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1.
Pathogens such as rabies virus and canine distemper virus present a significant risk to the long-term survival of some endangered African wild dog (Lycaon pictus) populations. Vaccination of wild dogs is one approach that might reduce population extinction risks; however clear guidelines for how best to do this are lacking. Hence, we developed a mathematical model of wild dog population dynamics that integrates a pathogen transmission model and a vaccination process. Simulations indicated that the most effective vaccination strategy includes all age classes (when pups are 2-months old), prioritizes the breeding pair, and vaccinates at least 4 animals per pack included in the vaccination effort. In addition, populations for which an Allee effect, high rates of pathogen introduction, or low rates of recovery and immunity were simulated, required greater vaccination coverage (dogs/pack), to protect an equivalent number of packs compared to populations for which no Allee effect, low rates of pathogen introduction, or high rates of recovery and immunity were simulated. For populations in which some packs (high-risk) have a greater risk of pathogen exposure than others (low-risk), vaccinating both high- and low-risk packs, or only low-risk packs, is more effective than vaccinating only high-risk packs when pathogen introduction rates are high. Finally, model results suggest that vaccination of wild dog populations against pathogens, such as canine distemper virus, that do not cause 100% mortality and against which some wild dogs develop acquired immunity, may be unnecessary. 相似文献
2.
African wild dogs are endangered, and in South Africa as elsewhere, they inhabit a fraction of their former range. In this study, we assessed the potential for economic benefits derived from ecotourism to offset the costs of three wild dog conservation options using a contingent valuation study of the willingness of visitors to four protected areas to pay to see wild dogs at the den - within a viable population in a large protected area (Kruger National Park), through reintroduction into nature reserves, and through the conservation of wild dogs occurring on ranchland in situ. Results indicated that tourism revenue from wild dogs in large protected areas is more than sufficient to offset the costs and could potentially be used to subsidise wild dog reintroductions or the conservation of wild dogs in situ on ranchland. On ranchland and for reintroductions, tourism revenue was generally predicted to offset most of the costs of conserving wild dogs where predation costs are low, and to exceed the costs where willingness to pay is high, and/or where the costs of predation by wild dogs are zero. Conservation efforts should facilitate the derivation of eco-tourism-related benefits from wild dogs on ranchland and in private reserves to create incentives for wild dog conservation. Ecotourism should be part of a multifaceted approach to wild dog conservation which also includes education and awareness campaigns, and efforts to encourage landowners to cooperate to form conservancies. 相似文献
3.
A 9-year study of the African wild dog, Lycaon pictus, was conducted in Hwange National Park, Zimbabwe, primarily in Colophospermum mopane woodland and Combretum thicket. A protocol using both playbacks and human simulations of long distance calls was developed to facilitate radio-collaring operations and data collection. Wild dogs were known to be in the area prior to each trial (n=32). Dogs approached calling stations in 84% of trials from distances up to 2-km. When dogs hooed (n=18; eight packs and one group), they approached the stimulus in all but one trial. Mean time to approach was ca. 13.9±2.6 min. (n =11 trials, range 1-56 min). Findings demonstrate that playbacks are an effective conservation tool particularly where road networks are limited and/or thick habitat restrict off-road driving. Potential application lies in park boundary areas where snaring occurs and in translocations from areas of high wild dog/human conflict to refuges. In dense habitat or less traveled areas, this technique, in conjunction with other methods, may prove useful in population surveys. 相似文献
4.
Giacomo Tavecchia Covadonga Viedma Alejandro Martínez-Abraín 《Biological conservation》2009,142(12):3005-3012
Translocations have become one of the most commonly used tools for biodiversity restoration worldwide, however one out of three re-introduction plans fails to create a viable population or to successfully reinforce the existing one. We used results from the analysis of individual-based information on the re-introduction of a threatened waterfowl species, the crested coots Fulica cristata, to provide guidelines to maximise re-introduction success. We found that about a third of the post-release mortality took place within the first month after release. This immediate ‘cost of release’ in terms of local survival or ‘release risk factor’ seems to be a common feature of re-introduction projects, and it is likely due to the inexperience of captive-born individuals to face the new environment. This hypothesis was supported by the positive association between survival and time spent in the wild Results suggested that coots released between February and May have a slightly higher survival. A joint measure of survival and breeding probabilities indicated that birds released in late winter (February-March) had a higher chance to survive and reproduce compared to birds released later in the year. From an applied perspective our results can be used within an adaptive management framework to determine the optimum period of release, providing substantial support for future decision-making in the management of waterfowl, and other long-term projects of re-introduction of threatened vertebrate species. 相似文献
5.
