卡拉麦里山有蹄类自然保护区水源地蒙古野驴的活动节律: 基于红外相机监测数据

蒙古野驴(Equus hemionus)主要分布在亚洲中部的荒漠、半荒漠和荒漠草原地区, 是我国I级重点保护野生动物。因其奔跑速度快、警惕性高、分布区域偏僻, 迄今为止对其活动节律仅有半散养条件下昼间的研究。我们于2013年4-11月在新疆卡拉麦里山有蹄类自然保护区选取13处水源地, 布设28台红外相机, 对其在荒漠水源地的全天候活动节律进行了调查。结果表明: (1)蒙古野驴在春、夏、秋季的有效照片数量分别为294张、1,990张、2,679张, 其活动频率为秋季>夏季>春季。(2)蒙古野驴昼间集群平均数量大于夜间。(3)蒙古野驴在水源地具有稳定的日活动节律, 时间分配上呈典型的“U”型, 其活动在0:00-1:00达到高峰, 7:00-9:00间快速下降, 12:00-13:00和16:00-17:00是一天中的两个低谷, 在21:00-22:00间快速上升。研究水源地周围蒙古野驴的活动节律可为卡拉麦里山有蹄类自然保护区乃至新疆北部荒漠有蹄类的监测及有效保护管理提供依据, 并能对同域生存的普氏野马(Equus przewalskii)的野化工作起借鉴作用。     

基于红外相机技术分析极旱荒漠有蹄类动物的活动节律

红外触发相机技术近年来不但广泛应用于野生动物种类、数量和分布的调查与观测,还可用于对动物活动节律和行为的研究分析。本研究在甘肃安西极旱荒漠国家级自然保护区采用公里网格法布设60台红外相机,于2017年9月至2018年9月累计完成14 657个相机工作日,采集到5种荒漠有蹄类动物的1 892张独立有效照片。通过计算相对多度指数,对它们的活动节律进行分析讨论。结果表明:(1)研究区域5种荒漠有蹄类动物总的相对多度达到129.08,其中岩羊(43.87)和北山羊(42.98)的相对多度较高,其次是盘羊(25.38)、蒙古野驴(15.62)和鹅喉羚(1.23);(2)5种荒漠有蹄类动物的年活动节律表现出一致性,即5—6月活动最为频繁,11—12月出现第二个活动高峰;(3)蒙古野驴不同季节在水源地出现的日活动节律没有明显的规律,但在22:00—24:00会出现一天的峰值;而春、夏季鹅喉羚在水源地出现的最大活动峰值是在12:00—14:00;(4)各季节北山羊和岩羊的日活动节律均呈双峰型,北山羊的第2个活动高峰时间比岩羊的更偏晚一些;盘羊在冬季和春季为双峰型,夏、秋季出现3个高峰;岩羊、盘羊和北山羊的夏季日活动节律在清晨的活动高峰提前、傍晚的活动高峰推后;(5)5种荒漠有蹄类动物中,北山羊的夜间相对多度较高。荒漠有蹄类动物的年活动节律主要随生活史周期而变化,日活动节律除了受行为习性和日照节律的影响之外,不同种类主要因其栖息环境的不同而有差异。     

红外相机技术在我国野生动物监测中的应用: 问题与限制

红外相机(camera traps)作为对野生动物进行“非损伤”性采样的技术, 已成为研究动物多样性、种群生态学及行为学的常用手段之一。其发展和普及为中国野生动物多样性和物种保育研究带来了诸多机会。如今, 国内大多数自然保护区都在运用红外相机技术开展物种监测工作。本文结合20年来已发表的相关研究, 从内容、实验设计以及发展趋势方面, 总结了目前红外相机技术在应用过程中出现的共性问题; 并就相机对动物的干扰性、影像识别、研究的适用范围及安全保障四个方面, 对该项技术在实践中存在的限制进行了探讨。最后结合红外相机技术未来的发展方向, 提出了建立技术规范、数据集成和共享、影像数据版权维护、提高监测效率等问题。     

