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George Ala Lackbu - One of the best experts on this subject based on the ideXlab platform.
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understanding the multi seasonal spectral and biophysical characteristics of Reedbed habitats in the uk
Geo-spatial Information Science, 2016Co-Authors: Alex Okiemute Onojeghuo, George Ala LackbuAbstract:Reedbed in the UK has been classified as priority habitat for most regional Biodiversity Partnerships. However, critical information pertaining to the quality and spatial coverage of Reedbed is currently lacking. This paper presents the results of a project conducted in collaboration with the Cumbria Wildlife Trust and Environment Agency aimed at monitoring and understanding variations in the spectral reflectance and biophysical properties of Reedbed canopies across Leighton Moss Nature Reserve in Lancashire, northwest England. Throughout the seasonal phenological cycle of the Reedbed habitats in the study area, optimal spectral indices required for quantifying its biophysical properties were determined using field spectroscopy and ground-based measurements. Results of the experiment showed that the narrow-band-derived Difference Vegetation Index (DVI) and Renormalised Difference Vegetation Index (RDVI), with the correlation coefficient R2 of 0.77 and 0.72, respectively, provided the most accurate estimates of the leaf area index for the Reedbed canopies.
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exploiting high resolution multi seasonal textural measures and spectral information for Reedbed mapping
Environments, 2016Co-Authors: Alex Okiemute Onojeghuo, George Ala LackbuAbstract:Reedbeds across the UK are amongst the most important habitats for rare and endangered birds, wildlife and organisms. However, over the past century, this valued wetland habitat has experienced a drastic reduction in quality and spatial coverage due to pressures from human related activities. To this end, conservation organisations across the UK have been charged with the task of conserving and expanding this threatened habitat. With this backdrop, the study aimed to develop a methodology for accurate Reedbed mapping through the combined use of multi-seasonal texture measures and spectral information contained in high resolution QuickBird satellite imagery. The key objectives were to determine the most effective single-date (autumn or summer) and multi-seasonal QuickBird imagery suitable for Reedbed mapping over the study area; to evaluate the effectiveness of combining multi-seasonal texture measures and spectral information for Reedbed mapping using a variety of combinations; and to evaluate the most suitable classification technique for Reedbed mapping from three selected classification techniques, namely maximum likelihood classifier, spectral angular mapper and artificial neural network. Using two selected grey-level co-occurrence textural measures (entropy and angular second moment), a series of experiments were conducted using varied combinations of single-date and multi-seasonal QuickBird imagery. Overall, the results indicate the multi-seasonal pansharpened multispectral bands (eight layers) combined with all eight grey level co-occurrence matrix texture measures (entropy and angular second moment computed using windows 3 × 3 and 7 × 7) produced the optimal Reedbed (76.5%) and overall classification (78.1%) accuracies using the maximum likelihood classifier technique. Using the optimal 16 layer multi-seasonal pansharpened multispectral and texture combined image dataset, a total Reedbed area of 9.8 hectares was successfully mapped over the three study sites. In conclusion, the study has demonstrated the value of utilizing multi-seasonal texture measures and pansharpened multispectral data for Reedbed mapping.
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mapping Reedbed habitats using texture based classification of quickbird imagery
Journal of remote sensing, 2011Co-Authors: Alex Okiemute Onojeghuo, George Ala LackbuAbstract:Many organisms rely on Reedbed habitats for their existence, yet, over the past century there has been a drastic reduction in the area and quality of Reedbeds in the UK due to intensified human activities. In order to develop management plans for conserving and expanding this threatened habitat, accurate up-to-date information is needed concerning its current distribution and status. This information is difficult to collect using field surveys because Reedbeds exist as small patches that are sparsely distributed across landscapes. Hence, this study was undertaken to develop a methodology for accurately mapping Reedbeds using very high resolution QuickBird satellite imagery. The objectives were to determine the optimum combination of textural and spectral measures for mapping Reedbeds; to investigate the effect of the spatial resolution of the input data upon classification accuracy; to determine whether the maximum likelihood classifier MLC or artificial neural network ANN analysis produced the most accurate classification; and to investigate the potential of refining the Reedbed classification using slope suitability filters produced from digital terrain data. The results indicate an increase in the accuracy of Reedbed delineations when grey-level co-occurrence textural measures were combined with the spectral bands. The most effective combination of texture measures were entropy and angular second moment. Optimal Reedbed and overall classification accuracies were achieved using a combination of pansharpened multispectral and texture images that had been spatially degraded from 0.6 to 4.8 m. Using the 4.8 m data set, the MLC produced higher classification accuracy for Reedbeds than the ANN analysis. The application of slope suitability filters increased the classification accuracy of Reedbeds from 71% to 79%. Hence, this study has demonstrated that it is possible to use high resolution multispectral satellite imagery to derive accurate maps of Reedbeds through appropriate analysis of image texture, judicious selection of input bands, spatial resolution and classification algorithm and post-classification refinement using terrain data.
