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Avoiding the undesirable impacts of invasive species requires robustly evaluating the effects of alternative management scenarios. Such evaluations depend on reliable spatio‐temporal projections of changes in the distribution and abundance of the invasive species under different scenarios. However, commonly used modelling approaches are constrained for this purpose because they do not incorporate demographic processes and are seldom validated.We develop a spatially and temporally explicit grid‐based population model for invasive fallow deer Dama dama in Tasmania, Australia, validated against observed distribution and abundance 'targets' using a pattern‐oriented approach. We use this validated model to project the future invasion patterns of deer, including encroachment into areas of high conservation value, under eight harvest and habitat suitability scenarios.Projected population sizes of deer differ greatly depending on harvest and habitat suitability scenarios. Without harvest, the population grows sixfold, from about 80,000 deer in 2019 to over 500,000 by 2100. In contrast, the population stabilises at 32,000–41,000 deer with 25% annual harvest. Abundance in the environmentally sensitive Tasmanian Wilderness World Heritage Area (TWWHA), a region of high conservation value, increases in all scenarios. We identify likely areas in the expanding range of deer where targeted removal should be most effective at minimising deer numbers in the TWWHA.Synthesis and applications: Using a pattern‐oriented model validated with spatio‐temporal data, we show how the future distribution and abundance of invasive fallow deer in Tasmania can be substantially reduced by targeted increases in harvest and prioritising areas for removal around high conservation value regions. Our approach can be used to project likely effects of management interventions on future distributions and abundances for a range of invasive taxa. [ABSTRACT FROM AUTHOR]

Invasive deer have undesirable impacts on native ecosystems. Culling is commonly used to reduce those impacts, but is expensive and sometimes controversial. It is therefore important to robustly assess how culling reduces the impacts of invasive deer.We conducted a Before‐After Control‐Impact (BACI) experiment to determine how culling affects the impacts of invasive sambar deer Cervus unicolor in an endangered alpine peatland ecosystem in south‐eastern Australia. We established two blocks, each with four 4300‐ha experimental units, in which two units were randomly assigned to a treatment of deer culling and the other two were non‐treatment areas. Sambar deer relative abundance (faecal pellet count) and three impacts (ground degradation, pugging intensity and water turbidity) in three peatland features (peatlands, natural pools and sambar deer wallows) were surveyed before and after culling was implemented. We used four metrics to quantify the culling intensity in each treatment unit: treatment versus non‐treatment, number of deer culled on each unit, deer culled within a 500‐m buffer of impact monitoring sites and local probability of use by the cullers (1‐ha grid). The effects of culling on deer abundance and impacts were estimated using Bayesian generalised linear mixed models.Our analysis revealed that the effect of culling differed between the two experimental blocks. In one block, culling reduced deer abundance and three impacts. In the other block, culling did not reduce deer abundance but reduced three impacts and increased two impacts. The effects of culling were generally stronger when culling was estimated using finer‐scale (500‐m) than coarser‐scale (experimental unit) culling metrics.Synthesis and applications. Our study provides experimental evidence that culling invasive sambar deer reduces some of their undesirable impacts on endangered peatlands. That not all impacts were reduced by culling suggests that some effects of invasive species are slow to recover or require higher culling intensities to be reversed. [ABSTRACT FROM AUTHOR]

Large herbivores typically have consistently high prime‐aged adult survival and lower, more variable, juvenile, and senescent survival. Many kangaroo populations undergo greater fluctuations in density compared with other large herbivores, but age‐ and sex‐specific survival of kangaroos and their response to environmental variation remain poorly estimated. We used long‐term capture–mark–recapture data on 920 individuals to investigate the survival component of eastern grey kangaroo (Macropus giganteus) population dynamics. Forage availability and population density were monitored quarterly and included as predictors of survival in Bayesian Cormack–Jolly–Seber models. Annual survival probabilities were estimated for five age classes: 0 years (juveniles), 1–2 years (subadults), 3–6 years (prime‐aged adults), 7–9 years (presenescent adults), and ≥10 years (senescent adults). Survival of juveniles varied widely during our 12‐year study, ranging from 0.07 to 0.90 for females and 0.05–0.92 for males. Subadult survival was 0.80–0.93 for females and 0.75–0.85 for males, while that of prime‐aged adults was ≥0.94 for females and ≥0.83 for males, despite large fluctuations in forage and density. The survival of presenescent adults spanned 0.86–0.93 for females and 0.60–0.86 for males. Senescent survival was variable, at 0.49–0.90 for females and 0.49–0.80 for males. Male survival was significantly lower than female survival in prime‐aged and presenescent adults, but not in other age classes. Although most of the models supported by Watanabe–Akaike Information Criterion selection included at least one environmental covariate, none of these covariates individually had a discernible effect on survival. Temporal variability in overall survival appeared mostly due to changes in the survival of juvenile and senescent kangaroos. Kangaroo survival patterns are similar to those of ungulates, suggesting a strong role of sex–age structure on population dynamics. [ABSTRACT FROM AUTHOR]

Estimating the abundance and density of mountain ungulates is difficult because of rugged and remote terrain, high elevations, and rapidly changing weather. Helicopter surveys could overcome these problems, but researchers have seldom applied helicopter‐based survey methods at large spatial scales in mountain terrain. We used helicopters to count introduced Himalayan tahr (Hemitragus jemlahicus) at 117 plots, each of 4 km2, in New Zealand's Southern Alps during 2016–2019. The sampling frame was 7,844 km2 and we located the plots at the vertices of an 8‐km grid superimposed over the sampling frame (i.e., a systematic random sampling design). We conducted 3 repeat counts at each plot during summer–autumn. We used the repeat counts to estimate tahr abundance and density, corrected for imperfect detection, using a dynamic N‐mixture model for open populations. We estimated the population of tahr in the sampling frame using design‐based, finite sampling methods and model‐based inference procedures. The mean estimated density of tahr on each plot varied from zero to 31.7 tahr/km2. The mean densities of tahr varied among management units, ranging from 0.3 to 10.7 tahr/km2, and exceeded specified intervention densities in 6 of the 7 management units. The total design‐based estimate of tahr abundance in the sampling frame was 34,500 (95% CI = 27,750–42,900), with a coefficient of variation (CV) of 0.11. The corresponding model‐based estimate of total abundance was similar (34,550, 95% CI = 30,250–38,700) but was substantially more precise (CV = 0.06) than the design‐based estimate. The precision of the estimates for the individual management units was also better than that of the design‐based estimates, with CVs of <0.20 for all but 1 management unit. Our study provides a repeatable method for sampling mountain ungulates. More generally, robust estimation of abundance and density of mountain ungulates is possible by combining aerial surveys and open population models with an objective, probabilistic sampling design. [ABSTRACT FROM AUTHOR]

