Raylene Cooke

A comparison of the effectiveness of camera trapping and live trapping for sampling terrestrial small-mammal communities

Context. There is an increasing reliance on the use of camera-trap technologies for surveys of medium to large terrestrial mammals. Camera trapping may, however, also have significant applications for broad-scale surveys of small mammals. Aims. The present study aims to compare results from camera-trapping surveys to those of the more traditional live-trapping techniques. Specifically, it aims to test the effectiveness of the techniques for detecting species, and the cost effectiveness of both approaches. Methods. Surveys were conducted across 36 sites in the Grampians National Park, Victoria, Australia, between April and July 2009. At each site, independent surveys were conducted for small mammals by using a combination of Elliot and cage trapping, then camera trapping. Results for the two different approaches were compared for both their ability to generate small-mammal presence data and their cost effectiveness. Key results. Camera-trapping surveys of 36 sites in the Grampians National Park compared favourably with those of live-trapping surveys. Similar species were detected across the sites, and camera trapping was a considerably more cost effective than live trapping. Conclusions. Camera-trapping surveys of small terrestrial mammals may provide a new and cost-effective technique for surveying terrestrial small mammals. This is particularly the case when presence data are the main requirement of the survey, with no requirement to capture and tag animals. Implications. Given the cost-effective nature of camera trapping, there is potential to use this approach to increase the level of replication and spatial coverage of small-mammal surveys. Improving the replication and spatial coverage of studies has the potential to significantly increase the scope of research questions that can be asked, thus providing the potential to improve wildlife management.

Optimizing the use of shed feathers for genetic analysis

Shed feathers obtained by noninvasive genetic sampling (NGS) are a valuable source of DNA for genetic studies of birds. They can be collected across a large geographical range and facilitate research on species that would otherwise be extremely difficult to study. A limitation of this approach is uncertainty concerning the quality of the extracted DNA. Here we investigate the relationship between feather type, feather condition and DNA quality (amplification success) in order to provide a simple, cost‐effective method for screening samples prior to genetic analysis. We obtained 637 shed feathers of the powerful owl (Ninox strenua) from across its range in southeastern Australia. The extracted DNA was amplified using polymerase chain reaction for a range of markers including mitochondrial DNA, ND3 and nuclear DNA, a simple sequence repeat (Nst02) and a portion of the CHD‐1 gene (P2/P8). We found that feather condition significantly influenced the amplification success of all three loci, with feathers characterized as ‘good’ having greater success. Feather type was found to be of lower importance, with good quality feathers of all types consistently producing high success for all three loci. We also found that the successful amplification of multilocus genotypes was dependant on the condition of the starting material and was highly correlated with successful amplification of the sex‐linked CHD‐1 locus. Samples with low DNA quality have a higher probability of amplification failure and are more likely to produce incorrect genotypes; therefore, identifying samples with high DNA quality can save substantial time and cost associated with the genetic analysis of NGS. As a result, we propose a method for screening shed feathers in order to provide a subset of samples which will have a greater probability of containing high quality DNA suitable for the amplification of multilocus genotypes.

Environmental sustainability in higher education: What do academics think?

The slow uptake of Education for Sustainability (EfS) curricula in universities has, partly, been attributed to academics’ perceptions that EfS has little relevance within some disciplines. Understanding teaching academics’ attitudes, values and experiences of EfS across disciplines can inform future EfS efforts in higher education. This paper presents one part of a larger study that sought the views of ≈6% of the entire university teaching workforce of Australia. One quarter of the teaching academics in every discipline of every Australian university (except one) (n = 38) was sent an online questionnaire asking for their opinions of EfS. Precisely, 1819 academics participated (26% response rate) and data was analysed with descriptive and inferential statistics. The findings suggest that academics are supportive of EfS for all university students. Support, perceived relevance and reported difficulties with EfS are discipline specific; academics would respond positively to EfS framed within their disciplinary worldviews.

The diet of powerful owls (Ninox strenua) and prey availability in a continuum of habitats from disturbed urban fringe to protected forest environments in south-eastern Australia

This study investigates the diet of six breeding pairs of powerful owls in the Yarra Valley Corridor in Victoria, Australia, and compares prey consumption with prey availability. The six sites represent a continuum of habitats, ranging from urban Melbourne, through the urban fringe interface to a more forested landscape. We found that powerful owls in the Yarra Valley Corridor are reliant almost exclusively on arboreal marsupial prey as their preferred diet, with 99% of their overall diet comprising four arboreal marsupial species. These four species (the common ringtail possum, common brushtail possum, sugar glider and greater glider) were also the most abundant species observed while spotlighting; however, their abundance varied along the continuum. There was a strong positive relationship with the presence of these species in the diet and their site-specific availability, indicating that the powerful owl is a generalist hunter, preying on the most available prey at a given site and in a given season. This study suggests that food resources are high in these disturbed urban fringe sites and it is unlikely that food availability in urban environments will limit the potential survival of urban powerful owls.