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optimising the use of hyperspectral and lidar data for mapping Reedbed habitats
Remote Sensing of Environment, 2011Co-Authors: Alex Okiemute Onojeghuo, George Ala LackbuAbstract:Abstract Reedbeds are important habitats for supporting biodiversity and delivering a range of ecosystem services, yet Reedbeds in the UK are under threat from intensified agriculture, changing land use and pollution. To develop appropriate conservation strategies, information on the distribution of Reedbeds is required. Field surveys of these wetland environments are difficult, time consuming and expensive to execute for large areas. Remote sensing has the potential to replace or complement such field surveys, yet the specific application to Reedbed habitats has not been fully investigated. In the present study, airborne hyperspectral and LiDAR imagery were acquired for two sites in Cumbria, UK. The research aimed to determine the most effective means of analysing hyperspectral data covering the visible, near infrared (NIR) and shortwave infrared (SWIR) regions for mapping Reedbeds and to investigate the effects of incorporating image textural information and LiDAR-derived measures of canopy structure on the accuracy of Reedbed delineation. Due to the high dimensionality of the hyperspectral data, three image compression algorithms were evaluated: principal component analysis (PCA), spectrally segmented PCA (SSPCA) and minimum noise fraction (MNF). The LiDAR-derived measures tested were the canopy height model (CHM), digital surface model (DSM) and the DSM-derived slope map. The SSPCA-compressed data produced the highest Reedbed accuracy and processing efficiency. The optimal SSPCA dataset incorporated 12 PCs comprised of the first 3 PCs derived from each of the spectral segments: visible (392–700 nm), NIR (701–972 nm), SWIR-1 (973–1366 nm) and SWIR-2 (1530–2240 nm). Incorporating image textural measures produced a significant improvement in the classification accuracy when using MNF-compressed data, but had no impact when using the SSPCA-compressed imagery. A significant improvement (+ 11%) in the accuracy of Reedbed delineation was achieved when a mask generated by applying a 3 m threshold to the LiDAR-derived CHM was used to filter the Reedbed map derived from the optimal SSPCA dataset. This paper demonstrates the value in combining appropriately compressed hyperspectral imagery with LiDAR data for the effective mapping of Reedbed habitats.
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characterising Reedbed habitat quality using leaf off lidar data
International Colloquium on Signal Processing and Its Applications, 2010Co-Authors: Alex Okiemute Onojeghuo, George Ala Lackbu, Zulkiflee Abd LatifAbstract:The aim of this paper was to investigate the potential of using leaf-off LiDAR data to characterise the quality of Reedbed habitats in Leighton moss, North west UK. The correlation between LiDAR derived and ground-measured heights were determined using six selected spatial buffers and the most significant selected. The results indicated that accurate estimates of canopy height were derivable from the first return data, a valuable indicator of Reedbed habitat quality. However, the lack of any subsequent returns from Reedbeds prevented the extraction of any further biophysical variables. This paper outlines the methodology of deriving suitable height estimates of reeds and the limitations of using leaf-off LiDAR data.
Igitte Pouli - One of the best experts on this subject based on the ideXlab platform.
