Remote Photography Research Articles

Using Semantic Segmentation Network to Measure Vibration Displacement of Rotating Body

Compared with traditional vibration measurement sensors, visual vibration displacement measurement technology has many advantages, such as long-distance, non-contact and non-interference. However, when it comes to complex working conditions or inconvenient pre-processing scene, visual measuring techniques usually can’t produce results with the high precision needed for vibration analysis. In this paper, we proposed a visual measurement algorithm for vibration displacement of rotating body using semantic segmentation network by taking a high-speed industrial camera as the image acquisition medium and rotor as the experimental object. To make the network better applicable to segmentation of rotating body targets in different illumination, blur and similarity contexts, the cross stage partial (CSP) connections, concat channel fusion module and shuffle attention (SA) are purposefully incorporated into proposed CMCS convolution module. During calculating the loss in the training network stage, we add the binary cross-entropy loss and Dice-loss to solve the problem of serious imbalance between positive and negative samples caused by remote photography. The vibration signal synchronously collected by eddy current sensor is exploited as standard signal to compare the different segmentation algorithms quantitatively and qualitatively. The experimental results show that the RMSE between vibration displacement signal regressed by our segmentation algorithm and standard signal is the smallest, and the time domain diagram, frequency domain diagram and shaft orbit diagram are also more fitted to the standard signal curve, which provides valuable guidance for the visual vibration displacement measurement of rotating body in complex industrial setting.

Applying a two‐dimensional hydrodynamic model to estimate fish stranding risk downstream from a hydropeaking hydroelectric station

AbstractFish stranding is of global concern with increasing hydropower operations using hydropeaking to respond to fluctuating energy demand. Determining the effects hydropeaking has on fish communities is challenging because fish stranding is dependent on riverscape features, such as topography, bathymetry and substrate. By using a combination of physical habitat assessments, hydrodynamic modelling and empirical data on fish stranding, we estimated the number of fish stranding over a 5‐month period for three model years in a large Prairie river. More specifically, we modelled how many fish potentially stranded during the years 2019, 2020 and 2021 across a 16 km study reached downstream from E.B. Campbell Hydroelectric Station on the Saskatchewan River, Canada. Fish stranding densities calculated from data collected through remote photography and transect monitoring in 2021 were applied to the daily area subject to drying determined by the River2D hydrodynamic model. The cumulative area subject to change was 90.05, 53.02 and 80.74 km2for years 2019, 2020 and 2021, respectively, from June to October. The highest number of stranded fish was estimated for the year 2021, where estimates ranged from 89,800 to 1,638,000 individuals based on remote photography and transect monitoring fish stranding densities, respectively, 157 to 2,856 fish stranded per hectare. Our approach of estimating fish stranding on a large scale allows for a greater understanding of the impact hydropeaking has on fish communities and can be applied to other riverscapes threatened by hydropeaking.

Evaluating the risk of fish stranding due to hydropeaking in a large continental river

AbstractWith the continuous development of hydropower on a global scale, stranding of freshwater fishes is of growing concern, and an understanding of the mechanisms and variables affecting fish stranding in hydropeaking rivers is urgently needed. In particular, a methodology is required to identify the magnitude and timing at which fish stranding occurs in relation to environmental conditions. Here, we studied fish stranding in three reaches downstream of a hydropeaking generation station in the Saskatchewan River, Saskatchewan, Canada, using an innovative remote photography approach with 45 trail cameras and traditional transect monitoring, conducting 323 transects. We observed that juvenile sport and commercial fish species are stranding at a higher proportion than small bodied fish species. The remote photography approach provided more precise fish stranding timing and associated the environmental and physical conditions with a given stranding event, but captured fewer fish and only rarely allowed species identification. The comparison of the two methodologies resulted in similar stranded fish densities, but the remote photography allowed for continuous observations whereas the transect monitoring was limited by the observer availability in the field. Remote photography allowed for additional information on the scavenging of stranded fish, with scavenging occurring on average within 240 minutes of the fish being stranded. The probability of fish stranding increased significantly with increasing water temperature and substrate particle size resulted in greater stranding on finer substrates. Our findings have important implications for hydroelectric flow management by introducing an innovative, standardized method to study the effects of hydropeaking events on fish stranding that can be applied to increase our understanding of the impacts of hydropeaking on fish communities.

