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1.
Wide-ranging species cannot persist in reserves alone. Consequently, there is growing interest in the conservation value of agricultural lands that separate or buffer natural areas. The value of agricultural lands for wildlife habitat and connectivity varies as a function of the crop type and landscape context, and quantifying these differences will improve our ability to manage these lands more effectively for animals. In southern California, many species are present in avocado orchards, including mammalian carnivores. We examined occupancy of avocado orchards by mammalian carnivores across agricultural-wildland gradients in southern California with motion-activated cameras. More carnivore species were detected with cameras in orchards than in wildland sites, and for bobcats and gray foxes, orchards were associated with higher occupancy rates. Our results demonstrate that agricultural lands have potential to contribute to conservation by providing habitat or facilitating landscape connectivity.  相似文献   

2.
Predator-prey body mass relationships are a vital part of food webs across ecosystems and provide key information for predicting the susceptibility of carnivore populations to extinction. Despite this, there has been limited research on the minimum and maximum prey size of mammalian carnivores. Without information on large-scale patterns of prey mass, we limit our understanding of predation pressure, trophic cascades and susceptibility of carnivores to decreasing prey populations. The majority of studies that examine predator-prey body mass relationships focus on either a single or a subset of mammalian species, which limits the strength of our models as well as their broader application. We examine the relationship between predator body mass and the minimum, maximum and range of their prey''s body mass across 108 mammalian carnivores, from weasels to baleen whales (Carnivora and Cetacea). We test whether mammals show a positive relationship between prey and predator body mass, as in reptiles and birds, as well as examine how environment (aquatic and terrestrial) and phylogenetic relatedness play a role in this relationship. We found that phylogenetic relatedness is a strong driver of predator-prey mass patterns in carnivorous mammals and accounts for a higher proportion of variance compared with the biological drivers of body mass and environment. We show a positive predator-prey body mass pattern for terrestrial mammals as found in reptiles and birds, but no relationship for aquatic mammals. Our results will benefit our understanding of trophic interactions, the susceptibility of carnivores to population declines and the role of carnivores within ecosystems.  相似文献   

3.
Track census is a widely used method for rapid faunal assessments, which assumes that differences in track count numbers mainly reflect differences in species abundance due to some biological factors. However, some methodological and climatic variables might affect results of track censuses. Here, we tested the effect of climatic variables, such as maximum temperature, humidity, wind speed or days since last rain, and methodological factors such as censusing day period, distance from transect to vegetation edge, substrate condition or observer, on the number of tracks of mammal carnivores and some of their potential prey detected in sandy substrates. We sampled 2?×?2 km2 located within the scrubland area of Doñana National Park (southwestern Spain) for carnivore and several potential prey tracks. Our results showed differences in the number of tracks detected between observers and a significant interaction between observers and the day period when censuses were carried out. Moreover, the variables increasing the quality of the substrate (higher environmental humidity, lower wind speed and days since last rain) not only led to a greater detection of carnivore tracks but, depending on the size of the species sampled other variables such as distance from transects to the vegetation border, also affected results. We recommend restricting sampling to certain fixed weather conditions when planning to monitor relative animal abundance from track censuses. When not possible, climatic or methodological variables should be included as covariates in analyses that try to test for the biological factors affecting wildlife abundance, taking into account that these variables, which affect the number of tracks detected could vary between years.  相似文献   

4.
Understanding carnivores’ diet is key to understanding their adaptability in a rapidly changing world. However, studying diet of large carnivores is difficult due to their elusive nature. In this study, we performed DNA metabarcoding analyses of 82 putative leopard scats collected from two distinct, but connected, habitat types (rainforest and grassland) in the Udzungwa Mountains, Tanzania. Two mitochondrial markers were used to identify predator and prey. Metabarcoding confirmed that 60 of the collected scats (73%) originated from leopards, and nineteen mammalian prey DNA sequences were identified to species. Using prey size correction factors for leopards, and covariates on habitat type and prey ecology, we investigated whether differences in leopard dietary composition were detectable between habitats. We found that leopards in grassland consumed a larger mean prey size compared with leopards in rainforest. Small prey (<19 kg) constituted >70% of the biomass consumed by leopards in rainforest, while large prey (≥80 kg) were only eaten in grassland. Arboreal species constituted 50% of the biomass consumed by rainforest leopards. Our results highlight the importance of arboreal species in their diet. From a management perspective, we suggest continued protection of all prey species in the protected areas to prevent human–wildlife conflicts.  相似文献   

