Research

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26 pages, 3820 KiB

Open AccessArticle

Performance Analysis of a Wildlife Tracking CubeSat Mission Extension to Drones and Stratospheric Vehicles

by Paolo Marzioli, Riccardo Garofalo, Lorenzo Frezza, Andrew Nyawade, Giancarlo Santilli, Munzer JahJah, Fabio Santoni and Fabrizio Piergentili

Drones 2024, 8(4), 129; https://doi.org/10.3390/drones8040129 - 29 Mar 2024

Viewed by 458

Abstract

This study presents a performance analysis for an Internet-of-Things wildlife radio-tracking mission using drones, satellites and stratospheric platforms for data relay with Spread Spectrum Modulation devices. The performance analysis is presented with link and data budgets, calculations of the area coverage, an estimation [...] Read more.

This study presents a performance analysis for an Internet-of-Things wildlife radio-tracking mission using drones, satellites and stratospheric platforms for data relay with Spread Spectrum Modulation devices. The performance analysis is presented with link and data budgets, calculations of the area coverage, an estimation of the time resolution and allowable data amount of each collar, a power and energy budget and consequent battery pack and collar weight estimations, cost budgets, and considerations on synergetic approaches to incorporate more mission segments together. The paper results are detailed with example species to target with each collar weight range, and with design drivers and guidelines to implement improved mission segments. Full article

(This article belongs to the Special Issue Drone Advances in Wildlife Research)

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12 pages, 5288 KiB

Open AccessFeature PaperArticle

Using YOLO Object Detection to Identify Hare and Roe Deer in Thermal Aerial Video Footage—Possible Future Applications in Real-Time Automatic Drone Surveillance and Wildlife Monitoring

by Peter Povlsen, Dan Bruhn, Petar Durdevic, Daniel Ortiz Arroyo and Cino Pertoldi

Drones 2024, 8(1), 2; https://doi.org/10.3390/drones8010002 - 24 Dec 2023

Viewed by 2139

Abstract

Wildlife monitoring can be time-consuming and expensive, but the fast-developing technologies of uncrewed aerial vehicles, sensors, and machine learning pave the way for automated monitoring. In this study, we trained YOLOv5 neural networks to detect points of interest, hare (Lepus europaeus), [...] Read more.

Wildlife monitoring can be time-consuming and expensive, but the fast-developing technologies of uncrewed aerial vehicles, sensors, and machine learning pave the way for automated monitoring. In this study, we trained YOLOv5 neural networks to detect points of interest, hare (Lepus europaeus), and roe deer (Capreolus capreolus) in thermal aerial footage and proposed a method to manually assess the parameter mean average precision (mAP) compared to the number of actual false positive and false negative detections in a subsample. This showed that a mAP close to 1 for a trained model does not necessarily mean perfect detection and provided a method to gain insights into the parameters affecting the trained models’ precision. Furthermore, we provided a basic, conceptual algorithm for implementing real-time object detection in uncrewed aircraft systems equipped with thermal sensors, high zoom capabilities, and a laser rangefinder. Real-time object detection is becoming an invaluable complementary tool for the monitoring of cryptic and nocturnal animals with the use of thermal sensors. Full article

(This article belongs to the Special Issue Drone Advances in Wildlife Research)

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22 pages, 9856 KiB

Open AccessFeature PaperArticle

Using Unoccupied Aerial Systems (UASs) to Determine the Distribution Patterns of Tamanend’s Bottlenose Dolphins (Tursiops erebennus) across Varying Salinities in Charleston, South Carolina

by Nicole Principe, Wayne McFee, Norman Levine, Brian Balmer and Joseph Ballenger

Drones 2023, 7(12), 689; https://doi.org/10.3390/drones7120689 - 26 Nov 2023

Viewed by 2506

Abstract

The Charleston Estuarine System Stock (CESS) of Tamanend’s bottlenose dolphins (Tursiops erebennus) exhibit long-term site fidelity to the Charleston Harbor, and the Ashley, Cooper, and Wando Rivers in Charleston, South Carolina, USA. In the Cooper River, dolphins have been irregularly sighted [...] Read more.