Исследование очагов эндогенных пожаров на породных отвалах угольных предприятий

The formed rock dumps of sections, mines and washing plants are composed of carbonaceous rocks and are capable of spontaneous combustion when the required amount of air is supplied. The conducted studies evaluated the efficiency of detecting a center of spontaneous combustion at the rock dumps of sections by measuring the temperature of rocks in the wells with a depth of 2.5 m, drilled at the distance of 20 m from each other, according to the current normative documents. For the landfill, a dump site with a long-existing center of spontaneous combustion was selected. The experiment showed the impossibility of drilling wells on the slopes of the dumps, as well as the need for casing the wells with pipes along the entire length. The temperature of rocks in the wells at a depth of 2.5 m varied from 69 to 773 °C. It was found that in the heated zone there are sharp temperature drops in the rocks, which cannot be detected with an interval between the measurement points equal to 20 m. With such a distance between the control wells, the places with a diameter of 1–10 m may remain undetected at the initial stage of spontaneous combustion. Measurements showed that in all the wells the rock temperature increases with depth. At the same time, the recommended well depth of 2.5 m does not allow determining the size of the heated zone deep into the rock dump. The upper layer of rocks above the center of spontaneous combustion exceeds the ambient temperature, so remote temperature measuring devices can be used to detect endogenous fires in the rock dumps. The use of thermal imagers installed on the unmanned aerial vehicles will significantly reduce the cost of detecting spontaneous combustion centers on the rock dumps and increase the efficiency of detecting fire centers not only on the dump sites, but on the slopes of the dump side and in other hard-to-reach places. Moreover, with a decrease in the atmospheric air temperature, the efficiency of remote thermal photography does not decrease. To clarify the parameters of the center of endogenous fires, it is advisable to use the temperature measurement of rocks with a contact thermometer at a depth of 0.5 m.

ТЕХНОЛОГИЯ КОМПЛЕКСНОЙ ОЦЕНКИ ДРЕВЕСНЫХ РЕСУРСОВ МЕТОДАМИ ДИСТАНЦИОННОГО ЗОНДИРОВАНИЯ ЗЕМЛИ

The relevance and significance of the problem of automated forest inventory is dictated by regulatory documents defining the main directions and principles of digitalization of the country’s economic sectors, including the forest sector. The article is devoted to the problem of automated inventory of forests and digitalization of wood resources by technical means of ground-based taxation of stands, as well as remote aerial photography methods, analytical decoding of the forest canopy and determination of the complex of taxation indicators through the use of information and reference systems of multidimensional forest taxation standards. To construct an orthophotoplane and obtain a digital vegetation model, aerial photography works that meet the requirements of the photogrammetric method and the method of air-laser scanning (ALS) are described. The requirements for the parameters of aerial photography using the photogrammetric method, as well as for the parameters in the BOS, are set out. Variants of the technology of inventory of stands are proposed, indicating the appropriate tools for obtaining remote sensing data of the Earth. An assessment of the reliability of contour decoding of the species composition of stands with different spatial resolution of remote sensing data is given. The accuracy of digital vegetation models with different spatial resolution of data, the possibility of evaluating morphometric and volumetric indicators of tree crowns, as well as the resulting indicators of canopy closeness as a result of automation are indicated. An important element of the automated digitalization of wood resources is the allocation and taxation of cutting areas, the assessment of the commodity-monetary potential of stands allocated for logging.

Individual identification via remote video verified by DNA analysis: a case study of the American black bear

Context Researchers and managers often use DNA analysis and remote photography to identify cryptic animals and estimate abundance. Remote video cameras are used less often but offer an increased ability to distinguish similar-looking individuals as well as to observe behavioural patterns that cannot be adequately captured with still photography. However, the use of this approach in species with minimally distinguishing marks has not been tested. Aims To determine the utility and accuracy of distinguishing characteristics of American black bears, Ursus americanus, observed on remote video for identifying individuals in an open population. Methods We compared individuals identified on video with individuals and their sex identified by DNA analysis of hairs collected from hair traps visited by the bears. Key results We found that remote video could be used to determine the number of male and female black bears sampled by the video cameras. Specifically, we matched 13 individual bear genotypes with 13 video identifications, one genotype for each individual. We correctly matched ~82% of video identifications with all 38 genotypes collected from hair traps. Conclusions We demonstrated that distinguishing characteristics of a cryptic animal in remote video can be used to accurately identify individuals. Remote video complements genetic analysis by providing information about habitat use and behaviour. Implications When remote video cameras can be used to identify individuals, a wealth of other information will subsequently be obtained. Multi-year video-based studies can show sex ratios, and relative physical condition; shed light on fine-scale habitat use, such as when and where animals feed and what they eat; and display social interactions and rare behaviours.

