Glen Saunders

Caching of baits by foxes (Vulpes vulpes) on agricultural lands

Baiting is widely used to control the introduced fox (Vulpes vulpes) in Australia. Caching of baits by foxes was observed through the use of miniature radio-transmitters. Both non-toxic and toxic (1080) baits were used to determine the number of baits cached, the location of these caches with respect to original placement and the extent to which these caches are later retrieved and consumed. These trials established that foxes cache 1080 baits. An average of 34% of transmitter baits offered were taken and 10% were cached. The mean distance from the bait station to the cache was 156 m, with some baits being cached up to 800 m away. Implications of these results for current fox management strategies and the consequences of using bait take as a population index are discussed.

Home range and movement of foxes (Vulpes vulpes) in coastal New South Wales, Australia

Data on the home range and activity of 14 foxes was collected from coastal habitat in Jervis Bay, New South Wales during 1993-95. Radio-collared foxes had a mean home range of 135 ha and core activity areas of 23 ha (determined by the Minimum Convex Polygon method). There were no significant differences in the home ranges of male and female foxes. The home ranges of some foxes shifted throughout the study. Some animals went on long forays beyond their normal range. All animals displayed nocturnal activity patterns except during the breeding season or after long spells of wet weather when some foraging occurred during daylight hours. The information col- lected in this study is discussed in the context of fox control.

Foxes are now widespread in Tasmania: DNA detection defines the distribution of this rare but invasive carnivore.

Summary 1. Invasive vertebrate species are a world-wide threat to biodiversity and agricultural production. The presence of foxes, one of the most damaging invasive vertebrates introduced to Australia, has now been confirmed in the island state of Tasmania, placing at risk many species of native vertebrates and substantial agricultural industry. 2. Effective eradication of such a rare but elusive carnivore requires robust strategies informed by novel but systematic detection. 3. We combine DNA detection approaches for trace samples with systematic stratified and opportunistic surveys of carnivore scats to estimate the current distribution of foxes in Tasmania. We use that DNA evidence and other hard evidence provided by carcasses and other material to build a predictive model of fox habitat suitability for all of Tasmania. 4. We demonstrate that this destructive species is widespread in northern and eastern Tasmania but has not yet reached the limits of its range. The widespread nature of this distribution reveals that targeting fox activity hotspots only for eradication is unlikely to be successful and that a strategic and statewide approach is required. Our habitat suitability model can provide a basis for prioritizing areas for fox management. 5. Synthesis and applications. Our approach highlights the importance of early and preemptive surveys of recently established, and therefore rare, invasive species and the necessity of providing a sound and defensible approach to determining the distribution of the invasive species. This approach provides a template for the systematic detection of rare cryptic carnivores.

Alien invasive vertebrates in ecosystems: pattern, process and the social dimension

The rate of biological invasions has increased dramatically over recent centuries. Alien invasive vertebrates have significant adverse effects on biodiversity, and island fauna are especially susceptible. Human-induced environmental change is likely to exacerbate these negative impacts of alien invasive species. However, invasion biology has advanced considerably over the last two decades, with improvement in understanding of the processes of establishment and spread. New developments in spatial modelling have elucidated the way in which behavioural processes at the individual level can drive population-level patterns such as spread. Combined with new genetic insights into the process of invasion, these advances may assist in the development of novel, better-targeted management strategies that provide new options in how to deal with the threat posed by invasive species. Decisions about whether to and how we should intervene are questions for all sectors of society, but research on the social and cultural impacts of invasive species is largely lacking. There are many opportunities for enhancing the social dimensions of invasive species research, and integrated assessments of the social, economic and environmental impacts of species provide one potential avenue. As part of this, there is also a need to increase stakeholder participation in the decision-making process regarding alien invasive species. These more holistic approaches are essential if we are to reduce the impact of alien invasive species to within acceptable limits in the face of rapid environmental change.

INITIAL EFFECTS OF RABBIT HAEMORRHAGIC DISEASE ON FREE-LIVING RABBIT (ORYCTOLAGUS CUNICULUS) POPULATIONS IN CENTRAL-WESTERN NEW SOUTH WALES

Quarterly spotlight counts of rabbits were conducted at three sites in central-western New South Wales. These counts commenced two years before the arrival of rabbit haemorrhagic disease (RHD) in the winter of 1996. The existing data on quarterly rates of change in rabbit abundance for the three populations provided a unique opportunity to study the effects of RHD on rabbit demography. Prior to the arrival of RHD, all three populations underwent phases of sequential increase and decrease in each year. On the basis of these patterns, RHD had a variable influence on the demography of the three rabbit populations. In 1996–97, the density of two populations declined over an expected period of increase, while at the third site the density increased as expected from pre-RHD patterns. Twelve months after their failure to generate expected positive rates of increase the two affected populations had returned to the normal sequence of increases and decreases in density although still at comparatively low numbers.

