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Drones for Biodiversity Conservation
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Drones for Biodiversity Conservation

A special issue of Drones (ISSN 2504-446X). This special issue belongs to the section "Drones in Ecology".

Deadline for manuscript submissions: closed (30 September 2022) | Viewed by 66870

Special Issue Editors

Dr. Margarita Mulero-Pazmany

E-Mail Website
Guest Editor
Department of Animal Biology, University of Malaga, 29010 Malaga, Spain
Interests: drones; biological conservation; wildlife; ecology
Special Issues, Collections and Topics in MDPI journals
Dr. Barbara Bollard

E-Mail Website
Guest Editor
Drone Lab, Auckland University of Technology, 55 Wellesley Street East, Auckland CBD, Auckland 1010, New Zealand
Interests: conservation planning; unmanned aerial vehicles; multi and hyperspectral imaging; marine mammal; habitat modelling; object recognition; spatial ecology; multitemporal remote sensing
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

In recent years, biodiversity loss has been taking place globally and at an unprecedented pace. There is an urgent need to collect basic data on plants’ and animals’ abundance and distribution that will eventually help to understand the changes that are taking place. Ecologists, conservationists, and wildlife managers are increasingly keen to incorporate new technologies that allow gathering field data in efficient and cost-effective ways. Drones (unmanned aircraft systems (UAS)) equipped with visible, thermal or multispectral cameras that provide high spatiotemporal resolution information have recently become popular tools for conducting surveys, assessing the state of ecosystems, and assessing the effects of environmental changes.

This Special Issue aims at bringing together scientists, developers, and advanced users who apply drone technology for biodiversity studies. We would like to invite you to contribute by submitting articles on your recent research, experimental work, reviews, and case studies related to drone applications to:

  • Wildlife and plant surveys/census
  • Wildlife management
  • Habitat monitoring
  • Invasive species
  • Drones for sampling
  • Combining drones with other technologies for biodiversity monitoring
  • Social implications of drones’ use for biodiversity studies
  • Good practices for using drones in natural areas

Dr. Margarita Mulero-Pazmany
Dr. Barbara Bollard
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Drones is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (16 papers)

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Research

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21 pages, 3209 KiB  
Article
Experimentally Determining Optimal Conditions for Mapping Forage Fish with RPAS
by Nicola R. Houtman, Jennifer Yakimishyn, Mike Collyer, Jennifer Sutherst, Cliff L. K. Robinson and Maycira Costa
Drones 2022, 6(12), 426; https://doi.org/10.3390/drones6120426 - 17 Dec 2022
Viewed by 1339
Abstract
RPAS (Remotely piloted aircraft systems, i.e., drones) present an efficient method for mapping schooling coastal forage fish species that have limited distribution and abundance data. However, RPAS imagery acquisition in marine environments is highly dependent on suitable environmental conditions. Additionally, the size, color [...] Read more.
RPAS (Remotely piloted aircraft systems, i.e., drones) present an efficient method for mapping schooling coastal forage fish species that have limited distribution and abundance data. However, RPAS imagery acquisition in marine environments is highly dependent on suitable environmental conditions. Additionally, the size, color and depth of forage fish schools will impact their detectability in RPAS imagery. In this study, we identified optimal and suboptimal coastal environmental conditions through a controlled experiment using a model fish school containing four forage fish-like fishing lures. The school was placed at 0.5 m, 1.0 m, 1.5 m, and 2.0 m depths in a wide range of coastal conditions and then we captured RPAS video imagery. The results from a cluster analysis, principal components, and correlation analysis of RPAS data found that the optimal conditions consisted of moderate sun altitudes (20–40°), glassy seas, low winds (<5 km/h), clear skies (<10% cloud cover), and low turbidity. The environmental conditions identified in this study will provide researchers using RPAS with the best criteria for detecting coastal forage fish schools. Full article
(This article belongs to the Special Issue Drones for Biodiversity Conservation)
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14 pages, 2738 KiB  
Article
Vegetation Cover Estimation in Semi-Arid Shrublands after Prescribed Burning: Field-Ground and Drone Image Comparison
by Antonio J. Pérez-Luque, María Eugenia Ramos-Font, Mauro J. Tognetti Barbieri, Carlos Tarragona Pérez, Guillermo Calvo Renta and Ana Belén Robles Cruz
Drones 2022, 6(11), 370; https://doi.org/10.3390/drones6110370 - 21 Nov 2022
Cited by 2 | Viewed by 2881
Abstract
The use of drones for vegetation monitoring allows the acquisition of large amounts of high spatial resolution data in a simple and fast way. In this study, we evaluated the accuracy of vegetation cover estimation by drones in Mediterranean semi-arid shrublands (Sierra de [...] Read more.
