Broad-scale Control Research Articles

A synoptic bridge linking sea salt aerosol concentrations in East Antarctic snowfall to Australian rainfall

Previous research has shown that aerosol sea salt concentrations (Southern Ocean wind proxy) preserved in the Law Dome ice core (East Antarctica) correlate significantly with subtropical eastern Australian rainfall. However, physical mechanisms underpinning this connection have not been established. Here we use synoptic typing to show that an atmospheric bridge links East Antarctica to subtropical eastern Australia. Increased ice core sea salt concentrations and wetter conditions in eastern Australia are associated with a regional, asymmetric contraction of the mid-latitude westerlies. Decreased ice core sea salt concentrations and drier eastern Australia conditions are associated with an equatorward shift in the mid-latitude westerlies, suggesting greater broad-scale control of eastern Australia climate by southern hemisphere variability than previously assumed. This relationship explains double the rainfall variance compared to El Niño-Southern Oscillation during late spring-summer, highlighting the importance of the Law Dome ice core record as a 2000-year proxy of eastern Australia rainfall variability.

Spatial Variability of Silver Carp Population Demographics in a Large Tributary River

AbstractSilver Carp Hypophthalmichthys molitrix have expanded their range to encompass most of the Mississippi River basin, including much of the Missouri River. However, there is a paucity of information concerning Silver Carp in the Missouri River basin, especially in tributaries. Little is known about how Silver Carp function in these tributaries or how connectivity with a main‐stem river can influence population demographics within either system. The Kansas River is a tributary to the Missouri River and has multiple physical anthropogenic barriers creating varying levels of connectivity within the system, as well as with the Missouri River. These varying levels of connectivity, or lack thereof, provide a unique opportunity to examine population demographics in river segments separated by barriers. We collected Silver Carp from upstream and downstream of the first two barriers on the Kansas River in the summers of 2018 and 2019. No Silver Carp were captured upstream of a hydropower dam at river kilometer 84 but were found upstream of a water diversion weir at river kilometer 24. Catch rates of adult Silver Carp were lower in the reach above the weir, but Silver Carp caught in this reach exhibited greater growth rates than Silver Carp captured below the weir. Catch rates of juveniles were also lower in the reach above the weir. Limited connectivity within the Kansas River via the water diversion weir could influence size structure and catch rates of Silver Carp captured above and below the weir. Lack of juveniles above the weir indicates that reproduction may be limited in this reach, and river conditions below the weir may be more suitable for rearing juvenile Silver Carp. This information is important for understanding Silver Carp population demographics across a range of river environments, providing critical information for the development and implementation of broadscale control plans.

Efficacy and safety of Eradicat® feral cat baits in eastern Australia: population impacts of baiting programmes on feral cats and non-target mammals and birds

Reducing the damage caused by feral cats (Felis catus) to wildlife, livestock and human health is a key objective for many land managers and human health agencies globally. The lack of safe and efficacious lethal control tools in many regions, however, makes the control of feral cats and their impacts challenging. We performed a baiting trial in central Queensland to measure the efficacy and safety of Eradicat®, a feral cat bait currently approved for use only in the state of Western Australia, as a potential tool for the broadscale control of feral cats in eastern Australian environments. We used camera traps, cat-borne GPS collars and chemical residue analysis to monitor mortality and changes in feral cat populations following baiting. We also used camera traps and bird count surveys to monitor the response of key at-risk non-target species, specifically wild dogs (Canis familiaris), common brush-tailed possums (Trichosurus vulpecula) and 10 bird species at risk of consuming baits. Feral cat abundance reduced significantly (29–40%) following baiting, with reductions observed across 83% of the site. There were no significant changes in wild dog, possum or potentially bait-consuming bird populations following baiting. Our findings suggest that Eradicat® could potentially be a safe and efficacious tool for the landscape control of feral cats at some sites in eastern Australia. Future research is required to test the safety and efficacy of Eradicat® at other sites in eastern Australia, as suites of non-target species will vary among sites in different environments.

