October 2024
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162 Reads
Journal of Raptor Research
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October 2024
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162 Reads
Journal of Raptor Research
March 2024
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133 Reads
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1 Citation
Many wildlife species, including hole-nesting raptors, occupy cavities that are challenging or unsafe for observers to examine. We conducted field tests using an inexpensive, off-the-shelf camera attached to an affordable commercial drone to assess the reproductive success of American kestrels (Falco sparverius), a small, cavity-nesting raptor. Specifically, we developed a system that consisted of (1) a wireless mini camera transmitting images to an observer’s phone and (2) a Mini-Mavic 2 drone controlled through direct line-of-sight piloting. Following successful preliminary flights involving chicken eggs and other inanimate objects, we field-tested the system in two kestrel nest boxes in the wild. The system accurately recorded the contents of all nest boxes during the trials, provided the wind speed remained below approximately 2.5 m/s (5 knots). However, wind speeds at this level were observed only 40% of the days in our study area during kestrel breeding, which limited the surveying opportunities. Our system offers a promising method for surveying wildlife inhabiting inaccessible cavities.
April 2023
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72 Reads
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5 Citations
Journal of Raptor Research
We analyzed long-term datasets from nest box programs, Breeding Bird Surveys run by the US Geological Survey, Christmas Bird Counts run by the National Audubon Society, and counts from two key fall migration watch sites, Hawk Mountain Sanctuary and Cape May Hawkwatch. We found that populations of American Kestrels (Falco sparverius) in North America are generally still declining, albeit with some caveats. Some populations are actually increasing, while others are remaining stable. Overall, the magnitude of annual change appears to be decreasing slightly during recent years. To understand potential causes of the decline, we recommend the following courses of action in no particular order: (1) determine whether the increase in Cooper's Hawk (Accipiter cooperii) populations is restricting kestrel distributions by the mere presence of the larger raptor; (2) study the effects of habitat loss and/or degradation on the falcon's wintering range; (3) further investigate on a broader spatial scale whether within-season habitat alterations are creating ecological traps for breeding kestrels; (4) determine the importance of arthropods in the diet of kestrels, especially the long-term population trends and timing of emergence of grasshoppers in relation to kestrel breeding chronology; (5) discover whether rodenticides pose a serious risk to American Kestrels across North America; (6) learn more about possible effects, both direct and indirect, that the use of neonicotinoids may have on kestrels; and (7) continue ongoing studies of the effect of climate change on these birds.
October 2022
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147 Reads
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8 Citations
The growing field of aeroecology is limited by difficulties associated with sampling in the air column. Aerial insects are particularly hard to sample, despite being the main prey in the air column, with some recent studies attempting to use drones as a collection method. We conducted a study to determine the optimal drone settings for collecting insects above the canopy, where drones are seldom used. By attaching a net to the body of a small, commercial drone, we tested yield from different height, speed, and net settings in wetlands, as well as compared insect diversity across different habitat canopies. Height was the most important setting; grazing the canopy yielded significantly more insects than flying one meter above it. Speed, drone type, and net size did not influence the number of insects caught per trial. Wetland canopies had higher abundance, diversity, and species richness in its arthropod populations compared to forest canopies or lakes. Compared to the yield of Lindgren funnels—a traditional sampling method in entomology—drones captured higher diversity and abundance of insects in a fraction of the time. This study confirms that drones are an efficient and accurate way to collect canopy arthropods.
August 2022
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1,171 Reads
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13 Citations
Biological Invasions
Free-roaming domestic cats (i.e., cats that are owned or unowned and are considered ‘at large’) are globally distributed non-native species that have marked impacts on biodiversity and human health. Despite clear scientific evidence of these impacts, free-roaming cats are either unmanaged or managed using scientifically unsupported and ineffective approaches (e.g., trap-neuter-release [TNR]) in many jurisdictions around the world. A critical first initiative for effective, science-driven management of cats must be broader political and legislative recognition of free-roaming cats as a non-native, invasive species. Designating cats as invasive is important for developing and implementing science-based management plans, which should include efforts to prevent cats from becoming free-roaming, policies focused on responsible pet ownership and banning outdoor cat feeding, and better enforcement of existing laws. Using a science-based approach is necessary for responding effectively to the politically charged and increasingly urgent issue of managing free-roaming cat populations.
