No abstract

No abstract

Alien mammalian carnivores have contributed disproportionately to global loss of biodiversity. In Australia, predation by the feral cat and red fox is one of the most significant causes of the decline of native vertebrates. To discover why cats have greater impacts on prey than native predators, we compared the ecology of the feral cat to a marsupial counterpart, the spotted-tailed quoll. Individual prey are 20–200 times more likely to encounter feral cats, because of the combined effects of cats' higher population densities, greater intensity of home-range use and broader habitat preferences. These characteristics also mean that the costs to the prey of adopting anti-predator behaviours against feral cats are likely to be much higher than adopting such behaviours in response to spotted-tailed quolls, due to the reliability and ubiquity of feral cat cues. These results help explain the devastating impacts of cats on wildlife in Australia and other parts of the world.

Habitat loss is a major cause of species loss and is expected to increase. Loss of habitat is often associated with fragmentation of remaining habitat. Whether species can persist in fragmented landscapes may depend on their movement behavior, which determines their capability to respond flexibility to changes in habitat structure and spatial distribution of patches. Movement is frequently generalized to describe a total area used, or segmented to highlight resource use, often overlooking finer‐scale individual behaviors. We applied hidden Markov models (HMM) to movement data from 26 eastern bettongs (Bettongia gaimardi) in fragmented landscapes. HMMs are able to identify distinct behavior states associated with different movement patterns and discover how these behaviors are associated with habitat features. Three distinct behavior states were identified and interpreted as denning, foraging, and fast‐traveling. The probability of occurrence of each state, and of transitions between them, was predicted by variation in tree‐canopy cover and understorey vegetation density. Denning was associated with woodland with low canopy cover but high vegetation density, foraging with high canopy cover but low vegetation density, and fast‐traveling with low canopy cover and low vegetation density. Bettongs did move outside woodland patches, often fast‐traveling through pasture and using smaller stands of trees as stepping stones between neighboring patches. Males were more likely to fast‐travel and venture outside woodlands patches, while females concentrated their movement within woodland patches. Synthesis and applications: Our work demonstrates the value of using animal movement to understand how animals respond to variation in habitat structure, including fragmentation. Analysis using HMMs was able to characterize distinct habitat types needed for foraging and denning, and identify landscape features that facilitate movement between patches. Future work should extend the use of individual movement analyses to guide management of fragmented habitat in ways that support persistence of species potentially threatened by habitat loss.

Birds are declining in agricultural landscapes around the world. The causes of these declines can be better understood by analysing change in groups of species that share life-history traits. We investigated how land-use change has affected birds of the Tasmanian Midlands, one of Australia's oldest agricultural landscapes and a focus of habitat restoration. We surveyed birds at 72 sites, some of which were previously surveyed in 1996-1998, and tested relationships of current patterns of abundance and community composition to landscape and patch-level environmental characteristics. Fourthcorner modelling showed strong negative responses of aerial foragers and exotics to increasing woodland cover; arboreal foragers were positively associated with projective foliage cover; and small-bodied species were reduced by the presence of a hyperaggressive species of native honeyeater, the noisy miner (Manorina melanocephala). Analysis of change suggests increases in large-bodied granivorous or carnivorous birds and declines in some arboreal foragers and nectarivores. Changes in species richness were best explained by changes in noisy miner abundance and levels of surrounding woodland cover. We encourage restoration practitioners to trial novel planting configurations that may confer resistance to invasion by noisy miners, and a continued long-term monitoring effort to reveal the effects of future land-use change on Tasmanian birds.