基于红外相机监测的藏酋猴日活动节律及其季节性变化

日活动节律是动物在一天中不同时间段的活动强度及其周期性变化规律,与身体控制代谢和能量收支成本密切相关。2015年8月至2017年8月,在贵州赤水桫椤国家级自然保护区,借助红外相机监测,对藏酋猴(Macaca thibetana)日活动节律及不同季节的日活动节律的变化进行了研究。调查期间红外相机累计6370个工作日,共收获687张藏酋猴照片,其中独立有效照片105张。日活动节律分析显示,藏酋猴属于典型性的昼行性动物,日活动呈现"M"型,活动高峰出现在12:00—16:00。不同季节的日活动节律比较结果显示,藏酋猴在雨季和旱季的行为节律差异不显著(P>0.05)。与雨季相比,旱季的行为差异表现为活动时间缩短、日出时段活动减少以及主要活动时间从中午推移到下午。另外,随着年气温的变化,藏酋猴日活动温度范围在-2~34℃,其中,15~25℃时活动频次较高(占比59%)。本研究从红外相机的视角揭示了藏酋猴的日活动节律及其变化,为藏酋猴行为生态学研究的深入提供了科学依据。     

四川王朗国家级自然保护区血雉的日活动节律

血雉Ithaginis cruentus是分布在青藏高原东部至喜马拉雅山脉的珍稀濒危雉类物种。本研究使用红外相机调查技术,于2014—2018年在四川王朗国家级自然保护区168个标准公里网格内布设调查位点283个,其中249个有效位点上总有效工作量为26 123相机日,共拍摄到血雉照片与视频合计8 907份(占鸡形目Galliformes总数的71.46%),独立探测922次(占鸡形目总数的70.11%),相对多度指数35.29。基于核密度函数绘制了血雉的日活动节律曲线,结果显示,血雉为严格的日行型动物,所有记录均发生在05∶50—19∶50;日活动曲线整体呈现单峰模式:活动强度在日出后快速增加,在09∶00—11∶00达到最高,之后强度逐渐降低,在18∶00后快速下降。在不同季节,血雉的日活动节律模式存在差异,繁殖期与非繁殖期的日活动节律模式差别较为明显。本研究基于可靠的调查手段和充足的数据量,分析了血雉的日活动模式,表明红外相机技术是动物行为研究的有效工具,为血雉及其他森林雉类行为生态的深入研究提供了基础资料与信息。     

·荒漠草地植物多样性对草食动物采食的响应机制

草食动物采食对草地植物多样性和生态系统功能的影响机制是放牧生态学研究的核心问题。该研究以内蒙古锡林郭勒盟苏尼特右旗荒漠草原的长期放牧控制实验为平台, 从既有草地植物多样性和动物偏食性两个层面系统地研究了荒漠草地植物多样性对草食动物采食的响应机制。结果显示: 1)荒漠草地植物对草食动物采食呈现4种响应模式: 放牧“隐没种”、放牧“敏感种”、放牧“无感种”、“绝对优势种”; 2)在群落尺度上, 物种多样性指数随放牧强度增加而减少, 与不放牧小区相比, 重度放牧(HG)与适度放牧(MG)小区植物多样性均下降, 且这一规律同样适用于功能群多样性, 灌木半灌木这一功能群内物种多样性对放牧干扰较敏感; 3)在草地既有植物的基础上, 以不放牧小区为参考系, 草食动物对植物功能群偏食性的排序为: 一二年生草本(AB) >多年生杂类草(PF) >灌木半灌木(SS) >多年生禾草(PG), 且偏食性物种主要分布于AB和PF中; 4)植物多样性与动物偏食性基本呈显著负相关关系(p < 0.05)。     