The use of drones for vegetation monitoring allows the acquisition of large amounts of high spatial resolution data in a simple and fast way. In this study, we evaluated the accuracy of vegetation cover estimation by drones in Mediterranean semi-arid shrublands (Sierra de Filabres; Almería; southern Spain) after prescribed burns (2 years). We compared drone-based vegetation cover estimates with those based on traditional vegetation sampling in ninety-six 1 m2 plots. We explored how this accuracy varies in different types of coverage (low-, moderate- and high-cover shrublands, and high-cover alfa grass steppe); as well as with diversity, plant richness, and topographic slope. The coverage estimated using a drone was strongly correlated with that obtained by vegetation sampling (R2 = 0.81). This estimate varied between cover classes, with the error rate being higher in low-cover shrublands, and lower in high-cover alfa grass steppe (normalized RMSE 33% vs. 9%). Diversity and slope did not affect the accuracy of the cover estimates, while errors were larger in plots with greater richness. These results suggest that in semi-arid environments, the drone might underestimate vegetation cover in low-cover shrublands. Full article
(This article belongs to the Special Issue Drones for Biodiversity Conservation)
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14 pages, 2044 KiB  
Article
Terrestrial Megafauna Response to Drone Noise Levels in Ex Situ Areas
by Geison Pires Mesquita, Margarita Mulero-Pázmány, Serge A. Wich and José Domingo Rodríguez-Teijeiro
Drones 2022, 6(11), 333; https://doi.org/10.3390/drones6110333 - 30 Oct 2022
Cited by 2 | Viewed by 2949
Abstract
Drone use has significantly grown in recent years, and there is a knowledge gap on how the noise produced by these systems may affect animals. We investigated how 18 species of megafauna reacted to drone sound pressure levels at different frequencies. The sound [...] Read more.
Drone use has significantly grown in recent years, and there is a knowledge gap on how the noise produced by these systems may affect animals. We investigated how 18 species of megafauna reacted to drone sound pressure levels at different frequencies. The sound pressure level on the low frequency generated by the drone did not change the studied species’ behavior, except for the Asian elephant. All other studied species showed higher noise sensitivity at medium and high frequencies. The Asian elephant was the most sensitive species to drone noise, mainly at low frequencies. Felines supported the highest sound pressure level before showing behavioral reactions. Our results suggest that drone sound pressure levels in different frequencies cause behavioral changes that differ among species, which is relevant to assessing drone disturbances in ex situ environments. The findings presented here can help to reduce drone impact for target species and serve as an experimental study for future drone use guidelines. Full article
(This article belongs to the Special Issue Drones for Biodiversity Conservation)
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17 pages, 3034 KiB  
Article
Aerial Drone Surveys Reveal the Efficacy of a Protected Area Network for Marine Megafauna and the Value of Sea Turtles as Umbrella Species
by Liam C. D. Dickson, Stuart R. B. Negus, Christophe Eizaguirre, Kostas A. Katselidis and Gail Schofield
Drones 2022, 6(10), 291; https://doi.org/10.3390/drones6100291 - 07 Oct 2022
Cited by 7 | Viewed by 2825
Abstract
Quantifying the capacity of protected area networks to shield multiple marine megafauna with diverse life histories is complicated, as many species are wide-ranging, requiring varied monitoring approaches. Yet, such information is needed to identify and assess the potential use of umbrella species and [...] Read more.
