10 research outputs found
A systematic review of the impacts and management of introduced deer (family Cervidae) in Australia
Deer are among the world's most successful invasive mammals and can have substantial deleterious impacts on natural and agricultural ecosystems. Six species have established wild populations in Australia, and the distributions and abundances of some species are increasing. Approaches to managing wild deer in Australia are diverse and complex, with some populations managed as 'game' and others as 'pests'. Implementation of cost-effective management strategies that account for this complexity is hindered by a lack of knowledge of the nature, extent and severity of deer impacts. To clarify the knowledge base and identify research needs, we conducted a systematic review of the impacts and management of wild deer in Australia. Most wild deer are in south-eastern Australia, but bioclimatic analysis suggested that four species are well suited to the tropical and subtropical climates of northern Australia. Deer could potentially occupy most of the continent, including parts of the arid interior. The most significant impacts are likely to occur through direct effects of herbivory, with potentially cascading indirect effects on fauna and ecosystem processes. However, evidence of impacts in Australia is largely observational, and few studies have experimentally partitioned the impacts of deer from those of sympatric native and other introduced herbivores. Furthermore, there has been little rigorous testing of the efficacy of deer management in Australia, and our understanding of the deer ecology required to guide deer management is limited. We identified the following six priority research areas: (i) identifying long-term changes in plant communities caused by deer; (ii) understanding interactions with other fauna; (iii) measuring impacts on water quality; (iv) assessing economic impacts on agriculture (including as disease vectors); (v) evaluating efficacy of management for mitigating deer impacts; and (vi) quantifying changes in distribution and abundance. Addressing these knowledge gaps will assist the development and prioritisation of cost-effective management strategies and help increase stakeholder support for managing the impacts of deer on Australian ecosystems
Assessment and genetic characterisation of Australian camels using microsatellite polymorphisms
Camels are substantial providers of transport, milk, sport, meat, shelter, fuel, security and capital in many countries. In Australia there are estimated to be over a million individuals, and growing at more than 80,000 per year. Australian dromedary camels may therefore represent a considerable resource for the world's camel production herd. Here we document the structure and assess the genetic diversity over a very large sampling area (> 3 million km2). Using a total of 484 reproductive individuals belonging to six sampling locations of dromedary camel (Camelus dromedaries) we analysed 28 microsatellite markers to assess polymorphism in the Australian herd. Eighteen of these markers were polymorphic, producing a total of 185 alleles. Unlike camel breeds from elsewhere in the world, the classification of Australian camels into distinguishable breeds was not supported by the program STRUCTURE at the microsatellite level. Australian camels also showed very weak levels of sampling structure (and genetic diversity) suggesting a small historical founder size
Quantifying the population dynamics of camels in the arid and semiarid rangelands of Australia. Final Report to the Bureau of Rural Sciences Agriculture, Fisheries and Forestry - Australia Prepared for the
The effective control and abatement of invasive species is an emerging wildlife management problem that is expected to increase in coming decades with the rise in globalisation, urban encroachment, climate change and spread of zoonotic diseases. A common thread with many of the pest species is that the ecological information pertaining to their ecology, such as understanding the movements and population structure remains undetermined. The other problem with invasive species is they share a number of common traits, namely that they are generalists, highly fecund, with expanding ranges and have high evolutionary potential. One such species is the dromedary, or one-humped camel in Australia.
Thirty seven percent of the Australian continent is now occupied by feral camels with recent population estimates of 1,000,000 individuals. At the current rate of increase, the population is estimated to double every six to eight years. There is growing evidence that at these densities, feral camels are adversely impacting on environmental and cultural values and infrastructure in the arid zone. Control of feral animal populations is best achieved when population (and social) structuring has been delineated, and as such the aim of this study was to generate the genetic data on feral camels in Australia. This report describes the development of nuclear and mitochondrial molecular markers for Camelus dromedaries with the aim of providing a greater understanding of feral camel dispersal and structuring
Introduced deer and their potential role in disease transmission to livestock in Australia
1. The transmission of pathogens between wildlife and livestock is a globally recognised threat to the livestock industry, as well as to human and wildlife health. Wild cervids are susceptible to many diseases affecting livestock. This presents a challenge for wildlife and domestic animal disease management because the frequent use of agricultural areas by wild cervids may hamper the effectiveness of disease control strategies. 2. Six deer species have established wild populations in Australia and are expanding in range and abundance. A comprehensive literature review of diseases impacting deer and livestock was undertaken, resulting in consideration of 38 pathogens. A qualitative risk assessment was then carried out to assess the overall risk posed by the pathogens to the livestock industry. 3. Five diseases (bovine tuberculosis, foot and mouth disease, malignant catarrhal fever, surra, and screw-worm fly infestation) ranked highly in our risk assessment. Of these five diseases, only one (malignant catarrhal fever) is currently present in Australia, but all five are notifiable diseases at a national level. Data on these diseases in deer are limited, especially for one of the most abundant species, the sambar deer Rusa unicolor, highlighting a further potential risk attributable to a lack of understanding of disease epidemiology. 4. This paper provides a detailed review of the pathogens affecting both cervids and livestock in Australia, and applies a qualitative framework for assessing the risk posed by deer to the livestock industry. The qualitative framework used here could easily be adapted to assess disease risk in other contexts, making this work relevant to scientists and wildlife managers, as well as to livestock industry workers, worldwide.Jemma K. Cripps, Carlo Pacioni, Michael P. Scroggie, Andrew P. Woolnough, David S.L. Ramse
