In seabirds, for instance, they have proven to be a reliable and a low-cost tool to estimate colony size with a minimum impact on the birds ( McClelland et al., 2016 Hodgson et al., 2018). High-resolution orthophotographic cameras and video equipment incorporated in UAVs have allowed for accurate estimates of the number and distribution of flora and fauna from a new perspective ( Hodgson, Kelly & Peel, 2013 Evans et al., 2015 Chrétien, Théau & Ménard, 2016 Cruzan et al., 2016 Fiori et al., 2017 Stark et al., 2018). Unmanned Aerial Vehicles (UAVs), or drones, are widely used for wildlife research ( Koh & Wich, 2012 Chabot & Bird, 2015 Arts, Van Der Wal & Adams, 2015). Likewise, this study provides a first step to develop guidelines and protocols of drone use for other potential activities on the Peruvian guano islands and headlands such as surveys of other seabirds and pinnipeds, filming and surveillance. We recommend performing drone flights at altitudes greater than 50 m from guano bird colonies and to select take-off spots far from gulls. It is feasible to use the drone DJI Phantom 3 for surveys on the guano islands of Peru. No significant differences were observed in the drone noise at different flight altitudes because the background noise of the colony was as loud as the drone. At 2 m above the ground, the noise of the cormorant colony was in average 71.34 ± 4.05 dB ( N = 420). Horizontal and vertical flights at different speeds had negligible effects (intensity behavioral response <1). At 5 m above the colony, cormorants were more sensitive to the drone presence than the other two species. Chick-rearing cormorants and pelicans were less sensitive than their non-breeding counterparts in the range of 5–30 m of drone altitude, but boobies reacted similarly irrespective of their condition. Birds, for all species either in breeding or non-breeding condition, reacted more often at altitudes of 5 and 10 m. No birds reacted at drone altitudes above 50 m from the colony. For the drone approach tests, only flight altitude had a significant effect in the intensity of the behavioral response of guano birds (intensity behavioral response <2).
In 74% of all test flights ( N = 507), guano birds did not react to the presence of the drone, whereas in the remaining flights, birds showed a sign of discomfort: HP (47.7%, N = 130), WF (18.5%), WR (16.9%) and TK (16.9%). Drone noise at specific altitudes was recorded with a sound meter close to the colony to discriminate visual from auditory effects of the drone. The intensity of the behavioral response of birds was scored and categorized as: 0-no reacting, 1-head pointing to the drone (HP), 2-wing flapping (WF), 3-walking/running (WR) and 4-taking-off/flying (TK). Drone flight tests considered an altitude range from 5 to 80 m from the colony level, a horizontal speed range from 0.5 to 15 m/s, and a vertical descent speed range from 0.5 to 3 m/s. MethodsĮleven locations along the Peruvian coast were visited in 2016–2017. The breeding and non-breeding condition was also evaluated. In this study, we examined the effects of the DJI Phantom 3 drone approach (altitude, horizontal and vertical descent speeds) on changes in the intensity of behavioral response of guano birds: guanay cormorants ( Phalacrocorax bougainvilli), Peruvian boobies ( Sula variegata) and Peruvian pelicans ( Pelecanus thagus). Although most research has focused on methods of improving the accuracy of bird counts, few studies have evaluated the impacts of these methods on bird behavior. PeerJ 7: e8129 ĭrones are reliable tools for estimating colonial seabird numbers.
Response of colonial Peruvian guano birds to flying UAVs: effects and feasibility for implementing new population monitoring methods. Cite this article Irigoin-Lovera C, Luna DM, Acosta DA, Zavalaga CB. For attribution, the original author(s), title, publication source (PeerJ) and either DOI or URL of the article must be cited. Licence This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. 2 Universidad Nacional Mayor de San Marcos, Lima, Lima, Peru DOI 10.7717/peerj.8129 Published Accepted Received Academic Editor Patricia Gandini Subject Areas Animal Behavior, Conservation Biology, Marine Biology Keywords Guano birds, Disturbance, Colonial birds, UAV, Aerial surveys, Peruvian islands, Cormorants, Boobies, Pelicans, Drone flights Copyright © 2019 Irigoin-Lovera et al.
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