Performance of camera trapping and track counts for surveying large mammals in rainforest remnants

Getting information on terrestrial large mammals is particularly difficult in tropical rainforests and in altered landscapes, since the traditionally used method (line-transect census) presents low efficiency in dense vegetation, and is difficult to standardize among heterogeneous, fragmented areas where the small size of patches restricts the length of transects. Aiming to generate information to guide the choice of field protocols for surveying terrestrial large mammals in heterogeneous rainforest remnants, we compared the performance and the correlation between the results of two alternative techniques (track counts and camera trapping), and of two types of bait, in 24 forest remnants in a fragmented Atlantic forest landscape. Techniques resulted in similar observed and estimated richness and species composition at the study landscape, including medium-sized and nocturnal species usually poorly represented in line-transect censuses. Although camera trapping resulted in a higher recording rate of the most common species (Didelphis aurita) and track counts in higher recording rates of some less common species (e.g. Dasypus novemcinctus), observed richness and recording rates of most species were correlated across the 24 sites between techniques. Conversely, the use of different baits strongly influenced results, indicating the importance of standardizing baits in comparative studies. Our results suggest that the two alternative techniques present similar performance and are suitable for studying the factors affecting the distribution of large mammals in altered rainforest landscapes. The choice of field protocols should then focus on the available resources and infrastructure, and on particularities of the study area.     

Determining the efficacy of camera traps,live capture traps,and detection dogs for locating cryptic small mammal species

Metal box (e.g., Elliott, Sherman) traps and remote cameras are two of the most commonly employed methods presently used to survey terrestrial mammals. However, their relative efficacy at accurately detecting cryptic small mammals has not been adequately assessed. The present study therefore compared the effectiveness of metal box (Elliott) traps and vertically oriented, close range, white flash camera traps in detecting small mammals occurring in the Scenic Rim of eastern Australia. We also conducted a preliminary survey to determine effectiveness of a conservation detection dog (CDD) for identifying presence of a threatened carnivorous marsupial, Antechinus arktos, in present‐day and historical locations, using camera traps to corroborate detections. 200 Elliott traps and 20 white flash camera traps were set for four deployments per method, across a site where the target small mammals, including A. arktos, are known to occur. Camera traps produced higher detection probabilities than Elliott traps for all four species. Thus, vertically mounted white flash cameras were preferable for detecting the presence of cryptic small mammals in our survey. The CDD, which had been trained to detect A. arktos scat, indicated in total 31 times when deployed in the field survey area, with subsequent camera trap deployments specifically corroborating A. arktos presence at 100% (3) indication locations. Importantly, the dog indicated twice within Border Ranges National Park, where historical (1980s–1990s) specimen‐based records indicate the species was present, but extensive Elliott and camera trapping over the last 5–10 years have resulted in zero A. arktos captures. Camera traps subsequently corroborated A. arktos presence at these sites. This demonstrates that detection dogs can be a highly effective means of locating threatened, cryptic species, especially when traditional methods are unable to detect low‐density mammal populations.     

Community structure and diversity of tropical forest mammals: data from a global camera trap network

Terrestrial mammals are a key component of tropical forest communities as indicators of ecosystem health and providers of important ecosystem services. However, there is little quantitative information about how they change with local, regional and global threats. In this paper, the first standardized pantropical forest terrestrial mammal community study, we examine several aspects of terrestrial mammal species and community diversity (species richness, species diversity, evenness, dominance, functional diversity and community structure) at seven sites around the globe using a single standardized camera trapping methodology approach. The sites-located in Uganda, Tanzania, Indonesia, Lao PDR, Suriname, Brazil and Costa Rica-are surrounded by different landscape configurations, from continuous forests to highly fragmented forests. We obtained more than 51 000 images and detected 105 species of mammals with a total sampling effort of 12 687 camera trap days. We find that mammal communities from highly fragmented sites have lower species richness, species diversity, functional diversity and higher dominance when compared with sites in partially fragmented and continuous forest. We emphasize the importance of standardized camera trapping approaches for obtaining baselines for monitoring forest mammal communities so as to adequately understand the effect of global, regional and local threats and appropriately inform conservation actions.     