5.
Human-carnivore conflicts are complex and are influenced by: the spatial distribution of the conflict species; the organisation and intensity of management measures such as zoning; historical experience with wildlife; land use patterns; and local cultural traditions. We have used a geographically stratified sampling of social values and attitudes to provide a novel perspective to the human – wildlife conflict. We have focused on acceptance by and disagreements between residents (measured as Potential Conflict Index; PCI) towards illegal hunting of four species of large carnivores (bear, lynx, wolf, wolverine). The study is based on surveys of residents in every municipality in Sweden and Norway who were asked their opinion on illegal hunting. Our results show how certain social values are associated with acceptance of poaching, and how these values differ geographically independent of carnivore abundance. Our approach differs from traditional survey designs, which are often biased towards urban areas. Although these traditional designs intend to be representative of a region (i.e. a random sample from a country), they tend to receive relatively few respondents from rural areas that experience the majority of conflict with carnivores. Acceptance of poaching differed significantly between Norway (12.7–15.7% of respondents) and Sweden (3.3–4.1% of respondents). We found the highest acceptance of illegal hunting in rural areas with free-ranging sheep and strong hunting traditions. Disagreements between residents (as measured by PCI) were highest in areas with intermediate population density. There was no correlation between carnivore density and either acceptance of illegal hunting or PCI. A strong positive correlation between acceptance of illegal hunting and PCI showed that areas with high acceptance of illegal hunting are areas with high potential conflict between people. Our results show that spatially-stratified surveys are required to reveal the large scale patterns in social dynamics of human-wildlife conflicts.  相似文献   

6.
Little is known about the dynamics of small mammals in tropical savanna: a critical gap in our understanding of Africa's best known ecosystems. Historical evidence suggested small mammals peak in abundance (outbreak) in Serengeti National Park (SNP), as in agricultural systems. We asked 1) what are bottom–up drivers of small mammals and 2) do predators have top–down effects? We documented dynamics of small mammals, birds of prey, and mammalian carnivores in SNP and agricultural areas. We used climatic fluctuations and differences between unmodified and agricultural systems as perturbations to examine trophic processes, key to understanding responses to climate change and increasing human pressures. Data were derived from intermittent measures of abundance collected 1968–1999, combined with systematic sampling 2000–2010 to construct a 42‐year time series. Data on abundance of black‐shouldered kites (1968–2010), eight other species of rodent‐eating birds (1997–2010), and 10 carnivore species (1993–2010) were also collated. Outbreaks occurred every 3–5 years in SNP, with low or zero abundance between peaks. There was a positive relationship between rainfall in the wet season and 1) small mammal abundance and 2) the probability of an outbreak, both of which increased with negative Southern Oscillation Index values. Rodent‐eating birds and carnivores peaked 6–12 months after small mammals. In agricultural areas, abundance remained higher than in natural habitats. Abundances of birds of prey and mammalian carnivores were extremely low in these areas and not related to small mammal abundance. Small mammals are an important food resource for higher trophic levels in the Serengeti ecosystem. Changes in climate and land use may alter their future dynamics, with cascading consequences for higher trophic levels, including threatened carnivores. Although outbreaks cause substantial damage to crops in agricultural areas, small mammals also play a vital role in maintaining some of the diversity and complexity found in African savanna ecosystems.  相似文献   

