No abstract

An understanding of the factors that drive inter-population variability in home-range size is essential for managing the impacts of invasive species with broad global distributions, such as the feral domestic cat (Felis catus). The assumption that home-range sizes scale negatively with landscape productivity is fundamental to many spatial behaviour models, and inter-site variation in landscape productivity has often been invoked to explain the vast differences in feral cat home-range sizes among different regions. However, the validity of this explanation has not been tested or described. We used regression models to examine the ability of remotely sensed landscape productivity data, average body weight and population density to explain differences in the size of feral cat home ranges estimated across a diverse collection of sites across the globe. As expected for a solitary polygynous carnivore, female cats occupied smaller home ranges in highly productive sites, and range sizes of male cats scaled positively with those of females. However, the relationship between range size and productivity broke down at highly seasonal sites. Home-range size also scaled negatively with population density, but there was no clear relationship with average body weight. The relationships we describe should be useful for predicting home-range sizes and for designing effective feral cat control and monitoring programmes in many situations. More generally, these results confirm the importance of landscape productivity in shaping the spatial distribution of solitary carnivores, but the nature of the relationship is more complicated than is often appreciated.

Principles contained in the 1993 publication "Managing Vertebrate Pests: Principles & Strategies" were developed during a review of past and current pest management practices. They were used to guide the development of a series of management guidelines for our major vertebrate pests -feral pigs, house mice, European rabbits, red fox, feral pigs, feral horses, wild dogs, and carp. The principles have been constantly refined through subsequent on ground experience in working with stakeholders to implement best practice management programs for pest animals. In this paper, we present what we now consider the seven principles that underpin best practice management of pest animals. They are:1. A pest is human construct. 2. All key stakeholders need to be actively engaged and consulted.3. Rarely can pests be eradicated. 4. Most pest management needs to focus on the outcome, reduction in damage, not just killing pests. 5. A whole-system approach is required for managing pest damage. 6. Most pest management occurs in ecosystems in which our knowledge is imperfect.7. An effective monitoring and evaluation strategy is essential for all management interventions. Together, the principles comprise the strategic approach to pest management. We explain the rationale behind these principles and illustrate them with examples.

Poison baiting is used frequently to reduce the impacts of pest species of mammals on agricultural and biodiversity interests. However, baiting may not be appropriate if non-target species are at risk of poisoning. Here we use a desktop decision tree approach to assess the risks to non-target vertebrate species in Australia that arise from using poison baits developed to control feral house cats (Felis catus). These baits are presented in the form of sausages with toxicant implanted in the bait medium within an acid-soluble polymer capsule (hard shell delivery vehicle, or HSDV) that disintegrates after ingestion. Using criteria based on body size, diet and feeding behaviour, we assessed 221 of Australia's 3,769 native vertebrate species as likely to consume cat-baits, with 47 of these likely to ingest implanted HSDVs too. Carnivorous marsupials were judged most likely to consume both the baits and HSDVs, with some large-bodied and ground-active birds and reptiles also consuming them. If criteria were relaxed, a further 269 species were assessed as possibly able to consume baits and 343 as possibly able to consume HSDVs; most of these consumers were birds. One threatened species, the Tasmanian devil (Sarcophilus harrisii) was judged as definitely able to consume baits with implanted HSDVs, whereas five threatened species of birds and 21 species of threatened mammals were rated as possible consumers. Amphibia were not considered to be at risk. We conclude that most species of native Australian vertebrates would not consume surface-laid baits during feral cat control programs, and that significantly fewer would be exposed to poisoning if HSDVs were employed. However, risks to susceptible species should be quantified in field or pen trials prior to the implementation of a control program, and minimized further by applying baits at times and in places where non-target species have little access.