scholarly journals Invasive species-driven trophic cascades: Are cane toads indirectly contributing to small mammal collapses across tropical Australia?

2019 ◽  
Author(s):  
Ian James Radford ◽  
Leigh-Ann Woolley ◽  
Chris R. Dickman ◽  
Ben Corey ◽  
Dane Trembath ◽  
...  
Keyword(s):  
Conceptual Model ◽  
Small Mammals ◽  
Small Mammal ◽  
Trophic Cascades ◽  
Apex Predator ◽  
Northern Australia ◽  
Apex Predators ◽  
Feral Cat ◽  
Future Studies ◽  
Tropical Australia

AbstractApex predators are fundamentally important in regulating many ecosystems, and perturbations of their populations are frequently implicated in ecosystem declines or collapses. In considering small mammal declines in northern Australia, most attention has focused on interactions between a mammalian apex predator—the dingoCanis dingo—and a meso-predator, the feral cat—Felis catus. Little consideration has been given to the possible implications of changed reptilian predator assemblages resulting from invasion by a toxic anuran invader, the cane toad (Rhinella marina), on small mammals. We used reptile removal records from licenced reptile catchers in three widely spaced towns in the savannas of northern Australia to explore potential impacts of toads on apex and meso-predatory snakes and large lizards. In addition, simultaneous fauna survey data from one town with reptile removal records, coinciding with toad invasion, were used to identify cascading impacts through the savanna ecosystem. Intervention analyses revealed empirical linkages between toad invasion, apex predator declines, meso-predator increases and declines of small mammals and other prey groups. Based on the timing and strength of intervention we postulate a novel conceptual model linking recent mammal declines with trophic cascades following toad invasion, where the loss of large, anurophagous (toad-eating) reptilian apex predators allowed increases in mammal-eating meso-predatory snakes. The conceptual model is discussed in relation to prevailing hypotheses regarding northern Australia’s dramatic small mammal declines. Future studies will need to quantify these putative interactions and test their comparative importance so that appropriate management can be implemented to stem the ongoing losses of mammal fauna.

Density and home range of feral cats in north-western Australia

2015 ◽  
Vol 42 (3) ◽  
pp. 223 ◽  
Author(s):  
Hugh W. McGregor ◽  
Sarah Legge ◽  
Joanne Potts ◽  
Menna E. Jones ◽  
Christopher N. Johnson
Keyword(s):  
Population Density ◽  
Home Range ◽  
Small Mammals ◽  
Small Mammal ◽  
Livestock Grazing ◽  
Home Ranges ◽  
Low Density ◽  
Northern Australia ◽  
Feral Cats ◽  
North Western

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.

Feral cats are more abundant under severe disturbance regimes in an Australian tropical savanna

2020 ◽  
Vol 47 (8) ◽  
pp. 624 ◽  
Author(s):  
Hugh F. Davies ◽  
Stefan W. Maier ◽  
Brett P. Murphy
Keyword(s):  
Small Mammals ◽  
Ground Layer ◽  
Northern Australia ◽  
Remotely Sensed Data ◽  
Feral Cat ◽  
Feral Cats ◽  
Environmental Correlates ◽  
Disturbance Regimes ◽  
High Severity ◽  
Severe Disturbance

Abstract ContextThere is an increasing awareness that feral cats play a key role in driving the ongoing decline of small mammals across northern Australia; yet, the factors that control the distribution, abundance and behaviour of feral cats are poorly understood. These key knowledge gaps make it near-impossible for managers to mitigate the impacts of cats on small mammals. AimsWe investigated the environmental correlates of feral cat activity and abundance across the savanna woodlands of Melville Island, the larger of the two main Tiwi Islands, northern Australia. MethodsWe conducted camera-trap surveys at 88 sites, and related cat activity and abundance to a range of biophysical variables, either measured in the field or derived from remotely sensed data. Key resultsWe found that feral cat activity and abundance tended to be highest in areas characterised by severe disturbance regimes, namely high frequencies of severe fires and high feral herbivore activity. ConclusionsOur results have contributed to the growing body of research demonstrating that in northern Australian savanna landscapes, disturbance regimes characterised by frequent high-severity fires and grazing by feral herbivores may benefit feral cats. This is most likely to be a result of high-severity fire and grazing removing understorey biomass, which increases the time that the habitat remains in an open state in which cats can hunt more efficiently. This is due to both the frequent and extensive removal, and longer-term thinning of ground layer vegetation by severe fires, as well as the suppressed post-fire recovery of ground layer vegetation due to grazing by feral herbivores. ImplicationsManagement that reduces the frequency of severe fires and the density of feral herbivores could disadvantage feral cat populations on Melville Island. A firm understanding of how threatening processes interact, and how they vary across landscapes with different environmental conditions, is critical for ensuring management success.