The Charleston Estuarine System Stock (CESS) of Tamanend’s bottlenose dolphins (Tursiops erebennus) exhibit long-term site fidelity to the Charleston Harbor, and the Ashley, Cooper, and Wando Rivers in Charleston, South Carolina, USA. In the Cooper River, dolphins have been irregularly sighted in upper regions where salinity levels are below what is considered preferred dolphin habitat. We conducted unoccupied aerial system (UAS) surveys in high-salinity (>15 parts per thousand) and low-salinity (<15 parts per thousand) regions (n = 8 sites) of the Cooper River and surrounding waters to assess dolphin distribution in terms presence/absence, detection rate, abundance, and density. We also assessed the influence of ecological factors (salinity, water temperature, season, and prey availability) on dolphin distribution. Dolphins were detected at five sites, with higher salinity and water temperature being significant predictors of presence and abundance. Dolphins were detected year-round across high-salinity sites, and were infrequently detected in low-salinity sites during months with warmer water temperatures. The results from this study contribute to the overall understanding of dolphin distribution across various habitats within the Charleston Estuary System and the potential drivers for their movement into low-salinity waters. Full article

(This article belongs to the Special Issue Drone Advances in Wildlife Research)

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21 pages, 3479 KiB

Open AccessFeature PaperArticle

Burrow-Nesting Seabird Survey Using UAV-Mounted Thermal Sensor and Count Automation

by Jacob Virtue, Darren Turner, Guy Williams, Stephanie Zeliadt, Henry Walshaw and Arko Lucieer

Drones 2023, 7(11), 674; https://doi.org/10.3390/drones7110674 - 13 Nov 2023

Viewed by 1911

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Drone Advances in Wildlife Research)

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22 pages, 13840 KiB

Open AccessArticle

Observing Individuals and Behavior of Hainan Gibbons (Nomascus hainanus) Using Drone Infrared and Visible Image Fusion Technology

by Shengshi Li, Guanjun Wang, Hui Zhang and Yonghua Zou

Drones 2023, 7(9), 543; https://doi.org/10.3390/drones7090543 - 22 Aug 2023

Viewed by 1070

Abstract

The Hainan gibbon (Nomascus hainanus) is one of the most endangered primates in the world. Infrared and visible images taken by drones are an important and effective way to observe Hainan gibbons. However, a single infrared or visible image cannot simultaneously [...] Read more.

The Hainan gibbon (Nomascus hainanus) is one of the most endangered primates in the world. Infrared and visible images taken by drones are an important and effective way to observe Hainan gibbons. However, a single infrared or visible image cannot simultaneously observe the movement tracks of Hainan gibbons and the appearance of the rainforest. The fusion of infrared and visible images of the same scene aims to generate a composite image which can provide a more comprehensive description of the scene. We propose a fusion method of infrared and visible images of the Hainan gibbon for the first time, termed Swin-UetFuse. The Swin-UetFuse has a powerful global and long-range semantic information extraction capability, which is very suitable for application in complex tropical rainforest environments. Firstly, the hierarchical Swin Transformer is applied as the encoder to extract the features of different scales of infrared and visible images. Secondly, the features of different scales are fused through the

l_{1}

-norm strategy. Finally, the Swing Transformer blocks and patch-expanding layers are utilized as the decoder to up-sample the fusion features to obtain the fused image. We used 21 pairs of Hainan gibbon datasets to perform experiments, and the experimental results demonstrate that the proposed method achieves excellent fusion performance. The infrared and visible image fusion technology of drones provides an important reference for the observation and protection of the Hainan gibbons. Full article

(This article belongs to the Special Issue Drone Advances in Wildlife Research)

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10 pages, 430 KiB

Open AccessFeature PaperArticle

Routine and Safe Operation of Remotely Piloted Aircraft Systems in Areas with High Densities of Flying Birds

by Karina J. Sorrell, Finella M. E. Dawlings, Claire E. Mackay and Rohan H. Clarke

Drones 2023, 7(8), 510; https://doi.org/10.3390/drones7080510 - 02 Aug 2023

Cited by 2 | Viewed by 2320

Abstract

Remotely Piloted Aircraft Systems (RPASs), or drones, have had a rapid uptake for scientific applications and are proving particularly valuable for data collection in the natural world. The potential for bird strikes presents a real hazard in these settings. While animal welfare is [...] Read more.

Remotely Piloted Aircraft Systems (RPASs), or drones, have had a rapid uptake for scientific applications and are proving particularly valuable for data collection in the natural world. The potential for bird strikes presents a real hazard in these settings. While animal welfare is a primary consideration when planning and executing RPAS operations, the safe operation and return of RPASs is the key to successful flight missions. Here, we asked if RPASs can be routinely and safely implemented to meet data collection requirements in airspaces with high densities of flying birds. We flew quadcopter RPASs over breeding seabird colonies in tropical island settings. A dedicated spotter adjacent to the pilot recorded all interactions between flying seabirds and the RPAS unit while aerial population surveys were being undertaken. Over 600 interactions were recorded for nine species of seabirds. We flew over 100 flights totaling 2104 min in airspace routinely occupied by dense aggregations of seabirds without a single collision. We demonstrate a high capacity to undertake safe and successful RPAS operations in airspaces that contain high densities of flying seabirds. While bird collisions remain possible, such outcomes are clearly rare and should be placed in context with routine disturbances by ground surveys to meet the same objectives. RPASs routinely offer the least invasive method for collecting ecological data compared to traditional field methods and can be undertaken with relatively low risk to the successful completion of the operation. Full article

