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Carnivore conservation and management is complex and expensive, and significant ongoing management costs may inhibit the development of new tools and any subsequent transition away from lethal control. We review and compare the economic costs and benefits of dingoes and domestic dogs in Australia and suggest that public affinity for domestic dogs may be co-opted into yielding more positive management outcomes for dingoes. Whereas Australians spend over AU$10 billion annually on purchasing and maintaining 4.2 million domestic dogs, landowners and government spend at least AU$30 million attempting to limit the density and distribution of dingoes, feral dogs, and their hybrids. These contrasting investments highlight the dual response of society towards domestic and wild members of the Canis genus. We suggest that a modest conservation levy on the sale of pet dogs or dog food, or both, could secure long-term funding to support efficacious non-lethal management of dingo impacts. A modest levy could generate AU$30 million annually, funding the development of non-lethal dingo-management tools without compromising existing management practices while new tools are investigated. Ultimately, a transition away from controlling dingoes through culling or exclusion fencing, to managing the negative impacts of dingoes could result in both more successful and sustainable management outcomes of dingoes and support the ecological, cultural and economic benefits they confer as Australia’s apex predator.
Patrick L. Taggart, Bronwyn A. Fancourt, Andrew J. Bengsen, David E. Peacock, Patrick Hodgens, John L. Read, Milton M. McAllister, Charles G. B. Caraguel
Context. Feral cats (Felis catus) impact the health and welfare of wildlife, livestock and humans worldwide. They are particularly damaging where they have been introduced into island countries such as Australia and New Zealand, where native prey species evolved without feline predators. Kangaroo Island, in South Australia, is Australia’s third largest island and supports several threatened and endemic species. Cat densities on Kangaroo Island are thought to be greater than those on the adjacent South Australian mainland, based on one cat density estimate on the island that is higher than most estimates from the mainland. The prevalence of cat-borne disease in cats and sheep is also higher on Kangaroo Island than the mainland, suggesting higher cat densities. A recent continental-scale spatial model of cat density predicted that cat density on Kangaroo Island should be about double that of the adjacent mainland. However, although cats are believed to have severe impacts on some native species on the island, other species that are generally considered vulnerable to cat predation have relatively secure populations on the island compared with the mainland.
Aims. The present study aimed to compare feral cat abundance between Kangaroo Island and the adjacent South Australian mainland using simultaneous standardised methods. Based on previous findings, we predicted that the relative abundance of feral cats on Kangaroo Island would be approximately double that on the South Australian mainland.
Methods. Standardised camera trap surveys were used to simultaneously estimate the relative abundance of feral cats on Kangaroo Island and the adjacent South Australian mainland. Survey data were analysed using the Royle–Nichols abundance-induced heterogeneity model to estimate feral cat relative abundance at each site.
Key results. Cat abundance on the island was estimated to be over 10 times greater than that on the adjacent mainland.
Conclusions. Consistent with predictions, cat abundance on the island was greater than on the adjacent mainland. However, the magnitude of this difference was much greater than expected.
Implications. The findings show that the actual densities of cats at local sites can vary substantially from predictions generated by continental-scale models. The study also demonstrates the value of estimating abundance or density simultaneously across sites using standardised methods.
Context. Understanding the environmental factors influencing the occurrence of wildlife has become increasingly important, contributing to better conservation actions for threatened species.
Aims. We aimed to understand the factors that influence the occurrence probability of the Southwest China serow (Capricornis milneedwardsii), a threatened species, thereby developing conservation interventions to save the species from local extirpation on the Cat Ba Archipelago, Vietnam.
Methods. An integrated approach, including literature reviews, interviews, field surveys, logistic generalised linear models and Bayesian networks, was applied to identify environmental variables and species occurrence, and model the occurrence probability of the species. Sensitivity analysis and scenarios were also performed to identify the influence of environmental variables on the probability of the species occurrence.
Key results. Distance to ranger station was found to be the most influential factor on serow occurrence, followed by total forest, distance to village, steepness and elevation. Hunting pressure has probably forced serows to inhabit the areas where they are well protected, and this need probably over-rides the effect of ecological variables.
Conclusion. Through combing knowledge of forest rangers and members of forest-protection groups, field surveys and logistic generalised linear models, a Bayesian network was developed to predict the occurrence probability of the threatened Southwest China serow on the Cat Ba Archipelago for conservation actions. The modelling results and findings from the present study provided further understanding of the relationships between environmental factors and the probability of the species occurrence, which have been rarely studied throughout the range of this species.
Implications. The modelling predictions give managers basic information for conservation and recovery planning in situations where integrated conservation interventions should be urgently conducted to save the threatened species from local extirpation.