Context. The Felixer grooming device ('Felixer') is a lethal method of feral cat control designed to be cost-effective and target specific. Aims. This study aims to test the target specificity of the Felixer in Tasmania, with a particular focus on Tasmanian devil and quoll species due to the overlap in size, habitats and behaviour between these native carnivores and feral cats. Methods. Our study deployed Felixer devices set in a non-lethal mode in nine field sites in Tasmania, one field site in New South Wales and two Tasmanian wildlife sanctuaries. Key results. Our study recorded 4376 passes by identifiable vertebrate species including 528 Tasmanian devil passes, 507 spottedtailed quoll passes and 154 eastern quoll passes. Our data showed that the Felixer can successfully differentiate quoll species from feral cats with spotted-tailed quolls and eastern quolls targeted in 0.19% and 0% of passes, respectively. However, Tasmanian devils and common wombats were targeted in 23.10% and 12% of passes, respectively, although sample size was low for common wombats (n = 25). Conclusions. The Felixer could not reliably identify Tasmanian devils and possibly common wombats as non-target species. Further data is needed to confirm the potential for impacts on the common wombat and other potential nontarget species in Tasmania, and the likelihood of the toxin being ingested by falsely targeted individuals. Implications. Our study suggest that the Felixer device is safe for use in the presence of two species of conservation concern, the eastern and spotted-tailed quoll. It also supports evidence from previous studies that the Felixer is unlikely to impact bettongs and potoroos. Use of Felixer devices across much of Tasmania would have to balance the conservation or economic benefits of cat control against potential impacts on Tasmanian devils. We suggest that active Felixer deployments be preceded by surveys to establish the range of species present at the control site, and the season of control considered carefully to minimise potential impacts on more susceptible juvenile animals. In addition, modifications to the Felixer device such as the proposed incorporation of AI technology should be tested against the Tasmanian devil and other non-target species.

Olfaction is a common sensory mode of communication in much of the Vertebrata, although its use by adult frogs remains poorly studied. Being part of an open signalling system, odour cues can be exploited by 'eavesdropping' predators that hunt by smell, making association with odour a high-risk behaviour for prey. Here, we show that adult great barred frogs (Mixophes fasciolatus) are highly attracted to odour cues of conspecifics and those of sympatric striped marsh frogs (Limnodynastes peronii). This attraction decreased significantly with the addition of odours of a scent-hunting predator, the red-bellied black snake (Pseudechis porphyriacus), indicating that frogs perceived predation risks from associating with frog odours. Male frogs, however, maintained some attraction to unfamiliar conspecific scents even with predator odours present, suggesting that they perceived benefits of odour communication despite the risk. Our results indicate that adult frogs can identify species and individuals from their odours and assess the associated predation risk, revealing a complexity in olfactory communication previously unknown in adult anurans.

Temperate woodlands are amongst the most threatened ecosystems in Australia because the land on which they occur is highly suited to agriculture. Two hundred years of habitat loss and fragmentation in the Midlands agricultural region in Tasmania have led to widespread declines in native vertebrates and landscapes with populations of predators including feral Cat (Felis catus) and the native-invasive Noisy Miner (Manorina melanocephala). Ecologists at the University of Tasmania co-designed mechanistic animal-centric research on mammals and birds in the Midlands to inform vegetation restoration carried out by Greening Australia that would support the recovery of wildlife species. We used speciesappropriate technologies to assess the decisions made by individual animals to find food and shelter and to disperse across this fragmented landscape, and linked these, together with patterns of occupancy, across multiple spatial and temporal scales. We focussed on a native (Spotted-tailed Quoll, Dasyurus maculatus) and an invasive (feral Cat, Felis catus) carnivore, a woodland-specialist herbivore (Eastern Bettong, Bettongia gaimardi) and woodland birds including the native-invasive Noisy Miner. Our results, which show intense predatory and competitive pressure of cats and populations of Noisy Miner on native fauna, highlight how grounding restoration in the context of ecological interactions is essential to success in managing the impacts of invasive species in restored landscapes. Successful restoration will require innovative approaches in plantings and field experimentation with artificial refuges, to reduce habitat suitability for the Noisy Miner and cats and provide refuges for native mammals and birds to live in the landscape where cats also occur. Our results emphasise the significance of structural complexity of restoration plantings for supporting the recolonisation and persistence of native fauna. At large landscape-scale, we demonstrate the importance of retaining small habitat elements, including ancient paddock trees, pivot irrigation corners and small, degraded remnants, in facilitating occupancy and dispersal and, therefore, persistence of wild animals across this agricultural region.