Biocontrol of the Common Carp (Cyprinus carpio) in Australia: A Review and Future Directions

Invasive pest species are recognized as one of the important drivers of reduced global biodiversity. In Australia, the 267 invasive plant, animal and microbial species, established since European colonization in the 1770s, have been unequivocally declared the most important threat to species diversity in this country. One invasive pest, the common carp (Cyprinus carpio), has been targeted in an integrated pest management plan that might include cyprinid herpesvirus 3 (CyHV-3) as a potential biocontrol agent. The species-specificity of the released virus (and of field variants that will inevitably arise) has been assessed, and the virus judged to be safe. It has also been hypothesised that, because the virulence of the CyHV-3 will likely decline following release, the virus should be used strategically: initially, the aim would be to markedly reduce numbers of carp in naive populations, and then some other, as yet uncertain, complementary broad-scale control measure would knock-down carp numbers even further. Brief results are included from recent studies on the modelling of release and spread of the virus, the ecological and social concerns associated with virus release, and the restoration benefits that might be expected following carp control. We conclude that, while further work is required (on the virus, the target species, environmental issues, and especially the identification of a suitable broad-scale complementary control measure), optimism must prevail in order to ensure an eventual solution to this important environmental problem.

On the right track: placement of camera traps on roads improves detection of predators and shows non-target impacts of feral cat baiting

Abstract ContextTo understand the ecological consequences of predator management, reliable and accurate methods are needed to survey and detect predators and the species with which they interact. Recently, poison baits have been developed specifically for lethal and broad-scale control of feral cats in Australia. However, the potential non-target effects of these baits on other predators, including native apex predators (dingoes), and, in turn, cascading effects on lower trophic levels (large herbivores), are poorly understood. AimsWe examined the effect that variation in camera trapping-survey design has on detecting dingoes, feral cats and macropodids, and how different habitat types affect species occurrences. We then examined how a feral cat poison baiting event influences the occupancy of these sympatric species. MethodsWe deployed 80 remotely triggered camera traps over the 2410-km2 Matuwa Indigenous Protected Area, in the semiarid rangelands of Western Australia, and used single-season site-occupancy models to calculate detection probabilities and occupancy for our target species before and after baiting. Key resultsCameras placed on roads were ~60 times more likely to detect dingoes and feral cats than were off-road cameras, whereas audio lures designed to attract feral cats had only a slight positive effect on detection for all target species. Habitat was a significant factor affecting the occupancy of dingoes and macropodids, but not feral cats, with both species being positively associated with open woodlands. Poison baiting to control feral cats did not significantly reduce their occupancy but did so for dingoes, whereas macropodid occupancy increased following baiting and reduced dingo occupancy. ConclusionsCamera traps on roads greatly increase the detection probabilities for predators, whereas audio lures appear to add little or no value to increasing detection for any of the species we targeted. Poison baiting of an invasive mesopredator appeared to negatively affect a non-target, native apex predator, and, in turn, may have resulted in increased activity of large herbivores. ImplicationsManagement and monitoring of predators must pay careful attention to survey design, and lethal control of invasive mesopredators should be approached cautiously so as to avoid potential unintended negative ecological consequences (apex-predator suppression and herbivore release).

Optimal control of irrupting pest populations in a climate-driven ecosystem.

Irruptions of small consumer populations, driven by pulsed resources, can lead to adverse effects including the decline of indigenous species or increased disease spread. Broad-scale pest management to combat such effects benefits from forecasting of irruptions and an assessment of the optimal control conditions for minimising consumer abundance. We use a climate-based consumer-resource model to predict irruptions of a pest species (Mus musculus) population in response to masting (episodic synchronous seed production) and extend this model to account for broad-scale pest control of mice using toxic bait. The extended model is used to forecast the magnitude and frequency of pest irruptions under low, moderate and high control levels, and for different timings of control operations. In particular, we assess the optimal control timing required to minimise the frequency with which pests reach ‘plague’ levels, whilst avoiding excessive toxin use. Model predictions suggest the optimal timing for mouse control in beech forest, with respect to minimising plague time, is mid-September. Of the control regimes considered, a seedfall driven biannual-biennial regime gave the greatest reduction in plague time and plague years for low and moderate control levels. Although inspired by a model validated using house mouse populations in New Zealand forests, our modelling approach is easily adapted for application to other climate-driven systems where broad-scale control is conducted on irrupting pest populations.

