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Comparison of conventional, ground-based surveys (1997/98) [7] and a UAV-based aerial photography survey (this study) of Black-vented Shearwaters on Isla Natividad
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![Comparison of conventional, ground-based surveys (1997/98) [7] and a...](publication/327656329/figure/tbl1/AS:11431281271975566@1723829860488/Comparison-of-conventional-ground-based-surveys-1997-98-7-and-a-UAV-based-aerial_Q320.jpg)
Estimating the population of burrow-nesting seabirds is a challenging task, as human presence in the colony creates disturbances and can damage burrows and occupants. Here, we present a novel method using aerial photographs taken with Unmanned Aerial Vehicles (UAVs) to estimate the population size of a burrow-nesting seabird, the Black-vented Shear...
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As population growth affects worldwide social and economic development , the importance of understanding a country's population density is unquestionable. Population size and population density are fundamental in sustainable development and are taken into consideration in the formation of various aspects of infrastructure progression. However, thes...
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... Using UAV RGB imagery to survey burrow nesting and nocturnally active species is, however, more difficult. Albores-Barajas et al. [24] used UAV RGB imagery to estimate the population of burrow-nesting black-vented shearwater (Puffinus opisthomelas) birds while ground-based work was needed to confirm occupation status. ...
Seabird surveys are used to monitor population demography and distribution and help us understand anthropogenic pressures on seabird species. Burrow-nesting seabirds are difficult to survey. Current ground survey methods are invasive, time-consuming and detrimental to colony health. Data derived from short transects used in ground surveys are extrapolated to derive whole-colony population estimates, which introduces sampling bias due to factors including uneven burrow distribution and varying terrain. We investigate a new survey technique for nocturnally active burrow-nesting seabirds using unoccupied aerial vehicles (UAVs) and thermal sensor technology. We surveyed a three-hectare short-tailed shearwater (Ardenna tenuirostris) colony in Tasmania, Australia. Occupied burrows with resident chicks produced pronounced thermal signatures. This survey method captured a thermal response of every occupied burrow in the colony. Count automation techniques were developed to detect occupied burrows. To validate the results, we compared automated and manual counts of thermal imagery. Automated counts of occupied burrows were 9.3% higher and took approximately 5% of the time needed for manual counts. Using both manual and automated counts, we estimated that there were 5249–5787 chicks for the 2021/2022 breeding season. We provide evidence that high-resolution UAV thermal remote sensing and count automation can improve population estimates of burrow-nesting seabirds.
... • Local, national and regional administrative regulations can affect possibility of data acquisition (Chabot et al. 2015, Nowak et al. 2019). • Upfront cost of training and purchasing a drone makes surveys more expensive than field observations (e.g., using notebook, pencil and binoculars) for one-off or a small number of surveys; and multiple flights may be required to cover larger areas, increasing survey time (Albores- Barajas et al. 2018). (Goebel et al. 2015). ...
... This should include details of the landscape to decide whether the objects of interest will be visible in drone images. Seabird nests may be camouflaged, hidden by vegetation and rocky outcrops, or be underground, with small entrance holes hard to see from the air (Albores- Barajas et al. 2018, Dickens et al. 2021. It should also document features that could affect site access (e.g., tidal forecasts for island surveys) or be a hazard to drone flight, namely physical obstructions (e.g., pylons, buildings), restricted areas in the vicinity (e.g., classified airspace and military operations), habitation and recreational activities, public access, and environmental regulations, as well as phone numbers to contact Air Traffic Control (ATC) at nearby aerodromes/airports if the pilot loses control of the drone. ...
... or ESRI Drone2Map (https://www.esri.com/en-us/arcgis/products/arcgis-drone2map/overview) (e.g., Rush et al. 2018, Albores-Barajas et al. 2018). This is difficult for surveys of vertical seabird colonies, as the software is designed to create a georeferenced image in the horizontal plane (i.e., a map), rather than the vertical plane. ...