Deer (Cervidae) are key components of many ecosystems and estimating deer abundance or density is important to understanding these roles. Many field methods have been used to estimate deer abundance and density, but the factors determining where, when, and why a method was used, and its usefulness, have not been investigated. We systematically reviewed journal articles published during 2004–2018 to evaluate spatio‐temporal trends in study objectives, methodologies, and deer abundance and density estimates, and determine how they varied with biophysical and anthropogenic attributes. We also reviewed the precision and bias of deer abundance estimation methods. We found 3,870 deer abundance and density estimates. Most estimates (58%) were for white‐tailed deer (Odocoileus virginianus), red deer (Cervus elaphus), and roe deer (Capreolus capreolus). The 6 key methods used to estimate abundance and density were pedestrian sign (track or fecal) counts, pedestrian direct counts, vehicular direct counts, aerial direct counts, motion‐sensitive cameras, and harvest data. There were regional differences in the use of these methods, but a general pattern was a temporal shift from using harvest data, pedestrian direct counts, and aerial direct counts to using pedestrian sign counts and motion‐sensitive cameras. Only 32% of estimates were accompanied by a measure of precision. The most precise estimates were from vehicular spotlight counts and from capture–recapture analysis of images from motion‐sensitive cameras. For aerial direct counts, capture–recapture methods provided the most precise estimates. Bias was robustly assessed in only 16 studies. Most abundance estimates were negatively biased, but capture–recapture methods were the least biased. The usefulness of deer abundance and density estimates would be substantially improved by 1) reporting key methodological details, 2) robustly assessing bias, 3) reporting the precision of estimates, 4) using methods that increase and estimate detection probability, and 5) staying up to date on new methods. The automation of image analysis using machine learning should increase the accuracy and precision of abundance estimates from direct aerial counts (visible and thermal infrared, including from unmanned aerial vehicles [drones]) and motion‐sensitive cameras, and substantially reduce the time and cost burdens of manual image analysis. [ABSTRACT FROM AUTHOR]

In response to health threats posed by toxic lead to humans and scavenging wildlife, there is currently a focus on transitioning from lead‐based to lead‐free bullets for shooting (harvesting, culling, or recreational hunting) of wild animals. However, the efficacy of lead‐free bullets for shooting small mammals has seldom been evaluated. We compared the animal welfare outcomes and costs of using lead‐based and lead‐free bullets in the world's most popular cartridge, the rimfire.22 LR, for shooting wild European rabbits (Oryctolagus cuniculus) in Australia, during August 2019. Ballistic testing revealed that lead‐free bullets were less precise than one type of commonly used lead‐based bullet when shot from one rifle. We shot at 53 and 115 rabbits with lead‐based and lead‐free bullets, respectively. A substantially lower percentage of rabbits that were hit were wounded (2%) with lead‐based bullets compared with lead‐free bullets (20%). Hence, fewer shots were needed to kill rabbits with lead‐based (1.27) than lead‐free (3.98) bullets. Radiographic examination of 28 rabbits shot with lead‐based bullets and 27 rabbits shot with lead‐free bullets revealed metallic fragments present in 82% and 41% of carcasses, respectively. In 52% of rabbits shot with lead‐free bullets, there was no radiographic evidence of bullets or fragments, indicating pass‐through shots. The greater cost per bullet and larger number of bullets required to kill a rabbit meant that using lead‐free bullets cost 6 times more per rabbit killed than using lead‐based bullets. The only commercially available lead‐free.22 LR bullets in Australia at the time of our study produced substantially poorer animal welfare outcomes, and were more expensive per killed rabbit, than lead‐based bullets. Lead‐free bullets designed to reduce lead exposure to scavenging wildlife and humans and should be assessed in terms of animal welfare outcomes and costs prior to being considered for widespread use. © 2020 The Wildlife Society. The efficacy of lead‐free rimfire.22 LR bullets was compared with lead‐based bullets for shooting European rabbits in Australia. Lead‐free bullets were less effective, emphasizing the need for animal welfare testing for new ballistic technology. [ABSTRACT FROM AUTHOR]

Apex predators can have substantial and complex ecological roles in ecosystems. However, differences in species‐specific traits, population densities, and interspecific interactions are likely to determine the strength of apex predators' roles. Here we report complementary studies examining how interactions between predator per capita metabolic rate and population density influenced the biomass, population energy use, and ecological effects of apex predators on their large mammalian prey. We first investigated how large mammal prey resources and field metabolic rates of terrestrial apex predators, comprising large mammals and the Komodo dragon (Varanus komodoensis), influenced their biomass densities and population energy use requirements. We next evaluated whether Komodo dragons, like apex mammalian predators, exerted top‐down regulation of their large mammal prey. Comparison of results from field studies demonstrates that Komodo dragons attain mean population biomass densities that are 5.75−231.82 times higher than that of apex mammalian predator species and their guilds in Africa, Asia, and North America. The high biomass of Komodo dragons resulted in 1.96−108.12 times greater population energy use than that of apex mammalian predators. Nevertheless, substantial temporal and spatial variation in Komodo dragon population energy use did not regulate the population growth rates of either of two large mammal prey species, rusa deer (Rusa timorensis) and wild pig (Sus scrofa). We suggest that multiple processes weaken the capacity of Komodo dragons to regulate large mammal prey populations. For example, a low per capita metabolic rate requiring an infrequent and inactive hunting strategy (including scavenging), would minimize lethal and nonlethal impacts on prey populations. We conclude that Komodo dragons differ in their predatory role from, including not being the ecological analogs of, apex mammalian predators. [ABSTRACT FROM AUTHOR]

Flightless birds were once the largest and heaviest terrestrial fauna on many archipelagos around the world. Robust approaches for estimating their population parameters are essential for understanding prehistoric insular ecosystems and extinction processes. Body mass and population density are negatively related for extant flightless bird species, providing a method for quantifying densities and population sizes of extinct flightless species. Here we assemble an updated global data set of body mass and population densities for extant flightless birds and estimate the relationship between these variables. We use generalised least squares models that account for phylogenetic relatedness and incorporate the effects of limiting factors (e.g. habitat suitability) on population density. We demonstrate the applicability of this allometric relationship to extinct species by estimating densities for each of the nine species of moa (Dinornithiformes) and generating a combined spatially explicit map of total moa density across New Zealand. To compare our density estimates with those previously published, we summed individual species' abundances to generate a mean national density of 2.02–9.66 birds km−2 for low‐ and high‐density scenarios, respectively. Our results reconcile the extreme bimodality of previous estimates (< 2 birds km−2 and > 10 birds km−2) and are comparable to contemporary densities of large herbivorous wild mammals introduced into New Zealand about 150 yr ago. The revised moa density has little effect on the harvest rates required to bring about extinction within 150–200 yr, indicating that rapid extinction was an inevitable response to human hunting, irrespective of the initial population of moa. [ABSTRACT FROM AUTHOR]

Multi‐strain, host‐disease dynamics describe a system where multiple strains of a pathogen compete for susceptible individuals of a single host. The theoretical properties of these systems have been well studied, but there are few empirical studies in wildlife hosts.We examined the impacts of two novel strains of rabbit haemorrhagic disease virus (RHDV) recently introduced into Australia, one inadvertently (RHDV2) and one deliberately for rabbit biocontrol (RHDV‐K5), by analysing long‐term monitoring data for introduced European rabbits Oryctolagus cuniculus from 18 sites throughout Australia. We examined population‐level impacts using rabbit spotlight counts pre‐ and post‐arrival of the two strains. We also analysed serological data to determine potential interactions among the introduced and existing field strains of RHDV, as well as a pre‐existing benign strain of calicivirus (RCV‐A1).Serological analyses suggested that RHDV2 arrived in Australia during spring 2014 and spread rapidly through the Australian rabbit population within 2 years. Following the establishment of RHDV2, rabbit abundance was reduced by an average of 60%, with impacts most pronounced in South and Western Australia. In contrast, the deliberate release of RHDV‐K5 had little impact on rabbit populations.Although RHDV2 has spread rapidly throughout Australia, our serological analyses do not support the observation that RHDV2 is rapidly replacing existing field strains of RHDV, as was previously reported in Australia and Europe. Nevertheless, RHDV2 has negatively impacted the ability of RHDV and RCV‐A1 to spread within rabbit populations, most likely due to its ability to infect juvenile rabbits, thereby removing them from the pool of susceptible individuals available to be infected by competing strains.Synthesis and applications. The impact of the release of a novel strain of rabbit haemorrhagic disease virus (RHDV‐K5) for rabbit biocontrol in Australia has been suppressed by the emergence of a competing strain, RHDV2. Hence, the success of further releases of similar RHDV strains for rabbit biocontrol appears doubtful. Despite this, RHDV2 has suppressed rabbit abundances by an average of 60%, with impacts most pronounced in South and Western Australia. Whether the incursion of RHDV2 leads to the competitive exclusion of other endemic RHDV strains remains to be resolved. However, the existence of partial cross‐immunity could allow some level of coexistence between RHDV2 and RHDV strains, at least in the medium term. [ABSTRACT FROM AUTHOR]

