Camera traps are an effective tool for monitoring insect–plant interactions

Insect and pollinator populations are vitally important to the health of ecosystems, food production, and economic stability, but are declining worldwide. New, cheap, and simple monitoring methods are necessary to inform management actions and should be available to researchers around the world. Here, we evaluate the efficacy of a commercially available, close‐focus automated camera trap to monitor insect–plant interactions and insect behavior. We compared two video settings—scheduled and motion‐activated—to a traditional human observation method. Our results show that camera traps with scheduled video settings detected more insects overall than humans, but relative performance varied by insect order. Scheduled cameras significantly outperformed motion‐activated cameras, detecting more insects of all orders and size classes. We conclude that scheduled camera traps are an effective and relatively inexpensive tool for monitoring interactions between plants and insects of all size classes, and their ease of accessibility and set‐up allows for the potential of widespread use. The digital format of video also offers the benefits of recording, sharing, and verifying observations.     

Optimising Camera Traps for Monitoring Small Mammals

Practical techniques are required to monitor invasive animals, which are often cryptic and occur at low density. Camera traps have potential for this purpose, but may have problems detecting and identifying small species. A further challenge is how to standardise the size of each camera’s field of view so capture rates are comparable between different places and times. We investigated the optimal specifications for a low-cost camera trap for small mammals. The factors tested were 1) trigger speed, 2) passive infrared vs. microwave sensor, 3) white vs. infrared flash, and 4) still photographs vs. video. We also tested a new approach to standardise each camera’s field of view. We compared the success rates of four camera trap designs in detecting and taking recognisable photographs of captive stoats ( Mustela erminea ), feral cats (Felis catus) and hedgehogs ( Erinaceus europaeus ). Trigger speeds of 0.2–2.1 s captured photographs of all three target species unless the animal was running at high speed. The camera with a microwave sensor was prone to false triggers, and often failed to trigger when an animal moved in front of it. A white flash produced photographs that were more readily identified to species than those obtained under infrared light. However, a white flash may be more likely to frighten target animals, potentially affecting detection probabilities. Video footage achieved similar success rates to still cameras but required more processing time and computer memory. Placing two camera traps side by side achieved a higher success rate than using a single camera. Camera traps show considerable promise for monitoring invasive mammal control operations. Further research should address how best to standardise the size of each camera’s field of view, maximise the probability that an animal encountering a camera trap will be detected, and eliminate visible or audible cues emitted by camera traps.     

An Assessment of the Effectiveness of High Definition Cameras as Remote Monitoring Tools for Dolphin Ecology Studies

Research involving marine mammals often requires costly field programs. This paper assessed whether the benefits of using cameras outweighs the implications of having personnel performing marine mammal detection in the field. The efficacy of video and still cameras to detect Indo-Pacific bottlenose dolphins (Tursiops aduncus) in the Fremantle Harbour (Western Australia) was evaluated, with consideration on how environmental conditions affect detectability. The cameras were set on a tower in the Fremantle Port channel and videos were perused at 1.75 times the normal speed. Images from the cameras were used to estimate position of dolphins at the water’s surface. Dolphin detections ranged from 5.6 m to 463.3 m for the video camera, and from 10.8 m to 347.8 m for the still camera. Detection range showed to be satisfactory when compared to distances at which dolphins would be detected by field observers. The relative effect of environmental conditions on detectability was considered by fitting a Generalised Estimation Equations (GEEs) model with Beaufort, level of glare and their interactions as predictors and a temporal auto-correlation structure. The best fit model indicated level of glare had an effect, with more intense periods of glare corresponding to lower occurrences of observed dolphins. However this effect was not large (-0.264) and the parameter estimate was associated with a large standard error (0.113). The limited field of view was the main restraint in that cameras can be only applied to detections of animals observed rather than counts of individuals. However, the use of cameras was effective for long term monitoring of occurrence of dolphins, outweighing the costs and reducing the health and safety risks to field personal. This study showed that cameras could be effectively implemented onshore for research such as studying changes in habitat use in response to development and construction activities.     