7.
Climate change is expected to alter biological phenomena across the world, including the numbers and distributions of species and the timing of significant events in their life cycles such as reproduction and migration. Understanding how species will respond to future climate change is essential for effective wildlife management and conservation. Accordingly, in this research, we advanced the understanding of avian ecology by developing a framework for how climate change affects birds. In the first step, we evaluated the vulnerability of 537 species to climate change based on the distribution, physiology, phenology, biotic interactions, and protection status of the species in Iran. Then, we used MaxEnt models to predict the potential changes in the ranges of vulnerable species due to climate change in the next 70 years. In the third step, hotspots for birds under current and future conditions were identified using an ensemble forecasting framework and the potential changes in the hotspots in the next 70 years were predicted. Results of the climate vulnerability evaluation showed that around 40% of bird species in Iran are highly vulnerable. Our results showed that small parts of suitable habitats are currently located within protected areas. Moreover, the results showed that even smaller portions of suitable habitats will fall within protected areas in the future. The reduced coverage in the future will diminish the benefits of protected areas for the species and make the species more vulnerable to climate change. These results can be used by wildlife managers to identify areas with protection priority, and for prediction of corridors, core habitats, and new areas to establish protected areas in the future.  相似文献   

8.
In French wildlife rescue centers, veterinarians or volunteers often note embedded lead projectiles in X-rayed birds of prey that are not the cause of admission. To know if embedded lead in birds of prey may result in lead poisoning, 77 individuals admitted in three wildlife rescue centers in France were X-rayed and separated into two groups and then submitted to a blood lead level analysis. Blood lead levels of birds of prey with embedded lead projectiles are significantly higher (224.2 μg/L, 95% confidence interval 197.0–251.4 μg/L) than those without (142.9 μg/L, 95% confidence interval 124.1–161.7 μg/L). Among the birds of prey included in this study, the same difference was demonstrated in two species, the common buzzard and the common kestrel, when analyzed separately. Clinical lead poisoning was not observed but birds of prey with embedded lead have a mean blood level higher than the threshold of 200 μg/L defining the risk of subclinical effect occurrences and 60% of the lead-exposed birds had blood lead concentrations above the threshold. This result suggests that embedded lead projectile may release lead and induce some long-term detrimental effects.  相似文献   

9.
为探讨鸟市贸易对野生鸟类的威胁与影响,给当地野生动物保护部门实施监管提供科学依据,于2016年11月—2017年11月对黑龙江省哈尔滨市最大鸟市——道外花鸟鱼市场进行调查。结果发现:(1)共记录6目34科83属117种18 729只鸟类,其中野生鸟类5目32科77属108种11 662只。有出售国家保护鸟种黄胸鹀 Emberiza aureola、猛禽及非法捕猎工具的现象。(2)所有被贩卖的野生鸟类中,在黑龙江省有分布的共69种,数量达9 707只。相关分析结果表明,黑龙江省有分布的野生鸟类是鸟市非法捕捉及贩卖的主要对象。(3)贩卖量为春、秋季多,夏、冬季少,7—10月鸟类迁徙季节时最多,占总贩卖量的45.2%,说明鸟类秋季迁徙是非法猎捕的高峰期。(4)调查中发现较多的南方鸟种(32.4%)也一定程度上说明野生鸟类非法运输的严重性。建议当地林业和草原局及时加强对道外花鸟鱼市场的监管,在鸟类迁徙季节从非法捕捉和运输环节实施严厉打击。  相似文献   

10.
Anticoagulant rodenticide (AR) poisoning has emerged as a significant concern for conservation and management of non-target wildlife. The purpose for these toxicants is to suppress pest populations in agricultural or urban settings. The potential of direct and indirect exposures and illicit use of ARs on public and community forest lands have recently raised concern for fishers (Martes pennanti), a candidate for listing under the federal Endangered Species Act in the Pacific states. In an investigation of threats to fisher population persistence in the two isolated California populations, we investigate the magnitude of this previously undocumented threat to fishers, we tested 58 carcasses for the presence and quantification of ARs, conducted spatial analysis of exposed fishers in an effort to identify potential point sources of AR, and identified fishers that died directly due to AR poisoning. We found 46 of 58 (79%) fishers exposed to an AR with 96% of those individuals having been exposed to one or more second-generation AR compounds. No spatial clustering of AR exposure was detected and the spatial distribution of exposure suggests that AR contamination is widespread within the fisher's range in California, which encompasses mostly public forest and park lands Additionally, we diagnosed four fisher deaths, including a lactating female, that were directly attributed to AR toxicosis and documented the first neonatal or milk transfer of an AR to an altricial fisher kit. These ARs, which some are acutely toxic, pose both a direct mortality or fitness risk to fishers, and a significant indirect risk to these isolated populations. Future research should be directed towards investigating risks to prey populations fishers are dependent on, exposure in other rare forest carnivores, and potential AR point sources such as illegal marijuana cultivation in the range of fishers on California public lands.  相似文献   