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Reedbed monitoring using classification trees and spot 5 seasonal time series
International Symposium on Advanced Methods of Monitoring Reed Habitats in Europe, 2010Co-Authors: Aurelie Davranche, Igitte Pouli, Gaeta LefebvreAbstract:The Rhone river delta (Camargue) in south of France, has lost 40,000 ha of natural areas, including 33,000 ha of wetlands over the last 60 years, following the extension of agriculture, salt exploitation and industry. Reed development and density in Camargue marshes is influenced by physical factors such as salinity, water depth, and water level fluctuations, which have an effect on reflectance spectra. Classification trees applied to time series of SPOT-5 images appear as a powerful and reliable tool for monitoring wetland vegetation experiencing different hydrological regimes. The resulting tree provided a cross-validation accuracy of 98.7% and a mapping accuracy of 98.6% (2005) and 98.1% (2006). Misclassifications were partly explained by digitizing inaccuracies, and were not related to biophysical parameters of Reedbeds. The resolution of SPOT-5 scenes provides an adequate scale for acquiring detailed field data within homogeneous stands, allowing to optimize the time spent for data collecting and to properly locate the sampled plots on the ground and on the scenes. Our results demonstrate that it is possible with a good field campaign to avoid repeated sampling for a long-term cost-efficient monitoring of reed marshes. The accuracy and reliability of our models provide a vision where the roles are reversed: the field campaigns become a complementary tool in wetland monitoring using satellite remote sensing.
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butorstar a role playing game for collective awareness of wise Reedbed use
Simulation & Gaming, 2007Co-Authors: Raphael Matheve, Christophe Le Page, Michel Etienne, Gaeta Lefebvre, Igitte Pouli, Guillaume Gigo, Sophie Proreol, Andre MauchampAbstract:A role-playing game (RPG) supported by computer simulations, called BUTORSTAR, has been developed in the context of a LIFE-Nature European Programme (2001-2005) aiming to improve Reedbed management for the conservation of a vulnerable heron, the Eurasian Bittern. The agent-based model simulates the impacts of Reedbed management resulting from decisions made by farmers, reed harvesters, hunters, and naturalists. The model is based on an archetypal wetland made of a virtual landscape. Different water regimes are proposed, each one adapted to a particular wetland use. Land-use and water-management decisions are made by the players at both estate and management-unit levels. These decisions are entered into the model each year as the results of the negotiation process between the players. This RPG is designed to promote student awareness of(a) biological and hydrological interdependencies and their dynamics on different spatial and temporal scales, (b) the technical and socioeconomic factors involved in the different types of Reedbed use, and (c) the usefulness of the negotiation process for establishing collective management rules. It is shown that BUTORSTAR creates a continuum of learning that crosses the traditional boundaries between disciplines and allows players to conduct multipurpose experiments that contribute to their comprehensive understanding of socioecosystems.
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habitat requirements of passerines and Reedbed management in southern france
Biological Conservation, 2002Co-Authors: Igitte Pouli, Gaeta Lefebvre, A MauchampAbstract:Reedbeds have high conservation value in Europe. In southern France, they are the major breeding habitat of five passerine species. Yet, habitat management is done primarily by water control to serve socio-economic rather than conservation interests, because we lack information on the species' ecological requirements. Determinants of passerine abundance were assessed through a comparative analysis of water regime, plant structure, and arthropod (food) distribution at 12 sites consisting of at least 10 ha of marsh densely covered with common reed (Phragmites australis). Overall bird abundance estimated through standardised mist netting was positively correlated with food availability (sweep-netted arthropods weighted by their occurrence in birds' diet), which was in turn negatively correlated with duration of ground dryness between June and December. Abundance of four of the five bird species was associated with specific vegetation parameters (reed diameter, dry reed density, growing reed height, etc.), which could be associated with particular management practices, especially with regard to water levels and salinity. Potential impact of socio-economic activities through their water management is addressed, as well as possible ways to minimise these impacts.
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quantifying the breeding assemblage of Reedbed passerines with mist net and point count surveys
Journal of Field Ornithology, 2000Co-Authors: Igitte Pouli, Gaeta Lefebvre, Philippe PilardAbstract:Abstract Data collected in a 40-ha Reedbed of southern France were used to compare the efficiency and limitation of mist-net and point-count techniques in estimating the composition and structure of a bird assemblage dominated by the Bearded Tit (Panurus biarmicus), the Moustached Warbler (Acrocephalus melanopogon), and the Reed Warbler (Acrocephalus scirpaceus). Null model analyses were used to determine the effect of spatial variability on estimates of species richness and relative abundance with the two sampling techniques. A 50-m net line operated during 5 h or two 50-m radius point counts of 10 min conducted 6 wk apart provided a similar estimation of species composition and relative abundance. While a sampling effort of 10 net lines or 13 point counts would permit the detection of a 25% difference in the relative abundance of most species (whether over time or among sites), the analyses on community structure suggest that 26 net lines or 13 point counts are necessary to sample adequately the structu...