Using remote underwater video to estimate freshwater fish species richness

Species richness records from replicated deployments of baited remote underwater video stations (BRUVS) and unbaited remote underwater video stations (UBRUVS) in shallow (<1 m) and deep (>1 m) water were compared with those obtained from using fyke nets, gillnets and beach seines. Maximum species richness (14 species) was achieved through a combination of conventional netting and camera‐based techniques. Chanos chanos was the only species not recorded on camera, whereas Lutjanus argentimaculatus, Selenotoca multifasciata and Gerres filamentosus were recorded on camera in all three waterholes but were not detected by netting. BRUVSs and UBRUVSs provided versatile techniques that were effective at a range of depths and microhabitats. It is concluded that cameras warrant application in aquatic areas of high conservation value with high visibility. Non‐extractive video methods are particularly desirable where threatened species are a focus of monitoring or might be encountered as by‐catch in net meshes.     

Behaviour of the abyssal grenadier, Coryphaenoides yaquinae, monitored using ingestible acoustic transmitters in the Pacific Ocean

Scavenging grenadier fishes, Coryphaenoides yaquinae , were tracked with ingestible acoustic tags at 5800 m depth in the central North Pacific. A free-fall vehicle comprising a video camera and recording system together with a hydrophone, ultrasonic acoustic receiver and recorder was deployed on the sea bed. Special acoustic transmitters (75 kHz) were wrapped in bait and attached below and in view of the camera. Grenadiers were observed to ingest the baited transmitters and move away to ranges of over 100 m within 5h, some returning several times to within range of the receiving system. Voluntary ingestion of transmitters by this grenadier demonstrates that an inacessible population can be studied and provides a basis for development of automated tracking systems for long-term monitoring of individual deep-sea fish.     

A Computer-Controlled Video System for Real-Time Recording of Insect Flight in Three Dimensions

A computer-controlled video system for real-time recording of insect flight in three dimensions is described. The flight paths of moths were recorded in a flight tunnel using two CCD cameras placed adjacent to each other at angles of 45 and 135° to the flight tunnel axis and separated by a distance of 120 cm. They were connected to two 2⁸-level gray-scale frame grabbers via two external synchronizers. The two-dimensional coordinates of the flying insect were obtained from the two cameras at 40-ms intervals and transferred to host computer for processing and monitor for real-time display. Due to speed limitation in the image acquisition hardware, construction of the three-dimensional file was carried off-line. The flying insect was rendered as a dark spot in a bright background using a homogeneous light source. As the insect enters into the field of view of the two cameras, the light distribution changes, and the frame grabber detects only those variation in the light distribution which results from a flying insect. The target insect can be as small as 3 pixels and can be tracked in a stereoscopic field of view 60 cm long and 50 cm high. A method was developed that allowed for scalar scoring of various pheromone sources to assess their attractiveness using vector flight parameters. This method was applied successfully for optimization of pheromone blend of the grapevine moth, Lobesia botrana.     

Monitoring of Heart and Breathing Rates Using Dual Cameras on a Smartphone

Some smartphones have the capability to process video streams from both the front- and rear-facing cameras simultaneously. This paper proposes a new monitoring method for simultaneous estimation of heart and breathing rates using dual cameras of a smartphone. The proposed approach estimates heart rates using a rear-facing camera, while at the same time breathing rates are estimated using a non-contact front-facing camera. For heart rate estimation, a simple application protocol is used to analyze the varying color signals of a fingertip placed in contact with the rear camera. The breathing rate is estimated from non-contact video recordings from both chest and abdominal motions. Reference breathing rates were measured by a respiration belt placed around the chest and abdomen of a subject; reference heart rates (HR) were determined using the standard electrocardiogram. An automated selection of either the chest or abdominal video signal was determined by choosing the signal with a greater autocorrelation value. The breathing rate was then determined by selecting the dominant peak in the power spectrum. To evaluate the performance of the proposed methods, data were collected from 11 healthy subjects. The breathing ranges spanned both low and high frequencies (6–60 breaths/min), and the results show that the average median errors from the reflectance imaging on the chest and the abdominal walls based on choosing the maximum spectral peak were 1.43% and 1.62%, respectively. Similarly, HR estimates were also found to be accurate.     

