Context. Wireless sensor networks (WSNs) are revolutionising areas of animal behaviour research and are advantageous based on their ability to be deployed remotely and unobtrusively, for long time periods in inaccessible areas.

Aims. We aimed to determine the feasibility of using a WSN to track detailed movement paths of small animals, e.g. rats (Rattus spp.) 100–400 g, too small for current GPS technology, by calibrating active Radio Frequency Identification (RFID) tags and loggers using Radio Frequency Signal Strength Indicator (RSSI) as a proxy for distance. Active RFIDs are also called Wireless Identification (WID) tags.

Methods. Calibration tests were conducted using a grid of loggers (n = 16) spaced at 45-m intervals in clear line-of-sight conditions. WID tags (n = 16) were placed between the loggers at 45-m intervals. Eight ‘walks’ were also conducted through the grid using a single WID tag. This involved attaching the tag to a small bottle of water (to simulate the body of an animal), towed around the grid using a 1-m long tow line attached to a volunteer walker. The volunteer also held a GPS device that logged their track. Models were constructed to test the effects of distance, tag movement and individual differences in loggers and tags on the reliability of movement data.

Key results. Loggers were most successful at detecting tags at distances <50 m. However, there was a significant difference in the detection probabilities of individual loggers and also the transmission performance of individual tags. Static tags were less likely to be detected than the mobile tag; and although RSSI was somewhat related to distance, the reliability of this parameter was highly variable.

Implications. We recommend caution in the future use of current radio frequency ID tags in wireless sensor networks to track the movement of small animals, and in the use of RSSI as an indicator of individual distance values, as extensive in situ calibration is required. ‘Off the shelf’ devices may vary in performance, rendering data unreliable. We emphasise the importance of calibrating all equipment in animal tracking studies to reduce data uncertainty and error.

Context. Changes in environmental conditions may influence bird populations, including pest bird species, and their distribution. In Argentina, particularly in the Pampas region, agricultural expansion has resulted in important changes in agroecosystems, with impacts on bird species.

Aims. This study analysed the relationship between pest bird densities and the environmental variables associated with land use and/or cover, vegetation productivity and climate. The study focused on the most important pest bird species to grain crops in Argentina and Uruguay: the eared dove (Zenaida auriculata) and the monk parakeet (Myiopsitta monachus).

Methods. An area in Central Argentina was divided into three agro-productive regions, one predominantly agricultural and two with mixed production activities: agricultural rangeland and agricultural forested rangeland. Bird populations were sampled on a yearly basis between 2003 and 2011 in point-transects located along secondary roads (47 routes in total). Linear mixed models and a multi-model inference approach were used to compare the effects of individual predictive variables on bird densities.

Key results. Mean estimated density for the eared dove was 0.39 individuals per ha (±0.02), almost three times the density of the monk parakeet (0.10 individuals per ha ± 0.02). The spatial distribution of changes in density of the eared dove and monk parakeet showed irregular patterns across the study area. Density of eared dove was directly related to cover of native and exotic woodlots and inversely related to cover of fallow and weedy fields, and to temperature and rainfall. Monk parakeet density, in turn, was directly related to cover of woodlots.

Conclusions. The density of eared doves and monk parakeets changed mostly in relation to land use and/or cover and, to a lesser extent, to climatic conditions. Information of pest bird populations in a long-term period allowed us to understand spatial patterns in bird population distribution and to identify the main environmental factors explaining them.

Implications. The consideration of land use and/or cover, vegetation productivity and climate variables at regional scale, measured during a long-term period, would be critical for anticipating population increases and, possibly, increases in crop damage.

Context. Documenting cause-specific mortality and deriving survival estimates for a population are both vital to understanding potential restrictions to population growth. Survival varies among populations of the same species and depends on several factors, including climatic events, density-dependent and density-independent factors, observed predator composition and whether recreational hunting occurs. Therefore, understanding factors affecting adult survival and estimating survival rates at biologically important times will help refine management of these populations.

Aims. We aimed to assess cause-specific mortality, estimate survival rates, and determine at what part of the winter (January to April) most mortalities occurred for female white-tailed deer located in the Northern Great Plains region of the USA.