Orla K. McEvoy, Susan M. Miller, Warren Beets, Tarik Bodasing, Natalia Borrego, André Burger, Brian Courtenay, Sam Ferreira, Cathariné Hanekom, Markus Hofmeyr, Craig Packer, Dave Robertson, Ken Stratford, Rob Slotow, Dan M. Parker
Context. Managed wild lions (Panthera leo) are lions found in smaller (<1000 km2), fenced protected areas that hold a substantial portion of South Africa’s wild lion population. Because the natural population control mechanisms are compromised within these properties, managers must actively control population growth rates. Fecundity control is used by wildlife managers, but long-term, empirical data on the impact and consequences of such interventions in lions are lacking.
Aims. The aim of the present study was to assess the effectiveness of two methods of contraception (deslorelin implant and unilateral hysterectomy) in reducing cub recruitment of managed wild lions.
Methods. Survey data spanning 14 years from 94 managed wild lions on 19 protected areas were used to evaluate the effectiveness of deslorelin implant treatments and unilateral hysterectomies on population growth rates through mimicking open system cub recruitment.
Key results. Deslorelin implants were effective at increasing the age of first reproduction and lengthening inter-birth intervals. There was also an unexpected decrease in litter size. Behavioural side-effects were recorded in 40% of individuals: 19% pride fragmentation; 13% lack of receptiveness towards males; 8% other. The more successive deslorelin implants a lioness had, the more likely it was that weight gain was reported. Unilateral hysterectomy resulted in a decrease in litter size post-surgery, but this was not statistically significant. No behavioural or physiological side-effects were noted after unilateral hysterectomy.
Conclusions. Deslorelin treatment was more effective in reducing the reproductive output of managed wild lionesses than unilateral hysterectomy surgery. While more side-effects were associated with deslorelin implants than unilateral hysterectomies, a single deslorelin treatment is currently a good option for fecundity reduction. More research is required on unilateral hysterectomy surgery.
Implications. Neither deslorelin implants nor unilateral hysterectomies offer a ‘silver bullet’ solution for reducing rapid population growth in managed wild lions. Reproductive control should be integrated with other best-practice approaches.
M. Di Vittorio, M. Lo Valvo, E. Di Trapani, A. Sanguinetti, A. Ciaccio, S. Grenci, M. Zafarana, G. Giacalone, N. Patti, S. Cacopardi, P. Rannisi, A. Scuderi, L. Luiselli, G. La Grua, G. Cortone, S. Merlino, A. Falci, G. Spinella, P. López-López
Context. Dietary analyses are essential to achieve a better understanding of animal ecology. In the case of endangered species, assessing dietary requirements is crucial to improve their management and conservation. The Bonelli’s eagle (Aquila fasciata) has experienced a severe decline throughout its breeding range in Europe and, in Italy, fewer than 50 pairs remain, and only in Sicily. This species is subject to major threats, including changes in landscape composition and, consequently, prey availability, which is further aggravated by the occurrence of viral diseases in the case of rabbits.
Aims. To provide current data on the diet of the Bonelli’s eagle in Sicily during the breeding period and to examine dietary shifts with regard to previous studies conducted in the same study area. To discuss possible implications for conservation of the Italian population of this endangered species.
Methods. We used a combination of three methods, including pellet analysis, collection of prey remains, and imagery from camera-traps installed at nests, to examine the diet of 12 breeding pairs of Bonelli’s eagle from 2011 to 2017. We compared this information with data collected between 1993 and 1998 in the same study area.
Key results. In number, birds were the most frequently predated items (61.6%), followed by mammals (36.88%) and reptiles (1.52%). However, in terms of biomass, mammals were the main prey (65.71%), followed by birds (34.12%) and reptiles (0.17%). There was a decrease over the course of the current decade in the consumption of European wild rabbit (Oryctolagus cuniculus), which was compensated for with an increase in both dietary diversity and breadth in bird consumption, a trend not observed in the earlier study in the same region.
Conclusions. Here, we provide an updated assessment of diet composition of Bonelli’s eagle during the breeding period. Interestingly, we found significant differences within the study period (2011–2017) in terms of frequency of occurrence, percentage of biomass, dietary diversity and dietary breadth in a species at risk. Furthermore, we found significant differences between the two study periods in both frequency and percentage of biomass, with significant changes in the consumption of lagomorphs and birds.
Implications. Our results indicated that shifts in the diet are linked to changes in prey abundance, which may be contributing to population declines in the Bonelli’s eagle population in Sicily. Overall, measures aimed at increasing main dietary prey should be promoted to favour occupation of new territories and enhance vital demographic parameters (i.e. breeding success and survival rate) of Bonelli’s eagle across the species range. This would be particularly important for small isolated populations such as the Sicilian one.
