Jennyffer Cruz Bernal

Project: Effects of predation and resource availability on western brushtail possum populations.

The establishment of the red fox (Vulpes vulpes) has coincided with the extinction or near extinction of several native species. The effects of a fox control program in the Northern Jarrah Forest (NJF) of Western Australia were monitored from 1994 until 2000 (termed operation Foxglove) and an increase in abundance of many native species including the western brushtail possum (Trichosurus vulpecula hypoleucus) was observed in baited areas relative to unbaited areas.

In light of these positive results, the largest aerial baiting program for the control of foxes in Australia (termed Western Shield) was introduced across the southwest of Western Australia. However, over the years, some of the native populations, including T. v. hypoleucus, have continued to decline despite ongoing fox control, suggesting that either fox control has become ineffective or that factors other than fox predation are limiting native populations. Research is needed to determine which factors are causing the declines of native populations in the northern jarrah forest in order to ensure their conservation.

This project seeks to test the hypothesis that resource availability (den and food) and predation limit western brushtail possum populations in the northern jarrah forest and impact their behaviour at micro- and macro-habitat scales.

This PhD project is part of a multi-project looking at whether mesopredator release has occurred in the northern jarrah forest of Western Australia as a result of long-term fox control and if so, the impacts on subordinate predators (mesopredators) and prey species. The project is a collaboration between the Department of Environment and Conservation (DEC) and the Invasive Animals Cooperative Research Centre.


Environmental Science Degree (Honours), Monash University.

Jennyffer has always had a passion for environmental issues and lately has discovered an interest in ecology.  Her PhD project allows her to combine these interests to hopefully develop better management strategies for the protection of endangered species.


Cruz, J., Leung, L. K.-P., Lisle, A., Rivera, D. F., Staples, L., Smith, M. (in press). Grain, pellet and wax block bait take by the house mouse (Mus musculus, Linnaeus 1758) and non-target species: implications for mouse eradications on coral cay islands in the Great Barrier Reef, Australia. Integrative Zoology.

Sutherland, D. R., Glen, A. S. and Cruz, J. (2008). An alternative spool-and-line device for medium sized animals. Australian Mammalogy. 30(2): 89-90.

de Tores PJ, Marlow N, Algar D, Morris KD, Glen AS, Sutherland DR, Cruz J, Bryant J (2007) Mesopredator release – a response to 1080 control of foxes in WA. What is the evidence and what are we doing? Ecological Society of Australia, Perth WA.


Project details

CRC Program:
Uptake of Products and Strategies

Department of Environment and Conservation (WA)
University of Queensland
Field work primarily in the Northern Jarrah forest of WA.

Mr Paul de Tores (WA DEC)
Dr Luke Leung (UQ, Gatton)
Dr Duncan Sutherland (WA DEC)
Dr Nicky Marlow (WA DEC)

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