January 2022
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256 Reads
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17 Citations
Advances in operational simplicity and cost efficiency have promoted the rapid integration of unoccupied aerial vehicles (UAVs) into ecological research, yet UAVs often disturb wildlife, potentially biasing measurements. Studies of UAV effects on wildlife to date have focused on UAV trajectory or distance; however, UAV size and noise could be critical variables influencing wildlife responses. Bats are cryptic aerial species that are difficult to survey using conventional means, and so we tested the effectiveness of drone‐based acoustic surveys for bats. We recorded the number of acoustic bat detections with and without a UAV present. We used three small, commercial rotary UAVs varying in size and noise intensity (249, 907, 1,380 g). Larger and louder UAVs deterred significantly more bats, with no effect of take‐off distance on bat activity. The smallest and quietest UAV model had a similar change in bat activity compared with control measurements. Drone noise increased with drone size, but all drones emitted in a similar range of frequencies that overlapped with the larger bat species that were also those most impacted by the UAV. During the 5‐minute surveys, there was no evidence of bat habituation to UAVs although bats returned quickly once the UAV survey ended. We urge wildlife researchers to consider drone size during wildlife surveys. Smaller and quieter models have negligible impacts on wildlife, eliminating the impact of drones on wildlife in some cases.
June 2021
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188 Reads
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14 Citations
Advances in technological capabilities, operational simplicity and cost efficiency have promoted the rapid integration of unmanned aerial vehicles (UAVs) into ecological research, providing access to study taxa that are otherwise difficult to survey, such as bats. Many bat species are currently at risk, but accurately surveying populations is challenging for species that do not roost in large aggregations. Acoustic recorders attached to UAVs provide an opportunity to survey bats in challenging habitats. However, UAVs may alter bat behaviour, leading to avoidance of the UAV, reduced detection rates and inaccurate surveys. We evaluated the number of bat passes detected with and without the presence of a small, commercial UAV in open habitats. Only 22% of bat passes were recorded in the presence of the UAV (0.23 ± 0.09 passes/min) compared to control periods without the UAV (1.03 ± 0.17 passes/min), but the effect was smaller on the big brown bat/silver-haired bat ( Eptesicus fuscus / Lasionycteris noctivagans ) acoustic complex. Noise interference from the UAV also reduced on-board bat detection rates. We conclude that acoustic records attached to UAVs may inaccurately survey bat populations due to low and variable detection rates by such recorders.
March 2021
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34 Reads
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6 Citations
Journal of Raptor Research
June 2020
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34 Reads
Drone Reporting Protocol Example # 2
June 2020
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1,074 Reads
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61 Citations
Journal of Unmanned Vehicle Systems
Drones are increasingly popular tools for wildlife research, but it is importantthat the use of these tools does not overshadow reporting of methodological detailsrequired for evaluation of study designs. Thediversity in drone platforms, sensors, andapplications necessitates the reporting of specific details for replication, but there is littleguidance available on how to detail drone use in peer-reviewed articles. Here, we presenta standardized protocol to assist researchers in reporting of their drone use in wildliferesearch. The protocol is delivered in six sections: Project Overview; Drone System andOperation Details; Payload, Sensor, and DataCollection; Field Operation Details; DataPost-Processing; and Permits, Regulations, Training, and Logistics. Each section outlinesthe details that should be included, along with justifications for their inclusion. To facilitateease of use, we have provided two example protocols, retroactively produced for publisheddrone-based studies by the authors of this protocol. Our hopes are that the current versionof this protocol should assist with the communication, dissemination, and adoption ofdrone technology for wildlife research and management.
... In general, most papers addressing the use of drones for nest/population monitoring compare (and even highlight) their utility over traditional techniques such as tree/cliff climbing and/ or ground-based observations (Potapov et al. 2013, Junda et al. 2016, Kilic and Purckhauer 2016, Gallego and Sarasola 2021, Charbonneau et al. 2024). A recent study involved using a small off-the-shelf drone to take photos of the nest contents of cavitynesting American Kestrels (Falco sparverius; Bird et al. 2024). The first published study using drones to monitor the breeding season of a raptor was by Potapov et al. (2013), in which the authors successfully used a drone to check Steller's Sea-Eagle (Haliaeetus pelagicus) nests in Russia. ...
March 2024
... Further aggravating this threat are introduced cavity nesters, including European Starlings (Sturnus vulgaris; hereafter starling), which compete with kestrels for nesting cavities (Koenig 2003, Bowers et al. 2023. Competition with starlings for nesting sites can reduce kestrel nesting success (Bowers et al. 2023), although the importance of the role that starlings play in the decline of kestrel populations remains unclear and under debate (e.g., McClure et al. 2017, Smallwood andBird 2023). ...