Context. Wildlife can be injured or orphaned through a range of (often anthropogenic) activities, creating need for volunteer rescuers and wildlife carers, of which a substantial number is active in Australia. However, the causes and contributing factors for rescued wildlife are rarely reported, which limits development of response options to these wildlife issues. An understanding of the distribution and number of rescuers and carers in relation to injured and orphaned wildlife allows training and outreach to be targeted around specific seasonal peaks, species and causes of injury.
Aims and methods. We conducted an analysis of 22 723 reports over 7 years to the Bonorong Wildlife Rescue Service in Tasmania, Australia, to determine the frequency of species and types of human–wildlife interaction, the report distances from the central facility, and the report distribution relative to the registered rescuer and carer networks.
Key results. Mammals accounted for over half of all reports, followed by birds, reptiles and invertebrates. Road trauma was the predominant cause for report, followed by orphans. Disease reports and animal attack were also common. Overall, reporting was highest in late spring and summer, but different seasonality in specific causes and species suggests that targeted response options are needed at different times of year. Areas with higher reporting relative to the number of registered rescuers and carers show where volunteer recruitment can be focussed.
Conclusions. We used a wildlife reporting dataset to illustrate trends (such as seasonality and species vulnerability) and causes of human–wildlife interaction to inform potential response options.
Implications. Continued citizen reporting can assist wildlife managers to allocate resources, plan training or recruit additional volunteers, track emerging issues, such as disease and climate-related stressors, and guide the planning of public education and mitigation initiatives, particularly for human-related wildlife issues.
Context. Temperament can affect an individual’s fitness and survival if it also influences behaviours associated with predator avoidance, interactions with conspecifics, refuge selection and/or foraging. Furthermore, temperament can determine an individual’s response to novel stimuli and environmental challenges, such as those experienced through translocation. Increasing our understanding of the effect of temperament on post-translocation fitness is thus necessary for improving translocation outcomes.
Aims. The aim was to test whether differences in an individual’s behaviour or physiology could help predict body mass changes post-translocation in the woylie (brush-tailed bettong, Bettongia penicillata ogilbyi). In the absence of predation (due to release into a predator-free exclosure), body mass was used as a proxy for an individual’s success in securing resources in the new habitat, and therefore fitness.
Methods. Forty woylies were translocated from two predator-free exclosures to a larger exclosure, all in Western Australia. Behavioural and physiological measures were recorded during trapping, processing, holding, and release, and again at re-capture ∼100 days post-release.
Key results. Translocated woylies generally increased in body mass post-translocation. This suggests that, in the absence of predation, the selected candidates were able to cope with the stress of translocation and possessed the behavioural plasticity to successfully find resources and adapt to a novel environment. The strongest predictors of body mass gain were sex, heart rate lability and escape behaviour when released (a convoluted escape path).
Conclusions. There was no significant difference in body mass between males and females pre-translocation but females showed greater mass gain post-translocation than did males, which could reflect greater investment in reproduction (all females had pouch young). Heart rate lability and escape behaviour are likely to reflect reactivity or fearfulness, a significant temperament trait in the context of translocation success.
Implications. Behavioural measures that can be easily incorporated into the translocation process – without increasing stress or affecting welfare of individuals – may hold promise for predicting the fate of translocated animals.
Context. Many of Australia’s threatened mammals were once widespread across the continent and present in both arid, semiarid and temperate habitats. However, data on breeding biology can be lacking for some climatic regions due to local extinctions of populations. The breeding biology of the greater bilby (Macrotis lagotis) has previously only been studied in captive colonies or free-ranging arid zone populations. Between 1997 and 2005, captive-bred bilbies were released at two sites in temperate South Australia. These populations provided an opportunity to determine whether bilbies adopt a seasonal reproductive strategy in the temperate zone, where this species has not been present since the early 1900s.
Aims. To determine the season of births, litter size and female reproductive potential in two free-ranging populations of the bilby in the temperate zone of South Australia.
Methods. Bilbies were regularly cage-trapped at Venus Bay Conservation Park and Thistle Island between August 2007 and April 2010 to obtain data on reproductive activity in both populations.
Key results. Births of pouch young in both populations occurred in winter (June–August), spring and early summer, but not between February and mid-May. Males had a significantly smaller mean testes size relative to head length in late summer, when breeding activity ceased. Average litter size at pouch emergence was between 1.00 and 1.47 pouch young, with females producing up to three litters per annum. The mean head length of females that successfully raised twins was significantly larger than that of females who raised a single pouch young.
Conclusions. The seasonal breeding pattern observed in the present study differs from that of year-round reproductive activity in captivity and the arid zone. The present study suggests that female body size influences fecundity, and that releasing large females at the start of the breeding season in temperate areas may maximise the initial rate of increase of a translocated bilby population.
Implications. The present study suggests previously widespread species such as the bilby can adapt their reproductive strategy to suit local conditions. Cessation of breeding in autumn, as observed in this study, has also been observed in other bandicoot species in southern Australia.
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