Forensic taphonomy: Vertebrate scavenging in the temperate southwestern Cape, South Africa

Vertebrate scavenging can significantly accelerate the rate of decomposition, which can hinder estimating the post-mortem interval (PMI). Patterns of decomposition and scavenging are highly specific to different environments in a forensic context, with no known data for South Africa. A better understanding of local decomposition patterns, taking scavenging into account, could increase the accuracy of PMI estimation and improve identification of human remains. Using a porcine model in the forensically significant thicketed Cape Flats Dune Strandveld habitat, the effect of vertebrate scavenging on the decomposition process was examined. This part of Cape Town suffers from poor socioeconomic conditions and a high murder rate, which is due in part to the dense population. Human decomposition was simulated using three small (∼20kg) domestic pig (Sus scrofa domesticus) carcasses, with ethical clearance. One pig served as a control and was caged to prevent vertebrate but not invertebrate access; the other two served as experimental treatments. They were deployed in Delft, Cape Town, and observed by motion-activated, time-lapse remote photography to record scavenger species and activity. A rapid increase in the decomposition rate was observed due to Cape grey mongoose (Galerella pulverulenta) scavenging, with early skeletonisation reached by both experimental pigs by day 14, compared to the control remaining in advanced decomposition after 93 days. Mongoose is the primary scavenger in this habitat, and showed notable patterns of feeding behaviour, exclusively within daylight hours. Scavenging activity was only influenced by rainfall later in the cycle. This research provides knowledge on locally relevant decomposition patterns and highlights the necessity for PMI estimation methods to consider vertebrate scavengers. This may improve human skeletal identification in forensic cases. There is scope for expansion of this study, with an investigation of seasonal effects, the interaction between invertebrate and vertebrate activity, as well as, the effect of clothing on scavenger access.

Effects of Perch Location on Wintering Raptor Use of Artificial Perches in a California Vineyard

Most raptor species rely on perches for hunting, resting, preening, and roosting, and in many agricultural areas the availability of adequate perches can limit raptor abundance and diversity. This has negative implications for both raptor conservation and for the provisioning of natural pest control services for farmers. Installing artificial perches on agricultural lands can therefore benefit both raptors and farmers, but perches must be installed in optimal locations to maximize raptor use and minimize unnecessary costs to farmers. We monitored raptor use of artificial perches in a California vineyard over winter using remote photography to compare two sets of perch types: perches at the top versus perches at the bottom of a steep hill, and perches located among trees versus perches located in an open area. We found that raptors preferred perches on hilltops over perches at the base of hills, and that raptors seem to prefer perches in open habitat over perches located adjacent to trees, although a small sample size for this comparison limited our analysis.

Assessment of Nestling Diet and Provisioning Rate by Two Methods in the Lesser KestrelFalco naumanni

Nowadays the use of remote photography systems is very popular for diet assessment. Despite the popularity, there is a greater need for evaluation of these systems against traditional methods of diet assessment, such as direct visual observation. The diet of Lesser Kestrel nestlings and adult provisioning rate were assessed using cameras and direct observations at four nests with various brood sizes during the breeding season in 2013. The study was conducted in an intensively cultivated area that belongs to a Special Protected Area of the Natura 2000 network in central Greece. Diet composition (prey type and size) was not affected by the recording method, the sex of adults, the brood size, the period of the day or the age of nestlings. Tettigoniidae was the most frequent prey delivered by adults. Our results from both methods showed that males delivered more prey items than females, supporting the general consensus of reversed sexual dimorphism for the Lesser Kestrel. The provisioning rate was not significantly related to brood size, but it was affected by the method of observation, parent sex and the interaction of method and nestling age. According to the direct observations, provisioning rates increased as nestlings grew up, while they decreased based on camera information. Higher provisioning rates recorded in direct observations at later nestling stages, can be explained by higher food requirements of nestlings. The decrease in provisioning rate with nestling age was mostly affected by the camera function, as a result of digital limitations, nest type and Lesser Kestrels behavior.