北京松山国家级自然保护区兽类活动节律初步研究

在动物行为生态学研究中,了解动物的活动节律是分析其生存策略的重要前提。基于2013年3月—2014年2月北京松山国家级自然保护区红外相机监测资料,通过相对丰富度指数分析10种最常见兽类的季节性节律和日活动节律。结果显示:(1)岩松鼠Sciurotamias davidianus、北花松鼠Tamias sibiricus、亚洲狗獾Meles leucurus、猪獾Arctonyx collaris、豹猫Prionailurus bengalensis和貉Nyctereutes procyonoides在夏季活动最频繁,果子狸Paguma larvata、中华斑羚Naemorhedus griseus和野猪Sus scrofa在秋季活动最频繁。通过分析松鼠的年活动节律,推测其可能为2013年11月人为放生至保护区的新物种。(2)果子狸、中华斑羚、猪獾、豹猫和野猪为典型的夜行性动物,北花松鼠、松鼠Sciurus vulgaris和岩松鼠为昼行性动物。(3)依据兽类探测红外相机的行为表现,发现不同种类动物对红外相机产生了回避或受到吸引的行为。研究表明,红外相机是一种长期监测林地兽类活动节律的有效技术手段,可为制定区域性生物多样性保护措施提供数据支持。     

基于红外相机对云南腾冲高黎贡山云猫的调查

云猫(Pardofelis marmorata)在中国分布狭窄、种群稀少, 目前尚缺少有关其调查与研究的报道。通过红外相机分析野生动物的空间分布以及日活动节律, 有助于了解濒危物种的生态学特征, 为保护管理提供科学依据。我们于2014年4月至2021年5月在云南高黎贡山国家级自然保护区腾冲辖区34个位点放置红外相机进行监测。基于监测数据分析了云猫的空间分布, 并利用核密度估计方法(kernel-density estimation)对云猫与豹猫(Prionailurus bengalensis)的日活动节律进行了比较。通过31,462个相机日的监测, 共获得230个云猫的独立探测事件。探测数据显示: 云猫在研究区域内主要分布于海拔2,300‒3,100 m保存完好的常绿阔叶林中。记录到的云猫主要出现在白天, 于6:00‒11:00和14:00‒19:00活动最为频繁。在云猫记录密集的北部地区, 同域分布的豹猫表现出明显的夜行性, 而在南部地区则倾向于晨昏活动, 与云猫活动节律的重叠度较低。腾冲高黎贡山云猫的相对多度指数明显高于低纬度的热带地区, 对该区域云猫进行更为深入的研究对于了解与保护此物种至关重要。     

中国草原/荒漠植物多样性监测网 模式植物群落监测方案

“模式群落”是指能够反映某种植被分类单元基本特征, 并可作为准确描述该植被类型“标准”的典型植物群落。中国生物多样性监测网络——草原/荒漠植物多样性监测网旨在统一监测方法和技术规范的基础上, 在草原/荒漠植被主要群系分布的典型地段建立模式植物群落监测固定样方, 定期复查, 长期监测草原和荒漠的植物多样性变化。文章强调了典型植物群落监测是生物多样性监测的重要组成部分, 阐述了模式群落的概念, 介绍了草原/荒漠植物多样性监测网的总体思路和布局, 以及主要监测内容、方法、指标和预期产出。     

利用红外相机视频数据进行库姆塔格沙漠地区野骆驼集群行为研究的可行性

野骆驼(Camelus ferus)生性机警, 且栖息于远离人迹、自然条件极端恶劣的荒漠、半荒漠地区, 其种群动态和行为生态学研究一直较为缺乏。本研究通过在库姆塔格沙漠地区进行不同季节的野外观测和连续水源地红外相机监测, 对野骆驼的集群行为进行了研究。2011-2013年, 在库姆塔格沙漠地区进行了8次野外调查, 共记录野骆驼64群, 个体430峰。非繁殖季节野骆驼集群大小平均为2.94±0.67峰; 而繁殖季节野骆驼集群大小平均为10.74±3.08峰。野外观测数据证明了野骆驼集群行为存在季节性差异, 倾向于冬季繁殖季节的集群。并于2012年10月至2013年9月期间, 在11个水源地设置11台红外相机, 共记录野骆驼281群745峰。与野外调查结果相比, 红外相机数据表明繁殖期间和非繁殖期间野骆驼集群大小没有显著差异(t = 0.322, P = 0.748)。水源地的地形因素、红外相机监测视角和监测时间的限制可能是造成这一差异的原因。但是两种方法的结果均表明野骆驼在阿尔金山北麓比西湖地区容易形成较大的集群; 同时, 繁殖季节野骆驼最大集群的规模要大于非繁殖季节。尽管利用红外相机进行动物集群行为研究存在一定的局限性, 但与传统基于野外调查的方法相比, 无论是经济上还是实用性方面, 利用红外相机都为我们开展动物行为学研究提供了新的手段。     