Facteurs influençant la détectabilité de l’activité myocardique en caméra à semi-conducteurs

Body weight was already shown to be a major factor for the detectability of myocardial activity with conventional cameras and thus, for the optimization of injected activities and or recording times. This study was aimed to identify the factors affecting this detectability on a new solid-state camera showing a high sensitivity of detection (D.SPECT camera Cyclopharma^®).Patients and methodsThe study population involved 101 patients, who underwent myocardial SPECT with Sestamibi on a one-day stress/rest protocol. Each conventional acquisition (DST-XL General Electric Healthcare^® USA) was immediately followed by a D-SPECT^® one. Myocardial activity was determined on each acquisition in counts per seconds and expressed in fraction of the injected activity for assessing the detectability of myocardial activity.ResultsMyocardial activity was on average 12 ± 3 fold higher when recorded with the D-SPECT^® camera than with the DST-XL^® one. Body weight and especially body mass index (BMI) were the most significant correlates of the detectability of myocardial activity for both cameras. According to these correlations, an increase in the BMI from 25 to 35 kg/m was associated with a 47% decrease in the detectability of myocardial activity at stress with the DST-XL^® and of only 30% with the D-SPECT.ConclusionThe detectability of myocardial activity provided by the D.SPECT camera is dramatically higher than that documented for conventional cameras of the DST-XL^® type and is affected by the increase in body weight and in body mass index but at a lower rate than for the Anger camera.     

Aphid flight-track analysis in three dimensions using video techniques

Abstract. A technique is described for the three-dimensional analysis of the flight paths of small insects using two video cameras placed alongside each other with the optical axes coincident at a point some distance beyond the area of interest. The video signals were mixed and a time base introduced before recording the superimposed images from both cameras on a single VCR. With suitable lighting and a black background, flying aphids appeared on the monitor as double, bright images on a dark background. The distance between the two images was inversely proportional to the distance of the aphid from the camera lenses. A calibration grid was used to insert the correct parameters into software designed to provide the x (vertical), y (horizontal) and z (distance from the cameras) Cartesian co-ordinates for a flying insect and to calculate the distances flown, flight speed and turning parameters. The advantages of the system are that it is designed for a single VCR and monitor, provides automatic synchrony between camera signals and can examine a larger visual arena than screen-splitting methods. It operates with insects as small as aphids, and wind-tunnel studies on the black bean aphid, Aphis fabae Scop., showed that some flight parameters (for the final one-second approach to a visually attractive landing platform) differed according to whether wind was present or not. Thus, ground speed and distance moved differed significantly but turning parameters were unchanged. In addition, flight trajectory on the approach to landing depended upon initial direction of flight and the presence of wind.     

Accuracy of nest fate classification and predator identification from evidence at nests of Least Terns and Piping Plovers

For federally listed species such as Least Tern Sternula antillarum and Piping Plover Charadrius melodus, correct determination of nest fates and causes of nest failure is crucial for understanding population dynamics and improving monitoring programmes. We used video cameras to evaluate nest fate misclassification rate and to identify factors that may cause researchers monitoring nests at different intervals to classify Least Tern and Piping Plover nest fates incorrectly. During the 2013–2015 breeding seasons, we installed miniature surveillance cameras at 65 of 294 Least Tern and 89 of 551 Piping Plover nests under observation on the Missouri River in North Dakota. Nest fates were assigned in the field from remains found at the nest‐site and then again by an independent researcher who reviewed camera footage. We used ordinal logistic regressions to examine whether monitoring interval, clutch age or temporal factors influenced a correct, partially misclassified (probable successful in the field vs. successful by camera) or misclassified nest fate classification. During a 7‐day monitoring interval between visits, 45% of nests were partially and 27.5% were fully misclassified. The percentage of partially (20%) and fully (8.0%) misclassified nests decreased with a more intensive (3‐day) monitoring schedule. Researchers were also less likely to correctly classify nest fates for Least Terns than for Piping Plovers, and as clutch age and monitoring interval increased for both species. Furthermore, causes of failure (e.g. predators, weather) as determined from field evidence vs. video disagreed for 53.5% of nests. The ability to identify accurately nest fate and cause of nest failure will facilitate a better understanding of factors that limit productivity and will lead to better informed management decisions for improving nest survival.     

