Control tools : Requirements of tools to control feral cats

In 2008, the background document to the ‘Threat abatement plan for predation by feral cats’ (DEWHA 2008) considered the main control techniques for feral cats as trapping, shooting and exclusion fencing. Baiting was recognised as the most cost-effective method for broad-scale control, but was not commonly employed on the Australian mainland, although it had been used successfully in island eradications (Campbell et al. 2011). A sausage bait using 1080, Eradicat, had recently been developed and employed in Western Australia (Algar and Burrows 2004), but there were concerns over its application to the eastern states where native species are less tolerant of 1080 (Johnston et al. 2011). Development of an effective, humane cat-specific toxin and bait was seen as a high priority for feral cat management in Australia (DEWHA 2008). There has been progress on this front with development of the Curiosity bait using PAPP as a toxin (Johnston et al. 2011, Johnston et al. 2012) and other toxin delivery methods (Read 2010, Read et al. 2014). There have also been further applications of Eradicat, including on the mainland (Algar et al. 2013), and other control methods, and there is a better understanding of cat ecology and impacts, which will help improve strategies for their control. A review of control techniques and their application is thus timely

Demography of feral camels in central Australia and its relevance to population control

Since their release over 100 years ago, camels have spread across central Australia and increased in number. Increasingly, they are being seen as a pest, with observed impacts from overgrazing and damage to infrastructure such as fences. Irregular aerial surveys since 1983 and an interview-based survey in 1966 suggest that camels have been increasing at close to their maximum rate. A comparison of three models of population growth fitted to these, albeit limited, data suggests that the Northern Territory population has indeed been growing at an annual exponential rate of r = 0.074, or 8% per year, with little evidence of a density-dependent brake. A stage-structured model using life history data from a central Australian camel population suggests that this rate approximates the theoretical maximum. Elasticity analysis indicates that adult survival is by far the biggest influence on rate of increase and that a 9% reduction in survival from 96% is needed to stop the population growing. In contrast, at least 70% of mature females need to be sterilised to have a similar effect. In a benign environment, a population of large mammals such as camels is expected to grow exponentially until close to carrying capacity. This will frustrate control programs, because an ever-increasing number of animals will need to be removed for zero growth the longer that culling or harvesting effort is delayed. A population projection for 2008 suggests ~10 500 animals need to be harvested across the Northern Territory. Current harvests are well short of this. The ability of commercial harvesting to control camel populations in central Australia will depend on the value of animals, access to animals and the presence of alternative species to harvest when camels are at low density

Effectiveness of commercial harvesting in controlling feral-pig populations

Context. The feral pig (Sus scrofa) is a widespread pest species in Australia and its populations are commonly controlled to reduce damage to agriculture and the environment. Feral pigs are also a resource and harvested for commercial export as game meat. Although many other control techniques are used, commercial harvesting of feral pigs is often encouraged by land managers, because it carries little or no cost and is widely perceived to control populations. Aims. To use feral-pig harvesting records, density data and simple harvest models to examine the effectiveness of commercial harvesting to reduce feral-pig populations. Methods. The present study examined commercial harvest off-take on six sites (246-657 km2) in southern Queensland, and 20 large blocks (~2-6000 km2) throughout Queensland. The harvest off-take for each site was divided by monthly or average annual population size, determined by aerial survey, to calculate monthly and annual harvest rates.Asimple harvest model assuming logistic population growth was used to determine the likely effectiveness of harvesting. Key results. Commercial harvest rates were generally low (50%) in long-term population size were isolated occurrences and not maintained across sites and years. High harvest rates were observed only at low densities. Although these harvest rates may be sufficiently high to hold populations at low densities, the population is likely to escape this entrapment following a flush in food supply or a reduction in harvest effort. Implications. Our results demonstrated that, at current harvest rates, commercial harvesting is ineffective for the landscape-scale control of feral-pig populations. Unless harvest rates can be significantly increased, commercial harvesting should be used as a supplement to, rather than as a substitute for, other damage-control techniques

Impacts on nontarget avian species from aerial meat baiting for feral pigs

Bait containing sodium fluoroacetate (1080) is widely used for the routine control of feral pigs in Australia. In Queensland, meat baits are popular in western and northern pastoral areas where they are readily accepted by feral pigs and can be distributed aerially. Field studies have indicated some levels of interference and consumption of baits by nontarget species and, based on toxicity data and the 1080 content of baits, many nontarget species (particularly birds and varanids) are potentially at risk through primary poisoning. While occasional deaths of species have been recorded, it remains unclear whether the level of mortality is sufficient to threaten the viability or ecological function of species. A series of field trials at Culgoa National Park in south-western Queensland was conducted to determine the effect of broadscale aerial baiting (1.7 baits per km2) on the density of nontarget avian species that may consume baits. Counts of susceptible bird species were conducted prior to and following aerial baiting, and on three nearby unbaited properties, in May and November 2011, and May 2012. A sample of baits was monitored with remote cameras in the November 2011 and May 2012 trials. Over the three baiting campaigns, there was no evidence of a population-level decline among the seven avian nontarget species that were monitored. Thirty per cent and 15% of baits monitored by remote cameras in the November 2011 and May 2012 trials were sampled by birds, varanids or other reptiles. These results support the continued use of 1080 meat baits for feral pig management in western Queensland and similar environs