Evaluation of risks for two native mammal species from feral cat baiting in monsoonal tropical northern Australia

Context Feral cats are a significant threat to native wildlife and broad-scale control is required to reduce their impacts. Two toxic baits developed for feral cats, Curiosity® and Hisstory®, have been designed to reduce the risk of baiting to certain non-target species. These baits involve encapsulating the toxin within a hard-shelled delivery vehicle (HSDV) and placing it within a meat attractant. Native animals that chew their food more thoroughly are predicted to avoid poisoning by eating around the HSDV. This prediction has not been tested on wild native mammals in the monsoonal wet–dry tropics of the Northern Territory. Aim The aim of this research was to determine whether northern quolls (Dasyurus hallucatus) and northern brown bandicoots (Isoodon macrourus) would take feral cat baits and ingest the HSDV under natural conditions on Groote Eylandt. Methods We hand-deployed 120 non-toxic baits with a HSDV that contained a biomarker, Rhodamine B, which stains animal whiskers when ingested. The species responsible for bait removal was determined with camera traps, and HSDV ingestion was measured by evaluating Rhodamine B in whiskers removed from animals trapped after baiting. Key results During field trials, 95% of baits were removed within 5 days. Using camera-trap images, we identified the species responsible for taking baits on 65 occasions. All 65 confirmed takes were by native species, with northern quolls taking 42 baits and northern brown bandicoots taking 17. No quolls and only one bandicoot ingested the HSDV. Conclusion The use of the HSDV reduces the potential for quolls and bandicoots to ingest a toxin when they consume feral cat baits. However, high bait uptake by non-target species may reduce the efficacy of cat baiting in some areas. Implications The present study highlighted that in the monsoonal wet–dry tropics, encapsulated baits are likely to minimise poisoning risk to certain native species that would otherwise eat meat baits. However, further research may be required to evaluate risks to other non-target species. Given the threat to biodiversity from feral cats, we see it as critical to continue testing Hisstory® and Curiosity® in live-baiting trials in northern Australia.

Foraging Ranges of Insectivorous Bats Shift Relative to Changes in Mosquito Abundance

The need to develop effective management strategies for insectivorous bat populations requires an understanding of factors influencing habitat use. Availability of pest prey, such as mosquitoes is likely to be one such factor. To assess whether this is the case, we radio-tracked Vespadelus vulturnus Thomas (little forest bat), a predator of Aedes vigilax Skuse (saltmarsh mosquito), in saltmarsh and adjacent coastal swamp forest during periods of high and low Ae. vigilax abundance. When mosquito abundance in structurally-open saltmarsh was similar to the more cluttered coastal swamp forest, use of saltmarsh by V. vulturnus was disproportionately greater than its availability, with saltmarsh selected preferentially for foraging. However, at times of low Ae. vigilax abundance in saltmarsh, use of saltmarsh by V. vulturnus was reduced and all habitats were used in proportion to availability in the study area. This is the first radio-tracking study to demonstrate a shift in foraging range by an insectivorous bat species correlated with fluctuations in the distribution and abundance of a particular prey resource. The shift in foraging range by V. vulturnus, corresponding with a spatio-temporal variation in abundance of Ae. vigilax highlights the importance of mosquitoes as a dietary item. Broadscale pest control of Ae. vigilax may have ecological implications for the diet and habitat use of V. vulturnus. An adaptive management approach is proposed, whereby careful monitoring of insectivorous bat populations is recommended before and after any application of broadscale mosquito control measures. We also suggest a precautionary approach is taken such that broadscale control of mosquitoes avoids the lactation period of bats, a time when their energetic demands are greatest and when there is reduced risk of contracting mosquito-borne diseases transmitted by Ae. vigilax.

Why 0.02%? A review of the basis for current broadscale control of rabbits in New Zealand

Rabbit (Oryctolagus cuniculus) populations in many parts of New Zealand have begun to increase dramatically as the impact of rabbit haemorrhagic disease wanes, and aerial poisoning control operations have resumed. Aerial 1080 poisoning of rabbits has historically used high prefeed and toxic bait sowing rates and low toxic loading. We review the extent to which this practice is based on a good mechanistic understanding of the process, or has evolved by trial and error to find a workable and affordable system. Current operational practices appear to have resulted from attempts to provide solutions to poor bait quality and concerns about the welfare of livestock. Current research on 1080 use on rabbits in Australia and possums (Trichosurus vulpecula) in New Zealand suggests that higher toxic loading and decreased sowing rates may be as effective as current practice, but with substantive reductions in the costs associated with control methods and the amount of toxin applied to the environment.

Eradication of rabbits from landscape scale exclosures: pipedream or possibility?