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。     

Using nest captures and video cameras to estimate survival and abundance of breeding Piping Plovers Charadrius melodus

The estimation of abundance is fundamental to ecology and conservation but often is difficult or impossible to accomplish reliably. Recent improvements in wildlife cameras and ecological modelling have allowed for improved accuracy in estimates of abundance. In this study, we paired nest captures and high-definition nest video camera monitoring with modelling for a novel approach to estimate survival and abundance of threatened Piping Plovers Charadrius melodus breeding on Missouri River sandbars. From 2005 to 2014, we captured individuals on nests and uniquely marked them and recaptured previously marked individuals. In 2015–2017, we resighted marked individuals using small, high-definition video cameras deployed at nests, and counted the number of marked and unmarked breeding individuals associated with nests. We estimated apparent survival and derived estimates of the abundance of breeding individuals and population growth each year using a state-space Jolly–Seber superpopulation model with the addition of a binomial band ratio model for data collected using nest video cameras. Apparent survival averaged 0.73 ± 0.03 (mean ± sd) throughout the study. The number of breeding individuals varied, with the population increasing from 2012 to 2017 following a major habitat creation event. This study provides one of the few examples of camera data being used to produce demographic parameter and abundance estimates for an avian species. The camera and modelling methods described in this study may be applicable to other avian species in which some portion of the breeding population is uniquely marked.     

A wireless video camera for viewing tree cavities

ABSTRACT Investigators have used a variety of methods to inspect nest cavities, including wireless battery‐powered video cameras mounted on telescoping poles. Using such a monitoring system to inspect cavities located well above ground can be difficult because the weight of the camera can cause flexing of the telescoping pole, making it difficult to insert the camera into cavity entrances. We constructed a system made from commercially available products that transmits wireless video images from nest cavities, and is both lightweight (198 g) and relatively inexpensive (about $520 US). During a study of Pileated Woodpeckers (Dryocopus pileatus), we inspected more than 100 cavities using our monitoring system and found that images were clear enough to allow us to count eggs and nestlings, and determine the sex of adults and nestlings. Because of its light weight, our wireless camera system allows quick inspection of cavities (typically less than 2 min). Although we used our cavity‐monitoring system to inspect cavities used by Pileated Woodpecker, we believe that the diameter of the camera could be reduced from 5.6 cm to 4.7 cm to allow inspection of cavities with smaller entrances.     

Automatic extraction and measurement of individual trees from mobile laser scanning point clouds of forests

Background and AimsIn addition to terrestrial laser scanning (TLS), mobile laser scanning (MLS) is increasingly arousing interest as a technique which provides valuable 3-D data for various applications in forest research. Using mobile platforms, the 3-D recording of large forest areas is carried out within a short space of time. Vegetation structure is described by millions of 3-D points which show an accuracy in the millimetre range and offer a powerful basis for automated vegetation modelling. The successful extraction of single trees from the point cloud is essential for further evaluations and modelling at the individual-tree level, such as volume determination, quantitative structure modelling or local neighbourhood analyses. However, high-precision automated tree segmentation is challenging, and has so far mostly been performed using elaborate interactive segmentation methods.MethodsHere, we present a novel segmentation algorithm to automatically segment trees in MLS point clouds, applying distance adaptivity as a function of trajectory. In addition, tree parameters are determined simultaneously. In our validation study, we used a total of 825 trees from ten sample plots to compare the data of trees segmented from MLS data with manual inventory parameters and parameters derived from semi-automatic TLS segmentation.Key ResultsThe tree detection rate reached 96 % on average for trees with distances up to 45 m from the trajectory. Trees were almost completely segmented up to a distance of about 30 m from the MLS trajectory. The accuracy of tree parameters was similar for MLS-segmented and TLS-segmented trees.ConclusionsBesides plot characteristics, the detection rate of trees in MLS data strongly depends on the distance to the travelled track. The algorithm presented here facilitates the acquisition of important tree parameters from MLS data, as an area-wide automated derivation can be accomplished in a very short time.     

Nursing behaviour of bighorn sheep: correlates of ewe age,parasitism, lamb age,birthdate and sex

The nursing behaviour of marked bighorn ewes, Ovis canadensis, and their lambs was observed in Alberta, Canada, for 2 years. Suckle duration decreased as lambs grew older. Nursing behaviour in midlactation was correlated with maternal condition; young ewes, ewes with high faecal counts of lungworm (Protostrongylus spp.) larvae, and ewes whose lambs were born late allowed shorter suckles and were less likely to nuzzle their lamb's rump during a suckle. Sons did not appear to receive more milk than daughters. Suckle duration in mid-lactation was correlated with survival for female lambs but not for males. Lambs born late were disadvantaged, probably because nutritious forage was accessible to their mothers only in early lactation.     