Quantifying the capacity of protected area networks to shield multiple marine megafauna with diverse life histories is complicated, as many species are wide-ranging, requiring varied monitoring approaches. Yet, such information is needed to identify and assess the potential use of umbrella species and to plan how best to enhance conservation strategies. Here, we evaluated the effectiveness of part of the European Natura 2000 protected area network (western Greece) for marine megafauna and whether loggerhead sea turtles are viable umbrella species in this coastal region. We systematically surveyed inside and outside coastal marine protected areas (MPAs) at a regional scale using aerial drones (18,505 animal records) and combined them with distribution data from published datasets (tracking, sightings, strandings) of sea turtles, elasmobranchs, cetaceans and pinnipeds. MPAs covered 56% of the surveyed coastline (~1500 km). There was just a 22% overlap in the distributions of the four groups from aerial drone and other datasets, demonstrating the value of combining different approaches to improve records of coastal area use for effective management. All four taxonomic groups were more likely to be detected inside coastal MPAs than outside, confirming sufficient habitat diversity despite varied life history traits. Coastal habitats frequented by loggerhead turtles during breeding/non-breeding periods combined overlapped with 76% of areas used by the other three groups, supporting their potential use as an umbrella species. In conclusion, this study showed that aerial drones can be readily combined with other monitoring approaches in coastal areas to enhance the management of marine megafauna in protected area networks and to identify the efficacy of umbrella species. Full article
(This article belongs to the Special Issue Drones for Biodiversity Conservation)
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14 pages, 6516 KiB  
Article
Aerial Branch Sampling to Detect Forest Pathogens
by Ryan L. Perroy, Philip Meier, Eszter Collier, Marc A. Hughes, Eva Brill, Timo Sullivan, Thomas Baur, Nina Buchmann and Lisa M. Keith
Drones 2022, 6(10), 275; https://doi.org/10.3390/drones6100275 - 24 Sep 2022
Cited by 5 | Viewed by 2875
Abstract
Diagnostic testing to detect forest pathogens requires the collection of physical samples from affected trees, which can be challenging in remote or rugged environments. As an alternative to traditional ground-based sampling at breast height by field crews, we examined the feasibility of aerially [...] Read more.
Diagnostic testing to detect forest pathogens requires the collection of physical samples from affected trees, which can be challenging in remote or rugged environments. As an alternative to traditional ground-based sampling at breast height by field crews, we examined the feasibility of aerially sampling and testing material collected from upper canopy branches using a small unoccupied aerial system (sUAS). The pathogen of interest in this study is Ceratocystis lukuohia, the fungal pathogen responsible for Ceratocystis wilt of ‘ōhi‘a, a vascular wilt disease which has caused widespread mortality to ‘ōhi‘a in native forests across the state of Hawai‘i. To characterize the minimum branch diameter needed to successfully detect the pathogen of interest in infected trees, we tested 63 branch samples (0.8–9.6 cm in diameter) collected from felled trees inoculated with C.lukuohia on Hawai‘i Island. Subsequently, we aerially sampled branches from ten symptomatic ‘ōhi‘a (Metrosideros polymorpha) trees using two different branch sampling systems, the Flying Tree Top Sampler from ETH Zurich and the new Kūkūau branch sampler system introduced in this work, producing 29 branch samples with a maximum diameter of 4.2 cm and length of >2 m. We successfully detected the target fungal pathogen from the collected branches and found that branch diameter, leaf presence and condition, as well as wood moisture content are important factors in pathogen detection in sampled branches. None of the smallest branch samples (those <1 cm in diameter) tested positive for C.lukuohia, while 77% of the largest diameter branch samples (5–10 cm) produced positive results. The Kūkūau branch sampler system is capable of retrieving branches up to 7 cm diameter, providing important capacity for pathogenic research requiring larger diameter samples for successful diagnostic testing. Inconclusive and/or non-detection laboratory results were obtained from sample materials that were either too desiccated or from a branch with asymptomatic leaves, suggesting there is an optimal temporal window for sampling. Full article
(This article belongs to the Special Issue Drones for Biodiversity Conservation)
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11 pages, 1840 KiB  
Communication
Testing Drones as a Tool for Surveying Lizards
by Joanne M. Monks, Harriet P. Wills and Carey D. Knox
Drones 2022, 6(8), 199; https://doi.org/10.3390/drones6080199 - 09 Aug 2022
Cited by 5 | Viewed by 3340
Abstract
A lack of effective methods for sampling lizards in terrain that is inaccessible to human observers limits our knowledge of their ecology and conservation needs. Drones are increasingly being used in wildlife monitoring, but their potential use for surveying lizards has not been [...] Read more.