Summary High densities of the European Rabbit (Oryctolagus cuniculus) were eradicated from 60 km2 of the Arid Recovery Reserve between 1996 and 2001. Eradication was possible due to an initial knockdown caused by rabbit haemorrhagic disease, followed by effective exclusion fencing, broadscale poison baiting, targeted shooting, warren destruction and trapping on rabbit burrows and buckheaps. The efficacy of different broadscale control and intensive rabbit eradication techniques was subsequently estimated in a 26 km2 expansion to the Reserve from 2002 to 2006. Non-target implications of these control techniques were also assessed where possible. An estimated 8000 rabbits were removed in total from both areas and results suggest that rabbit eradication is possible at a landscape scale. Strategies for eliminating rabbits from confined areas are suggested.

The use of poison baits to control feral cats and red foxes in arid South Australia I. Aerial baiting trials

Context Feral cats and foxes pose a significant threat to native wildlife in the Australian arid zone and their broadscale control is required for the protection of threatened species. Aims The aim of this research was to trial aerial poison baiting as a means of controlling feral cats and foxes in northern South Australia. Methods Eradicat baits or dried meat baits containing 1080 poison were distributed by air over areas of 650 to 1800 km2 in trials from 2002 to 2006. Different baiting density, frequency, bait type and area were trialled to determine the optimum baiting strategy. Baiting success was determined through mortality of radio-collared animals and differences in the track activity of cats and foxes in baited and unbaited areas. Key results Quarterly aerial baiting at a density of 10 baits per square km successfully controlled foxes over a 12-month period, while annual baiting led to reinvasion within four months. Despite the majority of radio-collared cats dying after baiting, a significant decline in cat activity was only recorded during one of the eight baiting events. This event coincided with extremely dry conditions and low rabbit abundance. Rabbit activity increased significantly in baited areas over the study period in comparison with control areas. Conclusions Despite trialling different baiting density, frequency and area over a five-year period, a successful long-term baiting strategy for feral cats could not be developed using Eradicat baits or dried meat baits. Implications Broadscale control of feral cats in the arid zone remains a significant challenge and may require a combination of control methods with flexible delivery times dependent on local conditions. However, it is doubtful that current methods, even used in combination, will enable cat numbers to be reduced to levels where successful reintroductions of many threatened wildlife species can occur.

Diffusional Self‐Organization in Exponential Layer‐By‐Layer Films with Micro‐ and Nanoscale Periodicity

The layer-by-layer (LBL) assembly technique is currently one of the most widely utilized methods for the preparation of nanostructured, multilayered thin films. The structure of LBL films is typically controlled by varying the deposition sequence of adsorbed layers, leading to stratified assemblies. For specific, non-spherical inorganic LBL components, such as sheets, or axial nanocolloids, such as nanotubes, nanowires, nanowiskers, or nanorods, the structure of the films can also be controlled by their orientation. As such, clay nanosheets spontaneously adsorb almost exclusively in the orientation parallel to the substrate, whilst assembly of axial nanocolloids under conditions of shear or dewetting results in partial alignment of the fibrous components. Morphological or structural control of the multilayers can also be imparted by the choice of the assembly method (e.g. spin coating versus dip coating), the assembly conditions, or post-assembly processing of the assembly. The shape and surface morphology of the assemblies can also be tailored by the structure or shape of the substrate, as has been shown in the preparation of hollow capsules or sculptured/perforated membranes. Both polymers and nanoparticles exhibit strong tendencies toward self-organization. This effect has not been utilized in the LBL assemblies, except for the recent observation by Yoo et al. of the organization of rod-shaped viruses on the surface of a film consisting of a few bilayers. Overall, the need for more sophisticated degrees of structural organization is quite extensive and commensurate with the increasingly complex applications for which they are being prepared. Importantly, this control must be possible on a nanometer and a micrometer scale. In principle, the LBL approach does allow such a broad-scale control, but microscale films require deposition of a great number of layers in traditional LBL. It would be exceptionally advantageous to design a method that can lead to well-organized materials combining fast deposition and hierarchical nano-, micro-, and macroscopic levels of organization. To achieve this aim, a degree of smartness and the presence of elements of selforganization in the film will most likely be required. Layered systems with alternating microand nanostrata of a stiff and an elastic nature might be particularly interesting because of mechanical properties associated with the distribution of stress in hierarchical structures and predicted theoretically unique mechanical properties. Exponentially grown LBL (e-LBL) films are multilayers in which polymer chains retain their mobility and diffuse through the deposited strata. The degree of mobility makes possible to observe self-organization phenomena in such structures. Herein, we show that a system with alternating nanometerand micrometer-scale layers of predominantly inorganic (stiff) and polymeric (elastic) layers forms upon LBL deposition of poly(diallyldimethylammonium chloride) (PDDA), poly(acrylic acid) (PAA), and sodium montmorillonite clay nanosheet (MTM) multilayers. Despite the expectations of fairly homogeneous coatings in the framework of both traditional and exponential LBL deposition, the deposition sequence (PDDA/PAA/PDDA/MTM)n (n is the number of deposition cycles), results in well-defined indexing of the films after the first few cycles, with a periodicity of (1.7 0.4) mm for 10 min deposition, and superimposed organization of MTM sheets at the interfaces with 0–10 nm spacing (Figure 1). The indexing can be further controlled by varying the deposition times for polyelectrolytes (Supporting Information, Figure S1). A typical assembly included alternate immersion of a glass slide into solutions of the polycation PDDA and an [*] Prof. N. A. Kotov Departments of Chemical Engineering, Materials Science and Engineering, and Biomedical Engineering University of Michigan, Ann Arbor, MI 48109 (USA) Fax: (+1)734-764-7453 E-mail: kotov@umich.edu