Estimating population abundances, densities, and interspecific interactions are common goals in wildlife management. Camera traps have been used to estimate the abundance and density of a single species, and are useful for carnivores that occur at low densities. Spatial capture–recapture (SCR) models can be used to estimate abundance and density from a camera trap array when all, some, or no individuals in the population can be uniquely identified. These SCR models also estimate locations of individual activity centers, the spatial patterning of which could provide important information about interspecific interactions. We used SCR models to estimate abundances, densities, and activity centers of each of 3 carnivore species (i.e., dingo [Canis familiaris], red fox [Vulpes vulpes], and feral cat) using photographs from 1 camera trap array in southeastern Australia during September to November 2015. Some dingoes and feral cats were uniquely identifiable and therefore, we used a spatial mark–resight model for these species. We could not uniquely identify fox individuals, however, so we used a spatial unmarked (SUN) model for this species. Our estimated dingo density was 0.06/km2. The fox (0.25/km2) and feral cat (0.16/km2) densities are within the ranges previously reported for these species in Australia. We obtained a relatively imprecise fox density estimate because we did not have detections of uniquely identifiable individuals; hence, the SUN model should be used as a last resort. We next modeled spatial dependence among the estimated activity centers for the 3 species using a spatial pair correlation function for a marked point process. Consistent with our expectations, the activity centers of dingoes and foxes were strongly negatively associated at distances of <1,000 m. Foxes and feral cats were also negatively associated at distances of <1,500 m. Surprisingly, dingoes and feral cats were positively associated at distances of >500 m, with no association evident at distances of <500 m. Our study extends the inferences that can be made from using a camera trap array and SCR methods to include spatial patterning and interspecific interactions, and provides new insights into the carnivore community of dingoes, foxes, and feral cats in southeastern Australia. © 2019 The Authors. The Journal of Wildlife Management Published by Wiley Periodicals, Inc. We used spatial capture–recapture models to estimate abundances, densities, and interspecific spatial associations of 3 carnivore species (dingo, red fox, and feral cat) using photographs from one camera‐trap array in southeastern Australia. Our methods can be used to estimate abundances, densities, and interspecific spatial associations elsewhere, providing robust information that will greatly assist managers and researchers working with wildlife communities. [ABSTRACT FROM AUTHOR]

Applied ecologists are often interested in understanding the effects of management on ecological systems. If management (treatment) is applied nonrandomly, as in observational studies, then analysis must account for the potential confounding caused by variables that could have influenced both treatment assignment and the outcome of interest. Methods that do not adjust for all confounding variables can only estimate associations between treatment and outcome, not treatment effects.Data collected in observational studies are usually analysed with linear or generalized linear models, which can estimate treatment effects by adjusting for confounding variables. However, if there is little overlap in the distributions of confounding variables among the treatment groups then conventional regression extrapolates to areas of the covariate space where at least one of the treatment groups was unlikely to be observed.An alternative procedure for assessing treatment effects is to use the propensity score, which is the probability of treatment assignment given potential confounding variables. The propensity score can be used to reduce systematic differences in confounding variables among the treatment groups, ensuring that data more closely resemble that expected under a randomized experiment. The propensity score also identifies situations where treatment inferences must rely on strong assumptions.We used Monte Carlo simulation to examine the properties of commonly used propensity score methods for estimating treatment effects in the presence of nonrandom allocation of treatments. We then illustrated their application in a case study estimating the effects of invasive herbivore management on tree condition.Our results indicate that propensity score methods can be robust to model misspecification, allowing the estimation of average causal effects and resulting in more reliable inferences. We discuss key considerations for using propensity score methods for analysing ecological data. [ABSTRACT FROM AUTHOR]

Conserving large carnivores is controversial because they can threaten wildlife, human safety, and livestock production. Since large carnivores often have large ranges, effective management requires knowledge of how their ecology and functional roles vary biogeographically.We examine continental‐scale patterns in the diet of the dingo – Australia's largest terrestrial mammalian predator. We describe and quantify how dingo dietary composition and diversity vary with environmental productivity and across five bioclimatic zones: arid, semi‐arid, tropical, sub‐tropical, and temperate.Based on 73 published and unpublished data sets from throughout the continent, we used multivariate linear modelling to assess regional trends in the occurrence of nine food groups (arthropods, birds, reptiles, European rabbits Oryctolagus cuniculus, medium‐sized [25–125 kg] and large [169–825 kg] exotic ungulates [including livestock], and other small [<0.5 kg], medium‐sized [0.5–6.9 kg] and large [≥7 kg] mammals) in dingo diets. We also assessed regional patterns in the dietary occurrence of livestock and the relationship between dietary occurrence of rabbits and small, medium‐sized and large mammals.Dingoes eat at least 229 vertebrate species (66% mammals, 22% birds, 11% reptiles, and 1% other taxa). Dietary composition varied across bioclimatic zones, with dingo diets in the arid and semi‐arid zones (low‐productivity sites) having the highest occurrence of arthropods, reptiles, birds, and rabbits. Medium‐sized mammals occurred most frequently in temperate and sub‐tropical zone diets (high‐productivity sites), large mammals least in the arid and sub‐tropical zones, and livestock most in the arid and tropical zones. The frequency of rabbits in diets was negatively correlated with that of medium‐sized, but not small or large mammals.Dingoes have a flexible and generalist diet that differs among bioclimatic zones and with environmental productivity in Australia. Future research should focus on examining how dingo diets are affected by local prey availability and human‐induced changes to prey communities. [ABSTRACT FROM AUTHOR]

Invasive mammalian predators commonly coexist with invasive mammalian herbivore prey. Managers often advocate controlling invasive prey in the belief that this will also reduce invasive predator abundance. Such an outcome would have desirable ecological and financial benefits, but there have been few tests of this hypothesis.We used large‐scale and long‐term monitoring data to test the prediction that invasive red fox Vulpes vulpes populations decline following control of invasive European rabbit Oryctolagus cuniculus populations in Australia. Both species severely impact natural and agricultural ecosystems, and significant resources are expended to reduce these impacts. We fitted a hierarchical state‐space model to spotlight counts of both species conducted at 21 transects between 1998 and 2015. The effects of rainfall, control activities (warren ripping and surface harbour removal), and density dependence on the population growth rates of both species were also evaluated.Control activities at 18 transects substantially reduced average rabbit abundances. Rabbit populations showed little response to rainfall, but exhibited negative density dependence and higher rates of increase during the autumn–spring interval.There was no numerical response of foxes to changes in rabbit abundance. Rather, fox populations increased rapidly after high rainfall and exhibited negative density dependence. The equilibrium abundance of foxes varied with rainfall and season, but was always <0.2 foxes per spotlight km.Synthesis and applications. We conclude that controlling rabbits to low abundances does not substantially reduce fox abundances in south eastern Australia. Rather, efforts to reduce fox abundance should directly target fox populations. Managers of invasive predator–invasive prey systems should not assume that controlling prey will, by itself, reduce predator abundances. Quantifying the numerical response is critical for understanding the likely response of predators to changes in prey abundance. We conclude that controlling rabbits to low abundances does not substantially reduce fox abundances in south eastern Australia. Rather, efforts to reduce fox abundance should directly target fox populations. Managers of invasive predator–invasive prey systems should not assume that controlling prey will, by itself, reduce predator abundances. Quantifying the numerical response is critical for understanding the likely response of predators to changes in prey abundance. [ABSTRACT FROM AUTHOR]