A lack of effective methods for sampling lizards in terrain that is inaccessible to human observers limits our knowledge of their ecology and conservation needs. Drones are increasingly being used in wildlife monitoring, but their potential use for surveying lizards has not been evaluated. We investigated: (1) the detectability of model lizards using a drone relative to a human observer, and (2) the response of four lizard species to an approaching drone in three habitat types. Model lizards placed in potential basking positions within a defined search area were detected by both the drone operator and human observer, but the probability of detection was lower with the drone. Jewelled geckos (Naultinus gemmeus) in shrubland and grand skinks (Oligosoma grande) in rocky habitats showed surprisingly little reaction to the approaching drone, enabling close approaches (means of 59 cm and 107 cm, respectively) and accurate species identification with photos taken by the drone camera. For highly patterned jewelled geckos, identification was also possible to individual level. However, the drone was unsuccessful at detecting two alpine skink species in a near-vertical cliff habitat. Collectively, our results suggest that drones have potential as a tool for detecting small-bodied lizards in habitats inaccessible to human observers. Full article
(This article belongs to the Special Issue Drones for Biodiversity Conservation)
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8 pages, 4253 KiB  
Article
Development of a Fixed-Wing Drone System for Aerial Insect Sampling
by Margarita Mulero-Pázmány, J. Ramiro Martínez-de Dios, Ana G. Popa-Lisseanu, Russell J. Gray, Francisco Alarcón, Carlos Albo Sánchez-Bedoya, Antidio Viguria, Carlos Ibáñez, Juan J. Negro, Aníbal Ollero and Pedro J. Marrón
Drones 2022, 6(8), 189; https://doi.org/10.3390/drones6080189 - 28 Jul 2022
Cited by 6 | Viewed by 3470
Abstract
Most current insect research techniques are ground-based and provide scarce information about flying insects in the planetary boundary layer (PBL), which remains a poorly studied ecological niche. To address this gap, we developed a new insect-sampling method consisting of a fixed-wing drone platform [...] Read more.
Most current insect research techniques are ground-based and provide scarce information about flying insects in the planetary boundary layer (PBL), which remains a poorly studied ecological niche. To address this gap, we developed a new insect-sampling method consisting of a fixed-wing drone platform with net traps attached to the fuselage, a mobile design that has optimal aerodynamic characteristics for insect capture in the PBL. We tested the proposed device on 16 flights in Doñana National Park (Spain) with two different trap designs fitted on the fuselage nose and wing. We collected 34 insect specimens belonging to four orders with a representation of twelve families at mean altitudes below 23 m above ground level and sampling altitudes between 9 and 365 m. This drone insect-sampling design constitutes a low-cost and low-impact method for insect monitoring in the PBL, especially in combination with other remote sensing technologies that directly quantify aerial insect abundance but do not provide taxonomic information, opening interesting possibilities for ecology and entomological research, with the possibility of transfer to economically important sectors, such as agriculture and health. Full article
(This article belongs to the Special Issue Drones for Biodiversity Conservation)
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17 pages, 8523 KiB  
Article
Using Drones to Monitor Broad-Leaved Orchids (Dactylorhiza majalis) in High-Nature-Value Grassland
by Kim-Cedric Gröschler and Natascha Oppelt
Drones 2022, 6(7), 174; https://doi.org/10.3390/drones6070174 - 15 Jul 2022
Cited by 2 | Viewed by 1964
Abstract
Dactylorhiza majalis is a threatened indicator species for the habitat quality of nutrient-poor grassland sites. Environmentalists utilize the species to validate the success of conservation efforts. Conventionally, plant surveys are field campaigns where the plant numbers are estimated and their spatial distribution is [...] Read more.