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spatial distribution of nesting and foraging sites of two acrocephalus warblers in a mediterranean Reedbed
Acta Ornithologica, 2000Co-Authors: Igitte Pouli, Gaeta Lefebvre, Slimane MetrefAbstract:Many Reedbed passerines forage outside their nesting territory. This peculiar behaviour could allow reproductive individuals to feed in areas where resources are plentiful and/or to nest in areas where predation risks are low. These hypotheses were investigated for the Moustached Warbler Acrocephalus melanopogon and the Reed Warbler A. scirpaceus in a 40-ha of Reedbed in southern France. Vegetation structure, abundance of arthropod-prey, location of singing males, and bird local abundance were estimated along three transects 1-km long and 125-m distant parallel to the shore. Reed density increased from the lake inland, concurrently with a decrease in plant diversity. Food availability (sweep-netted arthropods weighted by their occurrence in species diet) varied positively with plant diversity and negatively with reed density. The dummy-nest experiment suggested a negative relationship between predation risks and reed density. While local abundance of each Acrocephalus species correlated spatially with food abundance, singing males were distributed evenly among the three transects. This suggests that predation risk associated with vegetation density has little influence on nest-site selection. The regular spacing of singing males further suggests that predation risk is primarily affected by nest density.
Andras Aldi - One of the best experts on this subject based on the ideXlab platform.
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the importance of temporal dynamics of edge effect in Reedbed design a 12 year study on five bird species
Wetlands Ecology and Management, 2005Co-Authors: Andras AldiAbstract:Although edge effect is a key topic of conservation biology, we have no data on the temporal dynamics of it. I investigated the distribution of five passerine bird species across Reedbed (Phragmites australis) edges during large-scale construction work in the Kis-Balaton marshland, Hungary. The construction provided an “experimental” approach to study the effects of large timescale changes within a shorter period, because neither the locality nor the vegetation type changed. The water level was increased in the study area, which homogenised the internal structure of Reedbed by declining the scattered small willow bushes (Salix) and the grass/sedge layer. The sedge (Acrocephalus schoenobaenus) and reed warblers (Acrocephalus scirpaceus) preferred edges. The sedge warbler, however, declined after inundation, while the reed warbler did not respond. Savi’s warbler (Locustella luscinioides) sharply declined during the study with changing edge effect. The number of great reed warblers (Acrocephalus arundinaceus) increased during the study, mainly in the Reedbed interior, where the stands became patchy with open water. Reed bunting (Emberiza schoeniclus) avoided interiors, and declined over the study. Therefore, there were significant changes in the distribution of Reedbed birds across the edge, although the location of edges and the basic habitat, Reedbed, did not change. The results highlight the need to incorporate edge effect as a dynamic process in wetland planning.
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microclimate and vegetation edge effects in a Reedbed in hungary
Biodiversity and Conservation, 1999Co-Authors: Andras AldiAbstract:The aim of the study was to describe microclimate (surface and air temperature, humidity, light and wind intensity) and vegetation structure (density and height of reeds, and reed shoot structure) across the first 20 m of a sharp Reedbed edge at Lake Velence, Hungary, in June 1996. There was a significant edge effect, although different variables contributed differently to the pattern. The Reedbed edge had three bands: the first is characterised by very dense stand, where the shoots were thin and short; in the second band density declined, but reed shoots were thick and very high, and in the third band both density and height declined, but not shoot diameter. Microclimate variables showed similar pattern: Reedbed edges were warm, dry, bright and windy, further inside temperature, light and wind intensity declined, humidity increased, and still further temperature and light intensity increased, and humidity decreased. I estimated that the edge effect penetrates into the Reedbed up to ca. 15 m. The great variation of variables across the edge inevitable has significant impact on the occurrence of animals species; our knowledge, however, is too limited to predict the expected extinction of species owing to edge effect.
Alex Okiemute Onojeghuo - One of the best experts on this subject based on the ideXlab platform.