Abstract: Biological invasions by large herbivores involve the establishment of novel interactions with the receiving mammalian carnivore community, but understanding these interactions is difficult due to the large spatiotemporal scales at which such dynamics would occur. We quantified the functional responses of a native apex predator (the dingo (Canis familiaris), which includes wild dogs and their hybrids) and a non‐native mesopredator (red fox; Vulpes vulpes) to an invading non‐native ungulate (sambar deer; Cervus unicolor) in Australia. We predicted that the apex predator would exhibit a stronger functional response to increasing sambar deer abundance than the mesopredator. We used a state–space model to link two 30‐year time series: (i) sambar deer abundance (hunter catch‐per‐unit‐effort); and (ii) percentages of sambar deer in dingo (N = 4531) and fox (N = 5002) scats. Sambar deer abundance increased over fourfold during 1984−2013. The percentages of sambar deer in dingo and fox scats increased during this 30‐year period, from nil in both species in 1984 to 8.2% in dingoes and 0.5% in foxes in 2013. Dingoes exhibited a much stronger functional response to increasing sambar deer abundance than foxes. The prediction that invading deer would be utilized more by the apex predator than by the mesopredator was therefore supported. The increasing abundance of sambar deer during the period 1984−2013 provided an increasingly important food source for dingoes. In contrast, the smaller red fox utilized sambar deer much less. Our study demonstrates that prey enrichment can be an important consequence of large herbivore invasions and that the effect varies predictably with the trophic position of the mammalian carnivores in the receiving community. [ABSTRACT FROM AUTHOR]

ABSTRACT In wildlife shooting programs, the energy profile of the projectile or bullet (i.e., kinetic energy transferred to the animal), as distinct from caliber (projectile diameter), is an important factor for animal welfare. We examined the role of projectile energy in determining animal welfare outcomes for a typical European rabbit ( Oryctolagus cuniculus) sharpshooting program. We compared 2 projectiles of different energy profiles: low-energy 40-grain .22 long rifle rimfire (.22LR; 198 J) bullets and high-energy 40-grain .222 Remington® centerfire (.222R; 1,433 J) bullets, fired under similar conditions on 3 nights in September 2014, on a livestock grazing property near Broken Hill, New South Wales, southeastern Australia. We used a thermal-imaging camera to collect antemortem data from 500 rabbits that were shot at varying distance. We collected postmortem data via visual inspection from 482 rabbits that were killed. We used these data to compare 3 animal welfare parameters: wounding rate, duration of suffering, and ballistic injuries. We then used regression modeling to measure the effect of projectile type on these welfare parameters while accounting for shooting distance. All animal welfare parameters indicated that .222R projectiles were more humane than .22LR projectiles. When controlling for distance, for rabbits shot with a .22LR compared with a .222R, the odds of nonlethal wounding increased by a factor of 8 and noninstantaneous death increased by a factor of 9. All animal welfare parameters declined with increasing distance for both projectiles. Our results show that projectile energy and shooting distance were critical determinants of animal welfare outcomes in wildlife shooting programs. © 2016 The Wildlife Society. [ABSTRACT FROM AUTHOR]

The population dynamics of island species are considered particularly sensitive to variation in environmental, demographic and/or genetic processes. However, few studies have attempted to evaluate the relative importance of these processes for key vital rates in island endemics. We integrated the results of long-term capture-mark-recapture analysis, prey surveys, habitat quality assessments and molecular analysis to determine the causes of variation in the survival rates of Komodo dragons Varanus komodoensis at 10 sites on four islands in Komodo National Park, Indonesia. Using open population capture-mark-recapture methods, we ranked competing models that considered environmental, ecological, genetic and demographic effects on site-specific Komodo dragon survival rates. Site-specific survival rates ranged from 0.49 (95% CI: 0.33-0.68) to 0.92 (0.79-0.97) in the 10 study sites. The three highest-ranked models (i.e. ΔQAIC c < 2) explained ∼70% of variation in Komodo dragon survival rates and identified interactions between inbreeding coefficients, prey biomass density and habitat quality as important explanatory variables. There was evidence of additive effects from ecological and genetic (e.g. inbreeding) processes affecting Komodo dragon survival rates. Our results indicate that maintaining high ungulate prey biomass and habitat quality would enhance the persistence of Komodo dragon populations. Assisted gene flow may also increase the genetic and demographic viability of the smaller Komodo dragon populations. [ABSTRACT FROM AUTHOR]

Understanding the long-term impacts of invasive mammalian browsers and granivores in mixed forests is difficult due to the many processes potentially affecting the demography of long-lived trees. We constructed individual-based spatially explicit simulation models of two mixed conifer-angiosperm forests, growing on soils of contrasting phosphorus (P) availability, to investigate how browsing by invasive red deer (Cervus elaphus scoticus) and granivory by invasive rodents (primarily house mouse Mus musculus) might alter forest dynamics. Models were parameterized with field data. Seedling growth and survival rates were estimated inside and outside deer exclosures. Seed predation rates were estimated at high and low rodent densities in mast and non-mast seeding years. For the alluvial terrace forest, which grew on P-rich soil, our model contained 15 tree species dominated by angiosperms; our model of the P-poor marine terrace forest contained seven species dominated by conifers. The two forest models were used to explore four 500-year scenarios: deer and rodents present, deer present and rodents absent, deer absent and rodents present, and deer and rodents absent. Our field studies revealed that the highest probabilities of seed predation by rodents occurred for two canopy species in mast years and in neighborhoods of high species-specific basal area, and that deer browsing had the greatest negative effects on the growth and survival rates of angiosperm seedlings. Our simulation models predicted that the presence of deer and rodents would reduce the abundances of canopy codominants, and hence total basal area, in the alluvial terrace forest. The presence of deer increased the dominance of conifers in both forests, but effects of deer and rodents were much stronger in the alluvial terrace forest. Our study revealed two emergent properties. First, rodent- and deer-induced reductions in seedling abundances did not always translate into reduced sapling and adult tree abundances. Second, when deer changed the abundance of a canopy dominant, other species were affected by altered interspecific competition. We conclude that the effects of invasive deer and rodents will be greatest in forests growing on P-rich soils. Exclusion of deer is predicted to have greater long-term effects on forest dynamics than exclusion of rodents. [ABSTRACT FROM AUTHOR]