11.
As protected areas become more accessible via transportation networks, fragmentation, and encroachment from the borders, carnivores in these areas frequently decline. To counter these pressures, patrolling and active wildlife enforcement are widely accepted as fundamental conservation strategies. Using the case example of Khao Yai National Park (KYNP) and data from a camera trap survey, we modeled and evaluated the effectiveness of ranger stations in reducing human access and illegal activities, and in increasing prey and predator presence. This type of data and analysis is needed to monitor and evaluate enforcement effectiveness and develop adaptive management strategies. At KYNP, we used camera‐trapping data as a proxy to evaluate whether or not a positive impact of ranger stations on wildlife distribution could outweigh edge effects from human disturbance. We assessed factors affecting the distribution of poachers and wildlife using Maxent. Our analysis was based on 217 camera trap locations (6260 trap nights) and suggests that ungulates and poachers persist nearby ranger stations. Rangers should increase patrolling efforts of border areas; however, increasing wildlife patrolling in inaccessible areas with mobile range units may be more effective than establishing more ranger stations along park boundaries.  相似文献   

12.
The increased abundance of large carnivores in Europe is a conservation success, but the impact on the behavior and population dynamics of prey species is generally unknown. In Europe, the recolonization of large carnivores often occurs in areas where humans have greatly modified the landscape through forestry or agriculture. Currently, we poorly understand the effects of recolonizing large carnivores on extant prey species in anthropogenic landscapes. Here, we investigated if ungulate prey species showed innate responses to the scent of a regionally exterminated but native large carnivore, and whether the responses were affected by human‐induced habitat openness. We experimentally introduced brown bear Ursus arctos scent to artificial feeding sites and used camera traps to document the responses of three sympatric ungulate species. In addition to controls without scent, reindeer scent Rangifer tarandus was used as a noncarnivore, novel control scent. Fallow deer Dama dama strongly avoided areas with bear scent. In the presence of bear scent, all ungulate species generally used open sites more than closed sites, whereas the opposite was observed at sites with reindeer scent or without scent. The opening of forest habitat by human practices, such as forestry and agriculture, creates a larger gradient in habitat openness than available in relatively unaffected closed forest systems, which may create opportunities for prey to alter their habitat selection and reduce predation risk in human‐modified systems that do not exist in more natural forest systems. Increased knowledge about antipredator responses in areas subjected to anthropogenic change is important because these responses may affect prey population dynamics, lower trophic levels, and attitudes toward large carnivores. These aspects may be of particular relevance in the light of the increasing wildlife populations across much of Europe.  相似文献   

13.
Prey preferences of top carnivores in African ecosystems are well known, but far less is understood about the preferences of human hunters and the effects of their hunting activities. We interviewed 82 hunters living in Mpimbwe Division adjacent to Katavi National Park and Rukwa Game Reserve in western Tanzania. We compared stated preferences for different species of mammals with that reportedly hunted, and we used reportedly hunted species in Jacob's indices to examine proportional offtake of each species that would be expected as based on both encounters and density estimates of the wildlife species. Then, using general linear models, we tested whether the derived indices of preference were affected by the proportional density, habitat preference, and body mass of the mammalian prey species. We found that hunters would like to kill large mammals but, instead, hunt opportunistically when they cannot realize these preferences and so end up taking smaller species than would be expected. We found that a surprising amount of rarer species is taken in this ecosystem. Our study helps to unveil novel information that wildlife managers can use to predict what hunters take most from protected areas, and it highlights the importance of treating humans as apex predators in modern day Africa.  相似文献   