The Casentinesi Forests, in the northern Apennines, harbour a rich community of wild ungulates, with the wolf representing the largest predator in the area. Between 1993 and 2000, wolf pack distribution in the area was monitored and estimates of pack size were obtained by wolf-howling surveys, snow-tracking, and occasional observations. Three to five packs were detected yearly, with sizes averaging 4.2 ± 0.9 wolves (maximum 7). The overall density in the area was 4.7 wolves per 100 km2 with an average distance between adjacent packs of 11.1 km. The high wolf density in the Casentinesi Forests is mostly related to abundance and size of wild prey. In this, like in other areas at low latitudes, wolf density depends mainly on the number of packs, as pack size is rather small and recruitment limited by early dispersal and high mortality. Three homesites used in several years by resident packs were discovered. Homesite fidelity and pack reproductive success were higher in fully protected rather than harvested areas. Establishing a network of protected areas with high ungulate diversity and abundance is proposed as the main factor for allowing a full recovery of the wolf population in Italy. 相似文献
6.
Jennifer Smart Arjun Amar Brian Etheridge George Christie 《Biological conservation》2010,143(5):1278-1286
The re-introduction of extirpated species is a valuable conservation tool. Red kites Milvus milvus are declining over much of their European range and have been re-introduced to England and Scotland, following their extinction due to widespread human persecution during the 19th century. Considerable regional variation in population growth exists. This study aims to identify the proximate demographic and ultimate environmental constraints on red kites in north Scotland, a region with low population growth. Productivity in north Scotland was high compared to other Scottish and Welsh populations and equal to English populations with high population growth rates. In north Scotland, annual survival of wild-fledged birds was low for first-year birds compared to other Scottish populations and second-year survival declined over time. In north Scotland, 40% of 103 red kites found dead were killed illegally, mainly by direct poisoning. In the absence of illegal killing, we estimate that annual survival rates in wild red kites might increase from 0.37 to 0.54, 0.72 to 0.78 and 0.87 to 0.92 for first, second-year and adult birds respectively. Demographic rates from this study produce population trends that recapitulate observed trends for the north Scotland population (leading to a population of c40 pairs by 2006). Models in which the additive illegal killing mortality is excluded, predict a population trajectory and size (c300 pairs by 2006) very similar to that found in the Chilterns, a rapidly growing population (320 pairs in 2006) in south-east England re-introduced at the same time, but where rates of illegal killing are much lower. We conclude that illegal killing of red kites is the cause of poor population growth in north Scotland and the key challenge facing government is to find a way to eliminate this killing. 相似文献
7.
Domestic dogs (Canis familiaris) arrived in Zimbabwe ca. 1000 years ago. Numbers of free-ranging dogs have reached unprecedented levels in communal lands (agro-pastoralist rural areas), and interact with large wild carnivores along boundaries with wildlife reserves as predators and prey. This study examined a population of 236 dogs in a 33-km2 section of Gokwe Communal Land (GCL) bordering the Sengwa Wildlife Research Area (SWRA) in north-western Zimbabwe in 1995-1996. Dogs were found up to 6 km within the SWRA, and were the most common carnivore on the GCL-SWRA boundary. Observations of 16 radio-collared dogs showed that they were inefficient predators. Only 20 kills were recorded amongst the remaining dog population, of which three were wild ungulates. Dogs were unsuccessful predators due to their small group size (mean 1.7) and body mass (mean 14.7 kg), and the abundance of alternative food. It is therefore unlikely that they compete with large carnivores for wild prey. However, leopards (Panthera pardus), lions (P. leo) and spotted hyaenas (Crocuta crocuta) preyed on dogs in GCL, removing ?6% of the dog population in 1993. Such predation provides ideal circumstances for disease transmission. Canid disease was prevalent in the study area; including rabies and probably distemper. The risk of infection is greatest during the dry season (May-October), when peaks in rates of disease, carnivore incursions into GCL, and predation on dogs coincided. The role of jackals (Canis adustus and Canis mesomelas) and spotted hyaena predation of dogs is discussed in relation to disease epidemics within wildlife reserves. With a dog population growth rate of 6.5% per annum, and the prevalence of canid diseases, the conservation threat posed by dogs is escalating on communal land-wildlife reserve boundaries in Zimbabwe. Measures to control dog numbers and improve vaccination coverage of dogs are discussed. 相似文献
8.
