A MICROCOMPUTER MODEL FOR PREDICTING THE SPREAD AND CONTROL OF FOOT AND MOUTH DISEASE IN FERAL PIGS

A microcomputer software package (AUSPLAGUE) is being constructed for development and testing of management plans for eradicating an outbreak of foot and mouth disease (FMD) in the Australian Capital Territory (ACT). It will indicate when and where control of feral pigs (Sus scrofa) is necessary to contain and eradicate, the disease. The software simulates the distribution and prevalence of FMD in feral pigs from the start of an outbreak and throughout the subsequent eradication campaign. The procedure is to integrate landscape data, the distribution and social behavior of feral pigs, a model of disease dynamics, and appropriate control measures. The modular package design enables data bases and models of hostdisease dynamics to be updated as further information is acquired on feral pig ecology. When completed, AUSPLAGUE will be used as a decision-support system in developing control strategies for a wide range of outbreak scenarios, and it will serve as a prototype for other diseases of feral animals and native wildlife

Disentangling the Effects of Multiple Fires on Spatially Interspersed Sagebrush (\u3ci\u3eArtemisia\u3c/i\u3e spp.) Communities

Questions: Relative to a landscape with a mosaic of two sagebrush community types and increasing fire frequency, we asked (a) do vegetation characteristics very significantly with number of times burned for each sagebrush community; (b) how do vegetation responses to different fire frequencies compare between the two sagebrush communities? Location: Columbia Plateau Ecoregion, Washington, USA. Methods: We sampled vegetation across a landscape that burned three times over a 10-year period in two sagebrush community types that are interspersed on unique landforms: big sagebrush (Artemisia tridentata) communities that occur on small “mounds” and scabland sagebrush (A. rigida) communities that occur on surrounding “flats.” Spatially overlapping fires permitted a balanced sampling design to assess unburned and once-, twice-, and thrice-burned locations for each land form/community type. We utilized a suite of statistical analyses to determine differences among plant functional groups and biomass among unburned/burned strata by land form and compared results between land forms. Results: Big sagebrush and scabland sagebrush communities responded uniquely to multiple fires, due to different fuel loadings, fire severities, succession and invasion dynamics. Big sagebrush experienced nearly complete shrub loss and conversion from exotic-invaded shrubland to exotic annual grassland after only one fire. In contrast, scabland sagebrush retained a minor shrub component and higher relative cover of native herbaceous species, even after three fires. Both communities retained cover of native perennial grasses, including shallow- and deep-rooted species, likely reflecting decreasing fire intensity with number of times burned. Conclusions: Despite different community-level responses, increasing fire frequency is transforming the entire landscape to a non-native/native grassland mix. Quantifying unique ecosystem responses to altered wildfire regimes is critical to understanding the relative resilience of communities to disturbance and their resistance to exotic species invasion (and community type conversion). Management actions may help to maintain spatial heterogeneity of ecosystems and fire-tolerant native species

Non-target impacts of poison baiting for predator control in Australia

1. Mammalian predators are controlled by poison baiting in many parts of the world, often to alleviate their impacts on agriculture or the environment. Although predator control can have substantial benefits, the poisons used may also be potentially harmful to other wildlife. 2. Impacts on non-target species must be minimized, but can be difficult to predict or quantify. Species and individuals vary in their sensitivity to toxins and their propensity to consume poison baits, while populations vary in their resilience. Wildlife populations can accrue benefits from predator control, which outweigh the occasional deaths of non-target animals. We review recent advances in Australia, providing a framework for assessing non-target effects of poisoning operations and for developing techniques to minimize such effects. We also emphasize that weak or circumstantial evidence of non-target effects can be misleading. 3. Weak evidence that poison baiting presents a potential risk to non-target species comes from measuring the sensitivity of species to the toxin in the laboratory. More convincing evidence may be obtained by quantifying susceptibility in the field. This requires detailed information on the propensity of animals to locate and consume poison baits, as well as the likelihood of mortality if baits are consumed. Still stronger evidence may be obtained if predator baiting causes non-target mortality in the field (with toxin detected by post-mortem examination). Conclusive proof of a negative impact on populations of non-target species can be obtained only if any observed non-target mortality is followed by sustained reductions in population density. 4. Such proof is difficult to obtain and the possibility of a population-level impact cannot be reliably confirmed or dismissed without rigorous trials. In the absence of conclusive evidence, wildlife managers should adopt a precautionary approach which seeks to minimize potential risk to non-target individuals, while clarifying population-level effects through continued research