14.
Human–wildlife conflict, habitat loss, and prey hunting are the main threats to carnivore species worldwide. Forest conversion as consequence of deforestation and agricultural expansion increases the proximity between carnivores and humans, thereby escalating conflicts. Knowledge about carnivore species in data-poor countries, such as Colombia, is scarce which has the potential to result in poor landscape planning decisions. For many species, the only existing spatial information resides in expert-driven approaches which result in coarse-resolution ‘extent-of-occurrence’ maps. There is an increasing need for the development of methodologies to identify conservation and management areas at appropriate scales. Multi-criteria approaches will allow the inclusion of diverse species attributes enabling environmental institutions to address complex landscape decisions that result in conservation and management of carnivore habitat. We present a multi-criteria spatial identification tool for conservation and management areas, focused on Jaguars (Panthera onca) in the Sierra Nevada de Santa Marta, in northern Colombia. Our approach identifies areas based on the relationship between three spatial criteria: (1) suitable habitat patches, (2) habitat connectivity, and (3) zones of higher likelihood of human–jaguar conflict. We identified areas with the presence of at least one spatial criteria in 32% of the study area. Only 16.28% of these occur within protected areas (PAs) and the remaining fall on private lands (83.72%), either within (35.68%) or outside (48.04%) buffer zones of PAs. Our results highlight the need for multi-stakeholder collaborative approaches given that most proposed conservation areas fall on private rather than public lands.  相似文献   

15.
野生动物多样性的有效保护与管理,需要大范围、长时间的系统监测网络的支持。红外相机调查技术近年来已成为自然保护区鸟兽调查的最有效工具之一,为了解和掌握区域性乃至全国性的生物多样性现状,提供了最直接和最基础的数据。长青国家级自然保护区位于秦岭南坡,地处秦岭自然保护区群的核心地带。自2008年至2011年,使用被动式红外触发相机调查技术在长青保护区内调查了大中型兽类与鸟类的本底资源。共完成有效调查位点435个,相机工作日15767d。获得兽类有效拍摄3 282次,记录到分属5目12科的21种野生兽类和1种家畜,其中国家一级和二级重点保护野生动物各有5种,被IUCN物种红色名录评估为濒危(EN)、易危(VU)、近危(NT)的物种分别有2、3、4种。食肉目和偶蹄目是本次调查兽类记录中物种数量(分别有9种和7种)和有效拍摄数(分别占兽类有效拍摄数的13.5%和84.0%)最高的两个类群,食肉目中相对多度指数最高的物种是大熊猫(Ailuropoda melanoleuca, 12.30),偶蹄目中最高的物种是羚牛(Budorcas taxicolor, 114.04)。保护区内大型兽类(食肉目和偶蹄目)物种多样性沿海拔梯度,大体呈现中部高、两侧低的单峰模式,海拔1600-2200 m的中等海拔段是大型兽类多样性最高的区域。鸟类有效拍摄191次,记录到分属4目8科的17种鸟类,其中国家二级重点保护野生动物物种8种。鸡形目雉科鸟类是有效拍摄数最高的类群,占全部鸟类拍摄数的79.8%。调查中记录到的林猬(Mesechinus hughi)和鹰雕(Spizaetus nipalensis)为长青自然保护区的新记录种。调查结果提供了较为全面的区内大中型兽类和鸟类群落的本底信息,为后续的保护管理规划和长期监测提供了数据支持和指导。  相似文献   

16.
Mammals have evolved several morphological and behavioral adaptations to reduce the risk of predation, but we know little about the ecological factors that favor their evolution. For example, some mammalian carnivores have the ability to spray noxious anal secretions in defense, whereas other species lack such weaponry but may instead rely on collective vigilance characteristic of cohesive social groups. Using extensive natural history data on 181 species in the order Carnivora, we created a new estimate of potential predation risk from mammals and birds of prey and used comparative phylogenetic methods to assess how different sources of predation risk and other ecological variables influence the evolution of either noxious weaponry or sociality in this taxon. We demonstrate that the evolution of enhanced spraying ability is favored by increased predation risk from other mammals and by nocturnality, but the evolution of sociality is favored by increased predation risk from birds of prey and by diurnality, which may allow for enhanced early visual detection. These results suggest that noxious defenses and sociality are alternative antipredator strategies targeting different predator guilds under different lighting conditions.  相似文献   