Over the past decade, drones have become increasingly popular in environmental biology and have been used to study wildlife on all continents. Drones have become of global importance for surveying breeding seabirds by providing opportunities to transform monitoring techniques and allow new research on some of the most threatened birds. However, such fast-changing and increasingly available technology presents challenges to regulators responding to requests to carry out surveys and to researchers ensuring their work follows best practices and meets legal and ethical standards. Following a workshop convened at the 14th International Seabird Group Conference and a subsequent literature search, we collate information from over 100 studies and present a framework to ensure drone-seabird surveys are safe, effective, and within the law. The framework comprises eight steps: (1) Objectives and Feasibility; (2) Technology and Training; (3) Site Assessment and Permission; (4) Disturbance Mitigation; (5) Pre-deployment Checks; (6) Flying; (7) Data Handling and Analysis; and (8) Reporting. The audience is wide ranging with sections having relevance for different users, including prospective and experienced drone-seabird pilots, landowners, and licensors. Regulations vary between countries and are frequently changing, but common principles exist. Taking-off, landing, and conducting in-flight changes in altitude and speed at ≥ 50 m from the study area, and flying at ≥ 50 m above ground-nesting seabirds/horizontal distance from vertical colonies, should have limited disturbance impact on many seabird species; however, surveys should stop if disturbance occurs. Compared to automated methods, manual or semi-automated image analyses are, at present, more suitable for infrequent drone surveys and surveys of relatively small colonies. When deciding if drone-seabird surveys are an appropriate monitoring method long-term, the cost, risks, and results obtained should be compared to traditional field monitoring where possible. Accurate and timely reporting of surveys is essential to developing adaptive guidelines for this increasingly common technology
... A mixture of strategies was observed after the Warm-blob event with El Niño conditions in 2015-2016 winter. During the 2016 breeding period BVSH showed sexual segregation (Soldatini et al., 2019), shallower dives (this paper), and the population partially skipped the reproduction with a breeding population 15 % less abundant than in 2017 (Albores- Barajas et al., 2018). Individual behavioral plasticity (i.e., an individual changing their behavior in response to the environment) (Dingemanse et al., 2010;Gross et al., 2010) was tested on only a few birds tracked on more than one year and confirming the variability observed more clearly at the population level. ...
Oceanic mesoscale systems are characterized by inherent variability. Climatic change adds entropy to this system, making it a highly variable environment in which marine species live. Being at the higher levels of the food chain, predators maximize their performance through plastic foraging strategies. Individual variability within a population and the possible repeatability across time and space may provide stability in a population facing environmental changes. Therefore, variability and repeatability of behaviors, particularly diving behavior, could play an important role in understanding the adaptation pathway of a species. This study focuses on characterizing the frequency and timing of different dives (termed simple and complex) and how these are influenced by individual and environmental characteristics (sea surface temperature, chlorophyll a concentration, bathymetry, salinity, and Ekman transport). This study is based on GPS and accelerometer-recorded information from a breeding group of 59 Black-vented Shearwater and examine consistency in diving behavior at both individual and sex levels across four different breeding seasons. The species was found to be the best performing free diver in the Puffinus genus with a maximum dive duration of 88 s. Among the environmental variables assessed, a relationship was found with active upwelling conditions enhancing low energetic cost diving, on the contrary, reduced upwelling and warmer superficial waters induce more energetically demanding diving affecting diving performance and ultimately body conditions. The body conditions of Black-vented Shearwaters in 2016 were worse than in subsequent years, in 2016, deepest and longest complex dives were recorded, while simple dives were longer in 2017-2019. Nevertheless, the species' plasticity allows at least part of the population to breed and feed during warmer events. While carry-over effects have already been reported, the effect of more frequent warm events is still unknown.
... The inclusion of Bedolla-Guzmán et al. 2019 should await more definite results, restoration programs require an independent evaluation. This reference reports erroneous population estimates, particularly for the Black-vented Shearwater (Puffinus ophistomelas) on Natividad Island, see Albores- Barajas et al. 2018. Furthermore, the eradication of introduced predators in several sites has not been achieved (Albores-Barajas et al. 2020), and complete reproductive failure coincident with intrusive monitoring has been observed in Townsend's Shearwater (Puffinus auricularis) burrows (Hernández-Mendoza 2019). ...