基于红外相机技术对广东车八岭国家级自然保护区大中型兽类与雉类的编目清查与评估

近年来, 红外相机技术已被广泛应用于国内外自然保护地内地栖鸟兽的物种编目和动态评估。本文以广东车八岭国家级自然保护区为例, 探讨基于红外相机技术如何进行保护区全境大中型兽类和雉鸡类的物种编目清查与评估。通过对车八岭保护区全境为期1年的调查, 共记录兽类和雉鸡类18种, 其中兽类15种, 鸡形目鸟类3种。基于物种累计曲线, 采用全年数据所需的最小调查网格数、最少调查相机日均要少于雨季或旱季, 而旱季调查需要的最小调查网格数和最少调查相机日比雨季更少。通过红外相机图像数据获得了车八岭保护区的大中型兽类和地栖雉鸡类物种名录、物种丰富度、每个物种的相对多度、分布图和凭证标本等重要内容。     

Camera trapping mammals in the scrubland’s of the Cape Floristic Kingdom—the importance of effort,spacing and trap placement

As a non-invasive monitoring method camera traps are noted as being an effective, accurate and rapid means of compiling species richness estimates of medium to large terrestrial mammals. However, crucial elements of camera trap survey design are rarely empirically addressed, which has raised the need for both a standardised and optimised camera trapping protocol. Our study confirms that an appropriate camera placement buffer and targeting areas of animal activity, contributes to more complete species richness estimates as well as significantly reducing the rate of false trigger events. However, attaining the required survey effort in terms of camera days was the most important factor in providing accurate species richness estimates. Our results suggest that reliable estimates of species richness can be achieved in open scrubland when cameras are spaced 1 × 1 km apart and left in the targeted area until a survey effort of a 1000 camera days is realised.     

Who really ate the fruit? A novel approach to camera trapping for quantifying frugivory by ruminants

Tropical forest ruminants disperse several plants; yet, their effectiveness as seed dispersers is not systematically quantified. Information on frequency and extent of frugivory by ruminants is lacking. Techniques such as tree watches or fruit traps adapted from avian frugivore studies are not suitable to study terrestrial frugivores, and conventional camera traps provide little quantitative information. We used a novel time-delay camera-trap technique to assess the effectiveness of ruminants as seed dispersers for Phyllanthus emblica at Mudumalai, southern India. After being triggered by animal movement, cameras were programmed to take pictures every 2 min for the next 6 min, yielding a sequence of four pictures. Actual frugivores were differentiated from mere visitors, who did not consume fruit, by comparing the number of fruit remaining across the time-delay photograph sequence. During a 2-year study using this technique, we found that six terrestrial mammals consumed fallen P. emblica fruit. Additionally, seven mammals and one bird species visited fruiting trees but did not consume fallen fruit. Two ruminants, the Indian chevrotain Moschiola indica and chital Axis axis, were P. emblica’s most frequent frugivores and they accounted for over 95% of fruit removal, while murid rodents accounted for less than 1%. Plants like P. emblica that are dispersed mainly by large mammalian frugivores are likely to have limited ability to migrate across fragmented landscapes in response to rapidly changing climates. We hope that more quantitative information on ruminant frugivory will become available with a wider application of our time-delay camera-trap technique.     

Use of digital cameras for phenological observations

Vegetation phenology such as the onset of green-up and senescence is strongly controlled by climate and other environmental factors, and in turn affects the terrestrial carbon balance. Therefore, phenological observation is important as an indicator of global warming and for estimation of the terrestrial carbon balance. Because phenological responses differ from species to species, precise monitoring from the species scale to the global scale is required. In this study, we analyzed images from digital cameras, which have proliferated in recent years, to investigate their utility as remote sensors. We collected daily images taken by digital cameras in national parks across Japan over 8 years in wetland mixed deciduous forest, and evergreen broadleaved forest. Values of red, green, and blue (RGB) channels in each pixel within images were extracted, and a vegetation green excess index (2G-RBi) was calculated to detect phenology. The time series of 2G-RBi showed clear phenological patterns of each vegetation type in each year at the species or community scale. Even physiological damage due to a typhoon was detected. The dates of green-up were estimated easily and objectively from the second derivative of 2G-RBi, and a trend in yearly green-up dates of various types of vegetation was demonstrated. Furthermore, a strong correlation between interannual variations in green-up dates and local spring temperature was found, and the sensitivity of green-up date to temperature was revealed. The results suggest the utility of digital cameras for phenological observations at precise temporal and spatial resolutions, despite a year-to-year drift of color balance of camera as a technical device. As a form of near-surface remote sensing, digital cameras could obtain significant ecological information. Establishing camera networks could help us understand phenological responses at a wide range of scales.     

