In wildlife research, our ability to GPS track sufficient numbers of individuals is always limited by cost, which restricts inference of species–habitat relationships. Here, we describe the modification and use of a relatively new and inexpensive off-the-shelf GPS device, to provide detailed and accurate information on the movement patterns of individuals (mountain brushtail possums, Trichosurus cunninghami), including how movement varies through time, and how individuals interact with each other. Our results demonstrated that this technology has enormous potential to contribute to an improved understanding of the movement patterns and habitat preferences of wildlife at a fraction of the cost of traditional GPS technology.

Context . Measures of intake and digestibility from captive feeding experiments are often used to evaluate the nutritional value of plant species to herbivores; however, there is question about how well plant-quality rankings from these trials predict foraging patterns of free-ranging animals. Studies addressing the alignment of results from feeding trials and herbivory in the field using captive and free-roaming conspecifics are needed.

Aims . Our goal was to compare the feeding patterns of snowshoe hares in captive intake and digestion trials with those of free-living conspecifics in the species’ south-western range.

Methods . We conducted in vivo intake and digestion trials using captive hares to determine quality and consumption levels of the predominant conifer species in our study system. In the field, we quantified browsing intensity and over-winter depletion patterns of these conifers. We then compared voluntary intake and nutritional quality measured in captivity to consumption in the field.

Key results . Digestible energy (DE, kJ g^–1) of conifers ranged from 11.0 (Pinus contorta) to 13.8 (Pseudotsuga menziesii) among six conifers, and digestible protein (DP, g protein per 100 g feed) from 1.2 (Thuja plicata) to 2.7 (P. contorta). During digestion trials, single-species intake was correlated with the content of digestible protein (DP) and digestible energy (DE). Hares maintained energy balance when fed two single-species diets (Pinus contorta, Pseudotsuga menziesii) and a mixed-species diet. Conifer species on which hares were able to maintain body mass (Pinus contorta, Picea engelmannii, Pseudotsuga menziesii) also tended to be the most heavily exploited by free-living hares. DP content of browse species predicted both browsing intensity and overwinter depletion of conifer species.

Conclusions . Voluntary intake and nutritional quality of browse, especially DP, successfully predicted foraging patterns of free-ranging conspecifics.

Implications . Intake and digestion trials can be a useful tool for better understanding patterns of herbivory in the field, and winter habitat quality for populations in this region is likely to be influenced by access to the most energy- and protein-rich conifers.

Context . Large portions of the world’s forests and woodlands are currently affected by declines in canopy condition of dominant tree species; however, the effects of these declines on faunal communities are largely unknown. Eucalyptus wandoo woodlands in the south-west region of Western Australia have demonstrated declines in condition since the early 1990s. Such declines in tree condition can result in reduced understorey vegetation, increased leaf-litter cover and coarse woody debris, potentially altering the habitat and resource available to reptiles. Prescribed fire events, another mechanism of habitat change for reptiles, are a common occurrence in these woodlands.

Aims . The present research investigated whether reptile communities were influenced by E. wandoo tree condition, and the changes in the habitat associated with E. wandoo decline.

Methods . Reptile trapping was conducted at 24 E. wandoo-dominated sites (of varying condition) in Dryandra State Forest and Wandoo Conservation Park, Western Australia. Overall, reptile abundance, species richness and individual reptile species abundances (only those species captured in sufficient numbers for analysis) were compared with a range of habitat characteristics that are likely to be altered by changes in E. wandoo tree condition.

Key results . Overall, higher reptile abundance and species richness were observed at sites with longer time since fire and more site litter cover. There was also a greater abundance and diversity of reptiles at sites where E. wandoo trees exhibited fewer symptoms of tree decline. Similar analyses for the five most common skink species indicated species-specific relationships with tree-condition measures, time since last fire, site litter cover, distance to drift fence from E. wandoo trees, understorey vegetation density and the density of coarse woody debris.

Conclusions . Abundance and species diversity of the reptile communities in E. wandoo woodlands were strongly related to time since last fire, E. wandoo tree condition and habitat characteristics such as site litter cover and the density of coarse woody debris.

Implications . Decline in the condition of E. wandoo trees and the fire events in E. wandoo woodlands are both mechanisms of change correlated with reptile habitat and resources. Future management of E. wandoo woodlands may include reducing prescribed fire events in areas demonstrating symptoms of tree decline, to conserve reptile abundance and species richness.

Context . Bovine tuberculosis is a persistent disease of livestock in many parts of the world, especially where wildlife hosts co-exist with livestock. In south-western Spain, despite the widespread implementation of test-and-cull strategies for cattle, the herd prevalence in areas with high wild boar densities remains stable. The control of M. bovis infection in wild boar is likely to be essential for effective disease control in livestock.