Dactylorhiza majalis is a threatened indicator species for the habitat quality of nutrient-poor grassland sites. Environmentalists utilize the species to validate the success of conservation efforts. Conventionally, plant surveys are field campaigns where the plant numbers are estimated and their spatial distribution is either approximated by GPS or labor-intensively measured by differential GPS. In this study, we propose a monitoring approach using multispectral drone-based data with a very high spatial resolution (~3 cm). We developed the magenta vegetation index to enhance the spectral response of Dactylorhiza majalis in the drone data. We integrated the magenta vegetation index in a random forest classification routine among other vegetation indices and analyzed feature impact on model decision making using SHAP. We applied an image object-level median filter to the classification result to account for image artefacts. Finally, we aggregated the filtered result to individuals per square meter using an overlaying vector grid. The SHAP analysis showed that magenta vegetation index had the highest impact on model decision making. The random forest model could reliably classify Dactylorhiza majalis in the drone data (F1 score: 0.99). We validated the drone-derived plant count using field mappings and achieved good results with an RMSE of 12 individuals per square meter, which is within the error margin stated by experts for a conventional plant survey. In addition to abundance, we revealed the comprehensive spatial distribution of the plants. The results indicate that drone surveys are a suitable alternative to conventional monitoring because they can aid in evaluating conservation efforts and optimizing site-specific management. Full article
(This article belongs to the Special Issue Drones for Biodiversity Conservation)
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12 pages, 1561 KiB  
Article
Using Drones to Assess Volitional Swimming Kinematics of Manta Ray Behaviors in the Wild
by Vicky Fong, Sarah L. Hoffmann and Jessica H. Pate
Drones 2022, 6(5), 111; https://doi.org/10.3390/drones6050111 - 28 Apr 2022
Cited by 1 | Viewed by 3426
Abstract
Drones have become increasingly popular tools to study marine megafauna but are underutilized in batoid research. We used drones to collect video data of manta ray (Mobula cf. birostris) swimming and assessed behavior-specific kinematics in Kinovea, a semi-automated point-tracking software. We [...] Read more.
Drones have become increasingly popular tools to study marine megafauna but are underutilized in batoid research. We used drones to collect video data of manta ray (Mobula cf. birostris) swimming and assessed behavior-specific kinematics in Kinovea, a semi-automated point-tracking software. We describe a ‘resting’ behavior of mantas making use of strong currents in man-made inlets in addition to known ‘traveling’ and ‘feeding’ behaviors. No significant differences were found between the swimming speed of traveling and feeding behaviors, although feeding mantas had a significantly higher wingbeat frequency than traveling mantas. Resting mantas swam at a significantly slower speed and wingbeat frequency, suggesting that they were continuously swimming with the minimum effort required to maintain position and buoyancy. Swimming speed and wingbeat frequency of traveling and feeding behaviors overlapped, which could point to other factors such as prey availability and a transitional behavior, influencing how manta rays swim. These baseline swimming kinematic data have valuable applications to other emerging technologies in manta ray research. Full article
(This article belongs to the Special Issue Drones for Biodiversity Conservation)
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19 pages, 12394 KiB  
Article
Detection of Forest Tree Losses in Côte d’Ivoire Using Drone Aerial Images
by Tiodionwa Abdoulaye Ouattara, Valère-Carin Jofack Sokeng, Irié Casimir Zo-Bi, Koffi Fernand Kouamé, Clovis Grinand and Romuald Vaudry
Drones 2022, 6(4), 83; https://doi.org/10.3390/drones6040083 - 25 Mar 2022
Cited by 8 | Viewed by 4578
Abstract
The fight against deforestation and forest degradation is now a major challenge for the preservation of global forest ecosystems. The remote sensing forest monitoring methods that are currently deployed are not always adapted to the Ivorian context because of the high cloud cover, [...] Read more.