Factors Affecting Bait Uptake and Trapping Success for Feral Pigs (Sus Scrofa) in Kosciusko National Park.

An evaluation of the rate and extent of population reduction that can be achieved by trapping feral pigs was conducted in a subalpine area of Kosciusko National Park in south-eastern New South Wales. Movements of pigs during the programme were monitored by radio-telemetry. In total, 142 pigs, including 12-17 (71%) previously fitted with transmitters and known to be still on the study site, were captured over 330 trap-nights at a cost of

Spatial interactions and habitat use of rabbits on pasture and implications for the spread of rabbit haemorrhagic disease in New South Wales

A104 per pig. A model fitted to the change in percentage of bait stations eaten per day relative to the cumulative number of pigs caught estimated a population reduction of 62% of animals exposed to traps and only 28% of the entire population. Determinants of trap success are discussed. During the trapping evaluation and in 2 preceding seasons, factors that influenced the rate at which bait stations were found and eaten were also examined. Both the locality characteristics of bait stations and the time of year were found to have significant effects on this rate.

Stakeholder Participation in Management of Invasive Vertebrates

Successful control of European rabbit (Oryctolagus cuniculus) populations in Australia has been achieved with the use of disease, initially myxomatosis and more recently rabbit haemorrhagic disease (RHD). Predicting the effectiveness of disease as a control agent depends on understanding the spatial and social organisation of its host population. We radio-tracked 37 rabbits from adjacent burrow systems during May and June 1999. Surface-dwelling rabbits had larger home ranges and core areas and a higher proportion of vegetation cover in their ranges than warren-based rabbits. Interactions between rabbit dyads from the same warren showed greater range overlap than those involving rabbits from different warrens and those involving itinerants. Static interaction was high and positive for intra-warren dyads, but low and negative for inter-warren, warren–surface and surface–surface dyads. These patterns of range use and interaction behaviour create a hierarchical contact and transmission structure within the rabbit population that is likely to vary according to external factors such as population density, resource availability, season, climate and the environment. Quantifying these links between the environment and the transmission process is important to increase our understanding of RHD as an effective management tool for rabbit populations.

The Demography of Feral Pigs (Sus Scrofa) in Kosciusko National Park, New South Wales.

Stakeholders are increasingly involved in species conservation. We sought to understand what features of a participatory conservation program are associated with its ecological and social outcomes. We conducted a case study of the management of invasive vertebrates in Australia. Invasive vertebrates are a substantial threat to Australias native species, and stakeholder participation in their management is often necessary for their control. First, we identified potential influences on the ecological and social outcomes of species conservation programs from the literature. We used this information to devise an interview questionnaire, which we administered to managers of 34 participatory invasive-vertebrate programs. Effects of invasive species were related to program initiator (agency or citizen), reasons for use of a participatory approach, and stakeholder composition. Program initiator was also related to the participation methods used, level of governance (i.e., governed by an agency or citizens), changes in stakeholder interactions, and changes in abundance of invasive species. Ecological and social outcomes were related to changes in abundance of invasive species and stakeholder satisfaction. We identified relations between changes in the number of participants, stakeholder satisfaction, and occurrence of conflict. Potential ways to achieve ecological and social goals include provision of governmental support (e.g., funding) to stakeholders and minimization of gaps in representation of stakeholder groups or individuals to, for example, increase conflict mitigation. Our findings provide guidance for increasing the probability of achieving ecological and social objectives in management of invasive vertebrates and may be applicable to other participatory conservation programs.

Prospects for the future: is there a role for virally vectored immunocontraception in vertebrate pest management?

The demography of a sub-alpine population of feral pigs was examined at Kosciusko National Park in south-eastern New South Wales. Reproductive data and age structures indicated a seasonal pattern of breeding, most births occurring in summer and autumn. It is proposed that a decreasing availability of high protein food in the autumn and winter months caused reduced rates of conception. Sows produced 0.84 litters per year with postnatal mortality as high as 85%. The population appeared relatively stable at a density of 1.6 pigs kg-2. Hunting, although illegal in a national park, removed 4.4-15.4% of pigs each year. The overall health and body condition of pigs was good, with no evidence of heavy parasitic burdens or disease. Age-specific body weight and body length in this study were greater than those reported for pigs in semi-arid wester New South Wales.