Ecology, impacts and management of wild deer in Australia

We first provide the rationale for this special issue of Wildlife Research. We then summarise recent knowledge gains about the impacts, ecology and management of wild deer in Australia. Finally, we identify five priority areas for further investigation. Deer (Family Cervidae) have long been highly valued by people for their economic and resource values, as well as for aesthetic, cultural and spiritual reasons (Baker et al. 2014). Consequently, deer have been translocated far and wide, both within their ancestral strongholds in Eurasia and the Americas and, Antarctica aside, to all other continents (Long 2003; Nugent et al., in press). For Australia, the main motivation for the initial introductions in the 1800s and early 1900s appears to have been a combination of an enthusiastic interest in exotic species and a desire to recreate a resource symbolic of the wealth, power and prestige long associated with deer hunting in Europe in general (and Britain in particular) but more accessible to the common person. That motivation was clearly strong, because importing non-native deer into Australia in the 1800s was a major undertaking, involving long sea voyages in small sailing ships, with deer survival often depending on luck. Acclimatisation societies established captive breeding populations of deer so that more individuals could be released (Bentley 1998). Following release, these new deer populations were sometimes strictly protected from hunting for decades to help ensure their establishment and spread, a practice that continued until as recently as the 1980s. Indeed, the establishment of a new fallow deer (Dama dama) population on public land at Koetong, north-east Victoria, was actively supported by the state government during the 1970s and 1980s (Phillips 1985), and deer are today managed as game in Victoria and Tasmania. The advent of deer farming as a profitable enterprise in the 1970s and 1980s led to deer being captured from the wild, bred in captivity and then moved around the country to establish new farms. New wild populations have established from deer escaping from farms, and also from the deliberate (but now illegal) release by people wanting to establish new populations for hunting (Moriarty 2004). Wild deer are now present in all Australian states and territories

Optical Absorption Study by Ab initio Downfolding Approach: Application to GaAs

We examine whether essence and quantitative aspects of electronic excitation spectra are correctly captured by an effective low-energy model constructed from an {\em ab initio} downfolding scheme. A global electronic structure is first calculated by {\em ab initio} density-functional calculations with the generalized gradient approximation. With the help of constrained density functional theory, the low-energy effective Hamiltonian for bands near the Fermi level is constructed by the downfolding procedure in the basis of maximally localized Wannier functions. The excited states of this low-energy effective Hamiltonian ascribed to an extended Hubbard model are calculated by using a low-energy solver. As the solver, we employ the Hartree-Fock approximation supplemented by the single-excitation configuration-interaction method considering electron-hole interactions. The present three-stage method is applied to GaAs, where eight bands are retained in the effective model after the downfolding. The resulting spectra well reproduce the experimental results, indicating that our downfolding scheme offers a satisfactory framework of the electronic structure calculation, particularly for the excitations and dynamics as well as for the ground state.Comment: 14 pages, 6 figures, and 1 tabl

Application of an Ultralight Aircraft to Aerial Surveys of Kangaroos on Grazing Properties

A Drifter ultralight aircraft was used as a platform for line-transect aerial surveys of three species of kangaroo in the sheep rangelands south-east of Blackall and north of Longreach in central-western Queensland in winter 1993 and 1994. Favourable comparisons between the results of ultralight surveys and those made from a helicopter flying the same transects and foot surveys along another set of transects, all within a few days of the ultralight survey, confirmed the expectation we had that an ultralight would be a satisfactory and much cheaper vehicle for conducting aerial surveys of kangaroos. The comparisons are even more favourable when data for the three species surveyed are combined, pointing to a problem in species identification and underlining the importance of using only experienced observers for aerial survey of kangaroos, whatever the platform. The use of an ultralight aircraft could have particular value where a comparatively small area, such as an individual sheep or cattle property, is under consideration. In this paper, we present the numerical comparisons, along with an evaluation of the practicability of using this type of aircraft. We also describe a possible future scenario in which an accreditation process could see approved kangaroo surveyors undertaking property assessments by ultralight, under contract to graziers or other interested parties

Drones vs helicopters for broad-scale animal surveys considerations for future use