Management of apex predators is among the most controversial wildlife management issues globally. In Australia, some ecologists have advocated using the dingo, Canis dingo, as a tool for conservation management, due to evidence that they suppress invasive mesopredators., Hayward & Marlow ( Journal of Applied Ecology, 51, 2014 and 835) questioned the capacity of dingoes to provide benefits to native biodiversity due to their inability to eradicate foxes and cats. They also argued that indices of abundance commonly used in studies of mesopredator release by dingoes (namely, track-based indices) invalidate the conclusions of the studies. Hayward & Marlow caution conservation practitioners against incorporating dingoes into conservation programmes., Counter to their claims, we summarise research showing that the suppression of invasive mesopredators (cf. eradication) can enhance populations of native species and is therefore a meaningful conservation objective. We highlight literature supporting the hypothesis that dingoes suppress mesopredator abundance and activity, which in turn benefits native biodiversity., We show that Hayward & Marlow overlook many studies of carnivores that show track indices capture a large amount of the variation in the density of medium- and large-sized carnivores., Synthesis and applications. Practitioners cannot afford to wait to act given the perilous state of Australia's mammal species, and we argue that the evidence is sufficiently strong to justify managing dingoes for biodiversity conservation. [ABSTRACT FROM AUTHOR]

ABSTRACT Failure to account for dependencies among observers in multiple-observer capture-recapture studies will lead to biased inference yet methods that account for dependencies are poorly developed. We combined hierarchical capture-recapture models and finite sampling theory to infer population abundance of koala ( Phascolarctos cinereus) in the 5,812-ha Mount Eccles National Park, southeastern Australia. We used plot replication to build a Bayesian hierarchical model of koala sightings by multiple observers. Given the number of koala present on a plot, we modeled counts of koala by a multinomial log-linear model with interaction terms to account for between-observer dependencies. We modeled total numbers using a Poisson log-linear model with covariate and random effects. We estimated the number of koala as 1.9 koala/ha (95% CI = 1.6, 2.4). We found evidence of between-observer interactions, highlighting the importance of having at least 3 observers in multiple observer studies. © 2014 The Wildlife Society. [ABSTRACT FROM AUTHOR]

The exploitation ecosystems hypothesis (EEH) proposes that 1) plant biomass reflects the primary productivity of an ecosystem modified by the regulating effect of herbivory, and 2) herbivore abundance reflects the productivity of plants modified by the regulating effect of predation. Primary productivity thus determines the number of trophic levels in an ecosystem and the extent to which bottom-up and top-down regulation influence the biomass ratios of adjacent and non-adjacent trophic levels (i.e. trophic cascading). We constructed an interactive model of plant (pasture), herbivore (red kangaroo Macropus rufus) and predator (dingo Canis lupus dingo), a system in which trophic cascades have been suggested to occur, and used it to test the effects of increasing stochastic variation in primary productivity and dingo culling on predictions of the EEH. The model contained four feedback loops: the predator-herbivore and herbivore-plant feedback loops, and the predator and plant density-dependent feedback loops. The equilibrium conditions along the primary productivity gradient reproduced the three zones of trophic dynamics predicted by the EEH, plus an additional zone at productivities above which the maximum density of a predator is achieved due to social regulation: that zone is characterized by increasing herbivore density and decreasing plant biomass. Culling dingoes produced trophic cascades that were strongly attenuated at primary productivities below which the maximum density of dingoes was attained. Results were robust to uncertainty in kangaroo off-take by dingoes and to the efficacy of dingo culling, but prey switching by dingoes from red kangaroos to reptiles would weaken trophic cascades. We conclude that social regulation of carnivores has important implications for expression of the EEH and trophic cascades, and that attenuation of trophic cascades increases with increasing stochasticity in primary productivity. Our model also provides a framework for understanding the conditions in which dingo-mediated trophic cascades might be expected to occur, and generates testable predictions about the effects of higher dingo densities (e.g. by stopping culling or reintroduction to former range) on kangaroo and pasture dynamics. [ABSTRACT FROM AUTHOR]

Estimating diet is often an important step in understanding and managing the impacts of ungulates, particularly for non-native species, but there is uncertainty about whether rumen contents should be assessed using macroscopic or microhistological methods or both. Introduced sambar deer (Cervus unicolor) have a large and increasing distribution in south-east Australia, and there is concern about their impacts on native and non-indigenous plant species. We estimated the diets of 102 sambar deer harvested during 2007-2009 using macroscopic and microhistological rumen analysis techniques. We identified 105 plant species in the diets of sambar deer, 61 identified with both techniques and 22 identified only macroscopically or only microhistologically. Rumen species richness was 70% greater using the microhistological technique. Estimates of taxonomic (i.e., monocot and dicot) and functional (i.e., fern, shrub-tree, forb, climber, grass, and grass-like) group composition by the 2 techniques were similar. Shrubs-trees dominated the diet (macroscopic, 49.7%; microhistological, 52.7%), followed by grasses (macroscopic, 22.7%; microhistological, 17.5%) and ferns (macroscopic, 20.6%; microhistological, 22.2%). We identified 9 non-indigenous plant species, 2 of which we identified using only the microhistological technique. We detected seeds of the weed blackberry (Rubus fruticosus aggregate), sometimes in large amounts, only with the macroscopic technique, whereas we detected foliage of that species with both techniques. Both techniques classified sambar deer as an intermediate mixed feeder closer to a concentrate selector-browser than a bulk and roughage feeder. However, both techniques detected seasonal differences in the percentages of taxonomic and functional groups in the diet; sambar deer were more grazers in autumn and more browsers in spring. Our results indicate that both macroscopic and microhistological techniques may need to be used when it is important to identify plant species in the diet, as is often the case for non-native ungulates. However, either technique can be used to estimate broader taxonomic and functional diet composition, including feeding type. [ABSTRACT FROM AUTHOR]

Predicting the current and potential distributions of established invasive species is critical for evaluating management options, but methods for differentiating these distributions have received little attention. In particular, there is uncertainty among invasive species managers about the value of information from incidental sightings compared to data from designed field surveys. This study compares the two approaches, and develops a unifying framework, using the case of invasive sambar deer Cervus unicolor in Victoria, Australia. We first used 391 incidental sightings of sambar deer and 12 biophysical variables to construct a presence-only habitat suitability model using Maxent. We then used that model to stratify field sampling, with proportionately greater sampling of cells with high predicted habitat suitability. Field sampling, consisting of faecal pellet surveys, sign surveys and camera trapping, was conducted in 80 4-km grid cells. A Bayesian state-space occupancy model was used to predict probability of suitable habitat from the field data. The Maxent and occupancy models predicted similar spatial distributions of habitat suitability for sambar deer in Victoria and there was a strong positive correlation between the rankings of cells by the two approaches. The congruence of the two models suggests that any spatial and detection biases in the presence-only data were relatively unimportant in our study. We predicted the extent of suitable habitat from the occupancy model using a threshold that gave a false negative error rate of 0·05. The current distribution was the suitable habitat within a kernel that had a 99·5% chance of including the presence locations pooled from incidental sightings and field surveys: the potential distribution was suitable habitat outside that kernel. Several discrete areas of potential distribution were identified as priorities for surveillance monitoring with the aim of detecting and managing incursions of sambar deer. Synthesis and applications. Our framework enables managers to robustly estimate the current and potential distributions of established invasive species using either presence-only and/or presence-absence data. Managers can then focus control and/or containment actions within the current distribution and establish surveillance monitoring to detect incursions within the potential distribution. [ABSTRACT FROM AUTHOR]