Horizontal visibility of an underwater low-resolution video camera modeled by practical parameters near the sea surface

Underwater video cameras can be used for fisheries, aquacultures, and marine ecology to monitor the existence of fish. In order to assess marine structures, monitoring is also important to understand the effects on the local fish community. Underwater vision is sometimes degraded due to the condition of the water and sunlight. In particular, horizontal visibility is not easily obtained with regard to water quality. So far, an empirical relationship with horizontal visibility has been described according divers' vision, and it states that divers' horizontal visibility is approximately equal to 0.7 times the Secchi depth (Wright and Colling, 1995). If the video camera has a high resolution, visibility may be similar, however, if the camera has a low resolution, detectable distance can deteriorate. For practical usage, a video camera with low resolution has the advantage of reducing storage of data and it is easy to transmit video remotely, in other words, real-time monitoring. Real-time data will provide a prompt understanding of aquatic environmental changes. In order to obtain such data, a low-resolution video camera is still required for usage in a field. There are few models that describe horizontal visibility using a camera in water, therefore this study aims to model one. This paper showed a new approach to model horizontal visibility by water depth and Secchi depth, which are practical and obtainable parameters for underwater monitoring. In addition to this, global solar radiation is adopted for modeling. The model is expressed as relative contrast between target and background. Based on two observations near the sea surface (less than Secchi depth), the model is created. The model showed plausible horizontal visibility using an underwater video camera for real-time monitoring of fish and marine environment.     

Video and acoustic camera techniques for studying fish under ice: a review and comparison

Researchers attempting to study the presence, abundance, size, and behavior of fish species in northern and arctic climates during winter face many challenges, including the presence of thick ice cover, snow cover, and, sometimes, extremely low temperatures. This paper describes and compares the use of video and acoustic cameras for determining fish presence and behavior in lakes, rivers, and streams with ice cover. Methods are provided for determining fish density and size, identifying species, and measuring swimming speed and successful applications of previous surveys of fish under the ice are described. These include drilling ice holes, selecting batteries and generators, deploying pan and tilt cameras, and using paired colored lasers to determine fish size and habitat associations. We also discuss use of infrared and white light to enhance image-capturing capabilities, deployment of digital recording systems and time-lapse techniques, and the use of imaging software. Data are presented from initial surveys with video and acoustic cameras in the Sagavanirktok River Delta, Alaska, during late winter 2004. These surveys represent the first known successful application of a dual-frequency identification sonar (DIDSON^TM) acoustic camera under the ice that achieved fish detection and sizing at camera ranges up to 16 m. Feasibility tests of video and acoustic cameras for determining fish size and density at various turbidity levels are also presented. Comparisons are made of the different techniques in terms of suitability for achieving various fisheries research objectives. This information is intended to assist researchers in choosing the equipment that best meets their study needs.     

Microscope alignment using real-time Imaging FCS

Modern electron-multiplying charge-coupled device (EMCCD) and scientific complementary metal-oxide semiconductor (sCMOS) cameras read out fluorescence data with single-molecule sensitivity at thousands of frames per second. Exploiting these capabilities in full requires data evaluation in real time. The direct camera-read-out tool presented here allows access to the data while the camera is recording. This provides simplified and accurate alignment procedures for total internal reflection fluorescence microscopy (TIRFM) and single-plane illumination microscopy (SPIM), and simplifies and accelerates fluorescence experiments. The tool handles a range of widely used EMCCD and sCMOS cameras and uses imaging fluorescence correlation spectroscopy for its evaluation. It is easily extendable to other camera models and other techniques and is a base for automated TIRFM and SPIM data acquisition.     

The ray projection method: a numerical approach for determining ideal camera placement

Data piloting is important to ensure accurate marker coordinate data and to minimize camera dropout. Camera dropout results when a camera fails to image a marker, which often occurs when markers merge or become occluded. In this article, we present the conceptual framework for a numerical method of determining where video cameras, if placed, would have an occluded or a merged view of the tracking markers. Experimental data are presented to demonstrate the efficacy of the method as a tool to complement existing data piloting procedures.