Kangaroo Island Dunnart Occupancy

Files relevant to the mansucript: Hohnen et al., 2019, Detecting and protecting the Kangaroo Island dunnart (Sminthopsis fuligosus aitkeni), Conservation Science and Practic

Литературный канон и его значение

Fire regimes are changing throughout the world. Changed fire patterns across northern Australian savannas have been proposed as a factor contributing to recent declines of small- and medium-sized mammals. Despite this, few studies have examined the mechanisms that underpin how species use habitat in fire-affected landscapes. We determined the habitats and resources important to the declining golden-backed tree-rat (Mesembriomys macrurus) in landscapes partially burnt by recent intense fire. We aimed to (i) compare the relative use of rainforest and savanna habitats; (ii) examine the effect of fire history on use of savanna habitats; and (iii) identify key foraging and denning resources. Habitat selection was examined by comparing the availability of eight habitat types around real (used) and generated (available) location points. Individuals used a range of habitats, but consistently selected long unburnt rainforest in preference to recently burnt savanna (1-12 months post-fire); however, recently burnt savanna was used in preference to long unburnt savanna. Tree-rats foraged in Terminalia hadleyana, Planchonia rupestris, Celtis philippensis and Owenia vernicosa, tree species that are found in a variety of habitat types. Individuals used a range of den sites, including cliffs, trees, logs, scree and stags found throughout the study area. Although multiple factors may have led to the decline of Mes.macrurus across its range, these results are consistent with the idea that changes in the savanna structure as a consequence of contemporary fire patterns could also have a role. The continued persistence of Mes.macrurus in the northwest Kimberley may be supported by land management strategies that conserve fruiting and hollow-bearing trees, and maintain the availability of fire-sensitive vegetation types

Uptake of ‘Eradicat

Context: Predation by feral cats (Felis catus) threatens a range of vertebrate species across Australia, and cat-free islands increasingly act as safe havens for biodiversity. A feral cat eradication program has begun on Kangaroo Island (4405 km2) in South Australia, and poison baiting is likely to be one of the main methods used. Aims: Here, we trial a non-toxic version of a cat bait, ‘Eradicat’, on western Kangaroo Island, to examine its potential impact on non-target species. Methods: Non-toxic baits containing the biomarker Rhodamine B were deployed across four sites in early August and late November in 2018, with bait take and consumption assessed both by remote cameras and by the presence of Rhodamine B in mammalian whisker samples taken post-baiting. Key results: Cats encountered baits on very few occasions and took a bait on only one occasion in August (60% of all baits laid was taken by either the common brushtail possum (Trichosurus vulpecula), bush rat (Rattus fuscipes) or Australian raven (Corvus coronoides). In November, Rosenberg’s goanna (Varanus rosenbergi) and southern brown bandicoot (south-eastern subspecies; Isoodon obesulus obesulus), listed nationally as Endangered, also took baits (3% and 1% respectively). The Kangaroo Island dunnart (Sminthopsis fuliginosus aitkeni), listed nationally as endangered, approached a bait on only one occasion, but did not consume it. Evidence of bait consumption was visible in the whiskers of captured common brushtail possums (100% of post-baiting captured individuals in August, 80% in November), bush rats (59% in August and 50% in November), house mice (Mus musculus) (45% in November) and western pygmy-possums (Cercartetus concinnus) (33% in November). Conclusions: Although feral cat baiting has the potential to significantly benefit wildlife on Kangaroo Island, impacts on non-target species (particularly the bush rat and common brushtail possum) may be high. Implications: Alternative cat baits, such as those containing a toxin to which native species have a higher tolerance or that are less readily consumed by native wildlife, will be more appropriate

Occupancy of the invasive feral cat varies with habitat complexity

The domestic cat (Felis catus) is an invasive exotic in many locations around the world and is thought to be a key factor driving recent mammal declines across northern Australia. Many mammal species native to this region now persist only in areas with high topographic complexity, provided by features such as gorges or escarpments. Do mammals persist in these habitats because cats occupy them less, or despite high cat occupancy? We show that occupancy of feral cats was lower in mammal-rich habitats of high topographic complexity. These results support the idea that predation pressure by feral cats is a factor contributing to the collapse of mammal communities across northern Australia. Managing impacts of feral cats is a global conservation challenge. Conservation actions such as choosing sites for small mammal reintroductions may be more successful if variation in cat occupancy with landscape features is taken into account