Methods. We captured 165 adult female white-tailed deer (Odocoileus virginianus) located in western North Dakota and north-western South Dakota, USA, during the winters of 2014 and 2015. We fitted individuals with Very High Frequency (VHF) radio-collars and located them 1–3 times per week to monitor survival. We investigated all mortalities to establish proximate cause of death.

Key Results. Survival was lowest during our Hunt time period (S = 0.93), although hunter harvest was not the leading cause of mortality. Predation was the greatest source of mortality, particularly during our Post-hunt time period. Additionally, almost 90% of mortalities occurring during the Post-hunt time period happened during late winter before spring green up.

Conclusions and Implications. Predation was the main source of mortality for adult females in our study, with coyotes (Canis latrans) being the sole predator capable of depredation in our study area. Predation by coyotes may indicate that potential factors, including winter severity and nutritional restrictions, have decreased female body condition, making individuals more susceptible to predation. Although we report relatively high survival, managers should consider the possibility that coyotes may impact adult populations, particularly in regions where other large-sized predators occur, or in regions where coyotes are newly established. Managers should also acknowledge that overwinter density estimates may need to be adjusted during severe winters to account for mortalities that occur after population surveys are conducted.

Context. As urban landscapes proliferate globally, the need for research into urban wildlife interactions is magnified. The eastern grey kangaroo (Macropus giganteus) is a widespread species commonly involved in wildlife–vehicle collisions in urban areas in Australia. Despite the many urban kangaroo populations and associated conflicts with human activities, few studies have examined how eastern grey kangaroos interact with, and are affected by, the urban matrix.

Aims. The present study aimed to quantify kangaroo demography, movements, habitat utilisation and exposure to risks during a period of intensive urban development in a rapidly changing suburb located in a region undergoing high urban growth rates.

Methods. We utilised foot-based census surveys, global positioning system (GPS) collars, direct observations and reports of wildlife mortality between 2014 and 2016. Geographical information systems (GIS) were used to integrate GPS-tracking data with spatial layers, to quantify kangaroo movements and habitat utilisation.

Key results. The kangaroo population underwent a steep decline and kangaroo–vehicle collisions were the main source of mortality (73%) during the study period. Kangaroos were regularly exposed to the risk of injury, with roads intersecting many parts of their home range. Kangaroos showed positive habitat selection both for lawn and forest habitats and kangaroo movement and presence at the study site were influenced by high-quality forage and cover.

Conclusions. The present research has highlighted that despite areas of suitable habitat remaining, road-kill was a major contributor to localised kangaroo-population decline. We showed that habitat preferences of eastern grey kangaroos in this urban area were consistent with those in natural landscapes.

Implications. The present study is the first to implicate kangaroo–vehicle collisions as the major factor in population decline in kangaroos. These findings can be utilised to guide design and placement of kangaroo–vehicle collision mitigation and assist in planning of urban areas, particularly where kangaroo populations are in decline. Local extirpation of urban kangaroo populations would be greatly reduced by incorporating site-specific kangaroo habitat preferences and existing patterns of kangaroo habitat use in infrastructure planning. The study has contributed to our understanding of the effects of roads on urban wildlife in general and highlighted the importance of landscape permeability.

Context. Management of overabundant or invasive species is a constant challenge because resources for management are always limited and relationships between management costs, population density and damage costs are complex and difficult to predict. Metrics of management success are often based on simple measures, such as counts, which may not be indicative of impacts on damage reduction or cost-effectiveness under different management plans.

Aims. The aims of this study were to evaluate the effectiveness of aerial gunning for the management of wild pigs (Sus scrofa), and to evaluate how cost-effectiveness would vary under different relationships between levels of damage and densities of wild pigs.

Methods. Repeated reduction events were conducted by aerial gunning on three consecutive days at three study sites. Using a removal model, the proportion of the population removed by each flight was estimated and population modelling was used to show the time it would take for a population to recover. Three possible damage–density relationships were then used to show the level of damage reduction (metric of success) from different management intensities and levels of population recovery, and these relationships were expressed in terms of total costs (including both damage and management costs).