Methods . We developed an individual-based model to evaluate whether vaccinating wild boar piglets with oral bait would be an effective strategy to reduce the prevalence of M. bovis infection in wild boar populations. Specifically, we quantified the proportion of piglets requiring vaccination and the number of years the vaccination programme would need to continue to eradicate bTB from wild boar within 25 years, comparing ‘managed’ populations on hunting estates where supplementary food is provided, with ‘unmanaged’, free-living populations. Successful vaccination was defined as the proportion of piglets that were delivered the vaccine and were effectively protected from infection.

Key results . Longer-term (25-year) vaccination strategies were more successful than short-term (5-year) strategies at either eradicating M. bovis or reducing it to below 90% of its original prevalence. M. bovis infection could be eradicated under a 25-year vaccination strategy if 80% of piglets were vaccinated in a managed population or 70% of piglets were vaccinated in an unmanaged population. In contrast, 5-year strategies in which 80% of piglets were vaccinated reduced the prevalence of M. bovis only by 27% or 8% in the managed and unmanaged populations, respectively.

Conclusions . The results of our simulation model, coupled with the promising results of initial vaccine and oral bait-uptake trials in wild boar indicated that vaccination could be an effective strategy to reduce the prevalence of M. bovis infection in wild boar if used in conjunction with other disease-control measures.

Implications . The vaccination of piglets over a long-term period has the potential to make an important contribution to the eradication of M. bovis infection from wild boar reservoirs in southern Spain.

Context . The west coast of the Cape York Peninsula (CYP) is a major nesting ground for three species of threatened marine turtle, namely, the flatback (Natator depressus), olive ridley (Lepidochelys olivacea) and hawksbill (Eretemochelys imbricata). Marine turtle nests in this area experience high rates of depredation and unpublished data from numerous studies have suggested that feral pigs are responsible for most nest losses.

Aims . The aim of the present study was to identify the relative magnitude of nest mortality associated with physical processes versus depredation and to distinguishing between two possible pig depredation scenarios.

Methods . We documented laying and mortality patterns on Pennefarther Beach (CYP) over a 49-day period in 2007. We partitioned mortality into components attributable to beach erosion, inundation and depredation and also assessed the relative magnitude of depredation associated with different nest predators. We used these data to test whether the temporal and spatial pattern of pig depredation was random with respect to patterns of nest availability.

Key results . The overall level of nest mortality was 40.2%. Depredation was responsible for 93% of nest losses. Pig predation was high, accounting for 89.6% of all mortality. Depredation occurred equally across nests of all three turtle species. Although nests were laid uniformly in both time and space, pig depredation was significantly clustered.

Conclusions . Depredation by feral pigs was the principal cause of turtle nest mortality in the present study. The pattern of nest destruction was consistent with the occurrence of pig depredation by single individuals in discrete feeding areas.

Implications . Current feral pig management involves aerial shooting. This is effective at removing large numbers of animals over large areas. However, aerial shooting is also expensive. Our results suggest that targeted monitoring and eradication of locally active individuals depredating nests may better manage pig impacts, specifically those on turtle nests.

Context . Because they are dependent on water, drought can have a deleterious impact on aquatic-breeding amphibians. One such species, the threatened growling grass frog (Litoria raniformis) occurs in south-eastern Australia, a region that has recently emerged from a decade-long, severe drought.

Aims . We aimed to identify features of drought refugia that facilitate persistence of L. raniformis, so as to provide guidance to natural-resource managers attempting to conserve populations of this species during drought.

Methods . We conducted repeat surveys for L. raniformis at 90 water bodies at the end of the ‘millennium drought’. We recorded the following six environmental variables for each water body: origin (natural or not), type (lotic or lentic), proportion of aquatic vegetation cover, conductivity of water, riparian tree-canopy cover and distance to the nearest woodland. We used occupancy models to relate the presence of L. raniformis to these variables, while accounting for uncertain detection.

Key results . Water-body type (natural or artificial, lentic or lotic) had minimal influence on the probability of occupancy by L. raniformis. We found a strong negative relationship between occupancy and conductivity of water (a surrogate for salinity), and a positive relationship between occupancy and the proportion of aquatic vegetation. We found a negative relationship between detection and the extent of aquatic vegetation, and a mildly negative effect of canopy cover on occupancy.

Conclusions . Habitat characteristics are more important indicators of the quality of drought refugia for L. raniformis than is the type of water body per se. Consequently, we identified aquatic vegetation and salinity as important targets for management when planning the retention, creation or restoration of habitat to facilitate persistence of L. raniformis during drought.

Implications . Our results highlighted aquatic vegetation and water-quality parameters that are likely to facilitate the persistence of L. raniformis during drought. Assessing the effectiveness of our recommendations in an experimental framework would ensure that conservation management of this frog can be refined over time.

Context . Failure to acknowledge potential bias from imperfect detection of cryptic organisms such as frogs may compromise survey and monitoring programmes targeting these species.

Aims . The aims of the present study were to identify proximate factors influencing detection probabilities of a range of frog species in monsoonal northern Australia, and to estimate the number of repeat censuses required at a site to have confidence that non-detected species are absent.