Despite the apparent risks of the introduction of non-indigenous ungulates to biodiversity, relatively little is known globally about the pathways of introduction, propagule pressure and realized impacts of ungulate introductions. These issues were examined here by investigating ungulate introductions to South Africa within a global context. Across countries globally, introduced ungulate richness is not related to indigenous ungulate richness, and several countries are clear outliers. South Africa is second only to the USA in the number of ungulate species introduced to date. Zoos have traded more ungulate species and individuals to non-zoo recipients than to other zoos, highlighting the tensions that exist between in situ and ex situ conservation goals. Introductions to, and extralimital introductions within South Africa have increased through time, with propagule pressure being highest in areas with high human population density. The long distances ungulates have been translocated raise concerns for genetic homogenization. Translocations of indigenous ungulate species extralimitally have significantly altered range sizes, typically to a greater extent than is expected from range shifts associated with global climate change. Although ungulate introductions and translocations are likely to have impacts on biodiversity, evidence for such impacts in South Africa, and elsewhere, is limited. Whilst arguments may be made for a precautionary approach to ungulate introductions, an evidence-based one is much more likely to deliver efficient and convincing conservation decision-making. 相似文献
9.
The standard objective of a vaccination strategy is to reduce the reproductive ratio, R0, defined as the number of secondary host infections arising directly from introduction of a single infected individual into an otherwise fully susceptible population, to below 1. This ensures that only very small outbreaks are likely to arise. However, this objective usually requires a high level of vaccination coverage that is often expensive and logistically difficult to achieve. For the purposes of conserving rare species that are threatened by outbreaks of infectious disease, population persistence may be assured by a vaccination strategy designed to suppress only the largest outbreaks of disease that reduce the population to below a minimum viable population size. Such strategies targeting only a viable minimal ‘core’ of the population are likely to be logistically less demanding. Here we explore how these core vaccination strategies might be designed for African wild dogs (Lycaon pictus), an endangered canid species whose remaining populations are threatened by rabies outbreaks. We develop and analyse a population viability model with an explicit epidemiological model embedded within it. The model predicts that core vaccination campaigns, using vaccines that provide two years of immunity, and targets 30-40% of individuals within a population every 1-2 years would be successful in ensuring persistence of small populations, and required coverage levels can be even lower in larger populations. This strategy appears robust to synchronized introduction of rabies into packs, possible Allee effects, and the use of vaccines providing only one year of immunity. 相似文献
10.
Emmanuel O.A. Asibey 《Biological conservation》1974,6(1):32-39
The protein deficiency problems of Africa south of the Sahara are growing in seriousness with the increasing human population. Domestic livestock, on which very high hopes have hitherto been set, have continued to fail to meet existing demands, let alone to keep in step with increasing human population growth. There has been increasing exploitation of the meat of wild animals, whose management is ignored. This source of meat supplements domestic sources. The exploitation of wild animals, coupled with increasing pressure on the habitat of the animals, is exterminating most of the wild animal species involved. Advice that existing scientific knowledge on the management of wild animals must be applied to ensure their rational exploitation on a sustained-yield basis, has continued to be ignored— with the excuse that facts and figures are not available to justify investment in wildlife conservation that will ensure a sustained yield of the badly-needed animal protein. Every attempt must be made by those entrusted with the responsibility of wildlife conservation to bring together scattered information on the subject and, at the same time, begin to collect, systematically, statistical information on the utilization of wild animal meat as food—also to ensure that wildlife conservation receives the priority it deserves in the management of natural resources in Africa south of the Sahara. This is inevitable if wildlife conservation is to be able to meet the economic justification without which one nation after another will continue to give very low priority to wildlife conservation—to the detriment of the region—where malnutrition and poaching are serious realities as are also overgrazing, expansion of desert land, and human population explosion. Despite the fact that general experience indicates the need for concerted action, it appears that, in the absence of readily-available statistical data, which are supposed to be required by policy-makers and financiers, these people are not prepared to face their duty effectively to finance proper wildlife conservation and rational utilization of wildlife resources of Africa south of the Sahara. 相似文献
11.