Key results. Populations were typically reduced by ∼31% for the first flight, ∼56% after two flights and ∼67% after three flights. When the damage relationship suggests high damage even at low densities, the impact of one, two or three flights would represent a reduction in damage of 2%, 19% and 60% respectively after 1 year. Different damage relationships may show considerable damage reduction after only one flight. Removal rates varied by habitat (0.05 per hour in open habitats compared with 0.03 in shrubby habitats) and gunning team (0.03 versus 0.05).

Conclusions. Monitoring the efficacy of management provides critical guidance and justification for control activities. The efficacy of different management strategies is dependent on the damage–density relationship and needs further study for effective evaluation of damage reduction efforts.

Implications. It is critically important to concurrently monitor density and damage impacts to justify resource needs and facilitate planning to achieve a desired damage reduction goal.

Context. When measuring grazing impacts of vertebrates, the density of animals and time spent foraging are important. Traditionally, dung pellet counts are used to index macropod grazing density, and a direct relationship between herbivore density and foraging impact is assumed. However, rarely are pellet deposition rates measured or compared with camera-trap indices.

Aims. The aims were to pilot an efficient and reliable camera-trapping method for monitoring macropod grazing density and activity patterns, and to contrast pellet counts with macropod counts from camera trapping, for estimating macropod grazing density.

Methods. Camera traps were deployed on stratified plots in a fenced enclosure containing a captive macropod population and the experiment was repeated in the same season in the following year after population reduction. Camera-based macropod counts were compared with pellet counts and pellet deposition rates were estimated using both datasets. Macropod frequency was estimated, activity patterns developed, and the variability between resting and grazing plots and the two estimates of macropod density was investigated.

Key Results. Camera-trap grazing density indices initially correlated well with pellet count indices (r² = 0.86), but were less reliable between years. Site stratification enabled a significant relationship to be identified between camera-trap counts and pellet counts in grazing plots. Camera-trap indices were consistent for estimating grazing density in both surveys but were not useful for estimating absolute abundance in this study.

Conclusions. Camera trapping was efficient and reliable for estimating macropod activity patterns. Although significant, the relationship between pellet count indices and macropod grazing density based on camera-trapping indices was not strong; this was due to variability in macropod pellet deposition rates over different years. Time-lapse camera imagery has potential for simultaneously assessing herbivore foraging activity budgets with grazing densities and vegetation change. Further work is required to refine the use of camera-trapping indices for estimation of absolute abundance.

Implications. Time-lapse camera trapping and site-stratified sampling allow concurrent assessment of grazing density and grazing behaviour at plot and landscape scale.

Context. The toxic cane toad (Rhinella marina) has invaded over 50 countries and is a serious conservation issue in Australia. Because the cane toad has taken several decades to colonise northern Australia, due to the large size of the continent and the east–west invasion axis, there is scope for making testable predictions about how toads will invade new areas. The western toad invasion front is far from linear, providing clear evidence for heterogeneity in invasion speed.

Aims. Several ad hoc hypotheses have been offered to explain this heterogeneity, including the evolution of traits that could facilitate dispersal, and spatial heterogeneity in climate patterns. Here an alternative hypothesis is offered, and a prediction generated for the spatiotemporal pattern of invasion into the Kimberley Region – the next frontier for the invading toads in Australia.

Methods. Using observations of spatiotemporal patterns of cane toad colonisation in northern Australia over the last 15 years, a conceptual model is offered, based on the orientation of wet season river flows relative to the invasion axis, as well as toad rafting and floating behaviour during the wet season.

Key results. Our model predicts that toads will invade southern areas before northern areas; an alternative model based on rainfall amounts makes the opposite prediction. The models can now be tested by monitoring the spread of invasion front over the next 5–10 years.

Conclusions. Our conceptual models present a pleuralistic approach to understanding the spatiotemporal invasion dynamics of toads; such an approach and evaluation of the models could prove useful for managing other invasive species.