Change in the diet of sooty owls (Tyto tenebricosa) since European settlement: from terrestrial to arboreal prey and increased overlap with powerful owls

The current diet of the sooty owl (Tyto tenebricosa) was determined by analysing freshly regurgitated pellets collected beneath their roosting sites in East Gippsland, Victoria. Comparisons were then made with: (i) prehistoric and historic diet from bone deposits found in cave roosts, and (ii) diet of a sympatric owl species, the powerful owl (Ninox strenua). Sooty owls consumed a large array of terrestrial mammal species before European settlement, but only three terrestrial species were detected in their current diet, a reduction of at least eight species since European settlement. To compensate, sooty owls have increased their consumption of arboreal prey from 55% to 81% of their diet. Arboreal species are also a major component of the powerful owl diet and this prey shift by sooty owls has increased dietary overlap between these two species. Predation by foxes (Vulpes vulpes) and other feral species is likely to have reduced the amount of terrestrial prey available to sooty owls since European settlement. Investigation of changes in the diet of sooty owls may offer a unique monitoring system for evaluating the ability of fox-control strategies to influence increases in numbers of critical-weight-range mammals.

Camera Trapping: A Contemporary Approach to Monitoring Invasive Rodents in High Conservation Priority Ecosystems

Invasive rodent species have established on 80% of the worlds islands causing significant damage to island environments. Insular ecosystems support proportionally more biodiversity than comparative mainland areas, highlighting them as critical for global biodiversity conservation. Few techniques currently exist to adequately detect, with high confidence, species that are trap-adverse such as the black rat, Rattus rattus, in high conservation priority areas where multiple non-target species persist. This study investigates the effectiveness of camera trapping for monitoring invasive rodents in high conservation areas, and the influence of habitat features and density of colonial-nesting seabirds on rodent relative activity levels to provide insights into their potential impacts. A total of 276 camera sites were established and left in situ for 8 days. Identified species were recorded in discrete 15 min intervals, referred to as ‘events’. In total, 19 804 events were recorded. From these, 31 species were identified comprising 25 native species and six introduced. Two introduced rodent species were detected: the black rat (90% of sites), and house mouse Mus musculus (56% of sites). Rodent activity of both black rats and house mice were positively associated with the structural density of habitats. Density of seabird burrows was not strongly associated with relative activity levels of rodents, yet rodents were still present in these areas. Camera trapping enabled a large number of rodents to be detected with confidence in site-specific absences and high resolution to quantify relative activity levels. This method enables detection of multiple species simultaneously with low impact (for both target and non-target individuals); an ideal strategy for monitoring trap-adverse invasive rodents in high conservation areas.

Simplification of arboreal marsupial assemblages in response to increasing urbanization.

Arboreal marsupials play an essential role in ecosystem function including regulating insect and plant populations, facilitating pollen and seed dispersal and acting as a prey source for higher-order carnivores in Australian environments. Primarily, research has focused on their biology, ecology and response to disturbance in forested and urban environments. We used presence-only species distribution modelling to understand the relationship between occurrences of arboreal marsupials and eco-geographical variables, and to infer habitat suitability across an urban gradient. We used post-proportional analysis to determine whether increasing urbanization affected potential habitat for arboreal marsupials. The key eco-geographical variables that influenced disturbance intolerant species and those with moderate tolerance to disturbance were natural features such as tree cover and proximity to rivers and to riparian vegetation, whereas variables for disturbance tolerant species were anthropogenic-based (e.g., road density) but also included some natural characteristics such as proximity to riparian vegetation, elevation and tree cover. Arboreal marsupial diversity was subject to substantial change along the gradient, with potential habitat for disturbance-tolerant marsupials distributed across the complete gradient and potential habitat for less tolerant species being restricted to the natural portion of the gradient. This resulted in highly-urbanized environments being inhabited by a few generalist arboreal marsupial species. Increasing urbanization therefore leads to functional simplification of arboreal marsupial assemblages, thus impacting on the ecosystem services they provide.

