大型哺乳动物的趋势监测:青海野牛沟和甘肃阿克塞国际狩猎场的案例(英文)

大型野生动物种群数量估算的理想条件是使用数学模型以及严格的实验设计来选择样本。可是,野外条件状况往往违背数学模型假设前提,不可能随机地选择样本。于是,计算的结果不但不可靠,而且很可能没有意义。就野生动物管理来说,不需要获得一个准确的种群数量,只需一个长期的数量趋势,就足以指导相关管理工作。在中国大型哺乳动物长期监测还没有纳入常规。本文报道了位于青海省野牛沟和甘肃省阿克塞县两个野生有蹄类动物种群数量的长期趋势监测项目。我们这些年里一直用相同的方法持续监测,并明确了监测数值结果包含有不确定性。尽管存在不确定性,仍可以发现监测地点野生有蹄类动物种群变化趋势,这些结果可以帮助野生动物管理者据此变化及时作出相应管理计划。

从北美的研究看大熊猫的种群动态(英文)

尽管人们对大熊猫的种群动态了解很少 ,但是我们可以从对相似物种的研究和经历中了解一些基本原理。在不减少对后续的有关大熊猫种群特征、遗传学和行为研究的前提下 ,根据对北美食肉动物种群生物学的理解 ,我提出了下面一般性的结论。首先 ,弹性分析确认 ,大熊猫演变出了确保雌性个体高存活率的生活史。比较而言 ,繁殖率并不重要。成年雌性个体的存活率增加 ,比相应的繁殖输出要导致 5倍的保护效益。第二 ,在可能表现大熊猫种群特征的假设前提下 ,雄性 (甚至成年个体 )的存活率相对而言也是不重要的。第三 ,尽管都认为大熊猫繁殖很缓慢 ,但是从数学上来说 ,如果生境 (以及与其相关的存活率 )允许 ,大熊猫的种群能够比较快地增长。最后 ,北美西部对濒危物种再引入的经验提醒我们 ,保留大片尚未破碎化的生境非常重要。狼在 2 0世纪中叶就在美国西部灭绝了 ,但是目前由于有广阔的生存区域和丰富的食物 ,种群恢复很快。对比而言 ,最近从原野中消失的黑足鼬 ,在种群重建过程中遇到了很大的困难 ,尽管人们在科学上做出了巨大的努力。看来黑足鼬可能只是没有足够的野外栖息地 (猎物 )以维持生存。如果没有足够的栖息地 。

Testing whether adrenal steroids mediate phenotypic and physiologic effects of elevated salinity on larval tiger salamanders

Salinity(sodium chloride,NaCl)from anthropogenic sources is a persistent contaminant that negatively affects freshwater taxa.Amphibians can be susceptible to salinity,but some species are innately or adaptively tolerant.Physiological mechanisms mediating tolerance to salinity are still unclear,but changes in osmoregulatory hor-mones such as corticosterone(CORT)and aldosterone(ALDO)are prime candidates.We exposed larval barred tiger salamanders(Ambystoma mavortium)to environmentally relevant NaCl treatments(<32–4000 mg·L-1)for 24 days to test effects on growth,survival,and waterborne CORT responses.Of those sampled,we also quantified waterborne ALDO from a subset.Using a glucocorticoid antagonist(RU486),we also experimentally suppressed CORT signaling of some larvae to determine if CORT mediates effects of salinity.There were no strong differ-ences in survival among salinity treatments,but salinity reduced dry mass,snout–vent length,and body condition while increasing water content of larvae.High survival and sublethal effects demonstrated that salamanders were physiologically challenged but could tolerate the experimental concentrations.CORT signaling did not attenuate sublethal effects of salinity.Baseline and stress-induced(after an acute stressor,shaking)CORT were not influ-enced by salinity.ALDO was correlated with baseline CORT,suggesting it could be difficult to decouple the roles of CORT and ALDO.Future studies comparing ALDO and CORT responses of adaptively tolerant and previously unexposed populations could be beneficial to understand the roles of these hormones in tolerance to salinity.Nev-ertheless,our study enhances our understanding of the roles of corticosteroid hormones in mediating effects of a prominent anthropogenic stressor.

Using physiological conditions to assess current and future habitat use of a Subarctic frog

Species with especially close dependence on the environment to meet physiological requirements,such as ectotherms,are highly susceptible to the impacts of climate change.Climate change is occurring rapidly in the Subarctic and Arctic,but there is limited knowledge on ectotherm physiology in these landscapes.We investigated how environmental conditions and habitat characteristics influence the physiological conditions and habitat use of wood frogs(Rana sylvatica)in a Subarctic landscape near Churchill,Manitoba(Canada).We used plaster models to estimate water loss rates and surface body temperatures among different habitat types and at specific locations used by radio-tracked frogs.Water loss(R2=0.67)and surface temperature(R2=0.80)of plaster models was similar to that of live frogs.Model-based water loss rates were greater in tundra habitat than in boreal forest and ecotone habitat.Habitat use of wood frogs was strongly tied with available surface moisture and decreased water loss rates that were observed with plaster models.Environmental conditions,such as wind speed and ground tem-perature,explained 58%and 91%of the variation in water balance and temperature of plaster models.Maintaining physiological conditions may be challenging for semi-aquatic ectotherms in environments vulnerable to future cli-mate change.The ability to predict physiological conditions based on environmental conditions,as demonstrated in our study,can help understand how wildlife will respond to climatic changes.