Diet of Feral Cats in Hawai?i Volcanoes National Park

2007 ◽  
Vol 13 (4) ◽  
pp. 244 ◽  
Author(s):  
Steven C. Hess ◽  
Heidi Hansen ◽  
Daniel Nelson ◽  
Roberta Swift ◽  
Paul C. Banko
Keyword(s):  
Digestive Tract ◽  
Small Mammals ◽  
Small Mammal ◽  
Mus Musculus ◽  
National Park ◽  
Feral Cat ◽  
Feral Cats ◽  
Mauna Loa ◽  
Invertebrate Prey ◽  
Kīlauea Volcano

We documented the diet of feral cats by analysing the contents of 42 digestive tracts from Kilauea and Mauna Loa In Hawai'i Volcanoes National Park. Small mammals, invertebrates, and birds were the most common prey types consumed by feral cats. Birds occurred in 27.8?29.2% of digestive tracts. The total number of bird, small mammal, and invertebrate prey differed between Kilauea and Mauna Loa. On Mauna Loa, significantly more (89%) feral cats consumed small mammals, primarily rodents, than on Kilauea Volcano (50%). Mice (Mus musculus) were the major component of the feral cat diet on Mauna Loa, whereas Orthoptera were the major component of the diet on Kilauea. We recovered a mandible set, feathers, and bones of an endangered Hawaiian Petrel (Plerodroma sandwichensis) from a digestive tract from Mauna Loa. This specimen represents the first well-documented endangered seabird to be recovered from the digestive tract of a feral cat in Hawai'i and suggests that feral cats prey on this species.

A review of Elliott trapping methods for small mammals in Australia.

2001 ◽  
Vol 23 (2) ◽  
pp. 77 ◽  
Author(s):  
EM Tasker ◽  
CR Dickman
Keyword(s):  
Small Mammals ◽  
Small Mammal ◽  
Similar Species ◽  
Factors Affecting ◽  
Future Studies ◽  
Trapping Methods ◽  
Major Factors ◽  
The Way

Much of the knowledge of small mammal ecology in Australia has come from Elliott trapping, however the results of these studies are influenced by the way in which trapping is carried out. We review some of the major factors affecting the results of Elliott trapping: trap spacing, local placement, presence of odours on the trap (from conspecifics, similar species, predators, and humans), and duration of trapping. Most factors clearly influence trapping results and should be routinely considered, and preferably controlled, in future studies which use Elliott traps.

Understory use by terrestrial small mammals in an unflooded forest patch in the Pantanal floodplain

Mammalia ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Nayara Yoshie Sano ◽  
Heitor Miraglia Herrera ◽  
Grasiela Edith de Oliveira Porfirio ◽  
Filipe Martins Santos
Keyword(s):  
Small Mammals ◽  
Small Mammal ◽  
Understory Vegetation ◽  
Monodelphis Domestica ◽  
Forest Patch ◽  
Habitat Features ◽  
Species Characteristics ◽  
Local Habitat

AbstractTo date, there have been no studies that have evaluated small mammal utilization of the understory of forests. In this study, we described the use of vertical strata by small mammals in patches of unflooded forests, known as “cordilheiras”, in the Nhecolândia sub-region of the Pantanal, Brazil. We collected all species using the ground and understory, including the terrestrial didelphid Monodelphis domestica. We suppose that local habitat features (e.g., Acuri palms), rather than intrinsic species characteristics, may be more conducive to the use of understory vegetation by small mammals in the Nhecolândia region.

