Fox control and rock-wallaby population dynamics — II. An update

Abstract

The population dynamics of five remnant rock-wallaby populations (Petrogale lateralis) persisting on granite outcrops in the central wheatbelt region of Western Australia were monitored over a six year period. From 1979 to 1982 all populations remained relatively static or declined for unknown reasons, but circumstantial evidence implicated fox predation. A fox control program was implemented in 1982 on two outcrops and was maintained for four years with the result that the two resident rock-wallaby populations increased by 138 and 223%. Two rock-wallaby populations occupying sites not subjected to fox control declined by 14 and 85%, and the third population increased by 29%. It was concluded that the fox has probably been a significant factor in the demise and decline of native mammals in the past, and that surviving populations are still at risk. Control of predation pressure on nature reserves was shown to be feasible from a management perspective.

Predator-baiting experiments for the conservation of rock-wallabies in Western Australia: a 25-year review with recent advances

“…93-96) on statistical grounds and by Caughley and Gunn (1996: p. 259) on methodological grounds. Four years later, the 1990 census and its analysis produced a more convincing outcome (Kinnear et al 1998). Hone (1999) suggested additional tests by converting unbaited control sites to baited sites and by comparing the observed rate of increase with the maximum rate of increase if all predation were removed.…”

“…Following the 1990 census (Kinnear et al 1998), we had planned to continue the experiment as described; however, when we considered the precarious state of the control (unbaited) populations from the first experiments, we amended the experiment because, in the absence of fox poisoning, unbaited control populations were unstable and extinction prone-an observation supported from RW surveys in the arid zone of WA (Pearson 1992). These concerns prompted us after the 1990 census to amend the baiting protocol by extending fox control to the original three control sites (as recommended by Hone 1999), and to re-establish a population at one site that had gone extinct (Querekin).…”

The identity of the Depuch Island rock-wallaby revealed through ancient DNA

“…Having undergone severe population retractions, the remaining animals are highly vulnerable to introduced predators (Kinnear et al 1988(Kinnear et al , 1998, inbreeding depression and a multitude of interacting anthropogenic factors that further threaten population viability. Offshore islands have provided a refuge for many species, and currently harbor 14 species of Australian mammals (Eldridge et al 1999) that are now extinct on the mainland.…”

“…DI is well known to anthropologists as an important site of Aboriginal rock art and engravings (Ride 1964) and was declared a sanctuary in 1958 for the protection of engravings and fauna (McCarthy 1961). The island was previously inhabited by several bird, reptile and mammal species including a rock-wallaby (recorded as a small kangaroo by Péron 1807, and as Petrogale lateralis by Stokes 1846), which became extinct as a consequence of predation by the introduced red fox (Vulpes vulpes) (Kinnear et al 1988(Kinnear et al , 1998. Rock-wallaby colonies were reported on DI at the mouth of the Balla Balla River and the animals were known to be present in 1964.…”

Beyond population regulation and limitation

“…Populations of endangered species like the rock-wallaby Petrogale lateralis may decline at low density or at high density, and population density alone tells us nothing about their predicted dynamics. Predation is inferred to be severe enough at all levels of density to cause population declines (Kinnear et al 1998).…”