荒漠猫的演化遗传、分类和保护研究进展

荒漠猫(Felis bieti)是中国特有的野生猫科动物, 也是世界上最鲜为人知的猫科动物之一, 在IUCN濒危物种红色名录中列为易危(Vulnerable, VU), 在我国被列为国家一级重点保护野生动物。本文对荒漠猫的野外分布现状、分类学地位、遗传多样性、演化史以及致危因素等近期研究进展进行了综述和展望, 以期为荒漠猫的保护提供科学依据。荒漠猫定名于1892年, 其分类学地位长期存在争议。形态学证据支持其独立物种的划分, 但分子遗传学研究则表明荒漠猫与亚洲野猫(Felis silvestris ornata)等野猫亚种之间的演化距离相当, 建议将其归为野猫亚种(F. s. bieti)。然而研究也表明包括荒漠猫在内的各野猫支系之间的分歧时间已有100万年以上, 因此解决野猫类群分类学争议的另一种可能是将所有野猫亚种提升为物种水平, 从而维持荒漠猫的独立物种地位, 不过这需要对所有野猫类群在全基因组层面深入全面地分析。最新的基因组学研究揭示荒漠猫与亚洲野猫(F. s. ornata)存在着古老的基因交流, 与青藏高原同域家猫之间存在近期且广泛的基因渗透。该遗传杂交信号以荒漠猫到家猫为主并局限于荒漠猫分布区, 时间尺度对应于20世纪中叶, 可能与藏区社会经济的发展以及家猫种群在当地的增长有关。该发现也意味着青藏高原增长的家猫种群对于同域分布的野猫产生的遗传影响将是亟需关注的问题。IUCN最新评估结果显示, 荒漠猫明确分布区域仅限于青藏高原东部, 包括青海东部、四川西北部、甘肃西南部以及紧邻青海的西藏东南部局部区域。荒漠猫当前面临着包括鼠药施用造成的二次毒害、毛皮贸易、开发建设造成的栖息地的丧失和碎片化、路撞以及与同域家猫杂交等在内的直接或潜在威胁。对荒漠猫开展更全面的调查和深入的研究以及评估并制定有效的保护管理措施, 是保护我国唯一的特有猫科动物的重要举措。     

Patterns of Detection and Capture Are Associated with Cohabiting Predators and Prey

Avoidance behaviour can play an important role in structuring ecosystems but can be difficult to uncover and quantify. Remote cameras have great but as yet unrealized potential to uncover patterns arising from predatory, competitive or other interactions that structure animal communities by detecting species that are active at the same sites and recording their behaviours and times of activity. Here, we use multi-season, two-species occupancy models to test for evidence of interactions between introduced (feral cat Felis catus) and native predator (Tasmanian devil Sarcophilus harrisii) and predator and small mammal (swamp rat Rattus lutreolus velutinus) combinations at baited camera sites in the cool temperate forests of southern Tasmania. In addition, we investigate the capture rates of swamp rats in traps scented with feral cat and devil faecal odours. We observed that one species could reduce the probability of detecting another at a camera site. In particular, feral cats were detected less frequently at camera sites occupied by devils, whereas patterns of swamp rat detection associated with devils or feral cats varied with study site. Captures of swamp rats were not associated with odours on traps, although fewer captures tended to occur in traps scented with the faecal odour of feral cats. The observation that a native carnivorous marsupial, the Tasmanian devil, can suppress the detectability of an introduced eutherian predator, the feral cat, is consistent with a dominant predator – mesopredator relationship. Such a relationship has important implications for the interaction between feral cats and the lower trophic guilds that form their prey, especially if cat activity increases in places where devil populations are declining. More generally, population estimates derived from devices such as remote cameras need to acknowledge the potential for one species to change the detectability of another, and incorporate this in assessments of numbers and survival.     