scholarly journals Implications of Autonomous Vehicles for Accessibility and Transport Equity: A Framework Based on Literature

2021 ◽  
Vol 13 (8) ◽  
pp. 4448
Author(s):  
Alberto Dianin ◽  
Elisa Ravazzoli ◽  
Georg Hauger
Keyword(s):  
Conceptual Model ◽  
Transport System ◽  
Urban Areas ◽  
Autonomous Vehicles ◽  
Scientific Literature ◽  
Social Groups ◽  
Future Studies ◽  
Social Accessibility ◽  
The Relationship

Increasing accessibility and balancing its distribution across space and social groups are two fundamental goals to make transport more sustainable and equitable. In the next decades, autonomous vehicles (AVs) could significantly transform the transport system, influencing accessibility and transport equity. In particular, depending on the assumed features of AVs (e.g., private or collective) and the considered spatial, social, and regulative context (e.g., rural or urban areas), impacts may be very different. Nevertheless, research in this field is still limited, and the relationship between AV assumptions and accessibility impacts is still partially unclear. This paper aims to provide a framework of the key and emerging aspects related to the implications of AVs for accessibility and transport equity. To set this framework, we perform an analysis of the scientific literature based on a conceptual model describing the implications of AVs for the distribution of accessibility across space and social groups. We recognize four main expected impacts of AVs on accessibility: (1) accessibility polarization, (2) accessibility sprawl, (3) exacerbation of social accessibility inequities, and (4) alleviation of social accessibility inequities. These impacts are described and analyzed in relation to the main AV assumptions expected to trigger them through different mechanisms. Based on the results, some recommendations for future studies intending to focus on the relation between AVs, accessibility, and transport equity are provided.

scholarly journals Diversity and Diet Differences of Small Mammals in Commensal Habitats

Diversity ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 346
Author(s):  
Linas Balčiauskas ◽  
Laima Balčiauskienė ◽  
Andrius Garbaras ◽  
Vitalijus Stirkė
Keyword(s):  
Small Mammals ◽  
Small Mammal ◽  
Trophic Ecology ◽  
Mammal Species ◽  
Additional Food ◽  
Δ13c And Δ15n ◽  
Degree Of Separation ◽  
Kitchen Gardens ◽  
Dietary Plasticity ◽  
The Stability

The stability of diversity of syntopic (inhabiting the same habitat in the same time) small mammals in commensal habitats, such as farmsteads and kitchen gardens, and, as a proxy of their diet, their isotopic niches, was investigated in Lithuania in 2019–2020. We tested whether the separation of species corresponds to the trophic guilds, whether their diets are related to possibilities of getting additional food from humans, and whether their diets are subject to seasonal trends. We analyzed diversity, dominance and distribution of hair δ13C and δ15N values. Diversity and dominance was not stable and differed according to human influence. The highest small mammal species richness occurred in commensal habitats that provided additional food. The degree of separation of species was higher in homestead habitats than in kitchen gardens, where a 1.27 to 35.97% overlap of isotopic niches was observed between pairs of species. Temporal changes in δ13C and δ15N values in the hair of the mammals were not equally expressed in different species. The isotopic overlap may depend on dietary plasticity, minimizing interspecific competition and allowing co-existence of syntopic species. Thus, small mammal trophic ecology is likely related to intensity of agricultural activities in the limited space of commensal habitats.

Small mammal mycophagy in hemiboreal forest communities of Lithuania

2011 ◽  
Vol 6 (3) ◽  
pp. 446-456 ◽  
Author(s):  
Marija Kataržytė ◽  
Ernestas Kutorga
Keyword(s):  
Small Mammals ◽  
Small Mammal ◽  
Fungal Spores ◽  
Seasonal Effects ◽  
Deciduous Tree ◽  
Myodes Glareolus ◽  
Mammal Species ◽  
Hypogeous Fungi ◽  
Fecal Samples ◽  
Significant Difference

