Environmental Reviews and Case Studies: Applications of Unmanned Aircraft Systems (UAS) for Waterbird Surveys

Abstract

Utilizing unmanned aircraft systems (UAS) can be an efficient and repeatable means of surveying wildlife, especially waterbirds. As with any technology in its infancy, case studies offer opportunities to explore drawbacks and limitations, both anticipated and unanticipated. We examined the relationship between flight altitude and camera focal length on bird identification. We then conducted a post-hoc analysis to examine the effect of flight altitude on bird flushing behavior. We flew UAS missions at three locations in California and Nevada to assess the use of UAS for censusing non-nesting waterbirds. A minimum pixel resolution of approximately 5 mm was needed be able to identify most waterbird species from imagery. Sensors needed to be carefully calibrated in order to obtain images of sufficient quality to identify waterbirds over open water. Our results suggest that gas-powered UAS may result in increased rates of flushing at low flight altitudes for some waterbirds. With careful design of surveys and processing workflow, UAS show promise for censusing and monitoring waterbirds. Environmental Practice 17: 201-210 (2015)

Assessment of Chimpanzee Nest Detectability in Drone-Acquired Images

“…This finding is consistent with that of Mulero-Pázmány et al [39], who also found that the targets (i.e., rhinoceros, people acting as poachers) were better detected with a lower-flying drone. Our results are also consistent with those of Dulava et al [49], who reported a significant negative relation between ground sampling distance (GSD) and correct waterbird identification with a minimum of 5 mm GSD. In our study, we favored flight altitude AGL above GSD as a measure of resolution because of identical camera parameters, however, the two are conceptually interchangeable.…”

Wildlife research and management methods in the 21st century: Where do unmanned aircraft fit in?

“…Vas et al (2015) systematically assessed reactions of non-breeding mallards (Anas platyrhynchos), greater flamingos (Phoenicopterus roseus), and common greenshanks (Tringa nebularia) to small multirotor UAS of varying colour, speed, and approach angle. Most recently, Dulava et al (2015) evaluated the detectability of non-breeding waterbird species as well as decoys by small fixedwing UAS at varying flight altitudes and camera settings, while Brooke et al (2015) reported detection of various seabirds in UAS video footage.…”

“…Finally, a key consideration is whether UAS disturb target or non-target animals, which a growing number of studies have quantitatively assessed (Sarda-Palomera et al 2012;Chabot et al 2015;Ditmer et al 2015;Dulava et al 2015;Goebel et al 2015;Pomeroy et al 2015;Vas et al 2015). The general consensus has been that UAS cause low to no disturbance, in particular when compared to alternative methods, such as intrusive direct surveying by investigators or low-altitude surveying by larger and noisier conventional aircraft.…”

Computer-automated bird detection and counts in high-resolution aerial images: a review

“…, Dulava et al. ) due to their low flight altitude and small area footprint of individual images. The time required to manually review and analyze images may then negate any efficiency gained during data collection.…”

“…UAS can provide precise, lowdisturbance surveys of birds , Vas et al 2015, Hodgson et al 2016. Unlike manned aircraft, however, UAS are obligate photographic survey platforms that usually collect large numbers of images (Drever et al 2015, Dulava et al 2015 due to their low flight altitude and small area footprint of individual images. The time required to manually review and analyze images may then negate any efficiency gained during data collection.…”