Implications. Although control of cane toads has largely proved ineffective, knowledge of the spatiotemporal pattern of the toad invasion in the Kimberley could: (1) facilitate potential management tools for slowing the spread of toads; (2) inform stakeholders in the local planning for the invasion; (3) provide researchers with a temporal context for quantifying toad impacts on animal communities; and (4) reveal the mechanism(s) causing the heterogeneity in invasion speed.

Context. Predator-controlled environments can lead to prey species losing costly antipredator behaviours as they exploit their low-risk environment, creating a ‘predator-naïve’ population. If individuals lacking suitable antipredator behaviours are used as source populations for reintroductions to environments where predators are present, their behaviour could result in high post-release predation. In contrast, animals sourced from environments with predators (‘predator-exposed’) may show effective antipredator behaviours and thus higher survival post-release.

Aims. The aim was to compare the antipredator behaviour of brushtail possums (Trichosurus vulpecula) at predator-exposed and predator-naïve source populations, and then compare post-release survival after their reintroduction to a low predator environment.

Methods. Data were collected from possums at two sites, one with and one without mammalian predators. The behavioural responses of possums to a spotlighter, their willingness to use supplementary feeders at ‘safe’ and ‘risky’ heights, whether they avoided predator odour at traps and their general willingness to enter traps were recorded.

Key results. Predator-naïve possums showed weaker antipredator responses, were often found at ground level, engaged with novel objects, did not avoid predator scents and utilised different habitats regardless of associated predation risk. In contrast, predator-exposed possums had higher antipredator responses, chose connected trees, were rarely found at ground level and were generally difficult to capture. Post-translocation survival was high for both source populations. Predator-naïve-sourced female possums began to avoid predator urine (feral cat; Felis catus) 12 months after translocation.

Conclusions. Our research demonstrates that environmental predation risk can predict prey naïvety in brushtail possums. Some aspects of prey naïvety behaviour appear to be able to change in response to altered predation risk.

Implications. With many threatened species now existing only in feral predator-free areas, these results have implications for future reintroductions into unbounded areas where feral predators are present, and for the management of fenced reserves. The addition of a small number of predators to fenced reserves may aid in retaining antipredator behaviours in fenced prey populations.

Context. Climate change is having significant impacts on species worldwide. The endangered eastern quoll (Dasyurus viverrinus) has recently undergone rapid and severe population decline, with no sign of recovery. Spatially and temporally-explicit weather modelling suggests a prolonged period of unfavourable weather conditions during 2001–03 as the proximate cause of decline. However, the mechanisms of this weather-induced decline are not currently understood.

Aims. The aim of this study was to investigate the hypothesis that changing weather conditions have altered the availability of key prey species, potentially contributing to the species’ decline.

Methods. We analysed 229 scats collected from 125 individual wild quolls across four sites between July 2011 and May 2012. Variation in dietary composition and niche breadth was compared across sites and seasons. We also compared contemporary dietary composition and niche breadth to historic dietary studies performed before the species’ decline, to identify any key changes in dietary composition over time.

Key results. Dietary composition and niche breadth were similar across sites but differed between seasons. Dietary niche contracted during winter (July) and early spring (September) when insect larvae formed the bulk of quoll diet, rendering the species vulnerable to weather-related fluctuations in food availability at that time. Large differences were also evident between current and historic dietary composition, with a marked shift from insect larvae to mammals, predominantly due to a reduction in corbie (Oncopera intricata) and southern armyworm (Persectania ewingii) moth larvae. Quoll abundance appears positively related to corbie larva abundance during winter, and both quoll and corbie larva abundance appear negatively related to winter rainfall.

Conclusions. The lower contribution of insects at sites with low quoll densities suggests that insects represent an important food item for eastern quolls during winter, when dietary niche is narrowest and energy demands are highest. Our findings suggest that weather-induced fluctuations in quoll abundance, including the significant statewide decline during 2001–03, are potentially driven by weather-induced fluctuations in corbie larva abundance.

Implications. Continued deterioration in climatic suitability with recent and predicted climate change could further threaten eastern quolls through reductions in the availability and stability of reliable food sources at critical life-history stages when dietary options are already limited.