1. The maximum annual population growth rate ( rm) is a critical parameter in many models of wildlife dynamics and management. An important application of rm is the estimation of the maximum proportion of a population that can be removed to stop population growth ( p). 2. When rm cannot be estimated in the field, one option is to estimate it from demographic data. We evaluate the use of the relationship between rm and female age at first reproduction (α), which is independent of phylogeny, to estimate rm. We first demonstrate that the relationship between field and demographic estimates of rm is unbiased. We then show that the relationship provides an unbiased and simple method to estimate rm using data for 64 mammal species. We also show that p declines exponentially as α increases. 3. We use the fitted relationship to estimate annual rm and p for 55 mammal species in Australia and New Zealand for which there are no field estimates of rm. The estimates differ by species but have low precision (wide 95% credible intervals CIs). Our estimate of rm for the Tasmanian devil Sarcophilus harrisii is high (0·6, 95% CI: 0·05–2·39) and suggests devils would become extinct if >0·34 of the population is removed annually (e.g. by facial tumour disease). Our estimate of rm (0·77, 95% CI: 0·71–1·05) for brushtail possum Trichosurus vulpecula is much greater than published estimates and highlights the need for further field estimates of rm for the species in New Zealand. 4. Synthesis and applications. Since rm has not been estimated in the field for the majority of mammal species, our approach enables estimates with credible intervals for this important parameter to be obtained for any species for which female age at first reproduction is known. However, the estimates have wide ... [ABSTRACT FROM AUTHOR]

1. Prominent theories of plant defence have predicted that plants growing on nutrient-poor soils produce more phenolic defence compounds than those on richer soils. Only recently has the Protein Competition Model (PCM) of phenolic allocation suggested that N and P limitation could have different effects because the nutrients are involved in different cellular metabolic processes. 2. We extend the prediction of the PCM and hypothesize that N will have a greater influence on the production of phenolic defensive compounds than P availability, because N limitation reduces protein production and thus competition for phenylalanine, a precursor of many phenolic compounds. In contrast, P acts as a recyclable cofactor in these reactions, allowing protein and hence phenolic production to continue under low P conditions. 3. We test this hypothesis by comparing the foliar concentrations of phenolic compounds in (i) phenotypes of 21 species growing on P-rich alluvial terraces and P-depleted marine terraces in southern New Zealand, and (ii) 87 species growing under similar climates on comparatively P-rich soils in New Zealand vs. P-depleted soils in Tasmania. 4. Foliar P concentrations of plants from the marine terraces were about half those of plants from alluvial soils, and much lower in Tasmania than in New Zealand. However, foliar concentrations of N and phenolic compounds were similar across sites in both comparisons, supporting the hypothesis that N availability is a more important determinant of plant investment in phenolic defensive compounds than P availability. We found no indication that reduced soil P levels influenced plant concentrations of phenolic compounds. There was wide variation in the foliar N and P concentrations among species, and those with low foliar nutrient concentrations produced more phenolics (including condensed tannins). 5. Our study is the first trait comparison extending beyond standard leaf economics to include secondary metabolites related to defence in forest plants, and emphasizes that N and P have different influences on the production of phenolic defence compounds. [ABSTRACT FROM AUTHOR]

1. Many species of wildlife are harvested for sale but there are few time-series analyses of the factors determining the number of animals harvested. Economic theory predicts that price paid per animal is likely to be an important determinant of the harvest, but prices paid for alternative activities could reduce the harvest, and environmental factors such as rainfall could either constrain or enhance the harvest. 2. About 1 million feral goats Capra hircus L. are commercially harvested annually in the semi-arid rangelands of Australia, and there is much interest in how the harvest can be maximized so that the environmental impacts of the goats are minimized. 3. We developed 27 candidate models to explain monthly variation in the numbers of feral goats commercially harvested in Western Australia during July 1988 to June 2003. We fitted linear AR(1) models to the first 89 months of data and used Akaike's Information Criterion corrected for small sample size to identify the model(s) with substantial support. We then evaluated how much variation in the latter 88 months of the time series each model explained. 4. Almost 2·9 million feral goats were harvested in the study period. The two models with substantial support accounted for 70·5% and 70·6% of variation in the number of feral goats harvested during the first 89 months and 64·6% and 66·7% of variation in the subsequent 88 months. The models both included month of harvest and negative effects of rainfall in both the month of harvest and the previous month. One of the models also included a strong positive effect of the Australian Consumer Price Index-adjusted average price paid per feral goat on the number of feral goats harvested, and this model had the most support when fitted to the entire time series. 5. Synthesis and applications. This is the first study to demonstrate how both an environmental factor (rainfall) and an economic factor (average price paid per animal) can influence the size of a commercial wildlife harvest. Whilst managers can seldom modify environmental factors, our results suggest that the size of a wildlife harvest can be manipulated by altering the economics of the harvest. [ABSTRACT FROM AUTHOR]

1. Koala Phascolarctos cinereus populations sometimes exhibit eruptive dynamics, increasing to peak abundance and then crashing to low abundance. This dynamic is considered unacceptable because koalas die from starvation and food trees are killed by defoliation. There is concern that such dynamics may be occurring at a number of sites in south-eastern Australia. The only management option is fertility control of females. 2. We constructed a simulation model of koalas interacting with their food supply (manna gum Eucalyptus viminalis) in Mount Eccles National Park, Victoria, Australia. The amount of manna gum leaves consumed changed the survival and fecundity rates of koalas, and the amount of leaves removed changed the survival and transition rates of manna gums. 3. Without fertility control the koala population was predicted to increase to peak abundance within 10–18 years before crashing. The predicted dynamics of manna gum were more variable but abundance increased in most simulations for up to c. 5 years before declining to c. 25% of peak abundance within 20–30 years and then increasing subsequently. The maximum rate of koala population decline was an important determinant of the interaction between koalas and manna gum. 4. The best management strategy that was analysed involved estimating the number of unsterilized females in the population annually and then sterilizing a variable number to maintain a population of 1000 koalas: this strategy generated the least decline in manna gum at a consistently low cost. However, there was a delay between imposing fertility control and consequent reduction in koala abundance because of high adult female survival rates. Hence manna gum was predicted to decline for 5–10 years before increasing. 5. Synthesis and applications. Our results highlight important time-lags between implementing fertility control, reducing the abundance of a herbivore with high survival rates and subsequent changes in the abundance of its food supply. Our model is useful for understanding how controlling ‘overabundant’ herbivores impacts upon the dynamics of both the herbivore and its food supply. [ABSTRACT FROM AUTHOR]

Although fecal pellet counts have been widely used to index changes in deer abundance in forests, few studies have modeled the relationship between the indices and deer density. We examined the relationships between 3 fecal pellet indices (total pellets, pellet groups, and pellet frequency) and the density of deer (primarily red deer [Cervus elaphus scoticus]) in 20 enclosures in the North and South islands of New Zealand. In each enclosure we estimated the 3 indices on 30 randomly located 150-m transects, with each transect having 30 circular plots of 3.14 m². We developed 4 candidate models (1 linear and 3 nonlinear) to describe the relationship between the indices and deer density. We used a Bayesian analysis to account for uncertainty in the estimates of deer abundance and to facilitate fitting models that included random transect effects. The 4 models explained the relationship between the 3 indices and deer density similarly well. The slopes of the linear relationships between the 3 indices and deer density were positive. Our results suggest that fecal pellet counts may be useful indices of deer abundance. [ABSTRACT FROM AUTHOR]