Hydrologic Influences on Plant Community Structure in Vernal Pools of Northeastern California

Plant communities in vernal pools are distributed along continuous elevation gradients associated with subtle variations in microtopography, reflected in spatially heterogeneous hydrologic regimes. We quantified the role of hydrologic and environmental variables for influencing species assemblages within two vernal pool landscapes in northeastern California. A novel combination of approaches including remote photography of water depth stage gauges, vegetation sampling along elevation gradients, and topographic surveys were used to measure hydrology and plant community composition at precise locations. Multivariate analyses were used to classify vernal pool plant communities and classification tree analysis was used to model plant community distribution across hydrologic thresholds. Three plant community groups were distinguished according to localized hydrologic regimes. Inundation period and maximum depth were the only variables found to be predictive of plant distribution. Hydrologic thresholds for the three community groups were based on inundation period: Short (< 71 days), Medium (≥ 71 days but <209 days), and Long (≥ 209 days). The distribution of plant assemblages was strongly correlated with key hydrologic gradients. Quantification of such relationships will be useful in forecasting ecohydrological responses of vernal pool vegetation to climate change, helping to guide future monitoring, management and restoration efforts for these unique ecosystems.

Cryptic and Complex Nesting in the Yellow-Spotted Monitor,Varanus panoptes

Abstract Despite the general importance of nest site choice in reproductive success in taxa with little or no parental care, little is known for reptiles other than turtles. Here we report on the nesting ecology of the Yellow-Spotted Monitor, Varanus panoptes, a large tropical lizard that utilizes warrens (concentrated groups of burrows) in northern Australia. We used radio-telemetry, remote photography, and the complete excavation of a warren to test the hypotheses that 1) warrens are used by multiple individual V. panoptes; and if so, 2) they are used for communal nesting; or alternatively 3) they are used for communal estivation during the dry season. At least six individual V. panoptes utilized the warren system including four females and two males, and burrows were excavated by both sexes. Excavation of the warren revealed no estivating lizards at a time when four radio-telemetered V. panoptes had begun estivation. However, we found two nests in the warren, indicative of either communal nesting or mu...

Smartphone medical imaging: applications and future considerations

It is with great privilege that we welcome the third volume of the Journal with an issue that presents original research highlighting innovation and true practical advances in the role of smartphones in medical imaging. Myung et al, in their back-to-back papers in this edition offer excellent examples of the increasing role of smartphones to capture clinical images in ophthalmology. Their papers not only demonstrate creativity, but offer readers involved in eye care a template to develop their own examination equipment at limited expense. Through their publications the authors have highlighted and addressed practical barriers of cost, and training of health care cadres as major barriers that currently confront many low-resource countries. Ophthalmology in particular is a specialty that is critically dependent on visual diagnosis. Whilst cataract and refractive error remain the primary causes of blindness globally, there is a rise of posterior segment pathology, chiefly diabetic retinopathy, age-related macular degeneration, and glaucoma. 1 Many of these latter conditions are more indolent in progression which results in patients often presenting only when symptoms of vision loss manifest. This justifies the need for screening and timely referral when subtle changes develop. In the context of diabetic retinopathy, regular monitoring can be facilitated in a cost-effective manner through remote photography and using telemedicine networks. 2 Whilst the attention of global blindness prevention efforts of the past two decades have concentrated on cataract and infectious causes of vision loss (for example, trachoma, and oncocerchiasis) a major barrier to following up and monitoring for other causes of vision loss is affordability of sophisticated imaging equipment such as retinal cameras and ophthalmic slit-lamps. In this context, Myung et al offer a proof-of-concept model to perform anterior segment and retinal imaging. The enormous potential for translation into clinical practice rests with the user-friendliness, minimal training required for users, image resolution that offers the ability to capture clinically important details, and the ability to rapidly store and transfer images. As with any novel innovation there are practical limitations that offer opportunity for further refinement. In many low-resource settings, there remains a paucity of access to internet and 3G/4G cellular networks outside of major metropolitan centres. 3 Thus, image capture devices must also be accompanied with a platform for safe, ethical and legal storage of data. Thus, in the setting where dynamic transfer and reporting of data cannot occur image capturing technologies would need to advise users on how to temporarily store data (when unable to remotely transfer immediately), and subsequently follow-up on patients who may need urgent referral. These are real challenges that exist in many developing countries where patients may be nomadic, without fixed address, have poor literacy (consent issues), and live far from the point of health care. Despite this, there is clearly a growing body of evidence to support the surge in demand for affordable and accessible medical imaging. Further research into the accuracy, reliability and feasibility of such devices will only enhance their ability to revolutionise the manner in which we deliver healthcare.