One or two cameras per station? Monitoring jaguars and other mammals in the Amazon

Camera trapping has become a popular technique to monitor carnivore populations due to its usefulness in estimating abundance. Nevertheless, there are a number of problems associated with study design which are motivating researchers to search for a compromise that ensures improvement of precision while being cost-effective. We have used data from a capture?Crecapture study in a forested area in central Brazil to evaluate the effectiveness of using one versus two cameras per trapping station for determining jaguar (Panthera onca) density and capture rates of several other mammals. The capture rate for the jaguar and other species recorded with only one camera was lower than that with two cameras. The number of jaguars identified using photos from one camera ranged between six and seven animals, but reached ten individuals when two-camera sets were used where pictures of both flanks could be positively individualized. These differences, combined with different estimates of effective sampled area size, resulted in jaguar densities estimates ranging from 2.18 to 5.40 and 3.99?individuals/100?km² when one and two cameras were used per station, respectively (using the half-MMDM and Heterogeneity model). Based on our results, we recommend the use of two cameras per station for jaguar density monitoring to ensure reasonable levels of reliability and accuracy of estimates despite a small sample size.     

Monitoring small and arboreal mammals by camera traps: effectiveness and applications

Camera trapping has been widely applied to studies of medium to large terrestrial mammals, but its application to small arboreal mammals has hardly been tested. We employed camera trapping and other conventional monitoring methods during a mammal survey in a Site of Community Importance located within the Adda North Regional Park (Lombardy, Italy). Camera trapping was particularly successful for monitoring arboreal mammals, allowing the first detection of presence of the invasive grey squirrel (Sciurus carolinensis) in an area occupied by indigenous red squirrels (Sciurus vulgaris) and the collection of a large amount of data on squirrels and common dormice (Muscardinus avellanarius). When triggered, cameras were set to record short video clips (10 to 40 s). More than 400 events were recorded and analysed, mainly from the autumn and winter months. The daily activity pattern of both species displayed a trend from two to three activity peaks in summer to a unimodal pattern in winter, with the peaks of the two species temporally separated. Camera trapping could be a useful method also when applied to monitoring small mammals, particularly endangered arboreal or invasive alien species. For instance, the monitoring of the spread of S. carolinensis is particularly important, where the early detection of new population can be crucial for the conservation of indigenous European species. Camera trapping can be an effective addition to traditional survey methods. It provides a simple non-invasive technique for collecting a large amount of data per device with limited human effort.     

Prevalence of antibody to Toxoplasma gondii in terrestrial wildlife in a natural area

We conducted a cross-sectional study from 2008 to 2009 to evaluate the occurrence of feral and wild cats and the risk of Toxoplasma gondii infection in terrestrial wildlife in a natural area in Illinois, USA. Felids are definitive hosts for T. gondii and cats are a key component of rural and urban transmission of T. gondii. We selected four forest sites within the interior of the park and four edge sites within 300 m of human buildings. Feline and wildlife occurrence in the natural area was determined with the use of scent stations, motion-detection cameras, and overnight live trapping. Based on scent stations and trapping, feral cats used building sites more than forest sites (scent stations: P=0.010; trapping: P=0.083). Prevalence of T. gondii antibodies was determined with the use of the indirect immunofluorescent antibody test (IFAT) with a titer of 1:25 considered positive; T. gondii antibodies were detected in wildlife at all sites. Wildlife species were classified as having a large home range (LHR) or a small home range (SHR), based on published estimates and using a cutoff of 100 ha. Small-home-range mammals had a higher prevalence of antibody to T. gondii (odds ratio [OR]=4.2; P=0.018) at sites with a high frequency of cat occurrence (defined as ≥ 9 cat occurrences across three detection methods); this finding indicates that feral cats are the most likely source of environmental contamination. Overall, the prevalence of antibody to T. gondii among LHR mammals was significantly higher than the prevalence among SHR mammals (OR=7.1; P<0.001). Small-home-range mammals are an essential part of T. gondii-antibody prevalence studies and can be used as sentinels for risk of disease exposure to humans and wildlife in natural areas. This study improves our understanding of ecologic drivers behind the occurrence of spatial variation of T. gondii within a natural area.     