Occupancy of the Invasive Feral Cat Varies with Habitat Complexity

<div><p>The domestic cat (<i>Felis catus</i>) is an invasive exotic in many locations around the world and is thought to be a key factor driving recent mammal declines across northern Australia. Many mammal species native to this region now persist only in areas with high topographic complexity, provided by features such as gorges or escarpments. Do mammals persist in these habitats because cats occupy them less, or despite high cat occupancy? We show that occupancy of feral cats was lower in mammal-rich habitats of high topographic complexity. These results support the idea that predation pressure by feral cats is a factor contributing to the collapse of mammal communities across northern Australia. Managing impacts of feral cats is a global conservation challenge. Conservation actions such as choosing sites for small mammal reintroductions may be more successful if variation in cat occupancy with landscape features is taken into account.</p></div

Pre-eradication assessment of feral cat density and population size across Kangaroo Island, South Australia

Context:\ua0Feral cats (Felis catus) are a significant threat to wildlife in Australia and globally. In Australia, densities of feral cats vary across the continent and also between the mainland and offshore islands. Densities on small islands may be at least an order of magnitude higher than those in adjacent mainland areas. To provide cat-free havens for biodiversity, cat-control and eradication programs are increasingly occurring on Australian offshore islands. However, planning such eradications is difficult, particularly on large islands where cat densities could vary considerably.Aims:\ua0In the present study, we examined how feral cat densities vary among three habitats on Kangaroo Island, a large Australian offshore island for which feral cat eradication is planned.Methods:\ua0Densities were compared among the following three broad habitat types: forest, forest–farmland boundaries and farmland. To detect cats, three remote-camera arrays were deployed in each habitat type, and density around each array was calculated using a spatially explicit capture–recapture framework.Key results:\ua0The average feral cat density on Kangaroo Island (0.37 cats km−2) was slightly higher than that on the Australian mainland. Densities varied from 0.06 to 3.27 cats km−2\ua0and were inconsistent within broad habitat types. Densities were highest on farms that had a high availability of macropod and sheep carcasses. The relationship between cat density and the proportion of cleared land in the surrounding area was weak. The total feral cat population of Kangaroo Island was estimated at 1629 ± 661 (mean ± s.e.) individuals.Conclusions:\ua0Cat densities on Kangaroo Island are highly variable and may be locally affected by factors such as prey and carrion availability.Implications:\ua0For cat eradication to be successful, resources must be sufficient to control at least the average cat density (0.37 cats km−2), with additional effort around areas of high carcass availability (where cats are likely to be at a higher density) potentially also being required

Model specific coefficient estimates of feral cat occupancy in topographically simple and complex habitats in the north and central Kimberley, north-western Australia (where βCo = complex, βo = simple, and where βLn = north Kimberley, βo = central Kimberley).

<p>Model specific coefficient estimates of feral cat occupancy in topographically simple and complex habitats in the north and central Kimberley, north-western Australia (where βCo = complex, βo = simple, and where βLn = north Kimberley, βo = central Kimberley).</p

Feral cat occupancy estimates in topographically simple and complex habitats in the central and north Kimberley, north-western Australia.

<p>Feral cat occupancy estimates in topographically simple and complex habitats in the central and north Kimberley, north-western Australia.</p

Candidate models of feral cat occupancy in open and complex habitats of the north and central Kimberley, north-western Australia.

<p>Candidate models of feral cat occupancy in open and complex habitats of the north and central Kimberley, north-western Australia.</p

Measures of mammalian trap success pooled across fauna monitoring sites from around camera array locations in the north and central Kimberley, north-western Australia.

<p>Measures of mammalian trap success pooled across fauna monitoring sites from around camera array locations in the north and central Kimberley, north-western Australia.</p