Methods . Data on detection or non-detection of frog species based on calling individuals were recorded during 10 wet-season censuses of 29 survey sites in the Darwin region. Factors influencing detection probabilities were identified using occupancy models; model selection was based on the Akaike information criterion. Sampling effort for individual species was calculated using model predictions at different stages of the wet season.

Key results . The covariate water temperature featured in the best-supported models for 7 of the 14 frog species. Six of these species were more likely to be detected when water temperatures were below 30°C. Detection probabilities were also correlated with the number of days since the commencement of the wet season, time since last significant rainfall, air temperature and time after sunset. Required sampling effort for individual species varied throughout the wet season. For example, a minimum of two repeat censuses was required for detection of Litoria caerulea in the early wet season, but this number increased to 13 in the middle stage of the wet season.

Conclusions . Variability in environmental conditions throughout the wet season leads to variability in detection probabilities of frog species in northern Australia. Lower water temperatures, mediated by rainfall immediately before or during surveys, enhances detectability of a range of species. For most species, three repeat surveys under conditions resulting in a high detection probability are sufficient to determine presence at a site.

Implications . Survey and monitoring programmes for frogs in tropical northern Australia will benefit from the results of the present study by allowing targeting of conditions of high detection probability for individual species, and by incorporating sufficient repeat censuses to provide accurate assessment of the status of individual species at a site.

Context . Fertility control offers a non-lethal management technique for iconic yet overabundant wildlife. Slow-release hormonal implants containing deslorelin show promise for managing free-ranging populations, particularly in peri-urban reserves, but most studies have been limited to captivity.

Aims. . We investigated the efficacy and mechanism of deslorelin implants in free-ranging female eastern grey kangaroos (Macropus giganteus) under realistic management conditions.

Methods . We assigned females to a deslorelin (9.4 mg, n = 53) or placebo (n = 56) group at three peri-urban sites in Victoria, Australia, and monitored reproductive success for 3 years by observing young in the pouch. We tested the plasma LH response of control and treated females to exogenous GnRH, and compared the size of ovarian follicles between the two groups.

Key results . Deslorelin implants reduced fertility at all three sites. No deslorelin-treated females bred in Year 1 at Anglesea and Serendip versus 42% and 44% of control females respectively. At Plenty Gorge, 60% of deslorelin-treated females bred in Year 1 versus 100% of control females. In Year 2, between 11% and 39% of the treated females bred versus between 82% and 100% of control females at all sites. The contraceptive efficacy reduced by Year 3 when between 43% and 57% of the treated females bred versus between 85% and 100% of controls. A GnRH challenge elicited higher plasma LH concentrations in control than in treated females, and unlike untreated females, treated females lacked ovarian follicles >2 mm.

Conclusions . Deslorelin implants reduced fertility in free-ranging female eastern grey kangaroos over three successive breeding seasons. Chronic exposure to deslorelin desensitised the pituitary gland to GnRH and suppressed follicular development, but did not inhibit the development of a blastocyst, pregnancy or lactation in at least some females that had conceived before treatment.

Implications . Effective population management using deslorelin implants will require females to be re-treated on multiple occasions because the contraceptive effect lasts only a portion of their reproductive life. This would be practical only at sites where kangaroos are relatively easy to capture. The timing of treatment is also important in a species that undergoes embryonic diapause, particularly at sites providing high-quality habitat.

Context . Habitat thresholds are the critical point(s), below which the probability of occurrence of a species declines. Identifying thresholds assists land managers to decide how much habitat is needed to conserve a species. However, for any given species, a threshold may not exist, or might occur at one scale but not at others, and it may differ across regions. The use of critical habitat thresholds can negatively affect populations if simplified conservation targets for habitat retention are prescribed. This problem is relevant to the koalas where there is evidence of habitat thresholds in mesic regions, but no studies of thresholds in semiarid regions.

Aims . The aim of the present study was to investigate whether a threshold exists between the occupancy of a site by koalas and habitat variables at both the site and at four landscape scales in the semiarid Mulgalands Bioregion of Queensland, Australia.

Methods . We modelled habitat relationships using standard and piece-wise logistic regression, and an information-theoretic approach, to determine whether the best model that explained the occupancy–habitat relationships was linear or had a distinct threshold. The site-scale variable was the percentage of primary eucalypt species. The landscape-scale variables included the amount of primary and secondary habitat, and an interaction between them.

Key findings . There was a threshold relationship between the occurrence of koalas and the percentage of primary trees at the site scale. At the landscape scale, most threshold models failed to converge, and evidence pointed to a linear relationship between habitat amount and koala occupancy.

Conclusions . Conservation actions for koalas in the Mulgalands Bioregion should concentrate on protecting the primary tree resource for koalas, namely, river red gums (E. camaldulensis). However, the maintenance or restoration of primary and secondary habitat to distances of 1000 m from the creek is important because of the linear relationship between koala presence and habitat amount.

Implications . As habitat is lost in the semiarid Mulgalands Bioregion, koala occupancy declines. If known thresholds from mesic regions are used to define a minimum amount of habitat to be retained for koalas, conservation of local koala populations may well fail.

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.