Studying the quantity component of seed dispersal effectiveness from exclosure treatments and camera trapping

The quantity component of effectiveness of seed dispersal by animals is determined by two events: fruit removal (intensity of the interaction) and animal visitation to the plant (frequency of interactions). Considering dispersal of Prosopis flexuosa seeds as case study, this work aimed at investigating the strengths and weaknesses of the two methods for assessing the quantity component of seed dispersal effectiveness: exclosures and camera traps. Prosopis fruits were offered for 48 hr. Exclosure treatments were performed using two types of wire‐screen cages, allowing access to ants (“closed exclosure”) and to small mammals up to 100 g (“open to small mammals”), and a treatment without exclosure (“open to all removers”). The camera trapping experiment was carried out using vertically oriented cameras placed at approximately 1.80 m height and focused on the fruits. The cameras were set in “motion detect mode,” taking series of three consecutive photographs. The exclosures largely allowed estimation of fruit removal by size‐based groups of animals, but did not provide information on species identity. In contrast, camera traps were able to identify all visitors to species level and could not only determine the number of visits by each species but also the proportion of visits, which resulted in removal of fruits. Camera trapping allowed discriminating among small mammals playing different roles, without underestimating fruit removal by scatter‐hoarding species. The quality of estimation of the quantity component of seed dispersal is remarkably better when the camera trapping method is applied. Additional information obtained, such as activity patterns of visitors, can contribute to a better understanding of the seed dispersal process.     

利用红外相机调查北京松山国家级自然保护区的野生动物物种

红外相机是监测野生动物的有效工具,目前广泛用于兽类资源调查以及动物损害、鸟巢生态学、种群评估、行为生态学等研究领域。为了调查北京松山国家级自然保护区的野生动物,于2010年5—12月采用红外相机进行系统调查,在210个位点放置了红外相机,每台相机在每个地点上放置一个月。研究期间共拍摄到照片2203张,其中73%为兽类,12%为鸟类,13%为工作人员,2%为其它人员。共鉴定出17种兽类(分属5目10科)以及36种鸟类(分属5目17科)。兽类中拍摄率最高的前5种动物分别是岩松鼠(Sciurotamias davidianus)、猪獾(Arctonyx collaris)、豹猫(Prionailurus bengalensis)、狗獾(Meles meles)和貉(Nyctereutes procyonoides),鸟类中拍摄率最高的前5种动物分别是紫啸鸫(Myophonus caeruleus)、雉鸡(Phasianus colchicus)、松鸦(Garrulus glandarius)、勺鸡(Pucrasia macrolopha)和宝兴歌鸫(Turdus mupinensis)。红外相机在不同海拔、不同植被类型以及不同月份所拍摄动物的拍摄率不同:在1000—1400m的海拔段,拍摄率显著高于低海拔(600—1000m)以及中高海拔(1400—1700m);在阔叶林中的拍摄率最高,在针叶林、针阔混交林和灌丛中的拍摄率相似;秋季(8—10月)拍摄率较高,夏季(6—7月)次之,冬季(11—12月)最低。红外相机拍摄到的累积物种数与相机放置的时间成上升曲线,但曲线的增长速率逐渐变缓。研究表明红外相机适合于调查和监测大中型兽类和部分鸟类,所采集的动物数据以及拍摄的图片和视频资料将为保护区的监测、科研和环境教育提供资料。讨论了应用红外相机调查和监测野生动物的技术细节。     

Trapping Elusive Cats: Using Intensive Camera Trapping to Estimate the Density of a Rare African Felid