Many fundamental traits of species measured at different levels of biological organization appear to scale as a power law to body mass (M) with exponents that are multiples of ¼. Recent work has united these relationships in a "metabolic theory of ecology" (MTE) that explains the pervasiveness of quarter-power scaling by its dependence on basal metabolic rate (B), which scales as M0.75. Central to the MTE is theory linking the observed -0.25 scaling of maximum population growth rate (rm) and body mass to the 0.75 scaling of metabolic rate and body mass via relationships with age at first reproduction (α) derived from a general growth model and demographic theory. We used this theory to derive two further predictions: that age at first reproduction should scale inversely to mass-corrected basal metabolic rate α ∞ (B/M)-1 such that rm ∞ (B/M)¹. We then used phylogenetic generalized least squares and model selection methods to test the predicted scaling relationships using data from 1197 mammalian species. There was a strong phylogenetic signal in these data, highlighting the need to account for phylogeny in allometric studies. The 95% confidence intervals included, or almost included, the scaling exponent predicted by MTE for B ∞ M0.75, rm ∞ M-0.25, and rm ∞ α-1, but not for α ∞ M0.25 or the two predictions that we generated. Our results highlight a mismatch between theory and observation and imply that the observed -0.25 scaling of maximum population growth rate and body mass does not arise via the mechanism proposed in the MTE. [ABSTRACT FROM AUTHOR]

Despite having biomass and population-level energetic values that exceeded apex mammalian predators, Komodo dragons did not reduce populations of Rusa deer and wild pigs. However, the strength of these predatory interactions does not allow Komodo dragons to affect population growth in deer or wild pig populations. [Extracted from the article]

Government conservation agencies in New Zealand and the Australian state of Victoria spend 20% and 4%, respectively, of their annual budgets to manage a small part of the problem caused by introduced mammals. Managers' uncertainty about the optimal strategies for applying pest control has led to major differences in management practices within the single pest control programs in both countries. Monitoring under a trial-and-error approach has not removed uncertainty but has led managers to support the application of adaptive management for their pest control Control of brushtail possums (Trichosurus vulpecula) in New Zealand and red foxes (Vulpes vulpes) in Victoria, Australia, is conducted over large areas in many operations, but individual managers apply different control regimes based on the perceived benefits and opportunity costs. We report on the processes used to set up the first adaptive management experiments in pest control in New Zealand or Australia that combine the competing models approach (used when only a single management regime can be applied at one time) with an experimental approach (made possible when different management regimes are applied simultaneously in different places) with the aim of elucidating benefits and costs of the different strategies used to control the 2 pests. [ABSTRACT FROM AUTHOR]

A dominant paradigm in understanding and managing large herbivores is that, after introduction to new range or release from harvesting, the herbivore population increases to peak abundance, crashes to a lower abundance, and then increases to a carrying capacity lower than peak abundance. However, support for the paradigm has been largely anecdotal. We first developed two mathematical models to better describe irruptive dynamics. The models differed in the form of the postcrash growth toward carrying capacity: the ‘Caughley model’ included a time lag that generated dampening oscillations, and the ‘Leopold model’ did not'. We then evaluated which of four models (θ-logistic, delayed-logistic, Leopold, and Caughley) best described the dynamics of seven ungulate populations either introduced to new range (n = 5 populations) or released from harvesting (n = 2). The dynamics of six of the populations were best described by irruptive models (two by the Leopold, one by the Caughley, and three by the delayed-logistic), and one of the populations did not display irruptive dynamics (θ-logistic model). The limited data thus support the widespread existence of irruptive dynamics, and we encourage the consideration of irruptive models in studies of large-herbivore dynamics. [ABSTRACT FROM AUTHOR]

1 Angiosperm trees often dominate forests growing in resource-rich habitats, whereas conifers are generally restricted to less productive habitats. It has been suggested that conifers may be displaced by angiosperms except where competition is less intense, because conifer seedlings are inherently slow growing, and are outpaced by faster-growing angiosperm species. Here we investigate whether competition with ferns and deeply shading trees also contributes to a failure of conifers to regenerate in resource-rich habitats. 2 We examined how changes in soil nutrient availability and drainage affected vegetation along the retrogressive stages of a soil chronosequence in southern New Zealand. Vegetation composition shifted from angiosperm-tree dominance on ‘recent’ alluvial terraces (< 24 ky), via coniferous-tree dominance on older marine terraces (79–121 ky), to coniferous-shrub dominance on the oldest marine terraces (291 ky). Soil drainage deteriorated along the sequence, and N : Pleaves and N : Psoil indicate increasing P-limitation. Conifer species appear to be adapted to persistence on infertile and poorly drained soils. 3 The floor of the relatively fertile alluvial forests was deeply shaded (∼1% light transmission) by dense groves of tree-ferns and ground-ferns, and by large-leaved subcanopy trees. Few seedlings of any type were found on the forest floor, even in tree-fall gaps, and establishment was restricted to rotting logs and tree-fern trunks. Angiosperms were particularly successful at colonizing these raised surfaces. 4 Less shade was cast by the conifer-dominated forests on infertile marine terraces (∼5% light transmission), which lacked tall ferns. There were many opportunities for conifer establishment, with high seedling densities recorded on the forest floor and on logs. By contrast, angiosperm seedlings were mainly restricted to logs. 5 Our results suggest that several mechanisms act in concert to reduce regeneration opportunities for conifers in productive habitats. In particular, we suggest that tall ferns and deep shade are responsible for a restriction of regeneration opportunities in relatively productive forests in New Zealand, diminishing the opportunities for conifers to escape the competitive effects of fast-growing angiosperms. Thus ‘crocodiles’ may alter the outcome of the race between ‘hares’ and ‘tortoises’. [ABSTRACT FROM AUTHOR]

Whereas the energetic costs of reproduction for female ungulates are well documented, those of males are not. We investigated age- and sex-specific changes in the kidney fat reserves of a large sample of Himalayan tahr (Hemitragus jemlahicus), a highly sexually dimorphic and polygynous mountain ungulate, during and following the mating period. Subadult male tahr (2-4 years old) obtain copulations opportunistically by "coursing," whereas adult males (>4 years old) spend more time traveling and searching for females, and obtain copulations after engaging in more time-consuming "tending" and "blocking" displays. If there is a cost to these reproductive behaviors, we predicted that (1) the kidney fat index (KFI) of reproductive males (⩾2 years old) should decline during the mating period relative to females and nonreproductive males, and (2) that the KFI of adult males should decline more than that of subadult males. We formulated our predictions into a series of candidate models, including three covariates also likely to affect fat reserves, and compared support for these models using Akaike's information Criterion (AIC). The best-fitting model revealed that fat reserves in females and nonreproductive males changed similarly: Fat reserves increased during the mating period, in late autumn and early winter, reached a peak in mid-winter, and then declined throughout the remainder of winter and early spring. In contrast, the fat reserves of reproductive males declined during the mating period, as predicted, and remained low throughout winter. The extent of decline in fat reserves was greater in adult males than in subadult males, also as predicted. Our, results strongly imply that male tahr incur a substantial energetic cost for engaging in reproduction and that they trade off reproductive success with reduced body condition during winter, which may lower survival. [ABSTRACT FROM AUTHOR]