Potential competition between two top-order predators following a dramatic contraction in the diversity of their prey base

Two sympatric native top-order predators, the sooty owl (Tyto tenebricosa tenebricosa) and powerful owl (Ninox strenua) coexist throughout much of their range in south-eastern Australia. Following European settlement, however, major changes in resource availability for these predators potentially resulted in increased competition, especially for food. This study examined ecological attributes of both species, including intersexual differences in the sooty owl, potential resource partitioning and whether competition may be occurring. Dietary overlap was high between female sooty owls and powerful owls (0.90), compared to overlap between male sooty owls and powerful owls (0.67), with three mammalian species contributing over 74% of their diets. Sooty and powerful owls coexisted throughout the study region, regularly roosting within the same vegetation types, and in similar locations, although microhabitat differences were apparent. Sooty owls displayed aseasonal breeding, although a peak in fledging in spring coincided with powerful owl breeding. Both species exclusively nested in similar size mountain grey gums (Eucalyptus cypellocarpa), however, hollow characteristics differed slightly. Significant divergence along a single niche dimension was not detected between powerful and sooty owls, as they had similar diets, habitat usage and activity times, potentially resulting in competition. Reproductive output was low for both species, however, the degree to which competitive interactions influenced this remains unknown. To minimise potential competition, longterm feral predator control and improved habitat management is recommended to increase the density and diversity of small terrestrial mammals, as this should result in diversification of the sooty owl diet, reducing dietary overlap with powerful owls.

Response of a cryptic apex predator to a complete urban to forest gradient

Abstract Context. Urbanisation is one of the most damaging landscape-scale disturbance processes leading to significant and potentially irreversible changes in biodiversity. How apex predators respond to urbanisation is poorly understood, largely because of their low density and low detectability. Given the important functional roles of apex predators in ecosystems, it is critical that research investigates how they respond to urbanisation, and how urban systems can be designed to better support apex predators. Aims. The present research aims to examine how an avian apex predator, the powerful owl, responds to a complete urban–forest gradient in southern Victoria, Australia. Specifically, the research aims to understand the environmental attributes that drive habitat suitability for powerful owls across the urban–forest gradient. Methods. Using a total of 683 independent field- and atlas-derived records of powerful owls across the study site, the research takes a presence-only modelling approach. The presence points were modelled against a series of geospatial variables that were determined a priori on the basis of the known ecology of powerful owls. Key results. Potential powerful owl habitat declined in a dramatic fashion in response to increasing levels of urbanisation, ranging from 76% of the forest landscape to 21% of the urban landscape. Powerful owl habitat availability across the urban–forest gradient is positively influenced by tree cover, productivity (normalised difference vegetation index) and proximity to river systems and riparian vegetation. Conclusions. Presence-only modelling has provided a useful way for investigating the response of an apex predator to a gradient of urbanisation. Although powerful owl habitat availability is negatively reduced by urbanisation, there is significant scope to manage urban landscapes to either maintain or improve the availability of habitat across the gradient. Implications. High resource-requiring species, such as apex predators, have the capacity to be detrimentally affected by urbanisation processes. Presence-only modelling, however, provides a useful tool for investigating how these difficult-to-detect species are affected by urbanisation, and ultimately inform how landscapes can be managed to maximise habitat availability for apex predators.

Spatial ecology of Sooty Owls in south-eastern Australian coastal forests: implications for forest management and reserve design

Abstract We investigated the home-range size and habitat use of eight Sooty Owls (Tyto tenebricosa tenebricosa) in coastal forests in East Gippsland, Victoria, Australia, between November 2006 and January 2008. The size of home-ranges varied widely; based on 95% adaptive kernel estimates, the average size of home-ranges of males was 3025 ha (±1194 s.d., n = 3), whereas that of females was 994 ha (±654 s.d., n = 5). Sooty Owls utilised a broad range of ecological vegetation classes and topographical features for roosting and foraging at a greater scale than previously assumed. There was minimal selection for habitat types based on floristic composition, primarily only avoiding heathlands (for foraging and roosting) and selecting particular dense foliage (rainforest and riparian scrub) for foliage roosting. Two Owls maintained home-ranges close to logged areas, with logging regrowth (<45 years old) being strongly avoided by both individuals. We recommend that the size of individual reserves for Sooty Owls in commercial forests should be increased to more closely resemble the core spatial resource requirements needed by a pair. Reserves should be largest where they feed predominantly on hollow-dependent prey. Most importantly, rather than conservation measures just focussing on the spatial requirements of Sooty Owls, efforts should be directed towards retaining high densities of crucial resources, such as hollow-bearing trees and mammalian prey species throughout the landscape.