Recreational use assessment of water-based activities, using time-lapse construction cameras

Recreational exposure to surface waters during periods of increased pathogen concentration may lead to a significantly higher risk of illness. However, estimates of elementary exposure factors necessary to evaluate health risk (i.e., usage distributions and exposure durations) are not available for many non-swimming water-related activities. No prior studies have assessed non-swimming water exposure with respect to factors leading to impaired water quality from increased pathogen concentration, such as weather condition (rain events produce increased runoff and sewer overflows) and type of day (heavy recreational periods). We measured usage patterns and evaluated the effect of weather and type of day at eight water sites located within Philadelphia, by using a novel "time lapse photography" technology during three peak recreational seasons (May-September) 2008-2010. Camera observations validated with simultaneous in-person surveys exhibited a strong correlation (R(2)=0.81 to 0.96) between the two survey techniques, indicating that the application of remote photography in collecting human exposure data was appropriate. Recreational activities usage varied more on a temporal basis than due to inclement weather. Only 14% (6 out of 44) of the site-specific activity combinations showed dry weather preference, whereas 41.5% (17 out of 41) of the combinations indicated greater usage on weekends as compared with weekday. In general, the log normal distribution described the playing and wading duration distribution, while the gamma distribution was the best fit for fishing durations. Remote photography provided unbiased, real-time human exposure data and was less personnel intensive compared with traditional survey methods. However, there are potential limitations associated with remote surveillance data related to its limited view. This is the first study to report that time lapse cameras can be successfully applied to assess water-based human recreational patterns and can provide precise exposure statistics for non-swimming recreational exposures.

Assessment of temporal partitioning in foraging patterns of syntopic Virginia opossums and raccoons

Temporal partitioning in foraging patterns of syntopic Virginia opossums (Didelphis virginiana) and raccoons (Procyon lotor) was investigated at 3 sites in western Tennessee through the use of timers attached to live traps on trapping grids and through time-stamped remote photography using infrared-triggered cameras at bait stations. Data were analyzed using Watson’s U 2 -test, chi-square analyses, and probability tests. Results revealed no intraspecific differences in time of foraging for either species and a lack of interspecific differentiation. A high degree of overlap in foraging times of the species was observed. Virginia opossums and raccoons apparently did not partition their times of foraging. Foraging patterns of each species seem to be independent of the other (neutral association).

Influence of Forest Canopy and Snow on Microclimate in a Declining Yellow-Cedar Forest of Southeast Alaska

Abstract Site factors predispose yellow-cedar (Chamaecyparis nootkatensis D. Don (Spach)) to a widespread climate-induced mortality in Southeast Alaska. We investigated the influence of canopy cover and snow on microclimate at two small watersheds across a range of declining yellow-cedar stands on Baranof and Chichagof Islands in Southeast Alaska. Two measures of canopy cover, derived from hemispherical photography and LiDAR, were correlated (r = 0.74 and 0.80) at the two sites; both had significant relationships (all R2 ≥ 0.61) with basal area of live trees on plots. Reduced canopy cover increases soil warming in spring and leads to rapid changes in air temperature. There is also a positive feedback where the loss of tree overstory due to yellow-cedar mortality contributes to open, exposed site conditions. Variable patterns of snow depth in late winter and spring at one of the sites, documented with daily remote photography, were associated with elevation and cover. Dead trees predominate where lethal sh...

Estudio de la comunidad de carnívoros del Parque Natural del Montseny (Catalunya) mediante el trampeo fotográfico

Remote photography is a noninvasive technique that provides simultaneous data on most species that compose the carnivore community. This technique has recently become popular due to the availability of relatively simple and cost-effective automatic equipment. Between 2004 and 2007, the Montseny Natural Park area was meticulously sampled (30,000 ha), by placing a single photographic device with movement sensor in 234 1x1-km UTM squares (sample units [s.u.] formed 78% of the park area), for two consecutive nights each. Equipment was located in characteristic habitats at an altitudinal gradient of 1,465 m (165-1,630 m.a.s.l.). A total of 1,387 photographs were taken of carnivores representing 7 species (5 wild species and 2 domestic ones). The most frequently photographed species was the stone marten (Martes foina), with 800 photographs taken in 90 s.u. (38.4%), followed by the common genet (Genetta genetta), with 330 photographs in 38 s.u. (16.2%), the red fox (Vulpes vulpes), with 108 photographs in 28 s.u. (11.9%), the badger (Meles meles), with 4 photographs in 3 s.u. (1.3%), and the American mink (Neovison vison), with 1 photo in 1 s.u. (0.4%). Among the domestic species photographed were the cat (Felis catus), with 101 photographs in 17 s.u. (7.3%), and the dog (Canis familiaris), with 43 photographs in 12 s.u. (5.1%). Genets were detected between 175 and 1,206 m.a.s.l., but was absent from mountain tops in Montseny Park. Its probability of occurrence peaked between 400 and 600 m.a.s.l., progressively decreasing with altitude. Stone martens were located between 175 and 1,630 m.a.s.l., with peaks in the 400-600 m.a.s.l. range, progressively decreasing to 1,200 m.a.s.l., and increasing between 1,200 m.a.s.l. and the mountain tops. Foxes were detected between 302 and 1,318 m.a.s.l., with peaks between the 800 and 1,000 m.a.s.l., decreasing towards both extremes of the altitudinal gradient.

