The impact of cats and foxes on the small vertebrate fauna of Heirisson Prong, Western Australia. II. A field experiment

Published source details Risbey D.A., Calver M.C., Short J., Bradley J.S. & Wright I.W. (2000) The impact of cats and foxes on the small vertebrate fauna of Heirisson Prong, Western Australia. II. A field experiment. Wildlife Research, 27, 223-235.
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This study is summarised as evidence for the following.

	Action	Category
	Remove or control predators using fencing and/or aerial nets Action Link
	Remove or control predators using lethal controls: Snakes & lizards Action Link
	Remove/control non-native mammals Action Link

Remove or control predators using fencing and/or aerial nets

A controlled, before-and-after study in 1990–1994 in mixed heath and dune habitat in Western Australia, Australia (Risbey et al. 2000) found that a fenced area with cat Felis catus and fox Vulpes vulpes control had similar numbers of geckos and skinks but fewer dragon lizards than unfenced areas with an without fox control. The effects of fencing and predator control cannot be separated. The number of geckos and skinks were similar in the fenced area (with fox and cat control) and unfenced (fox control or no control) area (geckos: 1–2 individuals/trap grid; skinks: 2 individuals/trap grid). Dragon lizard numbers were lower in the fenced area with fox and cat control (fox and cat control: 2 individuals/trap grid) compared to unfenced areas with fox control (fox control only: 5 individuals/trap grid) and unfenced, no control areas (no predator control: 7 individuals/trap grid). In areas with predator control, there was no clear change in reptile numbers from before control began (0–24 individuals/group/year) compared to the three years after control began (0–12 individuals/group/year). In 1991, a mainland peninsula was divided into three areas: one area (12 km²) where cats and foxes were controlled (using electrified fencing, poison baiting, or secondary poisoning by poisoning European rabbits Oryctolagus cuniculus, trapping or shooting); one area (120–200 km²) where foxes were controlled by baiting but cats were not targeted; and one area where no control occurred. Reptiles were monitored with six pitfall-trap and drift fence grids in each area (18 in total). Each grid had eight pitfall traps, 30–50 m apart. Sampling was conducted over three consecutive days in March–April and June–July in 1990–1994 in predator control areas and 1992–1994 in the area without predator control. Reptiles captured included dragon lizards, skinks, geckos, snakes, and a species of monitor lizard and blind snake but only species that could be toe clipped (dragon lizards, skinks and geckos) were included in analysis.

(Summarised by: Katie Sainsbury)
Remove or control predators using lethal controls: Snakes & lizards

A controlled, before-and-after study in 1990–1994 in mixed heath and dune habitat in Western Australia, Australia (Risbey et al. 2000) found that where cats Felis catus and foxes Vulpes vulpes, or just foxes were controlled, captures of reptiles did not increase. The number of geckos and skinks were similar in areas with cat and fox control, fox control only or no control (geckos: 1–2 individuals/trap grid; skinks: 2 individuals/trap grid). Dragon lizard numbers were lower in areas with greater predator control (cat and fox control: 2 individuals/trap grid; fox control only: 5 individuals/trap grid; no predator control: 7 individuals/trap grid). In areas with predator control, there was no clear change in reptile numbers from before control began (0–24 individuals/group/year) compared to the three years after control began (0–12 individuals/group/year). In 1991, a mainland peninsula was divided into three areas: one area (12 km²) where cats and foxes were controlled (using electrified fencing, poison baiting, or secondary poisoning by poisoning European rabbits Oryctolagus cuniculus, trapping or shooting); one area (120–200 km²) where foxes were controlled by baiting but cats were not targeted; and one area where no control occurred. Reptiles were monitored with six pitfall-trap and drift fence grids in each area (18 in total). Each grid had eight pitfall traps, 30–50 m apart. Sampling was conducted over three consecutive days in March–April and June–July in 1990–1994 in predator control areas and 1992–1994 in the area without predator control. Reptiles captured included dragon lizards, skinks, geckos, snakes, and a species of monitor lizard and blind snake but only species that could be toe clipped (dragon lizards, skinks and geckos) were included in analysis.

(Summarised by: Katie Sainsbury)
Remove/control non-native mammals

A before-and-after, controlled study in 1990–1994 in three sites in Western Australia, Australia (Risbey et al. 2000) found that where both cats Felis catus and foxes Vulpes vulpes were controlled, captures of small mammals increased but where only foxes were controlled, they decreased. Combined fox and cat control doubled small mammal abundances (after: 93; before: 42 individuals captured), but counts fell by 80% where only foxes were controlled (after: 7; before: 55 individuals captured). Small mammal abundances remained similar where no predators were controlled. See original paper for full results. In 1991, a mainland peninsula was divided in three areas in which 1) both cats and foxes were controlled by using an electrified fence, poison baiting (dried meat or cat food with 4.5 mg 1080 poison or via secondary poisoning by poisoning rabbits Oryctolagus cuniculus), and trapping or shooting (12 km²), 2) foxes were controlled by baiting (120-200 km²) but cats were not targeted or 3) no control occurred. Predators were surveyed over 3-4 nights in vehicles using spotlights (transect length: 7.5-20 km). Small mammals were monitored with six pitfall-trap grids in each area. Each grid had eight pitfall traps, 30–50 m apart. Sampling was conducted over three consecutive days in March–April and June–July in 1990–1994 in predator control areas and 1992–1994 in the area without predator control.

(Summarised by: Ricardo Rocha)