Evaluation of camera placement for detection of free‐ranging carnivores; implications for assessing population changes

Abstract

1. Introduced carnivores are often cryptic, making it difficult to quantify their presence in ecosystems, and assess how this varies in relation to management interventions. Survey design should thus seek to improve detectability and maximize statistical power to ensure sound inference regarding carnivore population trends. Roads may facilitate carnivore movements, possibly leading to high detectability. Therefore, targeting roads may improve inferences about carnivore populations. 2. We assessed our ability to monitor feral cats Felis catus and red foxes Vulpes vulpes on-and off-road, with explicit consideration of the location of monitoring sites on our ability to detect population changes. We also assessed whether there was evidence of spatial or temporal interaction between these species that might influence their roaduse. 3. Surveys were conducted in a conservation reserve in southeastern Australia between 2016 and 2018. At each of 30 sites, we deployed two motion-sensor cameras, one on-road, and the other off-road. Using occupancy models, we estimated cat and fox occupancy and detectability, and conducted a power analysis to assess our ability to detect declines in occupancy under three monitoring regimes (efforts targeted equally on-and off-road, efforts targeted entirely off-road and efforts targeted entirely onroad). 4. On average, on-road detectability was seven times higher for cats and three times higher for foxes. Targeting survey effort on-road yielded the greatest power for detecting declines in both species, but our ability to detect smaller declines decreased with decreasing initial occupancy probability. No level of decline was detectable for cats This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Space use and interactions of two introduced mesopredators, European red fox and feral cat, in an arid landscape

“…This mirrors the findings of Geyle et al. (2020) in western Victoria, but contrasts with the results of Fancourt et al. (2019) that found little diurnal activity by feral cats during winter months.…”

Carnivore Detection at the Domestic/Wildlife Interface within Mpumalanga Province, South Africa

“…Although call-up surveys have been used for years, alternatives are available to either support [ 21 ] or replace traditional call-up surveys. Capture-recapture methods using camera traps can be an improvement over the traditional call-up survey [ 22 , 45 ]. Camera traps can be used to validate call-up survey sites and add additional information to the call-up survey technique.…”

Assessing the benefits of integrated introduced predator management for recovery of native predators

“…Cameras were placed within security boxes attached to metal poles 90–100 cm high and concreted in the ground along with the track network to reduce theft. Positioning cameras along tracks can increase predators' detectability (Hradsky et al 2017; Geyle et al 2020; Wysong et al 2020). Regrettably, on retrieving our cameras, we found that 20 units were stolen, with almost all taken from the unbaited western block.…”