(This article belongs to the Special Issue Drone Advances in Wildlife Research)

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12 pages, 3152 KiB

Open AccessArticle

A Drone Study of Sociality in the Finless Porpoise Neophocaena asiaeorientalis in the Ariake Sound, Japan

by Naruki Morimura, Akihiro Itahara, James Brooks, Yusuke Mori, Yige Piao, Hiroki Hashimoto and Itsuki Mizumoto

Drones 2023, 7(7), 422; https://doi.org/10.3390/drones7070422 - 25 Jun 2023

Cited by 1 | Viewed by 1306

Abstract

The social structure of animal populations is a fundamental component of their biology, influencing gene flow, habitat use, competition and co-operation around resources, and communication. However, ecological and social relationships can be challenging to describe in most marine mammals, who spend the majority [...] Read more.

The social structure of animal populations is a fundamental component of their biology, influencing gene flow, habitat use, competition and co-operation around resources, and communication. However, ecological and social relationships can be challenging to describe in most marine mammals, who spend the majority of their lives underwater. The finless porpoise (Neophocaena asiaeorientalis) is one such cetacean species with a largely unknown social structure. Recent advances in drone technology enable more systematic surveys, photogrammetry, and photo-identification for diverse animal species. The present study aimed to validate new survey methods and provide a preliminary description of the spatiotemporal distribution of free-ranging finless porpoises in the coastal open-sea area of Ariake Sound, Japan. A vertical take-off and landing (VTOL) drone equipped with an action camera yielded GPS location datasets through line and area surveys, covering a total sea area of 120 km². The results suggest highly flexible and varied aggregation sizes in finless porpoises. Distance analysis across individuals and aggregations revealed a cohesive tendency among groups, compared to solitaries and in pairs. Therefore, the present VTOL drone surveys both elucidated some social aspects of the study population and confirmed the efficacy of these standardized research protocols involving automated, programmed, and repeatable flight missions. Full article

(This article belongs to the Special Issue Drone Advances in Wildlife Research)

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14 pages, 3213 KiB

Open AccessFeature PaperArticle

A Novel Technique for Photo-Identification of the Fin Whale, Balaenoptera physalus, as Determined by Drone Aerial Images

by Eduard Degollada, Natalia Amigó, Seán A. O’Callaghan, Mila Varola, Katia Ruggero and Beatriu Tort

Drones 2023, 7(3), 220; https://doi.org/10.3390/drones7030220 - 22 Mar 2023

Cited by 4 | Viewed by 4947

Abstract

Drones have become a crucial research tool across marine environments over the past decade, being specifically useful in marine mammal research. Fin whales (Balaenoptera physalus) have been monitored feeding along the Catalan coast, Spain (NW Mediterranean), since 2014. To overcome issues [...] Read more.

Drones have become a crucial research tool across marine environments over the past decade, being specifically useful in marine mammal research. Fin whales (Balaenoptera physalus) have been monitored feeding along the Catalan coast, Spain (NW Mediterranean), since 2014. To overcome issues such as the distance between a whale and a research vessel or the lack of distinctive dorsal fin features, an aerial identification technique was developed. It uses the fin whales’ characteristic central chevron pattern (CCP) and blaze, which are clearly visible from an overhead position. A total of 237 individual whales were identified between 2015–2022 in this study area, of which there were 35 interannual recaptures. While the dorsal fin may undergo modifications over time, the CCP and blaze patterns did not naturally alter over the years, with one whale displaying the same characteristics 8 years apart between the first and the most recent sightings. As such, this coloration pattern provides a reliable identification feature to be used for the interannual identification and population monitoring of fin whales using drones. This novel technique aims to improve and unify this species cataloguing overseas by using the CCP and blaze obtained from UAV (unmanned aerial vehicle) zenithal videos as a robust identification tool. Full article

(This article belongs to the Special Issue Drone Advances in Wildlife Research)

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10 pages, 997 KiB

Open AccessFeature PaperCommunication

Blowing in the Wind: Using a Consumer Drone for the Collection of Humpback Whale (Megaptera novaeangliae) Blow Samples during the Arctic Polar Nights

by Helena Costa, Andrew Rogan, Christopher Zadra, Oddbjørn Larsen, Audun H. Rikardsen and Courtney Waugh

Drones 2023, 7(1), 15; https://doi.org/10.3390/drones7010015 - 26 Dec 2022

Cited by 2 | Viewed by 3472

Abstract

Analysis of cetacean blow offers a unique potential for non-invasive assessments of their health. In recent years, the use of uncrewed aerial vehicles (UAVs) has revolutionized the way these samples are collected. However, the high cost and expertise associated with purpose-built waterproof UAVs, [...] Read more.