Effective monitoring is key for effective wildlife management. Aerial surveys are a proven method for monitoring medium/large-sized mammals (e.g. macropods, feral pigs) in Australia's rangelands. However, conventional aircraft are noisy, expensive, and considered an occupational safety risk for biologists. UAS (unmanned aerial systems, or drones) may offer potential safety and efficiency gains, but need to be assessed against the current best-practice techniques. We tested the ability of a long-range, fixed-wing drone (300m agl, 65-93 km h-1 , thermal and colour imaging) to survey macropod populations and validated the results against those from conventional helicopter surveys (61m agl, 93 km h-1 , human observers). Four, 80-km long transects at Roma in southwestern Queensland were surveyed and the outputs analysed using line-transect distance sampling methods. The drone was able to survey over half (56%) of the 320 km transects, and over 448 km of survey flights in total. However, the drone technique was unable to distinguish between macropod species, recorded <13% of the macropod density observed during the helicopter survey, and required more flight and data processing time. Long-range drones clearly have potential for landscape-scale wildlife monitoring but results must match or exceed the conventional techniques. Future UAS applications to wildlife monitoring require a proven ability to identify animals, a similar or greater detection probability than conventional techniques, an efficient means of data collation/analysis, and comparable costs to current-best practice survey methods. We discuss the issues for potential users to consider to ensure that new survey technologies can be used to optimal benefit

Modelling the Spatial and Temporal Dynamics of Kangaroo Populations for Harvest Management: Final Report to the Department of Environment and Heritage, Canberra

For the past three years, university researchers (University of Queensland and University of New England), kangaroo managers (Queensland, New South Wales, South Australia and the Commonwealth) and Packer Tanning have been collaborating on a research project aimed at improving kangaroo management. The project has three broad aims: - Predict kangaroo numbers using rainfall or satellite imagery and other environmental data - Indirectly monitor kangaroo numbers and harvest rate using harvest statistics (e.g. sex ratio, carcass weight, catch-per-unit-effort) - Optimise survey methods, frequency and design The work has involved collating over 20 years of data in three states on kangaroo density from aerial surveys, harvest offtake, satellite imagery (greenness index or NDVI) and rainfall. Such a long time series of data covering vast areas has enabled models to be developed that should lead to improved kangaroo management. These models can be used to predict future kangaroo numbers, which should enable the frequency and intensity of expensive aerial surveys to be reduced. Better prediction of kangaroo distribution within management zones should also help quota and tag allocation. Rainfall and pasture conditions obviously influence changes in kangaroo numbers, but the relationships needed to be quantified. The sex ratio and average weight of carcasses vary regionally, for a variety of reasons. Most usefully for managers, these statistics track kangaroo density or harvest rate in some cases. Both harvest statistics and satellite imagery have the advantage of being regularly updated and a high spatial resolution, both shortcomings of broad-scale aerial survey. Aerial surveys have been conducted annually in the eastern states, which may not be the most efficient survey frequency. The optimal frequency can be identified by considering the risks of the population dropping to low density or rising to high density. These risks can be considered as costs to the kangaroo industry, graziers and to conservation, which must then be balanced. Risk can be reduced by increasing survey frequency or intensity, which is a cost to management, or reducing harvest rate, which is a cost to industry. In more arid, uncertain environments, regular surveys are required. However, in many of these areas, harvests are low and a reduced harvest rate is unlikely to be a cost to industry. The data also suggest a greater influence of movement on red kangaroo population dynamics than previously thought, with large areas experiencing rates of increase much higher than possible through birth and survival alone. This suggests movement needs to be considered when forecasting kangaroo density even at a regional (>10,000 square km) scale

Population dynamics of house mice in Queensland grain-growing areas

Context. Irregular plagues of house mice cause high production losses in grain crops in Australia. If plagues can be forecast through broad-scale monitoring or model-based prediction, then mice can be proactively controlled by poison baiting. Aims. To predict mouse plagues in grain crops in Queensland and assess the value of broad-scale monitoring. Methods. Regular trapping of mice at the same sites on the Darling Downs in southern Queensland has been undertaken since 1974. This provides an index of abundance over time that can be related to rainfall, crop yield, winter temperature and past mouse abundance. Other sites have been trapped over a shorter time period elsewhere on the Darling Downs and in central Queensland, allowing a comparison of mouse population dynamics and cross-validation of models predicting mouse abundance. Key results. On the regularly trapped 32-km transect on the Darling Downs, damaging mouse densities occur in 50% of years and a plague in 25% of years, with no detectable increase in mean monthly mouse abundance over the past 35 years. High mouse abundance on this transect is not consistently matched by high abundance in the broader area. Annual maximum mouse abundance in autumn–winter can be predicted (R2 = 57%) from spring mouse abundance and autumn–winter rainfall in the previous year. In central Queensland, mouse dynamics contrast with those on the Darling Downs and lack the distinct annual cycle, with peak abundance occurring in any month outside early spring.Onaverage, damaging mouse densities occur in 1 in 3 years and a plague occurs in 1 in 7 years. The dynamics of mouse populations on two transects ~70 km apart were rarely synchronous. Autumn–winter rainfall can indicate mouse abundance in some seasons (R2 = ~52%). Conclusion. Early warning of mouse plague formation in Queensland grain crops from regional models should trigger farm-based monitoring. This can be incorporated with rainfall into a simple model predicting future abundance that will determine any need for mouse control. Implications. A model-based warning of a possible mouse plague can highlight the need for local monitoring of mouse activity, which in turn could trigger poison baiting to prevent further mouse build-up