The fight against deforestation and forest degradation is now a major challenge for the preservation of global forest ecosystems. The remote sensing forest monitoring methods that are currently deployed are not always adapted to the Ivorian context because of the high cloud cover, diversity of shaded crops, and land clearing techniques. This study proposes a drone-based approach to assess intra-annual tree losses in the Bossématié classified forest. The method used is based on a detection analysis of tree losses in forest areas from a time series of aerial images acquired by drones from November 2018 to April 2019 on five sites in the studied forest. Based on photogrammetric models and photointerpretation, tree heights and tree crown sizes were estimated. Then, tree losses were detected based on the variation of tree heights during the study period. An analysis of the distribution of tree heights in Bossématié classified forest reveals that the maximum tree height was 65.06 m in November 2018 and 64.07 m in April 2019 with an average tree height of 34.29–37.00 m in November 2018 and 34.63–36.88 m in April 2019. The average tree crown area, meanwhile, was estimated to be 152 m². With an estimation accuracy of about 97%, these tree structural data indicate a minimum loss of 107 trees corresponding to a clearing area of 2 ha across all the surveyed sites from November 2018 to April 2019. This forest monitoring approach shows a considerable local loss of biodiversity and should be involved in the implementation of preservation, rehabilitation, and deployment strategies in an operational deforestation monitoring system in Côte d’Ivoire. Full article
(This article belongs to the Special Issue Drones for Biodiversity Conservation)
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14 pages, 1561 KiB  
Article
Drone Surveys Are More Accurate Than Boat-Based Surveys of Bottlenose Dolphins (Tursiops truncatus)
by Ticiana Fettermann, Lorenzo Fiori, Len Gillman, Karen A. Stockin and Barbara Bollard
Drones 2022, 6(4), 82; https://doi.org/10.3390/drones6040082 - 25 Mar 2022
Cited by 15 | Viewed by 6055
Abstract
Generating accurate estimates of group sizes or behaviours of cetaceans from boat-based surveys can be challenging because much of their activity occurs below the water surface and observations are distorted by horizontal perspectives. Automated observation using drones is an emerging research tool for [...] Read more.
Generating accurate estimates of group sizes or behaviours of cetaceans from boat-based surveys can be challenging because much of their activity occurs below the water surface and observations are distorted by horizontal perspectives. Automated observation using drones is an emerging research tool for animal behavioural investigations. However, drone-based and boat-based survey methods have not been quantitatively compared for small, highly mobile cetaceans, such as Delphinidae. Here, we conduct paired concurrent boat-based and drone-based surveys, measuring the number of individuals in 21 groups and the behaviour within 13 groups of bottlenose dolphin (Tursiops truncatus). We additionally assessed the ability to detect behaviour events by the drone that would not be detectable from the boat. Drone-derived abundance counts detected 26.4% more individuals per group on average than boat-based counts (p = 0.003). Drone-based behaviour observations detected travelling 55.2% more frequently and association in subgroups 80.4% more frequently than boat-based observations (p < 0.001 for both comparisons). Whereas foraging was recorded 58.3% and resting 15.1% less frequently by the drone than by boat-based surveys, respectively (p = 0.014 and 0.024). A considerable number of underwater behaviours ranging from individual play activities to intra- and inter-species interactions (including those with humans) were observed from the drone that could not be detected from the boat. Our findings demonstrate that drone surveys can improve the accuracy of population counts and behavioural data for small cetaceans and the magnitude of the discrepancies between the two methods highlights the need for cautious interpretation of studies that have relied on boat-derived data. Full article
(This article belongs to the Special Issue Drones for Biodiversity Conservation)
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10 pages, 2711 KiB  
Article
Drone Observations of Marine Life and Human–Wildlife Interactions off Sydney, Australia
by Vanessa Pirotta, David P. Hocking, Jason Iggleden and Robert Harcourt
Drones 2022, 6(3), 75; https://doi.org/10.3390/drones6030075 - 11 Mar 2022
Cited by 9 | Viewed by 7263
Abstract
Drones have become popular with the general public for viewing and filming marine life. One amateur enthusiast platform, DroneSharkApp, films marine life in the waters off Sydney, Australia year-round and posts their observations on social media. The drone observations include the behaviours of [...] Read more.