Free-ranging domestic cats (<Emphasis Type="Italic">Felis catus</Emphasis>) on public lands: estimating density,activity, and diet in the Florida Keys

Feral and free-ranging domestic cats (Felis catus) can have strong negative effects on small mammals and birds, particularly in island ecosystems. We deployed camera traps to study free-ranging cats in national wildlife refuges and state parks on Big Pine Key and Key Largo in the Florida Keys, USA, and used spatial capture–recapture models to estimate cat abundance, movement, and activities. We also used stable isotope analyses to examine the diet of cats captured on public lands. Top population models separated cats based on differences in movement and detection with three and two latent groups on Big Pine Key and Key Largo, respectively. We hypothesize that these latent groups represent feral, semi-feral, and indoor/outdoor house cats based on the estimated movement parameters of each group. Estimated cat densities and activity varied between the two islands, with relatively high densities (~4 cats/km²) exhibiting crepuscular diel patterns on Big Pine Key and lower densities (~1 cat/km²) exhibiting nocturnal diel patterns on Key Largo. These differences are most likely related to the higher proportion of house cats on Big Pine relative to Key Largo. Carbon and nitrogen isotope ratios from hair samples of free-ranging cats (n = 43) provided estimates of the proportion of wild and anthropogenic foods in cat diets. At the population level, cats on both islands consumed mostly anthropogenic foods (>80% of the diet), but eight individuals were effective predators of wildlife (>50% of the diet). We provide evidence that cat groups within a population move different distances, exhibit different activity patterns, and that individuals consume wildlife at different rates, which all have implications for managing this invasive predator.     

河南内乡宝天曼国家级自然保护区豹猫及其潜在猎物之间日活动节律的季节性

日活动节律是动物应对食物可利用性、天敌捕食风险和环境条件等变化的适应性特征。阐明捕食者与猎物之间的日活动节律以及相关影响因素, 对于理解不同物种的生存策略、指导保护对策至关重要。然而, 由于采样方法的限制和人类干扰下的快速环境变化, 人们对许多野生动物日活动节律的了解并不全面, 甚至与实际情况存在偏差。以往认为夜行性的豹猫(Prionailurus bengalensis)被发现有一定程度的日间活动, 并增加晨昏活动, 这说明有必要深入调查豹猫等野生动物的昼夜节律为何存在这些变化。本研究在河南内乡宝天曼国家级自然保护区通过红外相机技术对豹猫及其潜在猎物进行调查, 基于核密度函数比较分析了豹猫与其潜在猎物在冷、暖季节的日活动节律。2016年全年设置了55个红外相机位点, 累计14,972个相机工作日, 获得豹猫及其潜在猎物的独立有效照片1,343张。结果显示, 该保护区内豹猫、蒙古兔(Lepus tolai)和鼠类以夜间活动为主, 其中豹猫有明显的晨昏活动高峰, 而赤腹松鼠(Callosciurus erythraeus)、岩松鼠(Sciurotamias davidianus)、红腹锦鸡(Chrysolophus pictus)和勺鸡(Pucrasia macrolopha)均在昼间活动。活动重叠度分析结果显示, 豹猫与夜行性的蒙古兔和鼠类在冷季和暖季均有较高重叠度(Δ ≥ 0.50), 但与其他猎物之间的重叠度均相对较低(Δ ≤ 0.40)。本研究显示豹猫及其猎物的昼夜节律既有保守性, 也具有一定的季节可塑性, 可能受到季节性猎物分布和环境变化的影响。因此, 需要加强调查研究来充分认识不同物种日活动节律的季节性变化规律及其驱动因素。     