... reducing costs, improving efficiency, and minimizing the occurrence of human errors. In their study of black-vented shearwater (Puffinus opisthomelas) burrows, Albores- Barajas et al. (2018) note that it took them a total of 20 working days and two dedicated staff members to identify all the burrows in their aerial imagery. Incorporating a semi-automated methodology using OBIA techniques like those we implemented would almost certainly reduce the time spent looking for burrows and would reduce the number of staff members required to conduct the survey. ...
Remote sensing has long been used to study wildlife; however, manual methods of detecting wildlife in aerial imagery are often time-consuming and prone to human error, and newer computer vision techniques have not yet been extensively applied to wildlife surveys. We used the object-based image analysis (OBIA) software eCognition to detect laughing gull (Leucophaeus atricilla) nests in Jamaica Bay as part of an ongoing monitoring effort at the John F. Kennedy International Airport. Our technique uses a combination of high resolution 4-band aerial imagery captured via manned aircraft with a multispectral UltraCam Falcon M2 camera, LiDAR point cloud data, and land cover data derived from a bathymetric LiDAR point cloud to classify and extract laughing gull nests. Our ruleset uses the site (topographic position of nest objects), tone (spectral characteristic of nest objects), shape, size, and association (nearby objects commonly found with the objects of interest that help identify them) elements of image interpretation, as well as NDVI and a sublevel object examination to classify and extract nests. The ruleset achieves a producer’s accuracy of 98% as well as a user’s accuracy of 65% and a kappa of 0.696, indicating that it extracts a majority of the nests in the imagery while reducing errors of commission to only 35% of the final results. The remaining errors of commission are difficult for the software to differentiate without also impacting the number of nests successfully extracted and are best addressed by a manual verification of output results as part of a semi-automated workflow in which the OBIA is used to complete the initial search of the imagery and the results are then systematically verified by the user to remove errors. This eliminates the need to manually search entire sets of imagery for nests, resulting in a much more efficient and less error prone methodology than previous unassisted image interpretation techniques. Because of the extensibility of OBIA software and the increasing availability of imagery due to small unmanned aircraft systems (sUAS), our methodology and its benefits have great potential for adaptation to other species surveyed using aerial imagery to enhance wildlife population monitoring. © This work was authored as part of the Contributor’s official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no
... However, these studies were conducted in areas where the burrows could be directly recognized in images, were limited to vertebrates, and focused on single species. The burrows were then mapped using image segmentation [25] or classification approaches [17,[26][27][28]. The detection success predominantly depended on the vegetation density and height. ...
Burrowing animals are important ecosystem engineers affecting soil properties, as their burrowing activity leads to the redistribution of nutrients and soil carbon sequestration. The magnitude of these effects depends on the spatial density and depth of such burrows, but a method to derive this type of spatially explicit data is still lacking. In this study, we test the potential of using consumer-oriented UAV RGB imagery to determine the density and depth of holes created by burrowing animals at four study sites along a climate gradient in Chile, by combining UAV data with empirical field plot observations and machine learning techniques. To enhance the limited spectral information in RGB imagery, we derived spatial layers representing vegetation type and height and used landscape textures and diversity to predict hole parameters. Across-site models for hole density generally performed better than those for depth, where the best-performing model was for the invertebrate hole density (R² = 0.62). The best models at individual study sites were obtained for hole density in the arid climate zone (R² = 0.75 and 0.68 for invertebrates and vertebrates, respectively). Hole depth models only showed good to fair performance. Regarding predictor importance, the models heavily relied on vegetation height, texture metrics, and diversity indices.
... Aerial photography (Albores- Barajas et al., 2018), strip transects (e.g. Parker et al., 2017), plots (e.g. ...
Population estimates are commonly generated and used in conservation science. All estimates carry inherent uncertainty, but little attention has been given to when and how this uncertainty limits their use. This requires an understanding of the specific purposes for which population estimates are intended, an assessment of the level of uncertainty each purpose can tolerate, and information on current uncertainty.
We conducted a review and meta‐analysis for a widespread group of seabirds, the petrels, to better understand how and why population estimates are being used. Globally petrels are highly threatened, and aspects of their ecology make them difficult to survey, introducing high levels of uncertainty into population estimates.