Drones have become popular with the general public for viewing and filming marine life. One amateur enthusiast platform, DroneSharkApp, films marine life in the waters off Sydney, Australia year-round and posts their observations on social media. The drone observations include the behaviours of a variety of coastal marine wildlife species, including sharks, rays, fur seals, dolphins and fish, as well as migratory species such as migrating humpback whales. Given the extensive effort and multiple recordings of the presence, behaviour and interactions of various species with humans provided by DroneSharkApp, we explored its utility for providing biologically meaningful observations of marine wildlife. Using social media posts from the DroneSharkApp Instagram page, a total of 678 wildlife videos were assessed from 432 days of observation collected by a single observer. This included 94 feeding behaviours or events for fur seals (n = 58) and dolphins (n = 33), two feeding events for white sharks and one feeding event for a humpback whale. DroneSharkApp documented 101 interactions with sharks and humans (swimmers and surfers), demonstrating the frequent, mainly innocuous human–shark overlap off some of Australia’s busiest beaches. Finally, DroneSharkApp provided multiple observations of humpback and dwarf minke whales with calves travelling north, indicating calving occurring well south of traditional northern Queensland breeding waters. Collaboration between scientists and citizen scientists such as those involved with DroneSharkApp can greatly and quantitatively increase the biological understanding of marine wildlife data. Full article
(This article belongs to the Special Issue Drones for Biodiversity Conservation)
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19 pages, 4138 KiB  
Article
How Big Is That Manta Ray? A Novel and Non-Invasive Method for Measuring Reef Manta Rays Using Small Drones
by Edy Setyawan, Ben C. Stevenson, Muhamad Izuan, Rochelle Constantine and Mark V. Erdmann
Drones 2022, 6(3), 63; https://doi.org/10.3390/drones6030063 - 28 Feb 2022
Cited by 14 | Viewed by 8813
Abstract
This study explores the application of small, commercially available drones to determine morphometric the measurements and record key demographic parameters of reef manta rays (Mobula alfredi) in Raja Ampat, Indonesia. DJI Mavic 2 Pro drones were used to obtain videos of [...] Read more.
This study explores the application of small, commercially available drones to determine morphometric the measurements and record key demographic parameters of reef manta rays (Mobula alfredi) in Raja Ampat, Indonesia. DJI Mavic 2 Pro drones were used to obtain videos of surface-feeding M. alfredi with a floating, known-length PVC pipe as a reference scale—thus avoiding the need to utilize altitude readings, which are known to be unreliable in small drones, in our photogrammetry approach. Three dimensions (disc length (DL), disc width (DW), and cranial width (CW)) from 86 different individuals were measured. A hierarchical multivariate model was used to estimate the true measurements of these three dimensions and their population-level multivariate distributions. The estimated true measurements of these dimensions were highly accurate and precise, with the measurement of CW more accurate than that of DL and, especially, of DW. Each pairing of these dimensions exhibited strong linear relationships, with estimated correlation coefficients ranging from 0.98–0.99. Given these, our model allows us to accurately calculate DW (as the standard measure of body size for mobulid rays) using the more accurate CW and DL measurements. We estimate that the smallest mature M. alfredi of each sex we measured were 274.8 cm (males, n = 30) and 323.5 cm DW (females, n = 8). We conclude that small drones are useful for providing an accurate “snapshot” of the size distribution of surface-feeding M. alfredi aggregations and for determining the sex and maturity of larger individuals, all with minimal impact on this vulnerable species. Full article
(This article belongs to the Special Issue Drones for Biodiversity Conservation)
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11 pages, 4257 KiB  
Communication
Drone Technology for Monitoring Protected Areas in Remote and Fragile Environments
by Barbara Bollard, Ashray Doshi, Neil Gilbert, Ceisha Poirot and Len Gillman
Drones 2022, 6(2), 42; https://doi.org/10.3390/drones6020042 - 09 Feb 2022
Cited by 21 | Viewed by 6505
Abstract
Protected Areas are established to protect significant ecosystems and historical artefacts. However, many are subject to little structured monitoring to assess whether the attributes for which they have been protected are being maintained or degraded. Monitoring sensitive areas using ground surveys risks causing [...] Read more.