AbstractThe diets of small mammals in different hemiboreal spruce-dominated, oak-dominated and mixed forests in western part of Lithuania were studied by examination of fungal spores in fresh fecal pellets of caught animals. In the diets of mice (Apodemus spp.), bank voles (Myodes glareolus), and common and pygmy shrews (Sorex araneus and S. minutus), 22 different fungal taxa were identified, 15 of which were hypogeous fungi. The sporocarp abundance and the spores in fecal samples of Elaphomyces fungi prevailed in study area during this investigation. Although most of the captured individuals consumed fungi, the consumption varied among small mammal species. The data show that the fungi were more frequent and taxonomically diverse in Myodes glareolus than in Apodemus spp. diets. The study provided evidence that the fungal component in the diets of insectivorous Sorex species is more diverse than previously known. The availability of sporocarps and the fungal component in the diets of small mammals showed seasonal effects. Annual hypogeous and epigeous sporocarp abundances did not vary significantly across forest types. The significant difference in mycophagy was observed across all forest cover types, with the greatest fungal diversity in fecal samples collected in mixed coniferous-deciduous tree stands.

An attempt to determine the size of the Common Barn-owl’s (Tyto alba) hunting area based on its prey composition

2021 ◽  
pp. 175815592110660
Author(s):  
Jenő J Purger ◽  
Dávid Szép
Keyword(s):  
Functional Groups ◽  
Small Mammals ◽  
Small Mammal ◽  
Barn Owl ◽  
Tyto Alba ◽  
Mammal Species ◽  
Open Forest ◽  
Prey Composition ◽  
Small Mammal Species ◽  
Owl Pellets

The relative abundance of small mammal species detected from Common Barn-owl pellets reflects the landscape structure and habitat pattern of the owl’s hunting area, but it is also affected by the size of the collected pellet sample and the size of the supposed hunting area. The questions arise: how many pellets should be collected and analyzed as well as how large hunting area should be taken into consideration in order to reach the best correspondence between the owl’s prey composition and the distribution of habitats preferred by small mammals preyed in supposed hunting areas? For this study, we collected 1045 Common Barn-owl pellets in a village in southern Hungary. All detected small mammal species were classified into functional groups (guilds) preferring urban, open, forest and wetland habitats. The proportion of functional groups was compared to the proportion of these habitats around the pellet collection site within circles of one, two, and three km radius. Saturation curves showed that at least 300 pellets or ca. 600 mammalian remains are required for the detection of the 19 small mammal species. The share of small mammals detected in the prey and their functional groups according to their habitat preference showed an increasing consistency with the distribution of real habitats in the potential hunting area of a radius of 3 km around the owl’s breeding or resting place.

Changes in small mammal communities after logging in north-central Ontario

1983 ◽  
Vol 61 (5) ◽  
pp. 970-980 ◽  
Author(s):  
Arthur M. Martell
Keyword(s):  
Small Mammals ◽  
Small Mammal ◽  
Vegetative Cover ◽  
North Central ◽  
Clear Cut ◽  
Clear Cutting ◽  
Small Mammal Community ◽  
Small Mammal Communities ◽  
Mammal Community ◽  
Mammal Communities

Changes in small mammal communities following logging were monitored in clear-cut and strip-cut upland black spruce (Picea mariana) stands and in selectively cut mixed wood stands in north-central Ontario. Clear-cutting and subsequent scarification essentially eliminated the vegetative cover. Much of the ground cover recovered within 5 years and shrubs within 12 years, but mosses and lichens took much longer. The small mammal community in both clear-cut and strip-cut stands changed over the first three years after logging from one dominated by southern red-backed voles (Clethrionomys gapperi) to one dominated by deer mice (Peromyscus maniculatus) and then remained relatively stable for up to 13 years after harvest. That shift was not apparent in selectively cut mixed wood stands where the composition of the small mammal community was similar between uncut stands and stands 4–23 years after harvest. There was relatively little change in total numbers of small mammals after logging. In general, the diversity and evenness of small mammals increased or remained stable in the first 1–3 years following harvest, decreased on older (3–16 years) cuts, and then increased to values similar to those in uncut stands on the oldest (19–23 years) cuts.

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