We found that by far the most common intended use of population estimates was to inform status and trend assessments, while less common uses were trialling methods to improve estimates and assessing threat impacts and conservation outcomes.
The mean coefficient of variation for published estimates was 0.17 (SD = 0.14), with no evidence that uncertainty has been reduced through time. As a consequence of this high uncertainty, when we simulated declines equivalent to thresholds commonly used to trigger management, only 5% of studies could detect significant differences between population estimates collected 10 years apart for populations declining at a rate of 30% over three generations.
Reporting of uncertainty was variable with no dispersion statistics reported with 38% of population estimates and most not reporting key underlying parameters: nest numbers/density and nest occupancy. We also found no correlation between uncertainty in petrel population estimates and either island size, body size or species threat status – potential predictors of uncertainty.
Key recommendations for managers are to be mindful of uncertainty in past population estimates if aiming to collect contemporary estimates for comparison, to report uncertainty clearly for new estimates, and to give careful consideration to whether a proposed estimate is likely to achieve the requisite level of certainty for the investment in its generation to be warranted. We recommend a practitioner‐based value of information assessment to confirm where there is value in reducing uncertainty.
... Additional categories: advanced habitat-area models that used randomised burrow surveys and extrapolation of burrows based upon multiple environmental variables rather than simple habitat layers; informed guess (not included in the meta-analysis). Estimating burrow numbers/density Aerial photography (Albores- Barajas et al., 2018); strip transects (e.g. Parker et al., 2017); plots (e.g. ...
Population estimates are commonly generated and used in conservation science. All estimates carry inherent uncertainty, but little attention has been given to when and how this uncertainty limits their use. This requires an understanding of the specific purposes for which population estimates are intended, an assessment of the level of uncertainty each purpose can tolerate, and information on current uncertainty.
We conducted a review and meta-analysis for a widespread group of seabirds, the petrels, to better understand how and why population estimates are being used. Globally petrels are highly threatened, and aspects of their ecology make them difficult to survey, introducing high levels of uncertainty into population estimates.
We found that by far the most common intended use of population estimates was to inform status and trend assessments, while less common uses were trialling methods to improve estimates, and assessing threat impacts and conservation outcomes.
The mean coefficient of variation for published estimates was 0.17 (SD = 0.14), with no evidence that uncertainty has been reduced through time. As a consequence of this high uncertainty, when we simulated declines equivalent to thresholds commonly used to trigger management, only 5% of studies could detect significant differences between population estimates collected 10 years apart for populations declining at a rate of 30% over three generations.
Reporting of uncertainty was variable with no dispersion statistics reported with 38% of population estimates and most not reporting key underlying parameters: nest numbers/density and nest occupancy. We also found no correlation between population estimates and either island size, body size or species threat status—potential predictors of uncertainty.
Synthesis and applications —Key recommendations for managers are to be mindful of uncertainty in past population estimates if aiming to collect contemporary estimates for comparison, to report uncertainty clearly for new estimates, and to give careful consideration to whether a proposed estimate is likely to achieve the requisite level of certainty for the investment in its generation to be warranted. We recommend a practitioner-based Value of Information assessment to confirm where there is value in reducing uncertainty.
... Entre las bondades de esta herramienta se destaca su uso para la obtención de datos más precisos y confiables sobre la distribución, abundancia y densidad de fauna silvestre utilizando imágenes aéreas sobre grandes extensiones de terreno o ambientes de difícil acceso donde la vegetación o las características del mismo dificultan la observación de los animales así como sus nidos o madrigueras. También han demostrado ser útiles para realizar conteos de especies con comportamiento esquivo a la presencia humana o que se agrupan en grandes números para reproducirse lo que dificulta su conteo exacto (Potapov et al. 2013, Vermeulen et al. 2013, Evans et al 2016, Hodgson et al. 2016, Wich et al. 2016, Adame et al. 2017, Albores-Barajas et al. 2018. A esta tecnología se suma el uso de cámaras térmicas que hacen más evidentes a los organismos aumentando de esta forma la capacidad de detección tanto para el ojo humano como para métodos computacionales de detección automática y análisis (Israel 2011,Chrétien et al. 2015, Chabot y Francis 2016, Spaan et al. 2019. ...