Plantation clearcuts represent an important habitat for many open-area wildlife species – including conservation-concern species – in landscapes dominated by industrial forests. However, due to the ephemeral nature of clearcuts, species using this type of environment face a “shifting mosaic” in which their ability to successfully relocate to another habitat patch may play a crucial role in the species’ persistence in the landscape. Although several studies have shown a positive effect of patch size on the persistence of open-habitat species, forest clearcutting represents a special case in which, on average, larger patches also tend to be more isolated from each other, likely creating a trade-off between area and isolation effects. We developed an individual-based spatially-explicit model to test the effect of clearcut size (a critical management variable in plantation forestry) on the persistence of generic early-successional wildlife species in a landscape dominated by forest plantations. We simulated a landscape covered with a plantation harvested regularly over a 25-year rotation and different versions of a wildlife population whose habitat was constituted only by 1–4 year-old patches. We observed that when the species could perceive the attributes of the neighboring pixels persistence time was higher at intermediate clearcut sizes agreeing with our prediction. Also, species with a high dispersal capacity were less limited by connectivity and reached their maximum persistence at higher clearcut sizes. Results also showed a positive effect of habitat lifetime on persistence. Our results suggest large clearcuts may be incompatible with the conservation of many early-successional vertebrates that have limited dispersal capacity, unless additional conservation measures, such as the use of corridors or special spatial arrangement of clearcuts, are taken to overcome the lack of connectivity. 相似文献
12.
The bush dog (Speothos venaticus), listed as CITES Appendix 1 - vulnerable, is a small (5-6 kg), rarely seen canid from Central and South America. The World Conservation Union Canid Specialist Group (IUCN CSG) recommended that research with this species focus on their basic ecology so that a data-driven conservation strategy can be formulated. Information on the bush dog, however, has been lacking since standard field techniques have had little or no success with this species. The S. venaticus Status and Distribution Survey was developed in an attempt to use indirect methodologies to determine the bush dog’s conservation status in the wild, its current distribution, and identify ecological needs by correlating habitat types to bush dog sightings. Survey responses and literature generated a database with 399 historic bush dog locations recorded between 1834 and 2004. These locational records were used to update the species’ range extent map, an important conservation planning tool. With year and precision of data accounted for, we analyzed land use coverage at known locations where bush dogs have historically been reported to evaluate the likelihood that the species persists in the area today. In addition, these locations provided training data for generation of potential distribution maps (i.e., areas of occupancy) using ecological niche modeling (i.e., Maximum Entropy) and bioclimatic data. These analyses revealed that 20% of the historic bush dog locations are associated with fragmented or altered habitat. These results allowed the status of bush dog habitat to be re-evaluated and areas that require more intensive research and protection to be identified. 相似文献
13.
Poaching giant pandas (Ailuropoda melanoleuca) for their skins is a serious threat to the persistence of wild giant panda populations in China. An individual-based, age-structured stochastic simulation model was constructed to give a quantitative analysis of the effects of poaching. The model takes a total wild population of 1216 individuals divided among 16 ‘patches’. The model treats individual populations as being completely independent, with no dispersal, and density-dependence only enters into the model through local carrying capacity of patches. The model simulates three types of poaching: deterministic (constant) poaching, stochastic poaching with normal distribution and stochastic poaching with observed distribution. Results showed that, with a given initial population, poaching adult females produces lower average population size and higher average percentage extinction than poaching adult males or young. At the same poaching intensity, all three poaching simulations predicted a similar probability of extinction. However, they predicted different average population size and percentage extinction because of differences in the parameters in the three models. These results should therefore be treated with caution when constant poaching simulation or stochastic poaching with assumed normal distribution is used as a simplification of realistic poaching. Nevertheless, the results imply that giant pandas are threatened by any reduction in natural populations. Effective measures are essential to reduce poaching. It is also important to limit the capturing of wild animals for zoos or breeding facilities as this also has a serious effect on the total population. 相似文献
14.