基于红外相机数据评估华南地区豹猫的种群密度和活动节律

可靠的种群密度数据对野生动物的保护和管理十分重要。豹猫(Prionailurus bengalensis)是中国分布最广且常见的猫科动物, 但野生种群密度估算的研究并不多。本研究于2020年6月至2021年5月在香港新界嘉道理农场暨植物园开展红外相机调查, 利用空间标记-重捕法估算当地豹猫的种群密度并用核密度估计方法分析其活动节律。本次调查以网格方式布置红外相机, 在约1.5 km²的研究范围之内设置了19个相机位点, 每个位点安装2台相机以获取豹猫身体两侧花纹来进行个体识别。连续12个月调查共捕获113次有效的豹猫拍摄事件, 当中仅61次事件的照片足够清晰以进行个体识别。基于种群封闭的要求, 我们以2个月为单位将12个月的数据分为6个采样期去分析豹猫种群密度, 结果显示仅两个采样期的估算值最为准确, 分别为0.64 ± 0.31 (0.26-1.55)只/km²和0.87 ± 0.48 (0.31-2.40)只/km², 是已知全球豹猫密度最高的地点之一。结果还发现, 雨季研究地点的豹猫并无明显的日活动节律, 在旱季则偏夜行-晨昏行性多一些, 但也有一定的日间活动; 雨季和旱季的日活动节律无显著差异。本研究是首次以个体识别配以空间标记-重捕模型对中国大陆地区豹猫种群密度调查的研究; 我们也提出一些关于红外相机架设方法的建议, 以提高照片个体识别的准确度并增加重捕次数, 最后提高密度估算的准确度。本研究也进一步证明豹猫适应性极强, 在活动节律上表现出极高的可塑性, 在严格保护下可以恢复健康的种群。     

Devil Declines and Catastrophic Cascades: Is Mesopredator Release of Feral Cats Inhibiting Recovery of the Eastern Quoll?

The eastern quoll (Dasyurus viverrinus) is a medium-sized Australian marsupial carnivore that has recently undergone a rapid and severe population decline over the 10 years to 2009, with no sign of recovery. This decline has been linked to a period of unfavourable weather, but subsequent improved weather conditions have not been matched by quoll recovery. A recent study suggested another mechanism: that declines in Tasmanian devil (Sarcophilus harrisii) populations, due to the spread of the fatal Devil Facial Tumour Disease, have released feral cats (Felis catus) from competitive suppression, with eastern quoll declines linked to a subsequent increase in cat sightings. Yet current evidence of intraguild suppression among devils, cats and quolls is scant and equivocal. We therefore assessed the influences of top-down effects on abundance and activity patterns among devils, feral cats and eastern quolls. Between 2011 and 2013, we monitored four carnivore populations using longitudinal trapping and camera surveys, and performed camera surveys at 12 additional sites throughout the eastern quoll’s range. We did not find evidence of a negative relationship between devil and cat abundance, nor of higher cat abundance in areas where devil populations had declined the longest. Cats did not appear to avoid devils spatially; however, there was evidence of temporal separation of cat and devil activity, with reduced separation and increasing nocturnal activity observed in areas where devils had declined the longest. Cats and quolls used the same areas, and there was no evidence that cat and quoll abundances were negatively related. Temporal overlap in observed cat and quoll activity was higher in summer than in winter, but this seasonal difference was unrelated to devil declines. We suggest that cats did not cause the recent quoll decline, but that predation of juvenile quolls by cats could be inhibiting low density quoll populations from recovering their former abundance through a ‘predator pit’ effect following weather-induced decline. Predation intensity could increase further should cats become increasingly nocturnal in response to devil declines.     

Mark-Recapture and Mark-Resight Methods for Estimating Abundance with Remote Cameras: A Carnivore Case Study