Analysis of cetacean blow offers a unique potential for non-invasive assessments of their health. In recent years, the use of uncrewed aerial vehicles (UAVs) has revolutionized the way these samples are collected. However, the high cost and expertise associated with purpose-built waterproof UAVs, paired with the challenges of operating during difficult meteorological conditions, can be prohibitive for their standardized use worldwide. A pilot study was conducted in a Northern Norwegian fjord during winter, to assess the feasibility of using a minimally modified and affordable consumer drone to collect blow samples even during the polar nights’ challenging weather conditions. For each flight, six petri dishes were attached with velcro to a DJI Mavic 2 Pro. The flights were conducted under temperatures ranging from -1 to -18 degrees Celsius, wind speeds ranging from 9 to 31 km/h, and with the absence of the sun. During the 6-day-long boat survey, 16 blow samples were successfully collected from 11 distinct groups of humpback whales (Megaptera novaeangliae). With this study, we further validated the use of a consumer drone as a practical, affordable, and simplified tool for blow collection, functional under harsh meteorological conditions. Full article

(This article belongs to the Special Issue Drone Advances in Wildlife Research)

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18 pages, 5259 KiB

Open AccessArticle

Hidden Hippos: Using Photogrammetry and Multiple Imputation to Determine the Age, Sex, and Body Condition of an Animal Often Partially Submerged

by Victoria L. Inman and Keith E. A. Leggett

Drones 2022, 6(12), 409; https://doi.org/10.3390/drones6120409 - 12 Dec 2022

Cited by 2 | Viewed by 1944

Abstract

Demographic Information on threatened species is important to plan conservation actions. Due to their aquatic lifestyle, the subtle nature of hippo sexual dimorphism, and their occurrence in inaccessible areas, it is difficult to visually determine hippo ages and sexes. Previously, hippo body lengths [...] Read more.

Demographic Information on threatened species is important to plan conservation actions. Due to their aquatic lifestyle, the subtle nature of hippo sexual dimorphism, and their occurrence in inaccessible areas, it is difficult to visually determine hippo ages and sexes. Previously, hippo body lengths have been measured from drone images and used to estimate age. However, due to hippos’ propensity to be partially submerged, it is often difficult to obtain the required measurements. We used the novel technique of multiple imputation to estimate missing body measurements. Further, we explored if male and female hippos could be differentiated in drone images based on body proportions, also examining body condition indices and how these varied seasonally. Multiple imputation increased the number of hippos that we aged threefold, and the body lengths we obtained fell within the range provided in literature, supporting their validity. We provide one of the first age structure breakdowns of a hippo population not from culled hippos. Accounting for overall size, males had wider necks and snouts than females. Hippo body condition varied seasonally, indicating responses to resources and reproduction. We provide a new technique and demonstrate the utility of drones to determine age and sex structures of hippo populations. Full article

(This article belongs to the Special Issue Drone Advances in Wildlife Research)

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10 pages, 1261 KiB

Open AccessBrief Report

Attenuation of Responses of Waterbirds to Repeat Drone Surveys Involving a Sequence of Altitudes and Drone Types: A Case Study

by Lachlan G. Howell, Blake M. Allan, Don A. Driscoll, Daniel Ierodiaconou, Todd A. Doran and Michael A. Weston

Drones 2023, 7(8), 497; https://doi.org/10.3390/drones7080497 - 28 Jul 2023

Cited by 3 | Viewed by 1194

Abstract

Remotely piloted aircraft systems (RPAS, or ‘drones’ hereafter) have potential for surveying waterbird species and habitats, but there is a risk that the disturbance from drones could compromise count accuracy and bird welfare. We examined the response of 16 waterbird species to repeated [...] Read more.

Remotely piloted aircraft systems (RPAS, or ‘drones’ hereafter) have potential for surveying waterbird species and habitats, but there is a risk that the disturbance from drones could compromise count accuracy and bird welfare. We examined the response of 16 waterbird species to repeated up-and-back overhead drone flights (n = 50 flights) at multiple flight heights (80, 60, 40 and 20 m) using three common drone platforms (DJI Matrice 300, DJI Mavic 2 Enterprise Advanced and DJI Phantom 4). A ground observer scored the species’ responses to overhead drone flights, which ranged from no response (no change to initial behavior), vigilance (head turning and tracking), movement within the site (swimming, diving, flight into or on the water) and substantial flight resulting in departure from the pond (fleeing). A total of 280 waterbird encounters with overhead drones were observed. The most common response across all flights was no response (70.7%), followed by vigilance (27.5%), whereas more intense responses were comparatively rare (1.8%). The responses were of higher intensity during earlier overhead drone flights, before moderating substantially during later flights. Thus, our case study provides the first unambiguous evidence of the attenuation of responses of bird species to drones. Full article

(This article belongs to the Special Issue Drone Advances in Wildlife Research)

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