Peter Adams

Under ‘Western Shield’, the Western Australian Department of Environment and Conservation have aerially deployed 1080 meat baits seasonally over the last 15 years, covering almost 3.5 million hectares. Supplementary hand baiting is also carried out at high conservation significance sites (e.g. swamps harbouring threatened quokka populations). Previous bait uptake studies have predominantly focussed on unbaited areas, with foxes taking large percentages of baits. Few studies have investigated bait uptake under established baiting programs. We monitored 1080 bait uptake at 7 monthly hand-baited sites (baited over 14 years to protect known quokka populations). Our study shows that very few baits are taken by target pest species (i.e. <10% of baits were taken by foxes, cats or feral pigs), with non-target species, including quokkas (~45% of baits monitored), western grey kangaroos, bandicoots, brush tail possums, and mardo, frequently consuming baits. Baits were out for an average of 4 days after deployment; the longest duration monitored was 30 days. This study indicates that only a small proportion of baits are being taken by target feral species. The large uptake by non-target species, particularly native species that are already of conservation importance, suggests that greater focus needs to be placed on bait delivery mechanisms.

The microscopic examination of naturally infected plant material for the presence of Phytophthora cinnamomi can be problematic as structures such as hyphae, hyphal swellings, chlamydospores, and oospores are often indistinguishable from those of other oomycetes or fungi. Frequently, it would be useful to be able to clearly differentiate P. cinnamomi from other microorganisms, especially when trying to determine how the pathogen is surviving in plant material particularly in harsh environments. Consequently, the lack of stains that can clearly and definitively localise hyphae and reproductive structures of P. cinnamomi within plant material is a limitation in increasing our understanding of the biology of the pathogen in susceptible and tolerant plant species in different ecosystems. This study demonstrates that a P. cinnamomi specific, fluorescently labelled DNA probe can be used to specifically detect and visualise P. cinnamomi in plant material using fluorescent in situ hybridization (FISH) without damage to plant or pathogen cell integrity. The method will allow us to more accurately study plant‐P. cinnamomi interactions in plants, and to be particularly useful in naturally infected material.

Conducting population studies on elusive species can be challenging. Despite intensive sampling effort, individuals can vary markedly in their trappability. These differences in detection probabilities are problematic for population estimates, where models incorporate assumptions that, if they are present within an area, all animals have an equal probability of being trapped. This study investigates the use of remote cameras to estimate detectability of a medium-sized macropod. We conducted intensive monitoring of quokkas (Setonix brachyurus) at four riparian sites in southwest Western Australia. Quokkas were trapped (seasonally over 18 months) and marked. Camera traps were placed out for 12 months in the vicinity of the trapping area. Camera trap events were reviewed and animals were classified as marked or not-marked. Animals were identified from photos as adult or juvenile and sexed (presence of pouch young, head size) where possible. Cameras indicated the presence of trap-shy animals which had not been marked during the course of the 18 months trapping, and allowed the estimation of detection probabilities for different cohorts. We conclude that camera trapping can enhance the robustness of population estimates of these elusive animals.

The quokka is a medium sized macropod endemic to southwest WA and two islands: Rottnest and Bald. Quokkas were once ‘commonly observed’ in swamps, although few surveys were conducted to establish historical presence. Quokkas suffered a major decline in the 1930s; by the 1950s, the quokka was thought to be extinct on the mainland. Fox predation was highlighted as an ongoing threat and fox baiting began in the mid-1990s targeting protection of this species (and other native fauna). Post-fox control monitoring at eight sites in the northern jarrah forest (1998-2000; Hayward and colleagues) identified small, fragmented populations, but no detectable response to fox baiting. The aim of our research was to establish the current status of quokka populations at these sites (7 of the 8 sites were suitable). Seasonal trapping during 2010-2011 indicated that these populations have increased over the last decade: trap success of the present study (9.4 new individuals/100 trap nights; 85 individuals over 900 trap nights) was substantially higher than previously (0.3 new individuals/100 trap nights; 71 individuals over 21,287 trap nights). Viable quokka populations were found in six of the seven sites surveyed, including two where quokkas had been pronounced ‘locally extinct’. Unlike a number of other native mammal species, and contrary to predictions of further decline, northern jarrah forest quokka populations have increased over the past decade. The quokka may be one ‘good news story’ for native species recovery in WA.

Since the 1970s, there has been a decreasing trend in annual rainfall coupled with increasing temperatures in southwest Western Australia. Over the last decade, this region has experienced three drought years. Models of future groundwater levels in the northern jarrah forest show decreasing groundwater availability, which is particularly apparent within riparian zones. These changes will affect vegetation assemblages present and the fauna which rely on this habitat. The quokka, a Vulnerable medium-sized macropod relies on dense riparian assemblages for food and refuge. This study presents data predicting potential impacts of ongoing reductions in water availability and potential forest management options in a drying climate. These management options will have direct impacts on quokkas, based on their known habitat preferences, and will potentially influence survival of the already fragmented populations of these iconic animals.

Viewing of Phytophthora cinnamomi by microscopic examination in planta is often difficult as structures such as hyphae, chlamydospores and oospores are often indistinguishable from those of other fungi with histological stains not enabling species differentiation. This lack of staining specificity makes the localisation of P. cinnamomi hyphae and reproductive structures within plant tissue difficult, especially in woody tissues. This study demonstrates that utilising a species-specific fluorescently labelled DNA probe allowed P. cinnamomi to be specifically detected and visualised using fluorescent in situ hybridisation (FISH) without damage to plant or pathogen cell integrity. This approach provides a new application of FISH with potential use in the study of plant-pathogen interactions in planta.

Feral pigs have long been implicated as vectors in the spread of the plant pathogen Phytophthora cinnamomi. The wallowing and rooting activities of feral pigs predispose them to the transport of infested soil. These activities not only disturb the soil structure but also reduce leaf litter and vegetation cover which can lead to an increased susceptibility of an area to colonisation with P. cinnamomi. The non-fastidious diet and use of rub and tusk trees by feral pigs may also represent an avenue of pathogen spread. However, there is very little evidence to support these ideas. Replicated feeding trials using P. cinnamomi inoculated millet seed, fine roots and pine have shown that the pathogen can survive passage through the pig gut, in some instances for up to seven days before being passed. The study is also investigating the home range of pigs within the forest and potential distances over which spread is likely to occur. The controlled experiments and field work from this research will be presented and the implications for the management of feral pig populations as an important component of P. cinnamomi management will be discussed.