Drone-conducted counts as a tool for the rapid assessment of productivity of Sandwich Terns (Thalasseus sandvicensis)

Valle, Roberto G.; Scarton, Francesco

doi:10.1007/s10336-020-01854-w

Cited by 16 publications

(14 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…3B). However, these differences refer to the total time invested in the process, including the time spent analyzing drone imagery, which is usually long (Poysa et al 2018, Valle & Scarton 2021a). When considering only the time spent in the field, where direct and indirect disturbances to the nesting individuals may happen, we spent an average of 4.6 ± 1.9 min per drone survey, which translates into a difference of 81.22% in the total time spent in the breeding grounds (that is, a six-fold reduction).…”

Section: Discussionmentioning

confidence: 99%

Faster and Better: Comparison between Traditional and Drone Monitoring in a Cryptic Species, the Purple Heron Ardea purpurea

Corregidor-Castro

Scarton

Panzarin³

et al. 2023

Acta Ornithologica

Self Cite

View full text Add to dashboard Cite

Monitoring waterbirds is fundamental to understand the health status of wetland habitats. However, this monitoring has to be conducted by means of reliable data collection that can provide accurate information on population trends. Usually, waterbird monitoring is difficult, as nesting grounds are usually located in inaccessible reedbed, and by eye detection of cryptic species is hard. Drones have the capacity to overcome most of these problems, as they can provide with an aerial view of places otherwise unreachable, while reducing the disturbance and time spent in the field. The present study aims to compare the accuracy, disturbance levels, and managerial efficiency between ground (traditional) and drone counts of a cryptic species, the Purple Heron Ardea purpurea. Traditional monitoring methods were only capable of detecting 35% of the nesting pairs detected by the drone surveys (8.0 ± 11.8 versus 22.9 ± 38.2 nesting pairs in ground and drone surveys, respectively). Consequently, colony size estimates between methods showed poor agreement, to the point that traditional methods missed colonies otherwise detected by the drone. No apparent negative effects on nesting pairs where found when flying the drone. In addition, mean time spent to survey breeding sites with a drone was far less than with the traditional approach, down to a six-fold time reduction. This reduction, together with a lack of disturbance observed when conducting the drone monitoring, and an increasing monitoring precision and accuracy, supports the use of drones as the least invasive option for studies on population monitoring on hardly accessible sites.

show abstract

Section: Discussionmentioning

confidence: 99%

Faster and Better: Comparison between Traditional and Drone Monitoring in a Cryptic Species, the Purple Heron Ardea purpurea

Corregidor-Castro

Scarton

Panzarin³

et al. 2023

Acta Ornithologica

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, we are cautious in interpreting this UAS distance as a causal factor because in one case the flushes occurred just after take-off when the UAS was still > 100 m from the island, and in two cases the flushes occurred as the UAS was returning to the vessel. Still, prior work has found that distance of aircraft strongly determines flush responses across a range of species, with higher incidence of response for approaches closer than 30 m (Rümmler et al 2016;Fuller et al 2018;Krause et al 2021;Valle and Scarton 2021) and for vertical approaches relative to horizontal ones (Vas et al 2015, Rümmler et al 2016. We selected conservative treatments of flight distance to avoid mass flushing events and based our closest approach on these prior studies as a threshold that minimized disturbances (Barnas et al 2018;Brisson-Curadeau et al 2017;Reintsma et al 2018;Weimerskirch et al 2018).…”

Section: Behavioral Responsesmentioning

confidence: 99%

“…For example, comparisons between UAS and ground surveys of large bird colonies suggest that UAS counts are accurate and often more time-or cost-effective (Dunn et al 2021;Renner et al 2021). Behavioral responses from ground-nesting bird colonies varied from minimal observed responses (Sardà-Palomera et al 2017;Rush et al 2018;Magness et al 2019;Barr et al 2020) to increased agitation with closer approaches from the UAS (Rümmler et al 2016;Valle and Scarton 2021;Krause et al 2021), with fewer responses among colonial species (Weimerskirch et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Surveying cliff-nesting seabirds with unoccupied aircraft systems in the Gulf of Alaska