The impact of introduced predators on two threatened prey species: A case study from western New South Wales

Summary Since European settlement, many Australian mammals have become extinct; numerous others survive within substantially reduced ranges. Predation by the Red Fox (Vulpes vulpes) and House Cat (Felis catus) are two of the major drivers of this decline. The demise of Australia's native fauna continues, with ground‐nesting birds such as the Malleefowl (Leipoa ocellata) now being at greatest risk of extinction. In regions of Western Australia, this situation has been partially reversed through the broadscale control of the Fox and the re‐introduction of locally extinct species. In this paper, we review research undertaken on Yathong Nature Reserve (YNR) in western New South Wales to (i) evaluate current threats, and (ii) assess our ability to restore locally extinct species across this particular landscape. We conducted releases of both the Malleefowl and Brush‐tailed Bettong (Bettongia penicillata), two species that were once common in the region. Despite the potential for food resources to have been diminished by exotic herbivores, we found no evidence that food shortage was a limiting factor for either of the two species we released. Predation by the Fox was the greatest single cause of Malleefowl mortality. Localized, intensive ground baiting of the Fox was essentially ineffective in mitigating this threat, whereas broadscale aerial baiting substantially enhanced Malleefowl survival, at least during the first few years. Accordingly, thrice‐yearly aerial baiting for the Fox has been conducted on YNR since 1996. Despite this, and a long‐term restocking programme, the size of the Malleefowl population has not increased since aerial baiting began. The release of the Brush‐tailed Bettong into YNR in 2001 confirmed the effectiveness of the ongoing fox‐control programme but demonstrated the detrimental impact of another introduced predator – the Cat. We conclude that, while current management actions continue, the Fox is no longer a threat to wildlife on YNR, and suggest that the Cat is now the major impediment to both the recovery of depleted faunal populations (including the Malleefowl) and the restoration of locally extinct species (such as bettongs) within this landscape.

Migration of feral pigs (Sus scrofa) in rainforests of north Queensland: fact or fiction?

The Wet Tropics bioregion of north Queensland has been identified as an area of global significance. The world-heritage-listed rainforests have been invaded by feral pigs (Sus scrofa) that are perceived to cause substantial environmental damage. A community perception exists of an annual altitudinal migration of the feral-pig population. The present study describes the movements of 29 feral pigs in relation to altitudinal migration (highland, transitional and lowland areas). Feral pigs were sedentary and stayed within their home range throughout a 4-year study period. No altitudinal migration was detected; pigs moved no more than a mean distance of 1.0 km from the centre of their calculated home ranges. There was no significant difference between the mean (±95% confidence interval) aggregate home ranges for males (8.7 ± 4.3 km2, n = 15) and females (7.2 ± 1.8 km2, n = 14). No difference in home range was detected among the three altitudinal areas: 7.2 ± 2.4 km2 for highland, 6.2 ± 3.9 km2 for transitional and 9.9 ± 5.3 km2 for lowland areas. The aggregate mean home range for all pigs in the present study was 8.0 ± 2.4 km2. The study also assessed the influence seasons had on the home range of eight feral pigs on the rainforest boundary; home ranges did not significantly vary in size between the tropical wet and dry seasons, although the mean home range in the dry season (7.7 ± 6.9 km2) was more than twice the home range in the wet season (2.9 ± 0.8 km2). Heavier pigs tended to have larger home ranges. The results of the present study suggest that feral pigs are sedentary throughout the year so broad-scale control techniques need to be applied over sufficient areas to encompass individual home ranges. Control strategies need a coordinated approach if a long-term reduction in the pig population is to be achieved.