Populations of threatened taxa in captivity within their natural ranges can make important contributions to conservation, but these may be compromised by the inappropriate application of population management goals developed in other contexts. We conducted demographic, genetic, and population viability analyses on the captive population of Andean bears (Tremarctos ornatus) in Venezuela to investigate the management of within-range captive populations in general, and to better integrate this population into the conservation of Andean bears in particular. We found that although the present population is very small and not internally self-sustaining, incorporation of confiscated wild individuals has resulted in a low average number of generations in captivity and low inbreeding, with moderate gene diversity and a high probability of future population persistence. However, past imports from extra-range populations have been from over-represented lineages of unknown origin, which have mixed with under-represented Venezuelan ones, reducing the future value of the Venezuelan population as a source for founder stock. Our analyses indicate that the rate of incorporation of wild recruits is a major factor influencing proxy measures of conservation value, and distinguishing within- from extra-range populations. This implies that, contrary to conventional wisdom, internal self-sustainability can be a misguided goal in within-range populations, which furthermore may not be suitable destinations for surplus animals from captive populations elsewhere. 相似文献
15.
Re-introduction is a technique widely used in the conservation of threatened bird species. With advances in aviculture the use of captive-produced individuals as the release stock is becoming more commonplace, and ideally, survival of captive-produced, released individuals should be no different from their wild-bred counterparts. During the late 1980s the Critically Endangered Mauritius kestrel (Falco punctatus) was successfully re-introduced into the Bambous mountain range, Mauritius, some 30 years after its local extinction. Between 1987 and 2001 the developing population was closely monitored enabling us to construct re-sighting histories for 88 released and 284 wild-bred kestrels. We used age-structured models in the survival analysis software program MARK to determine if an individual's origin influenced its subsequent survival. Our analysis indicated no compelling evidence for reduced survival among juvenile captive-reared and released individuals, relative to their wild-bred counterparts, across the majority of cohorts and only limited evidence of a cohort-specific effect. This study illustrates that despite the lack of a formal experimental approach it is still feasible to conduct an assessment of re-introduction outcomes and techniques. 相似文献
16.
To organize and prioritise species-specific conservation efforts, we delineate `functional conservation units' for the threatened Alcon Blue butterfly Maculinea alcon in Belgium. We used detailed distribution data on the butterfly, its host plant and its habitat, present-day population sizes and its mobility and colonization capacity to determine functional conservation units (FCUs) on different spatial scales: FCU-1, i.e., the 12 presently occupied habitat patches plus the area within a range of 500 m surrounding them (the maximum local movement distance, based on mark-release-recapture data), FCU-2, i.e., the areas within a range of 2 km around the occupied habitat patches (the maximum observed colonization capacity) and FCU-3, i.e., potential re-introduction sites (sites where M. alcon went extinct recently). We suggest different management and planning measures for each type of functional conservation unit and discuss translocation and re-introduction as `intensive care' conservation measures for this threatened and sedentary species. 相似文献
17.
Legal and illegal killing of animals near park borders can significantly increase the threat of extirpation for populations living within ecological reserves, especially for wide-ranging large carnivores that regularly travel into unprotected areas. While the consequences of human-caused mortality near protected areas generally focus on numerical responses, little attention has been given to impacts on social dynamics. For wolves, pack structure typically constitutes an unrelated breeding pair, their offspring, and close relatives, but intense harvest may increase adoption of unrelated individuals into packs. Concerns that high human-caused mortality outside Algonquin Park, Canada threatened the persistence of eastern wolves, led to implementation of a harvest ban in surrounding townships. We combined ecological and genetic data to show that reducing anthropogenic causes of mortality can restore the natural social structure of kin-based groups despite the absence of a marked change in density. Since implementation of the harvest ban, human-caused mortality has decreased (P = 0.000006) but been largely offset by natural mortality, such that wolf density has remained relatively constant at approximately three wolves/100 km2. However, the number of wolf packs with unrelated adopted animals has decreased from 80% to 6% (P = 0.00003). Despite the high kinship within packs, incestuous matings were rare. Our results indicate that even in a relatively large protected area, human harvesting outside park boundaries can affect evolutionarily important social patterns within protected areas. This research demonstrates the need for conservation policy to consider effects of harvesting beyond influences on population size. 相似文献
18.