Estimating abundance and density of Amur tigers along the Sino- Russian border

As an apex predator the Amur tiger(Panthera tigris altaica)could play a pivotal role in maintaining the integ­rity of forest ecosystems in Northeast Asia.Due to habitat loss and harvest over the past century,tigers rapidly declined in China and are now restricted to the Russian Far East and bordering habitat in nearby China.To fa­cilitate restoration of the tiger in its historical range,reliable estimates of population size are essential to assess effectiveness of conservation interventions.Here we used camera trap data collected in Hunchun National Na­ture Reserve from April to June 2013 and 2014 to estimate tiger density and abundance using both maximum likelihood and Bayesian spatially explicit capture-recapture(SECR)methods.A minimum of 8 individuals were detected in both sample periods and the documentation of marking behavior and reproduction suggests the presence of a resident population.Using Bayesian SECR modeling within the 11400 km2 state space,den­sity estimates were 0.33 and 0.40 individuals/100 km^(2) in 2013 and 2014,respectively,corresponding to an es­timated abundance of 38 and 45 animals for this transboundary Sino-Russian population.In a maximum likeli­hood framework,we estimated densities of 0.30 and 0.24 individuals/100 km^(2) corresponding to abundances of 34 and 27,in 2013 and 2014,respectively.These density estimates are comparable to other published estimates for resident Amur tiger populations in the Russian Far East.This study reveals promising signs of tiger recovery in Northeast China,and demonstrates the importance of connectivity between the Russian and Chinese popula­tions for recovering tigers in Northeast China.

Mortality of Amur tigers:The more things change,the more they stay the same

Poaching as well as loss of habitat and prey are identified as causes of tiger population declines.Although some studies have examined habitat requirements and prey availability,few studies have quantified cause-specific mortality of tigers.We used cumulative incidence functions(CIFs)to quantify cause-specific mortality rates of tigers,expanding and refining earlier studies to assess the potential impact of a newly emerging disease.To quantify changes in tiger mortality over time,we re-examined data first collected by Goodrich et al.(2008;study period 1:1992–2004)as well as new telemetry data collected since January 2005(study period 2:2005–2012)using a total of 57 tigers(27 males and 30 females)monitored for an average of 747 days(range 26–4718 days).Across the entire study period(1992 to 2012)we found an estimated average annual survival rate of 0.75 for all tigers combined.Poaching was the primary cause of mortality during both study periods,followed by suspected poaching,distemper and natural/unknown causes.Since 2005,poaching mortality has remained relatively constant and,if combined with suspected poaching,may account for a loss of 17–19%of the population each year.Canine distemper virus(CDV)may be an additive form of mortality to the population,currently accounting for an additional 5%.Despite this relatively new source of mortality,poaching remains the main threat to Amur tiger survival and,therefore,population growth.

Review of research methodologies for tigers:Telemetry

Over the past half century,wildlife research has relied on technological advances to gain additional insight into the secretive lives of animals.This revolution started in the 1960s with the development of radio telemetry and continues today with the use of Global Positioning System(GPS)-based research techniques.In the present paper we review the history of radio telemetry from its origins with grizzly bears in Yellowstone to its early applications in tiger research and conservation in Asia.We address the different types of data that are available using radio telemetry as opposed to using other research techniques,such as behavioral observations,camera trapping,DNA analysis and scat analysis.In the late 1990s,the rapid development of GPS collar technology revolutionized wildlife research.This new technology has enabled researchers to dramatically improve their ability to gather data on animal movements and ecology.Despite the ecological and conservation benefits of radio telemetry,there have been few telemetry studies of tigers in the wild,and most have been on the Bengal or Amur subspecies.We close with an assessment of the current tiger conservation efforts using GPS technology and discuss how this new information can help to preserve tigers for future generations.

Unexpected ecotone dynamics of a sand dune vegetation complex following water table decline

Aims Central Hungarian inland dune ranges harbor heterogeneous grassland vegetation with an extensive network of ecotones,arranged perpendicular to topography-driven hydrologic gradients.The area suffers from severe aridification due to climate change and local anthropogenic factors,which have led to a dramatic decline of the water table.As a result,groundwater is no longer reachable for lowlying plant communities;thus,we expect they are bound to undergo profound changes.This study investigates how the plant communities respond to this changing environment over time by monitoring ecotones,since they are frequently the hotspots of ecosystem change.We monitored five ecotones along permanent belt transects for 15 years to characterize their dynamic response,and to identify the internal structural changes of the plant communities the ecotones delimit.Methods Ecotones were delineated with the split moving window technique.The dynamics of two ecotone parameters,location and contrast,were analyzed with linear regression models incorporating two independent variables:study year as a measure of time since the loss of groundwater,and precipitation as a possible driver of interannual variations.The internal changes of the patches separated by the ecotones were analyzed using plant functional groups.Important Findings Precipitation had no detectable effect on the ecotone descriptors,but study year influenced ecotones in an unusual fashion.The position of the ecotones appeared to be very stable in time;their dynamics are stationary,not directional as we predicted.The contrasts had clear tendencies;two ecotones disappeared,one new one was formed and two ecotones showed no trend.The internal changes of the patches over time were dramatic,showing a shift toward more xeric and more open plant assemblages in most stretches of the transects.Thus,the dynamic response of the vegetation was not patch expansion vs.shrinking,but fusion vs.division,which profoundly restructured the vegetation pattern.Analysis of plant functional groups revealed that the trends of the ecotone contrasts could be traced back to internal changes of the patches and not to processes within ecotones.Hence,in situations where stationary ecotone dynamics prevail,ecotone position may be a poor indicator of the effects of strong directional environmental changes.However,in this study we show that ecotone contrast can serve as a sensitive tool for monitoring landscape pattern transformations in these cases.Also,this highlights the long-term nature of ecotone responses,which can have implications in landscape planning and restoration measures.