Differential Particle Size Ingestion: Promoting Target-Specific Baiting of Feral Cats

Abstract Predation by feral cats (Felis catus) is believed to threaten the conservation of a range of terrestrial vertebrates in southeastern Australia, and new baiting techniques are sought for broad-scale control of feral cats. In southeastern Australia there are 34 native mammals that may consume meat baits, and ways to minimize their exposure to bait toxicants are needed. We determined the potential of cats to ingest larger particles relative to most nontarget species as a mechanism to increase baiting selectivity. Feral cats reliably ingested inert, spherical bearings up to 4.7 mm in diameter when the bearings were implanted within a specialized bait medium. Presence of bearings did not affect bait consumption relative to untreated baits. Repetitive ingestion was highly reliable in the first 9 days of a feeding trial and diminished only marginally in a consecutive trial. We presented captive plains rats (Pseudomys australis), fat-tailed dunnarts (Sminthopsis crassicaudata), eastern barred-bandicoots ...

Postglacial water-level changes of a small lake in southern Québec, Canada

Sediment stratigraphy and palaeobotanical data from five cores were used to reconstruct the postglacial water-level changes of a small lake in southern Québec. The cores were taken along two transects from the centre of the lake to the margins. Lake level was relatively high before 11 000 cal. BP, when sedimen tation was characterized by the deposition of silty gyttja (.13 000 cal. BP) and marl (13 000–11 000 cal. BP). From 11 000 to 7000 cal. BP, a sediment hiatus was indicated by the lack of two regional pollen zones between the marl and the overlying gyttja, suggesting either nondeposition or erosion of the previously deposited sedi ments due to a low lake level. The lake level was approximately 2 m lower than present on the basis of macrofossil assemblages. A rise in the water level of about 1 m occurred around 7000 cal. BP, which was interrupted by a second lowering between 6100 and 4400 cal. BP, as indicated by a hiatus in the pollen stratigra phy. During this low period, the water level was at least 2 m lower than present. The last 4400 years are characterized by a continuous rise. The lake-level fluctuations are broadly synchronous with other palaeo hydrological records in northeastern United States, Ontario, and Subarctic Québec, implying broad-scale climatic control.

Alteration of the clutch size of raptors in response to a change in prey availability: evidence from control of a broad-scale rabbit infestation.

The claim that the clutch size of three species of raptor-the wedge-tailed eagle (Aquila audax), little eagle (Hieraaetus morphnoides) and brown goshawk (Accipiter fasciatus)-increased following the introduction and spread of the rabbit (Oryctolagus cuniculus) in Western Australia was tested by comparing historical data contained in oological collections for all 24 Australian diurnal raptors and eight owls over three time-periods: before introduction of the rabbit, during the heyday of the rabbit, and after successful broad-scale control. No significant changes were found in clutch size of the little eagle either in Western Australia or more-southerly Australia in general. Clutch size of the wedge-tailed eagle, brown goshawk and whistling kite (Haliastur sphenurus) decreased significantly after rabbit control. Clutches of two eggs were more common for the wedge-tailed eagle and those of three and four eggs were more prevalent for the brown goshawk when rabbits were uncontrolled than when controlled. These changes were not due to a shift in laying date, suggesting instead an adaptive response to changes in food availability.

Expert advice for shrub control.

SHRUBKILL is a microcomputer based decision-support system which provides expert advice on the use of fie to control non-desirable shrubs and thus improve grazing potential in the semi-arid woodlands of eastem Australia. Pescribed fire is argued to be the only economically viable management option for broad-scale shrub control in these rangelands. Management decisions about "when" and "how" to bum and the cost and expected economic benefit of buming involve answering many difficult questions which can be aided by the advice of experts. However, these experts are not always available to give on-the-spot advice to managers. SHRUBKILL is a decision-support system that has incorporated the knowledge of fire-experts in an easy-to-use microcomputer program to: advise the user on what the "expert" would have recommended; provide detailed information supporting the expert's recommendation; and give summaries of the consultation. SHRUBKILL was written in BASIC on an IBM Personal Computer but it will run on IBMPC compatibles.