et al. 2022

View full text Add to dashboard Cite

Drones, or unoccupied aircraft systems (UAS), can transform the way scientific information on wildlife populations is collected. UAS surveys produce accurate estimates of ground-nesting seabirds and a variety of waterbirds, but few studies have examined the trade-offs of this methodology for counting cliff-nesting seabirds. In this study, we examined how different UAS survey parameters might influence seabird counts for population monitoring and assessed behavioral responses to aerial surveys for three sub-Arctic seabird taxa in the Gulf of Alaska: common murres (Uria aalge), black-legged kittiwakes (Rissa tridactyla), and pelagic and double-crested cormorants (Phalacrocorax pelagicus and Phalacrocorax auritus). We flew two commercially available models of UAS in planned approaches at different speeds and distances from colonies during incubation and chick-rearing periods. We compared counts from UAS-derived images with those from vessel-based photography and assessed video recordings of individual birds’ behaviors for evidence of disturbance during UAS operations and control phases. Count estimates from UAS images were similar to or higher than those from conventional vessel-based images, and UAS were particularly effective at photographing birds at sites with high cliff walls or complex topography. We observed no significant behavioral responses to the UAS by murres or cormorants, but we did observe flushing by black-legged kittiwakes during UAS flights; most of these birds were not incubating or brooding. At both the colony and individual level, we observed slightly greater responses to the smaller UAS platform and closer approaches. These results inform both species specific and general best practices for research and recreational usage of UAS near cliff-nesting seabird colonies.

show abstract

“…In recent years, small, unmanned aircraft systems (sUAS) have become widely used tools to survey seabird abundance at breeding colonies, including surveys of multiple tern species (Hodgson et al 2016, Bell and Harborne 2019, Valle and Scarton 2021). Magness et al (2019) showed that sUAS surveys could provide a useful and low disturbance means to estimate numbers of Aleutian Terns, although the ability to distinguish it from similar species remains unresolved.…”

Section: Introductionmentioning

confidence: 99%

Aleutian Tern Onychoprion aleuticus abundance estimates at four globally significant colonies

Renner

Renner²,

LYONS

et al. 2021

Bird Conservation International

View full text Add to dashboard Cite

Summary Aleutian Tern Onychoprion aleuticus numbers have been in steep decline at known Alaskan breeding colonies in recent decades (IUCN recently uplisted to ‘Vulnerable’). Available data suggest that most of the species may currently breed in Russia. Efforts to document global abundance and trends have been hampered by remoteness of colonies, lack of a formal monitoring programme, and the absence of reproducible population estimates with quantifiable errors, especially for large colonies. We surveyed four historically large colonies in Russia (2018) and Alaska (2019), which together may comprise 30–50% of the global breeding population. At each colony we obtained high resolution aerial photographs using a small Unmanned Aircraft System (sUAS). The large size of the colonies and the minimum altitude required to identify terns made it impractical to collect imagery of the entire colony. Instead, we employed a sampling approach, with sample locations selected based on spatially balanced acceptance sampling. Statistically sampled, low altitude sUAS images provided a fast, reproducible, and rigorous count of abundance for geographically large colonies, with low disturbance, and were generally consistent with concurrent ground-based observations. Concurrence among observers in photo counts indicated high precision in counts of attending birds and unattended nests, although species attribution in mixed tern colonies remains a source of significant uncertainty. Our results indicate that the four colonies surveyed here together supported <2,500 pairs of Aleutian Terns in the survey years. None of the colonies approached their peak size reported previously, likely due to recent predation, long-term decline, cold early season weather, or other factors. If these reduced colony sizes are representative of the current conditions, the implications for the global population would be dire.

show abstract

Drone-conducted counts as a tool for the rapid assessment of productivity of Sandwich Terns (Thalasseus sandvicensis)

Cited by 16 publications

References 33 publications

Faster and Better: Comparison between Traditional and Drone Monitoring in a Cryptic Species, the Purple Heron Ardea purpurea

Faster and Better: Comparison between Traditional and Drone Monitoring in a Cryptic Species, the Purple Heron Ardea purpurea

Surveying cliff-nesting seabirds with unoccupied aircraft systems in the Gulf of Alaska

Aleutian Tern Onychoprion aleuticus abundance estimates at four globally significant colonies

Contact Info

Product

Resources

About