Protected Areas are established to protect significant ecosystems and historical artefacts. However, many are subject to little structured monitoring to assess whether the attributes for which they have been protected are being maintained or degraded. Monitoring sensitive areas using ground surveys risks causing damage to the values for which they are being protected, are usually based on limited sampling, and often convey insufficient detail for understanding ecosystem change. Therefore, there is a need to undertake quick and accurate vegetation surveys that are low impact, cost effective and repeatable with high precision. Here we use drone technology to map protected areas in Antarctica to ultra-high resolution and provide baseline data for future monitoring. Our methods can measure micro-scale changes, are less expensive than ground-based sampling and can be applied to any protected area where fine scale monitoring is desirable. Drone-based surveys should therefore become standard practice for protected areas in remote fragile environments. Full article
(This article belongs to the Special Issue Drones for Biodiversity Conservation)
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11 pages, 2636 KiB  
Article
Surveys of Large Waterfowl and Their Habitats Using an Unmanned Aerial Vehicle: A Case Study on the Siberian Crane
by Ding Wen, Lei Su, Yuanman Hu, Zaiping Xiong, Miao Liu and Yingxian Long
Drones 2021, 5(4), 102; https://doi.org/10.3390/drones5040102 - 23 Sep 2021
Cited by 9 | Viewed by 2819
Abstract
Waterfowl surveys, especially for endangered waterfowl living in wetlands, are essential to protect endangered waterfowl and to create a management scenario of their habitats. Unmanned aerial vehicles (UAVs) are powerful new tools for waterfowl surveys. In this paper, we propose one method for [...] Read more.
Waterfowl surveys, especially for endangered waterfowl living in wetlands, are essential to protect endangered waterfowl and to create a management scenario of their habitats. Unmanned aerial vehicles (UAVs) are powerful new tools for waterfowl surveys. In this paper, we propose one method for a habitat survey and another for a waterfowl species distribution survey. The habitat survey method obtained the waterfowl’s habitat and spatial distribution with a UAV automatic flight plan in the aggregation area. The waterfowl species distribution survey was used to detect and identify waterfowl species with high-spatial-resolution images from a free UAV flight plan in the aggregation area or areas where individuals were suspected to be present. The UAV-based data showed not only the area where waterfowl were found, but also additional ground surveys. The results showed that the species and locations of the waterfowl were recorded more accurately and efficiently using the distribution method based on the images from the UAV. The waterfowl habitat type and the number of waterfowl were obtained in detail using the habitat survey method. UAV-derived counts of waterfowl were greater (+37%) than ground counts. The results indicated the feasibility and advantages of using a low-cost UAV survey of large waterfowl in wetland regions with complex vegetation. This study provides one case study of large waterfowl numbers and habitat surveys. The UAV-based methods also provide a feasible and scientific way to obtain basic data for the protection and management of waterfowl. Full article
(This article belongs to the Special Issue Drones for Biodiversity Conservation)
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Review

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21 pages, 775 KiB  
Review
Unmanned Aerial Vehicles (UAVs) in Marine Mammal Research: A Review of Current Applications and Challenges
by Miguel Álvarez-González, Paula Suarez-Bregua, Graham J. Pierce and Camilo Saavedra
Drones 2023, 7(11), 667; https://doi.org/10.3390/drones7110667 - 09 Nov 2023
Viewed by 3151
Abstract
Research on the ecology and biology of marine mammal populations is necessary to understand ecosystem dynamics and to support conservation management. Emerging monitoring tools and instruments offer the opportunity to obtain such information in an affordable and effective way. In recent years, unmanned [...] Read more.
Research on the ecology and biology of marine mammal populations is necessary to understand ecosystem dynamics and to support conservation management. Emerging monitoring tools and instruments offer the opportunity to obtain such information in an affordable and effective way. In recent years, unmanned aerial vehicles (UAVs) have become an important tool in the study of marine mammals. Here, we reviewed 169 research articles using UAVs to study marine mammals, published up until December 2022. The goals of these studies included estimating the number of individuals in populations and groups via photo-identification, determining biometrics and body condition through photogrammetry, collecting blow samples, and studying behavioural patterns. UAVs can be a valuable, non-invasive, and useful tool for a wide range of applications in marine mammal research. However, it is important to consider some limitations of this technology, mainly associated with autonomy, resistance to the marine environment, and data processing time, which could probably be overcome in the near future. Full article
(This article belongs to the Special Issue Drones for Biodiversity Conservation)
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