17.
18.
Clouded Leopard, Leopard, and Tiger are threatened felids in Southeast Asia, but little is known about the factors influencing their distributions. Using logistic regression, we assessed how habitat variables, prey detection patterns, and presence of intraguild predators affect the occurrence of these felids across 13 protected areas within Thailand. Our analysis is based on data from 1108 camera‐trap locations (47,613 trap‐nights). Clouded Leopard and Leopard are associated with habitat where Red Muntjac and Eurasian Wild Pig were most likely to be present. Tiger are associated with habitat with a higher likelihood for the presence of Gaur, Eurasian Wild Pig, and Sambar. Clouded Leopard and Tiger were both weakly associated with areas with mature evergreen forest. Besides availability of prey, associations with potential competitors also appear to influence the distribution of these felids, although the strength of these effects requires further investigation. Occurrence rates for Clouded Leopard were no different in protected areas with Leopard versus without Leopards. Leopard had similar occurrence rates regardless of the presence of Tiger, but Leopards were less likely to be detected at the same camera‐trap points with the larger felid. Our results suggest that the two most commonly photographed prey species in the study areas serve as key prey species, Eurasian Wild Pig for all three carnivores and Red Muntjac for Leopard and Clouded Leopard.  相似文献   

19.
The prey base for Patagonian carnivores has been altered greatly over the past 150 years due to widespread overgrazing by livestock, invasions by exotic wildlife, and hunting. On ranches in northern Patagonia carnivores consume mostly exotic species, and native herbivores are ecologically extinct in their role as prey. In this study we compare diets of the culpeo (Lycalopex culpaeus), chilla (L. griseus), puma (Puma concolor), Geoffroy's cat (Leopardus geoffroyi), colocolo (L. colocolo), and hog-nosed skunks (Conepatus chinga and C. humboldtii) in a reserve with a mostly native prey base to their diets on the ranches, and evaluate how differences in prey bases affect trophic interactions among carnivores. Carnivores in the reserve consumed mostly native prey. Dietary overlap among carnivores was not significant on the reserve, but was highly significant on the ranches. This homogenization of diets where densities of native species are reduced could lead to stronger negative interactions among carnivores, altering the composition of the carnivore assemblage to the detriment of the more specialized species. Study of carnivore diets may be a relatively quick way to evaluate the conservation status and ecological functionality of prey assemblages in Patagonia and other areas where these have been altered.  相似文献   

20.
Positive interactions between birds and mammals are a fascinating aspect of animal behaviour. Feeding associations may consist of local enhancement or facilitation, and in the latter case, of commensalism or mutualism depending on the benefits received by the facilitator. We report here on a previously undescribed feeding association between piscivorous birds and Eurasian otters Lutra lutra. In Spain, common kingfisher Alcedo atthis and grey heron Ardea cinerea were observed closely following foraging otters and benefited from feeding opportunities provided by these. Behavioural observations of otters in central Spain (28.4 hr; 19 days) revealed that an association with kingfishers occurred in 33% of otter foraging events (n = 92). Simultaneous observations in northern Spain (14.2 hr; 16 days) showed an association between otters and kingfishers or grey herons in 41.6% and 11.7% of otter foraging events (n = 77), respectively. The association probability between kingfishers and otters increased significantly when otters foraged closer to the shore and on small fish rather than other prey (crayfish or large fish). Birds fed on prey remain left by the feeding otters, on small fish captured by otters when these were satiated and playing, or on prey displaced by otters. Our observations are consistent with facilitation and commensalism: piscivorous birds gained feeding opportunities provided by the otters, with no apparent costs or benefits to the latter. Similar feeding associations have been described between other species of otters and piscivorous birds (kingfishers, herons, egrets, storks) in Asia, South America and Southern Africa, but had not yet been described in Europe. The occurrence of piscivorous bird–otter associations in different species and regions suggests that this commensalism may be often overlooked but widespread. We have shown that the association can be frequent and is context‐dependent, with benefits for associating birds depending on otters´ behaviour and targeted prey.  相似文献   

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