Removal and eradication of introduced species in a fenced reserve: Quantifying effort, costs and results

Abstract

Summary Given the difficulty of effective landscape‐scale control of introduced predators, fenced areas that exclude them (i.e. ‘mainland islands') can play an important role in conserving threatened mammal species in Australia. Despite this, the effort required to eradicate or remove introduced species from within fenced areas remains poorly quantified. This study was conducted at Mt Gibson Wildlife Sanctuary in semi‐arid Western Australia, where a 43 km predator‐exclusion fence surrounding 7832 ha was completed in June 2014. The subsequent effort expended in eradicating feral Cat (Felis catus) and removing European Rabbit (Oryctolagus cuniculus) populations was logged daily during 11 months of active population removal and 3.5 months of monitoring. The total effort expended on cat eradication, rabbit removal and monitoring included over 4800 person‐hours of work and nearly 67,000 km of driving (of which 6700 km was for spotlighting), and the conduct of over 15,000 trap nights, 2300 km of sand tracking transects, and over 7800 camera‐trap nights. Total costs (in 2015 figures) were estimated at just over AUD $390,000, which equates to approximately $50 per hectare. Cage trapping was most efficacious for catching cats, although it took nine months to capture the last individual, which was detected independently by both sand tracking transects and camera traps. This research provides baseline data on the resources required for future eradication and removal projects, particularly those within fenced reserves.

The impact of a fox‐ and cat‐free safe haven on the bird fauna of remnant vegetation in southwestern Australia

“…Surveys were conducted over 6 years: 2012–2017. Surveys commenced 3 years prior to the final eradication of cats in May 2015 (no foxes were found inside the safe haven post closure of the fence) until 3 years post eradication (Ruykys & Carter ). Note that the surveys from 2013 to 2015 extended over the period of fence construction (September 2013–June 2014) and eradication/post‐eradication monitoring (June 2014–August 2015).…”

Rapid evolution in predator‐free conservation havens and its effects on endangered species recovery

“…The setup costs of conservation fences vary markedly among countries, landscapes, and the taxa intended for isolation. Set‐up costs of between US$8500 and 29,000/km of fence in Australia (Moseby & Read 2006; Ruykys & Carter 2019) and up to US$100,000/km (KRWSSC 1994; Hayward & Kerley 2009) in New Zealand have been reported. Maintenance costs are variable, context‐dependent, and largely unknown but are required in perpetuity.…”

Feral cat GPS tracking and simulation models to improve the conservation management of night parrots

“…Recently developed poison delivery systems that exploit cat grooming behaviour show some promise (Moseby et al 2020); however, they rely on installation along predictable pathways where target predators move, such as watercourses, which can frequently be inundated. For the foreseeable future, cat control must rely largely on refining existing control techniques, both direct and indirect, via habitat management (Ruykys and Carter 2019). This means developing integrated strategies that use multiple control methods, sensitive land management that improves the quality of the resources available for the potentially affected species, and most significantly, gaining a better understanding of cat movements and behaviour to target control programs more cost-effectively (Comer et al 2020).…”