of a design allows us to determine whether our methods have the potential to produce a statistically significant result, when the effect size (in this case a change in occupancy) is biologically important (Guillera‐Arroita & Lahoz‐Monfort, 2012). Therefore, power analysis provides an important and useful metric to compare alternate trap designs using data from existing monitoring programs (Gálvez et al, 2016; Hohnen et al, 2019; Ward et al, 2017).…”

“…Many studies have directly compared the effectiveness of live and camera trapping surveys for monitoring wildlife populations (De Bondi et al 2010, Welbourne et al, 2015), although cost comparisons between the two methods have primarily focused on resource requirements for optimizing detection probabilities. For example, Hohnen et al (2019) found that camera traps are more cost effective than live traps for detecting Kangaroo Island dunnarts ( Sminthopsis fuliginosus aitkeni ). However, costing designs based solely on optimizing detectability can be problematic (Quinn and Keough 2002).…”