Evaluation of three remote camera systems for detecting mammals and birds

Automated camera systems have widespread application in wildlife studies and their use is increasing (Kucera & Barrett 1993; Cutler & Swann 1999; Swann et al. 2004; Parker et al. 2008). Among other applications, they have been used to produce species inventories, estimate population sizes, study behaviour and examine the impact and activity of predators (Cutler & Swann 1999; Swann et al. 2004). Modern camera systems can operate for extended durations, are relatively non-invasive, easy to operate, portable, durable and can take good-quality images by day and night (Kucera & Barrett 1993; Peterson & Thomas 1998; Allison & Destefano 2006; Parker et al. 2008). Beyond their scientific applications, the generation of high-quality images can be useful for educational and conservation purposes (Cutler & Swann 1999). The two most common types of systems currently used in ecological research are passive and active infrared (IR) systems (Cutler & Swann 1999; Parker et al. 2008). An older form of remote photography is video which captures a continuous record of activity at a focal site (Stewart et al.1997; King et al. 2001). Camera systems have certain limitations and biases (Swann et al. 2004), yet these have not been well studied. Refinement of the use of camera systems is required to fully realize their value (Towerton et al. 2008). Here, we describe a comparison of detection rates of mammals and birds by passive and active IR camera systems, using a video system to benchmark detection rates.

Mammalian Records by Remote Photography and Direct Night Observations in the Koboyama-Park, Hadano City, Kanagawa Prefecture

Mammalian Records by Remote Photography and Direct Night Observations in the Koboyama-Park, Hadano City, Kanagawa Prefecture

Equipment and Techniques for Nocturnal Wildlife Studies

Many biologists speculate on the nocturnal behavior of wildlife. Night-vision technologies may provide ways to move beyond speculation to observation of nocturnal activity. Nocturnal activity data collection is often secondary to broader study objectives; consequently, techniques for such studies are poorly understood and infrequently used. We reviewed 53 papers to examine image enhancement (i.e., night vision) and assess trends in nocturnal research techniques. We also conducted a field study on nocturnal behavior of roosting cranes (Grus spp.) to evaluate equipment function and efficacy for wildlife studies. A third-generation night-vision scope greatly outperformed a pair of first-generation night-vision binoculars, and we were able to identify cranes by species and observe and record their behaviors while they were on their nocturnal roost sites. Techniques reported in the literature included use of moonlight or natural ambient light, spotlight or simulated luminosity, remote photography, surveillance radar, infrared thermal imaging, and image enhancement. With the many techniques available, scientists can select the procedure or a combination of strategies explicit to their purpose. We believe night-viewing technologies are an exceptional, nonintrusive, functional tool for wildlife ecology studies. However, even the best equipment will have problems or issues with contrast, inclement weather, and large group size and density. Regardless of the specific method used and the inherent challenges, we believe third-generation, American-manufactured night-vision equipment can provide valuable insight into the complete life history of animals and can promote a more comprehensive approach to wildlife studies.

Using time-lapse digital video recording for a nesting study of birds of prey

Remote photography using various photo, movie or video devices has been employed in numerous studies in wildlife research during the last 50 years. Given the rapid advances in digital technologies, digital video and photo techniques are becoming more common in use, and publications that introduce a new method or equipment for video surveillance in wildlife research (and in ornithological studies particularly) are appearing almost every year. However, still no special guide to the great variety of equipment and methods is available, and the choice and use of suitable gear for scientific purposes may be difficult for non-specialists. In this paper, we review the most common surveillance techniques used in today’s nest studies, as well as the most essential properties of image recording equipment. We also describe the digital video recording technique, which we used for observations of raptor nests, and summarise our experience of its operation. As an example of the obtained data, we present the timing of prey deliveries of goshawks and common buzzards.