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understanding the multi seasonal spectral and biophysical characteristics of Reedbed habitats in the uk
Geo-spatial Information Science, 2016Co-Authors: Alex Okiemute Onojeghuo, George Ala LackbuAbstract:Reedbed in the UK has been classified as priority habitat for most regional Biodiversity Partnerships. However, critical information pertaining to the quality and spatial coverage of Reedbed is currently lacking. This paper presents the results of a project conducted in collaboration with the Cumbria Wildlife Trust and Environment Agency aimed at monitoring and understanding variations in the spectral reflectance and biophysical properties of Reedbed canopies across Leighton Moss Nature Reserve in Lancashire, northwest England. Throughout the seasonal phenological cycle of the Reedbed habitats in the study area, optimal spectral indices required for quantifying its biophysical properties were determined using field spectroscopy and ground-based measurements. Results of the experiment showed that the narrow-band-derived Difference Vegetation Index (DVI) and Renormalised Difference Vegetation Index (RDVI), with the correlation coefficient R2 of 0.77 and 0.72, respectively, provided the most accurate estimates of the leaf area index for the Reedbed canopies.
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exploiting high resolution multi seasonal textural measures and spectral information for Reedbed mapping
Environments, 2016Co-Authors: Alex Okiemute Onojeghuo, George Ala LackbuAbstract:Reedbeds across the UK are amongst the most important habitats for rare and endangered birds, wildlife and organisms. However, over the past century, this valued wetland habitat has experienced a drastic reduction in quality and spatial coverage due to pressures from human related activities. To this end, conservation organisations across the UK have been charged with the task of conserving and expanding this threatened habitat. With this backdrop, the study aimed to develop a methodology for accurate Reedbed mapping through the combined use of multi-seasonal texture measures and spectral information contained in high resolution QuickBird satellite imagery. The key objectives were to determine the most effective single-date (autumn or summer) and multi-seasonal QuickBird imagery suitable for Reedbed mapping over the study area; to evaluate the effectiveness of combining multi-seasonal texture measures and spectral information for Reedbed mapping using a variety of combinations; and to evaluate the most suitable classification technique for Reedbed mapping from three selected classification techniques, namely maximum likelihood classifier, spectral angular mapper and artificial neural network. Using two selected grey-level co-occurrence textural measures (entropy and angular second moment), a series of experiments were conducted using varied combinations of single-date and multi-seasonal QuickBird imagery. Overall, the results indicate the multi-seasonal pansharpened multispectral bands (eight layers) combined with all eight grey level co-occurrence matrix texture measures (entropy and angular second moment computed using windows 3 × 3 and 7 × 7) produced the optimal Reedbed (76.5%) and overall classification (78.1%) accuracies using the maximum likelihood classifier technique. Using the optimal 16 layer multi-seasonal pansharpened multispectral and texture combined image dataset, a total Reedbed area of 9.8 hectares was successfully mapped over the three study sites. In conclusion, the study has demonstrated the value of utilizing multi-seasonal texture measures and pansharpened multispectral data for Reedbed mapping.
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mapping Reedbed habitats using texture based classification of quickbird imagery
Journal of remote sensing, 2011Co-Authors: Alex Okiemute Onojeghuo, George Ala LackbuAbstract:Many organisms rely on Reedbed habitats for their existence, yet, over the past century there has been a drastic reduction in the area and quality of Reedbeds in the UK due to intensified human activities. In order to develop management plans for conserving and expanding this threatened habitat, accurate up-to-date information is needed concerning its current distribution and status. This information is difficult to collect using field surveys because Reedbeds exist as small patches that are sparsely distributed across landscapes. Hence, this study was undertaken to develop a methodology for accurately mapping Reedbeds using very high resolution QuickBird satellite imagery. The objectives were to determine the optimum combination of textural and spectral measures for mapping Reedbeds; to investigate the effect of the spatial resolution of the input data upon classification accuracy; to determine whether the maximum likelihood classifier MLC or artificial neural network ANN analysis produced the most accurate classification; and to investigate the potential of refining the Reedbed classification using slope suitability filters produced from digital terrain data. The results indicate an increase in the accuracy of Reedbed delineations when grey-level co-occurrence textural measures were combined with the spectral bands. The most effective combination of texture measures were entropy and angular second moment. Optimal Reedbed and overall classification accuracies were achieved using a combination of pansharpened multispectral and texture images that had been spatially degraded from 0.6 to 4.8 m. Using the 4.8 m data set, the MLC produced higher classification accuracy for Reedbeds than the ANN analysis. The application of slope suitability filters increased the classification accuracy of Reedbeds from 71% to 79%. Hence, this study has demonstrated that it is possible to use high resolution multispectral satellite imagery to derive accurate maps of Reedbeds through appropriate analysis of image texture, judicious selection of input bands, spatial resolution and classification algorithm and post-classification refinement using terrain data.