Abundance estimation of carnivore populations is difficult and has prompted the use of non-invasive detection methods, such as remotely-triggered cameras, to collect data. To analyze photo data, studies focusing on carnivores with unique pelage patterns have utilized a mark-recapture framework and studies of carnivores without unique pelage patterns have used a mark-resight framework. We compared mark-resight and mark-recapture estimation methods to estimate bobcat (Lynx rufus) population sizes, which motivated the development of a new "hybrid" mark-resight model as an alternative to traditional methods. We deployed a sampling grid of 30 cameras throughout the urban southern California study area. Additionally, we physically captured and marked a subset of the bobcat population with GPS telemetry collars. Since we could identify individual bobcats with photos of unique pelage patterns and a subset of the population was physically marked, we were able to use traditional mark-recapture and mark-resight methods, as well as the new “hybrid” mark-resight model we developed to estimate bobcat abundance. We recorded 109 bobcat photos during 4,669 camera nights and physically marked 27 bobcats with GPS telemetry collars. Abundance estimates produced by the traditional mark-recapture, traditional mark-resight, and “hybrid” mark-resight methods were similar, however precision differed depending on the models used. Traditional mark-recapture and mark-resight estimates were relatively imprecise with percent confidence interval lengths exceeding 100% of point estimates. Hybrid mark-resight models produced better precision with percent confidence intervals not exceeding 57%. The increased precision of the hybrid mark-resight method stems from utilizing the complete encounter histories of physically marked individuals (including those never detected by a camera trap) and the encounter histories of naturally marked individuals detected at camera traps. This new estimator may be particularly useful for estimating abundance of uniquely identifiable species that are difficult to sample using camera traps alone.     

Movements and space use of feral cats in Kerguelen archipelago: a pilot study with GPS data

The domestic cat has been introduced on several sub-Antarctic islands such as the Kerguelen archipelago (48°28′–50°S, 68°28′–70°35E), causing a worrying impact on the viability of some seabird populations. A better understanding of the biology of this introduced predator is needed to help design appropriate management actions. To investigate the effectiveness of a GPS study on feral cats living on the Kerguelen main island and to gain preliminary results on cat space use and fine-scale movement patterns, we fitted GPS collars on three young adult males and recorded cat location at a high frequency (every 5 min) for 2–3 weeks, during the austral summer. Home-range sizes varied from 0.30 to 0.73 km², with large overlaps in space but not in time. Cats were active during the warmest hours of the day, with a peak of activity around 2:00 p.m. This preliminary result suggests that trapping for management of the population should therefore yield the highest number of captures in the afternoon and before sunrise, when cats are more active. Our pilot study demonstrated the potential of using GPS to track feral cats in sub-Antarctic islands, opening up opportunities to get deep insights in the spatial ecology of these introduced predators.     

Fix Success and Accuracy of Global Positioning System Collars in Old-Growth Temperate Coniferous Forests

Abstract: Global Positioning System (GPS) telemetry is used extensively to study animal distribution and resource selection patterns but is susceptible to biases resulting from data omission and spatial inaccuracies. These data errors may cause misinterpretation of wildlife habitat selection or spatial use patterns. We used both stationary test collars and collared free-ranging American black bears (Ursus americanus) to quantify systemic data loss and location error of GPS telemetry in mountainous, old-growth temperate forests of Olympic National Park, Washington, USA. We developed predictive models of environmental factors that influence the probability of obtaining GPS locations and evaluated the ability of weighting factors derived from these models to mitigate data omission biases from collared bears. We also examined the effects of microhabitat on collar fix success rate and examined collar accuracy as related to elevation changes between successive fixes. The probability of collars successfully obtaining location fixes was positively associated with elevation and unobstructed satellite view and was negatively affected by the interaction of overstory canopy and satellite view. Test collars were 33% more successful at acquiring fixes than those on bears. Fix success rates of collared bears varied seasonally and diurnally. Application of weighting factors to individual collared bear fixes recouped only 6% of lost data and failed to reduce seasonal or diurnal variation in fix success, suggesting that variables not included in our model contributed to data loss. Test collars placed to mimic bear bedding sites received 16% fewer fixes than randomly placed collars, indicating that microhabitat selection may contribute to data loss for wildlife equipped with GPS collars. Horizontal collar errors of >800 m occurred when elevation changes between successive fixes were >400 m. We conclude that significant limitations remain in accounting for data loss and error inherent in using GPS telemetry in coniferous forest ecosystems and that, at present, resource selection patterns of large mammals derived from GPS telemetry should be interpreted cautiously.