Camera trapping studies have become increasingly popular to produce population estimates of individually recognisable mammals. Yet, monitoring techniques for rare species which occur at extremely low densities are lacking. Additionally, species which have unpredictable movements may make obtaining reliable population estimates challenging due to low detectability. Our study explores the effectiveness of intensive camera trapping for estimating cheetah (Acinonyx jubatus) numbers. Using both a more traditional, systematic grid approach and pre-determined, targeted sites for camera placement, the cheetah population of the Northern Tuli Game Reserve, Botswana was sampled between December 2012 and October 2013. Placement of cameras in a regular grid pattern yielded very few (n = 9) cheetah images and these were insufficient to estimate cheetah density. However, pre-selected cheetah scent-marking posts provided 53 images of seven adult cheetahs (0.61 ± 0.18 cheetahs/100km²). While increasing the length of the camera trapping survey from 90 to 130 days increased the total number of cheetah images obtained (from 53 to 200), no new individuals were recorded and the estimated population density remained stable. Thus, our study demonstrates that targeted camera placement (irrespective of survey duration) is necessary for reliably assessing cheetah densities where populations are naturally very low or dominated by transient individuals. Significantly our approach can easily be applied to other rare predator species.     

笼捕法和陷阱法对森林小型兽类多样性监测效率比较

<正>小型兽类包括食虫目(Insectivora)、啮齿目(Rodentia)、翼手目(Chiroptera)、兔形目(Lagomorpha)等,物种数量多,分布广,适应能力强,对环境变化敏感,因此其群落组成和种群数量变化可较好地反映生境变化的质量和人类活动的干扰程度(肖治术等,2002;李俊生等,2003;仝磊和路纪琪,2010)。小型兽类多样性一直是生物多样性和生态环境监测与评价的重要指示类群之一(周立志和马勇,2002)。统计动物毛发、粪便、巢穴、叫声、足迹等动物痕迹以及直接观察等方法已被广泛用于兽类物种监测和种群密度估计(Eberhardt and Van Etten,1956;Bider,1968;Gannon     

A preliminary study of the biodiversity of ground-dwelling small mammals in Badagongshan National Nature Reserve,Hunan Province

Little is known about the diversity patterns of mammals in the Badagongshan National Nature Reserve, Hunan Province, although the reserve was established in 1982. During September and October of 2012, the diversity of ground-dwelling small mammals was investigated using live traps, pitfalls and camera traps in a permanent forest dynamics plot and other nearby vegetation types. We captured 12 species of ground-dwelling small mammals, including eight species of Rodentia and four species of Insectivora. Presently, there are 20 species of ground-dwelling small mammals recorded in the Badagongshan National Nature Reserve, including six new species recorded in this study, i.e., Eothenomys melanogaster, Typhlomys cinereus, Apodemus draco, Anourosorex squamipes, Blarinella griselda, and Sorex thibetanus. The body mass of the individuals captured by live traps was much larger than that of the individuals captured by pitfall traps. Our study also indicates that the diversity patterns of ground-dwelling small mammals are affected by the habitat types. Therefore, we recommend that a combination of different methods be used to effectively monitor mammal diversity in the Badagongshan National Nature Reserve.     

Beyond the fragmentation threshold hypothesis: regime shifts in biodiversity across fragmented landscapes

Ecological systems are vulnerable to irreversible change when key system properties are pushed over thresholds, resulting in the loss of resilience and the precipitation of a regime shift. Perhaps the most important of such properties in human-modified landscapes is the total amount of remnant native vegetation. In a seminal study Andrén proposed the existence of a fragmentation threshold in the total amount of remnant vegetation, below which landscape-scale connectivity is eroded and local species richness and abundance become dependent on patch size. Despite the fact that species patch-area effects have been a mainstay of conservation science there has yet to be a robust empirical evaluation of this hypothesis. Here we present and test a new conceptual model describing the mechanisms and consequences of biodiversity change in fragmented landscapes, identifying the fragmentation threshold as a first step in a positive feedback mechanism that has the capacity to impair ecological resilience, and drive a regime shift in biodiversity. The model considers that local extinction risk is defined by patch size, and immigration rates by landscape vegetation cover, and that the recovery from local species losses depends upon the landscape species pool. Using a unique dataset on the distribution of non-volant small mammals across replicate landscapes in the Atlantic forest of Brazil, we found strong evidence for our model predictions--that patch-area effects are evident only at intermediate levels of total forest cover, where landscape diversity is still high and opportunities for enhancing biodiversity through local management are greatest. Furthermore, high levels of forest loss can push native biota through an extinction filter, and result in the abrupt, landscape-wide loss of forest-specialist taxa, ecological resilience and management effectiveness. The proposed model links hitherto distinct theoretical approaches within a single framework, providing a powerful tool for analysing the potential effectiveness of management interventions.     