April 2023
Journal of Raptor Research
... Commercially available drones offer unprecedented opportunities to monitor insects thanks to their small size, maneuverability, speed and hovering capabilities (Hassanalian and Abdelkefi 2017;Nowak et al. 2018). Recent studies have successfully tested the use of drones to monitor insects in agricultural contexts as well A c c e p t e d M a n u s c r i p t as natural environments (Kim et al. 2018;Löcken et al. 2020;Almstedt et al. 2023;Giannetti et al. 2024a;Kakutani et al, 2021;Madden et al, 2022;Mulero-Pázmány et al, 2022 ). ...
October 2022
... Cats are one of the most damaging invasive predators (Lowe et al. 2000) and the removal of feral and free-roaming individuals substantially benefits native wildlife (Campbell et al. 2011;Jones et al. 2016) and human health (de Wit et al. 2019). Yet, many outdoor cat populations remain unmanaged, even when natural resource managers recognize cats and TNR colonies as an unaddressed threat to conservation Trouwborst et al. 2020;Lepczyk et al. 2022). Here, we have shown cats have a strong, negative association with the nest and brood survival of piping plovers, a species protected under the U.S. Endangered Species Act (USFWS 1985). ...
August 2022
Biological Invasions
... Multicopters with four propellers, also known as quadcopters, have been tested in further studies. These include DJI Spreading Wings S900 (3.3 kg and 15-inch propeller) [22], DJI Phantom 3 Pro (1.3 kg and 9-inch propeller) [15], DJI Phantom 4 (1.3 kg, 9.4-inch propeller) [23][24][25], DJI Mavic 2 Pro (907 g, 8.7-inch propeller) and DJI Mavic Mini (249 g, 4.7-inch propeller) [24] and DJI M210 V2 (4.69kg and 17-inch propellor) [16]. These multicopters emitted noise mainly below the 25-30 kHz frequency range [15,21,23]. ...
January 2022
... Multicopters with four propellers, also known as quadcopters, have been tested in further studies. These include DJI Spreading Wings S900 (3.3 kg and 15-inch propeller) [22], DJI Phantom 3 Pro (1.3 kg and 9-inch propeller) [15], DJI Phantom 4 (1.3 kg, 9.4-inch propeller) [23][24][25], DJI Mavic 2 Pro (907 g, 8.7-inch propeller) and DJI Mavic Mini (249 g, 4.7-inch propeller) [24] and DJI M210 V2 (4.69kg and 17-inch propellor) [16]. These multicopters emitted noise mainly below the 25-30 kHz frequency range [15,21,23]. ...
June 2021
... Furthermore, temporal variation in behaviour, and particularly food preferences, may also affect the likelihood of HPAIV infection. For example, there were fewer bald eagle mortalities in "Wave 2", which may reflect the fact that bald eagles preferentially consume salmon in the fall and winter and may be more likely to scavenge HPAIV-infected birds in the spring and summer when salmon are not available [31]. ...
March 2021
Journal of Raptor Research
... The American Kestrel (Falco sparverius; hereafter kestrel) is a species of cavity-nesting falcon inhabiting open landscapes including grasslands and agricultural areas throughout the western hemisphere (Smallwood and Bird 2020). Over the past several decades, kestrel populations have declined across much of their North American range Smallwood 2023, Oleyar et al. 2023). ...
March 2020
... Of the works included in this review, approximately half-presented information that can only be used to infer growth stage (e.g., reporting in days after planting or weeks after applying a treatment, reporting dates of imaging with and without providing planting dates), a task which is likely to be error prone due to variable rates of maturity; approximately 10% contained no information that would allow any inference. Additionally, more so than any other remote sensing platform, research using UAS has been criticized for omission of key details necessary to evaluate the research quality and inform replication (e.g., K. K. Singh & Frazier, 2018;Barnas et al., 2020;Fraser et al., 2022). A related but separate issue is that researchers are often limited by the technology they can access and the methods they can confidently utilize. ...
June 2020
Journal of Unmanned Vehicle Systems
... Biotelemetry tags in marine monitoring are not massively produced and often require customization for specific applications, which makes them expensive. Researchers therefore mostly opt for biologgers that are typically recaptured using very high frequency (VHF) when tags are detached from the animal and found at the sea surface [15] or by underwater triangulation (using acoustical pingers) [16]. Still, recovering data from species living in remote areas relies either on very low recapture rate or satellite uplink with narrow bandwidths, which severely limits the amount of biotelemetry data that can be recovered [17]. ...
December 2018
Drones