Identification and management of a single large population of wild dromedary camels
The dromedary camel (Camelus dromedarius) is a significant invasive species in Australia. It is an unusual pest species that is of large body size with relatively low fecundity compared with other pest species. Camels are highly adapted to the arid regions that characterize a large proportion of Australia and occupy an almost completely undisturbed area of â„3 million km 2. They have no history of invasion elsewhere in the world. Despite this, their population has been expanding at approximately 80,000 camels per annum, with the most recent estimate of population size around 1,000,000 individuals. We employed a landscape-genetic approach to evaluate the population structure and molecular ecology of Australian camels. We combined mitochondrial control region sequence (n = 209 animals) with 18 microsatellite markers to profile over 800 adult camels to identify the presence of a single panmictic population. We showed that demographically defined neighborhoods for wild camels are about 200 km; this value was supported by home range estimates. Distances greater than this display no pattern of isolation by distance across the Australian continent. The result is the largest single geographical population so far recorded for an invasive species in Australia. This pattern may be explained by the impressive and near-nomadic dispersal pattern of camels, in combination with an unpredictable environment virtually devoid of barriers to movement and predatory suppression. Although it is technically feasible, the reality is that it would not be economically or politically viable to have continental eradication of wild camels in Australia because of the vast size and movement dynamics of the camel population. As such, we advocate a change away from an expensive solution to an intractable reduction program (that is almost entirely focused on protection of biological refugia) and moves to include cultural, economic, and biodiversity asset protection for the management of this most unorthodox of invasive species
Molecular techniques, wildlife management and the importance of genetic population structure and dispersal: a case study with feral pigs
1. Understanding the spatial structure of populations is important in developing effective management strategies for feral and invasive species, such as feral pigs Sus scrofa. World-wide, feral pigs can act as 'triple threat' pests, impacting upon biodiversity, agricultural production and public health; in Australia they are a significant vertebrate pest. We utilized a molecular approach to investigate the structure of populations of feral pigs in south-western Australia. These approaches have been underutilized in pest management. 2. Using 14 highly polymorphic microsatellite markers from 276 adult pigs, we identified eight inferred (K = 8) pig populations that would be difficult to define with standard ecological techniques. All populations had moderate heterozygosity (HE = 0.680) and moderate to high levels of differentiation (FST = 0.118; RST = 0.132) between populations. 3. The molecular approach identified feral pig groups that appeared to be acting as a source for reinvasion following control operations. It also identified populations where current control measures were less successful in reducing 'effective population size'. Additionally, the data indicated that dispersal rates between, but not within, the inferred feral pig populations were relatively low. 4. The potential for the spread of directly transmitted wildlife diseases between the pig populations studied was low. However, under some circumstances, such as within major river catchments, the role of feral pigs in the transmission of endemic or exotic diseases is likely to be high. 5. Synthesis and applications. A molecular-based approach allowed us to determine the genetic structure and dispersal patterns of a cryptic, destructive and invasive vertebrate pest. Our results indicated that the feral pig populations studied were unlikely to be acting as closed populations and, importantly, it identified where movement between groups was likely to occur. This should lead to more informed decisions for managing the potential risk posed by feral species, such as pigs, in the transmission of wildlife diseases. The suggested technique could help in understanding the dynamics of many other free-ranging pest animal populations
Evaluation of medetomidine-ketamine and medetomidine-ketamine-butorphanol for the field anesthesia of free-ranging dromedary camels (Camelus dromedarius) in Australia
We report the clinical course and physiologic and anesthetic data for a case series of 76 free-ranging dromedary camels (Camelus dromedarius) chemically restrained, by remote injection from a helicopter, in the rangelands of Western Australia and South Australia, 2008â11, to attach satellite-tracking collars. Fifty-five camels were successfully anesthetized using medetomidine-ketamine (MK, nâ=â27) and medetomidine-ketamine-butorphanol (MKB, nâ=â28); the induction of anesthesia in 21 animals was considered unsuccessful. To produce reliable anesthesia for MK, medetomidine was administered at 0.22 mg/kg (±SDâ=â0.05) and ketamine at 2.54 mg/kg (±0.56), and for MKB, medetomidine was administered at 0.12 mg/kg (±0.05), ketamine at 2.3 mg/kg (±0.39), and butorphanol at 0.05 mg/kg (±0.02). Median time-to-recumbency for MKB (8.5 min) was 2.5 min shorter than for MK (11 min) (Pâ=â0.13). For MK, the reversal atipamezole was administered at 0.24 mg/kg (±0.10), and for MKB, atipamezole was administered at 0.23 mg/kg (±0.13) and naltrexone at 0.17 mg/kg (±0.16). Median time-to-recovery was 1 min shorter for MK (5 min) than MKB (6 min; Pâ=â0.02). Physiologic parameters during recumbency were not clinically different between the two regimes. Both regimes were suitable to safely anesthetize free-ranging camels; however, further investigation is required to find the safest, most consistent, and logistically practical combination