八大公山自然保护区地栖性小兽多样性初步研究

湖南省八大公山自然保护区自1982年设立以来, 尚未进行过兽类资源的深入研究。为此, 作者于2012年9–10月, 采用笼捕法、陷阱法和红外相机法等对保护区内森林动态永久监测样地及周边常见植被类型中的地栖性小型兽类多样性进行了初步研究。共捕获小型兽类12种, 其中啮齿目8种, 食虫目4种。结合以往记录, 该保护区现已记录的小型兽类有20种, 而本次调查新增分布记录物种6种, 即黑腹绒鼠(Eothenomys melanogaster)、猪尾鼠(Typhlomys cinereus)、中华姬鼠(Apodemus draco)、四川短尾鼩(Anourosorex squamipes)、灰黑齿鼩鼱(Blarinella griselda)和藏鼩鼱(Sorex thibetanus)。陷阱法所捕获个体的体重显著小于笼捕法。此外, 不同生境类型对小兽多样性有重要影响。建议综合采用多种调查方法对整个保护区兽类多样性资源进行深入监测与研究。     

红外相机安放于地面和林冠层对野生动物监测结果的影响

红外相机技术在野生动物研究中日趋普及, 逐渐成为重要的生物多样性监测手段。过去的监测常局限于地面, 而针对林冠层的监测较少, 这对野生动物的多样性评估影响尚未可知。为此, 本研究在生物多样性丰富的碧罗雪山南段, 将20台红外相机分别拍摄地面层(0.5-1.5 m)和林冠层(5-10 m)配对比较, 累计拍摄2,319个有效相机日, 平均每对相机同步进行112.5 d的监测。监测期间共拍摄到44种野生动物(不包括鼠形啮齿类), 其中兽类20种, 鸟类24种; 冠层和地面红外相机监测的物种相似度为29.54%; 15种动物仅拍摄于林冠层, 16种动物仅拍摄于地面, 13种动物拍摄于两个林层。研究结果表明不同林层监测的物种组成存在显著差异, 林冠层与地面层监测都具有不可替代性; 不同林层红外相机的监测手段也能用于研究野生动物的空间选择和生态位分化。红外相机监测中根据目标物种的习性在相应的林层设置相机能提高物种发现率; 为全面掌握区域森林生态系统野生动物的多样性, 红外相机监测需要兼顾不同林层这一点需要在监测规范中明细。     

Factors conditioning the camera-trapping efficiency for the Iberian lynx (Lynx pardinus)

Camera trapping is the most used method for surveying medium-sized carnivores in Spain. The main target for these surveys has been the Iberian lynx, the most endangered cat in the world. The Iberian lynx conservation program has received the largest EU LIFE projects grant. So, efficiency is a key goal for managing this grant. During 2003 and 2007, we have applied these funds to the survey of the Iberian lynx in Eastern Sierra Morena (Spain). Using two different techniques, we have studied both to see which is the most efficient. The survey developed in active latrines resulted more efficient than that of scent stations and live prey camera trapping throughout the years, although there has been a variation between years. Otherwise, the live prey method has been the one providing the greatest speed and number of pictures per entrance. We suggest that camera-trapping surveys can be improved in terms of efficiency for a wide range of species, or at least for the Iberian lynx. To improve the results, cameras might be placed in relation to breeding territories. With this determinant, camera-trapping surveys would be shorter than 120 days. Finally, we suggest how those surveys for medium carnivores should be designed.     

Mammal Diversity and Conservation in a Secondary Forest in Peninsular Malaysia

A comprehensive survey on large mammal diversity from a disturbed forest in Peninsular Malaysia has been carried out for over a period of 21 months. A total of 24 camera traps which accumulated to 5972 trap days. A total of 33 species 27 genera and 15 families of mammals were recorded via camera trapping and observations. The use of camera traps provides detailed information on diversity of some cryptic and secretive mammals. Secondary forest may support a wide diversity of mammals at a stable condition where intrusion, excision and fragmentation are reduced or avoided. The threats to mammals in the study are also discussed.