Suchergebnisse

Many species of reptiles are sedentary and depend on ground-layer habitats, suggesting that they may be particularly vulnerable to landscape changes that result in isolation or degradation of native vegetation. We investigated patterns of reptile distribution and abundance in remnant woodland across the Victorian Riverina, south-eastern Australia, a bioregion highly modified (>90%) by clearing for agriculture. Reptiles were intensively surveyed by pitfall trapping and censuses at 60 sites, stratified to sample small (<30 ha) and large (>30 ha) remnants, and linear strips of roadside and streamside vegetation, across the regional environmental gradient. The recorded assemblage of 21 species was characterised by low abundance and patchy distribution of species. Reptiles were not recorded by either survey technique at 22% of sites and at a further 10% only a single individual was detected. More than half (53%) of all records were of two widespread, generalist skink species. Multivariate models showed that the distribution of reptiles is influenced by factors operating at several levels. The environmental gradient exerts a strong influence, with increasing species richness and numbers of individuals from east (moister, higher elevation) to west (drier, lower elevation). Differences existed between types of remnants, with roadside vegetation standing out as important; this probably reflects greater structural heterogeneity of ground and shrub strata than in remnants subject to grazing by stock. Although comparative historical data are lacking, we argue that there has been a region-wide decline in the status of reptiles in the Victorian Riverina involving: (1) overall population decline commensurate with loss of >90% of native vegetation; (2) disproportionate decline of grassy dry woodlands and their fauna (cf. floodplains); and (3) changes to populations and assemblages in surviving remnants due to effects of land-use on reptile habitats. Many species now occur as disjunct populations, vulnerable to changing land-use. The status of reptiles in rural Australia warrants greater attention than has been given to date. Effective conservation of this component of the biota requires better understanding of the population dynamics, habitat use and dispersal capacity of species; and a commitment to landscape restoration coupled with effective ecological monitoring.

Context The introduced red fox has driven the decline or extinction of numerous wildlife species in Australia, yet little information exists on the population densities of foxes in most ecosystems. Fox monitoring programs will differ widely depending on the goals of management, which, in turn, will determine whether the appropriate metric is a density estimate, or some proxy thereof, and the time and resources required. Aims This study aims to assist wildlife managers to design fit-for-purpose monitoring programs for foxes by providing a better understanding of the utility and precision of various monitoring methods. Methods We surveyed foxes monthly over four consecutive years in a semi-arid region of Australia by using sand plots, camera traps and GPS telemetry. The resultant data were used to produce population estimates from one count-based method, two spatially explicit methods, and two activity indices. Key results The incorporation of GPS-collar data into the spatial capture–recapture approaches greatly reduced uncertainty in estimates of abundance. Activity indices from sand plots were generally higher and more variable than were indices derived from camera traps, whereas estimates from N-mixture models appeared to be biased high. Conclusions Our study indicated that the Allen–Engeman index derived from camera-trap data provided an accurate reflection of change in the underlying fox density, even as density declined towards zero following introduction of lethal control. This method provides an efficient means to detect large shifts in abundance, whether up or down, which may trigger a change to more laborious, but precise, population monitoring methods. If accuracy is paramount (e.g. for reintroduction programs) spatially explicit methods augmented with GPS data provide robust estimates, albeit at a greater cost in resources and expertise than does an index. Implications Our study demonstrated that the shorter the survey period is, the greater is the likelihood that foxes are present but not detected. As such, if limited resources are available, longer monitoring periods conducted less frequently will provide a more accurate reflection of the underlying fox population than do shorter monitoring periods conducted more often.

Pharmacovigilance and risk minimization must be planned during drug development and forms a critical part of the regulator's decision on whether a medicinal product can be authorized. Pharmacovigilance systems should ensure proactive monitoring of all authorized medicines throughout their lifecycle in clinical use. Signal detection and management are core activities in pharmacovigilance, rapidly delivering new information on the safety of medicines in real‐world use which helps to fill knowledge gaps. The first 6 years of the European Union (EU) signal management system resulted in 453 recommendations issued by the Pharmacovigilance Risk Assessment Committee (PRAC), of which more than half were for drug labeling changes. The EU pharmacovigilance network has demonstrated its ability to detect and evaluate new drug safety signals. This has resulted in new warnings to guide the safe and effective use of medicines in Europe.

Context Feral cats (Felis catus) pose a significant threat to biodiversity in Australia, and are implicated in current declines of small mammals in the savannas of northern Australia. Basic information on population density and ranging behaviour is essential to understand and manage threats from feral cats. Aims In this study, we provide robust estimates of density and home range of feral cats in the central Kimberley region of north-western Australia, and we test whether population density is affected by livestock grazing, small mammal abundance and other environmental factors. Methods Densities were measured at six transects sampled between 2011 and 2013 using arrays of infrared cameras. Cats were individually identified, and densities estimated using spatially explicit capture–recapture analysis. Home range was measured from GPS tracking of 32 cats. Key results Densities were similar across all transects and deployments, with a mean of 0.18 cats km–2 (range = 0.09–0.34 km–2). We found no evidence that population density was related to livestock grazing or abundance of small mammals. Home ranges of males were, on average, 855 ha (±156 ha (95% CI), n = 25), and those of females were half the size at 397 ha (±275 ha (95% CI), n = 7). There was little overlap in ranges of cats of the same sex. Conclusions Compared with elsewhere in Australia outside of semiarid regions, feral cats occur at low density and have large home ranges in the central Kimberley. However, other evidence shows that despite this low density, cats are contributing to declines of small mammal populations across northern Australia. Implications It will be very difficult to reduce these already-sparse populations by direct control. Instead, land-management practices that reduce the impacts of cats on prey should be investigated.

Abstract
ContextThe success of conservation fences at protecting reintroduced populations of threatened mammals from introduced predators has prompted an increase in the number and extent of fenced exclosures. Excluding introduced species from within conservation fences could also benefit components of insitu faunal assemblages that are prey for introduced predators, such as reptiles and small mammals. Conversely, reintroduced mammals may compete with smaller mammals and reptiles for resources, or even prey on them.
AimsIn a 10-year study from 2008, we examine how small terrestrial vertebrates respond to the exclusion of introduced predators, the feral cat (Felis catus) and red fox (Vulpes Vulpes), introduced herbivores and the reintroduction of regionally extinct mammal species.
MethodsDifferences in the yearly relative abundance of reptiles and mammals according to habitat type and whether sites were fenced or not, were tested using multivariate generalised linear models. Next, we calculated univariate P-values to identify individual species that showed significant relationships, positive and negative, with any of the explanatory variables.
Key resultsTotal captures of reptiles were lower inside the conservation fence in all years, whereas total captures of small mammals were markedly higher inside the fenced area, notably in dasyurids.
ConclusionOur results showed that conservation fences can deliver benefits for some fauna (but not all) beyond facilitating the reintroduction of highly threatened mammals.
ImplicationsOur results demonstrated the consequential impacts of introduced predators on the Australian small mammal fauna, and showed that predator-exclusion fences can be an effective conservation intervention for this guild.