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optimising the use of hyperspectral and lidar data for mapping Reedbed habitats
Remote Sensing of Environment, 2011Co-Authors: Alex Okiemute Onojeghuo, George Ala LackbuAbstract:Abstract Reedbeds are important habitats for supporting biodiversity and delivering a range of ecosystem services, yet Reedbeds in the UK are under threat from intensified agriculture, changing land use and pollution. To develop appropriate conservation strategies, information on the distribution of Reedbeds is required. Field surveys of these wetland environments are difficult, time consuming and expensive to execute for large areas. Remote sensing has the potential to replace or complement such field surveys, yet the specific application to Reedbed habitats has not been fully investigated. In the present study, airborne hyperspectral and LiDAR imagery were acquired for two sites in Cumbria, UK. The research aimed to determine the most effective means of analysing hyperspectral data covering the visible, near infrared (NIR) and shortwave infrared (SWIR) regions for mapping Reedbeds and to investigate the effects of incorporating image textural information and LiDAR-derived measures of canopy structure on the accuracy of Reedbed delineation. Due to the high dimensionality of the hyperspectral data, three image compression algorithms were evaluated: principal component analysis (PCA), spectrally segmented PCA (SSPCA) and minimum noise fraction (MNF). The LiDAR-derived measures tested were the canopy height model (CHM), digital surface model (DSM) and the DSM-derived slope map. The SSPCA-compressed data produced the highest Reedbed accuracy and processing efficiency. The optimal SSPCA dataset incorporated 12 PCs comprised of the first 3 PCs derived from each of the spectral segments: visible (392–700 nm), NIR (701–972 nm), SWIR-1 (973–1366 nm) and SWIR-2 (1530–2240 nm). Incorporating image textural measures produced a significant improvement in the classification accuracy when using MNF-compressed data, but had no impact when using the SSPCA-compressed imagery. A significant improvement (+ 11%) in the accuracy of Reedbed delineation was achieved when a mask generated by applying a 3 m threshold to the LiDAR-derived CHM was used to filter the Reedbed map derived from the optimal SSPCA dataset. This paper demonstrates the value in combining appropriately compressed hyperspectral imagery with LiDAR data for the effective mapping of Reedbed habitats.
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characterising Reedbed habitat quality using leaf off lidar data
International Colloquium on Signal Processing and Its Applications, 2010Co-Authors: Alex Okiemute Onojeghuo, George Ala Lackbu, Zulkiflee Abd LatifAbstract:The aim of this paper was to investigate the potential of using leaf-off LiDAR data to characterise the quality of Reedbed habitats in Leighton moss, North west UK. The correlation between LiDAR derived and ground-measured heights were determined using six selected spatial buffers and the most significant selected. The results indicated that accurate estimates of canopy height were derivable from the first return data, a valuable indicator of Reedbed habitat quality. However, the lack of any subsequent returns from Reedbeds prevented the extraction of any further biophysical variables. This paper outlines the methodology of deriving suitable height estimates of reeds and the limitations of using leaf-off LiDAR data.
Andras Molna - One of the best experts on this subject based on the ideXlab platform.
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accurate non disturbance population survey method of nesting colonies in the Reedbed with georeferenced aerial imagery
Sensors, 2020Co-Authors: Gabo Ako, Zsol Molna, Zsofia Szilagyi, Csaba Iro, Edina Morvai, Ors Abram, Andras MolnaAbstract:High altitude aerial surveys have the potential to improve disturbance-free data collection in wildlife research, but previously, bird species were not recognizable in high-altitude orthophotos. This method of aerial surveying is effective and can be repeated frequently due to its low cost; it also has the additional advantage of being able to monitor the status of protected areas. In the case of waterbirds, due to the low vegetation coverage, aerial remote sensing is an exceptionally effective technique for surveying populations and detecting nests. Aerial surveys made at low altitudes can cause serious stress for birds. The method we developed and employed is unlikely to be detected by either ground-based or nesting birds but is far more reliable compared to the low-resolution imaging methods and to the evaluation of non-georeferenced photo series. The modern sensors and photogrammetric procedures enable the use of the present method worldwide; furthermore, the large-scale ortho image-derived information has become obtainable more frequently. Direct georeferencing makes the field geodetic survey unnecessary. Orthophotos with a 0.7 cm spatial resolution allow us to reliably identify even the individuals of smaller species, and by the use of oblique images, they can be tracked from two or four different directions.