Introduced brushtail possums (Trichosurus vulpecula) are a widespread pest of conservation and agriculture in New Zealand, and considerable effort has been expended controlling populations to low densities. A national protocol for monitoring the abundance of possums, termed trap catch index (TCI), was adopted in 1996. The TCI requires that lines of leghold traps set at 20-m spacing are randomly located in a management area. The traps are set for 3 fine nights and checked daily, and possums are killed and traps reset. The TCI is the mean percentage of trap nights that possums were caught, corrected for sprung traps and nontarget captures, with trap line as the sampling unit. We studied 1 forest and 1 farmland area in the North Island, New Zealand, to address concerns that TCI estimates may not be readily comparable because of seasonal changes in the capture probability of possums. We located blocks of 6 trap lines at each area and randomly trapped 1 line in each block in 3 seasons (summer, winter, and spring) in 2000 and 2001. We developed a model to allow for variation in local population size and nightly capture probability, and fitted the model using the Bayesian analysis software BUGS. Capture probability declined with increasing abundance of possums, generating a nonlinear TCI. Capture probability in farmland was lower during spring relative to winter and summer, and to forest during summer. in the absence of a proven and cost-effective alternative, our results support the continued use of the TCI for monitoring the abundance of possums in New Zealand. Seasonal biases in the TCI should be minimized by conducting repeat sampling in the same season. [ABSTRACT FROM AUTHOR]

Conservation actions could be more efficient if there is congruence among taxa in the distribution of species. Patterns in the geographical distribution of five taxa were used to identify nationally important regions for conservation in Canada. Two measures of surrogacy were significantly and positively correlated among taxa, and conservation areas selected for one taxon represented other taxa significantly better than random selections. However, few large protected areas exist in the sites of highest conservation value in southern Canada; these regions are therefore a priority for future conservation regard. By focusing this effort on threatened and endangered species, which are a national priority in Canada, most other species could also benefit. [ABSTRACT FROM AUTHOR]

Major progress in understanding biological invasions has recently been made by quantitatively comparing successful and unsuccessful invasions. We used such an approach to test hypotheses about the role of climatic suitability, life history, and historical factors in the establishment and subsequent spread of 40 species of mammal that have been introduced to mainland Australia. Relative to failed species, the 23 species that became established had a greater area of climatically suitable habitat available in Australia, had previously become established elsewhere, had a larger overseas range, and were introduced more times. These relationships held after phylogeny was controlled for, but successful species were also significantly more likely to be nonmigratory. A forward-selection model included only two of the nine variables for which we had data for all species: climatic suitability and introduction effort. When the model was adjusted for phylogeny, those same two variables were included, along with previous establishment success. Of the established species, those with a larger geographic range size in Australia had a greater area of climatically suitable habitat, had traits associated with a faster population growth rate (small body size, shorter life span, lower weaning age, more offspring per year), were nonherbivorous, and had a larger overseas range size. When the model was adjusted for phylogeny, the importance of climatic suitability and the life-history traits remained significant, but overseas range size was no longer important and species with greater introduction effort had a larger geographic range size. Two variables explained variation in geographic range size in a forward-selection model: species with smaller body mass and greater longevity tended to have larger range sizes in Australia. These results mirror those from a recent analysis of exotic-bird introductions into Australia, suggesting that, at least among vertebrate taxa, similar factors predict establishment and spread. Our approach and results are being used to assess the risks of exotic vertebrates becoming established and spreading in Australia. [ABSTRACT FROM AUTHOR]

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Summary 1.We investigated factors hypothesized to influence introduction success and subsequent geographical range size in 52 species of bird that have been introduced to mainland Australia. 2.The 19 successful species had been introduced more times, at more sites and in greater overall numbers. Relative to failed species, successfully introduced species also had a greater area of climatically suitable habitat available in Australia, a larger overseas range size and were more likely to have been introduced successfully outside Australia. After controlling for phylogeny these relationships held, except that with overseas range size and, in addition, larger-bodied species had a higher probability of introduction success. There was also a marked taxonomic bias: gamebirds had a much lower probability of success than other species. A model including five of these variables explained perfectly the patterns in introduction success across-species. 3.Of the successful species, those with larger geographical ranges in Australia had a greater area of climatically suitable habitat, traits associated with a faster population growth rate (small body size, short incubation period and more broods per season) and a larger overseas range size. The relationships between range size in Australia, the extent of climatically suitable habitat and overseas range size held after controlling for phylogeny. 4.We discuss the probable causes underlying these relationships and why, in retrospect, the outcome of bird introductions to Australia are highly predictable. [ABSTRACT FROM AUTHOR]

1. Sexual differences in behaviour and ecology have important implications for the management of harvested ungulate populations. 2. This study investigated the long-term effects of harvesting on the abundance and distribution of sexes within an introduced population of Himalayan tahr in the Two Thumb and Sibbald Ranges, New Zealand. Annual counts of tahr were made from 1984 to 1996 in two catchments subject to different harvest regimes. 3. Although populations in the two catchments increased at similar rates over the study period, their adult sex ratios diverged significantly in the late 1980s. In Carneys Creek, which was subject to unrestricted harvest, the adult sex ratio was initially equivalent to the estimated population sex ratio, but from 1991 it was significantly male-biased. In North Branch, 10 km from Carneys Creek but subject only to adult (trophy) male harvest, the population was significantly female-biased in all years. 4. There was a large and male-biased harvest in Carneys Creek in 1993, suggesting that immigration of males may have been responsible for the long-term changes in sex ratio observed there. In contrast, the harvest of males in North Branch was insufficient to explain its female-biased population. 5. Monthly counts of male and female tahr in Carneys Creek between December 1993 and February 1996 revealed a consistent seasonal change in the abundance of sub-adult males, and perhaps adult males, but not females. Sub-adult males immigrated into Carneys Creek during spring, increasing to a summer maximum before emigrating during autumn; few sub-adult males were present during winter. 6. Counts at six additional sites during summer and autumn 1996 indicated that the probable source of these males was an adjacent hunting reserve. This hunting reserve, which included North Branch, contained a female-biased population with moderate female density. 7. The observed changes appear to have been a consequence of sexual differences in habitat... [ABSTRACT FROM AUTHOR]

With ongoing introductions into Australia since the 1700s, the European rabbit (Oryctolagus cuniculus) has become one of the most widely distributed and abundant vertebrate pests, adversely impacting Australia's biodiversity and agroeconomy. To understand the population and range dynamics of the species and its impacts better, occurrence and abundance data have been collected by researchers and citizens from sites covering a broad spectrum of climatic and environmental conditions in Australia. The lack of a common and accessible repository for these data has, however, limited their use in determining important spatiotemporal drivers of the structure and dynamics of the geographical range of rabbits in Australia. To meet this need, we created the Australian National Rabbit Database, which combines more than 50 yr of historical and contemporary survey data collected from throughout the range of the species in Australia. The survey data, obtained from a suite of complementary monitoring methods, were combined with high‐resolution weather, climate, and environmental information, and an assessment of data quality. The database provides records of rabbit occurrence (689,265 records) and abundance (51,241 records, >120 distinct sites) suitable for identifying the spatiotemporal drivers of the rabbit's distribution and for determining spatial patterns of variation in its key life‐history traits, including maximum rates of population growth. Because all data are georeferenced and date stamped, they can be coupled with information from other databases and spatial layers to explore the potential effects of rabbit occurrence and abundance on Australia's native wildlife and agricultural production. The Australian National Rabbit Database is an important tool for understanding and managing the European rabbit in its invasive range and its effects on native biodiversity and agricultural production. It also provides a valuable resource for addressing questions related to the biology, success, and impacts of invasive species more generally. No copyright or proprietary restrictions are associated with the use of this data set other than citation of this Data Paper. [ABSTRACT FROM AUTHOR]