... Además se ha observado que el uso de cámaras infrarrojas mejoran la detección humana, especialmente en los momentos más fríos del día, aunque esto se ve limitado significativamente cuando la cobertura de Para el caso del Lobo Marino de California (Zalophus californianus) se ha observado que los conteos realizados con VANTs son más precisos que aquellos realizados de modo tradicional, y con base en modelos aditivos generalizados se encontró que los conteos tradicionales pierden aproximadamente un tercio de los lobos marinos de todas las clases de edad (crías, juveniles, subadultos y adultos) presentes en la colonia (Fig. 1), incluso más en el caso de las crías (Adame 2016, Adame et al. 2017 Con aves, se han realizado censos de Pardela Mexicana (Puffinus opisthomelas), ave marina de hábitos nocturnos que anida en madrigueras y es considerada como "casi amenazada" por el bajo número colonias reproductivas presentes en islas y la introducción de gatos en las mismas. Dado que la presencia humana puede crear disturbios en sus sitios de anidación y destruir sus madrigueras se ha observado que el uso de fotografías aéreas tomadas desde VANTs ( Fig. 2) es una buena opción para estimar el tamaño de la población con un error de detección muy bajo (5,6%), siendo esta una metodología fácil de replicar para otras especies que anidan en madrigueras en hábitats sin cobertura vegetal densa (Alcalá-Santoyo 2018, Albores- Barajas et al. 2018). También se realizaron estudios de aves zancudas (ibis y garzas) que utilizan los manglares próximos a la ciudad de La Paz, encontrando que el uso de fotografías obtenidas con VANTs es una herramienta de monitoreo de bajo disturbio que permite observar tanto aves como nidos en áreas de difícil acceso dentro del manglar (Fig. 3), además de que ha mostrado ser un instrumento poderoso para el seguimiento de los cambios espaciales y temporales de los atributos poblacionales de las aves que utilizan los manglares como área de descanso y anidación (Arreola-García 2019). ...
En la última década la irrupción de los vehículos aéreos no tripulados (VANTs) o drones ha transformado y revolucionado las ciencias ambientales frente a los métodos tradicionales, creando una nueva frontera del conocimiento al mejorar la calidad y la obtención de los datos de campo. Entre las bondades de esta herramienta se destaca su uso para la obtención de datos más precisos y confiables sobre la distribución, abundancia y densidad de fauna silvestre.
... Tryjanowski et al. 2009, Kosicki 2010. Because the use of drones may help by saving a large proportion of time spent on fieldwork, it may soon become a common tool in bird studies, especially for open-nesters, but recent data also even suggest a use for burrow nesting seabirds (Albores- Barajas et al. 2018). We believe that drones will soon become an important and common tool in the research on White Stork for determining hatching or breeding success and species protection such as monitoring nests for hazards, e.g. ...
Due to their falling cost, unmanned aerial vehicles, often called drones, are increasingly used as a tool in bird research and conservation. However, behavioural responses of birds to flying drones are still not well understood, for example do birds recognize drones as predators, as benign, or as neutral elements? How do they react to drones? We answered these questions and described the behaviour of birds toward drones during a study with White Stork Ciconia ciconia in north-eastern Poland. We used a small quadrocopter and noted flight initiation distances (FID) of adult storks on nests and behavioural reactions of their young towards drones. During nest inspections by drone, adult WhiteStorks showed FIDs of between 1 and 20 metres, but occasionally did not even flush during drone approaches. FID was mainly affected by breeding stage, but some storks even ignored the working drones close to the nest (14%). Birds that escaped from the nest at the egg stage, returned to it on average within 23 seconds. The most common reactions of young White Storks to the drone were scaring (42%) and akinesis (34%). The rapid return of adult storks to the nest,even when scared away, shows that drones are not an highly invasive tool for examining their breeding outputs, even during the most sensitive period, i.e. egg stage. We believe that drones will soon become an important and common tool in research of the White Stork for determining breeding success and examining nests for hazards, e.g. waste, strings or electrocution risk. Our research can be a useful guide to researchers for predicting stork behaviour during inspection of their nests in the near future.