There is an extraordinary assortment of technical approaches to conserving carnivore populations, but the effectiveness of conservation activities is rarely evaluated. Accordingly, we initiated a study to assess the impact of several conservation interventions on the dynamics and persistence of a leopard (Panthera pardus) population in Phinda Private Game Reserve, South Africa. These included revisions of the statutory systems that regulate problem animal control and trophy hunting, and we instituted a program intended to reduce human–leopard conflict in the region. We compared demographic rates of radiocollared leopards from two sampling periods: a pre-treatment period prior to intervention, and a treatment period after intervention. The average annual mortality rate of the population decreased from 0.401 ± 0.070 to 0.134 ± 0.016, with fewer leopards killed by humans and in intraspecific clashes after intervention. The overall reproductive output of the population increased in the treatment period, although annual cub production was higher in the pre-treatment period. This was mainly due to larger litter sizes prior to intervention, which may have been a strategy used by female leopards to offset high levels of infanticide. Results from camera-trap surveys and a Leslie-matrix model indicated an increase in annual population growth rate (λ) of 14–16% after the implementation of conservation measures. Our findings highlight the importance of addressing both the numerical and functional components of population dynamics when managing large carnivores exposed to hunting or persecution. 相似文献
19.
Most conservation practitioners rely on experience-based information for management decisions. In South Africa, government policy thus directs managers to base decisions for elephant management on the best available scientific information. The reliance of their management decisions on science, however, is unknown. We interviewed 30 managers from small to large protected areas in South Africa to evaluate whether science underpinned strategic and applied management decisions regarding elephants. We also evaluated their perspectives on limitations to, and opportunities for, greater reliance on science. Twenty-nine managers valued science as a platform for their decisions. However, most managers based decisions on experience-based information. Only 28%, 30% and 8% of managers respectively developed objectives, identified issues and selected management methods on science-based information. Furthermore, only 30% selected a desired number of elephants, and 5% selected a population control method, according to science-based information. The probability of managers basing decisions on science-based information differed with management area size, tenure, planning timeframes and manager experience. However, except for experience, these relationships were weak, and overall an implementation gap between science and elephant management existed. Limitations for science to inform decisions included lack of relevance and application of science findings to respective management areas, and scientists’ attitudes and credibility. Opportunities included more site specific studies, better communication of, and easier access to scientific material. These opportunities could enable scientists to contribute more effectively to elephant management decisions and improve the reliance on science among the wider community of conservation practitioners in Africa. 相似文献
20.
Jonathan R. Rhodes Chooi Fei Ng Deidré L. de Villiers Harriet J. Preece Clive A. McAlpine Hugh P. Possingham 《Biological conservation》2011,(3):1081-1088
Many species of conservation concern are in decline due to threats from multiple sources. To quantify the conservation requirements of these species we need robust estimates of the impact of each threat on the rate of population decline. However, for the vast majority of species this information is lacking. Here we demonstrate the application of integrated population modelling as a means of deriving robust estimates of the impact of multiple threats for a rapidly declining koala (Phascolarctos cinereus) population in South-east Queensland, Australia. Integrated population modelling provides a basis for reducing uncertainty and bias by formally integrating information from multiple data sources into a single model. We quantify mortality rates due to threats from dog attacks, vehicle collisions and disease and the extent to which each of these mortality rates would need to be reduced, or how much habitat would need to be restored, to stop the population declining. We show that the integrated population modelling approach substantially reduces uncertainty. We also show that recovery actions that only address single threats would need to reduce those threats to implausibly low levels to recover the population. This indicates that strategies for simultaneously tackling multiple threats are necessary; a situation that is likely to be true for many of the world’s threatened species. This study provides an important framework for quantifying the conservation requirements of species undergoing declines due to multiple threats. 相似文献