Nest defense behaviour of four raptor species (osprey, bald eagle, ferruginous hawk, and red-tailed hawk) to a novel aerial intruder – a small rotary-winged drone

• Published in: Journal of Unmanned Vehicle Systems
• Main Authors: Junda, James H., Greene, Erick, Zazelenchuk, Dan, Bird, David M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 2016
• Subjects: osprey; Pandion haliaetus
• Online Access: http://dx.doi.org/10.1139/juvs-2016-0004; http://www.nrcresearchpress.com/doi/full-xml/10.1139/juvs-2016-0004; http://www.nrcresearchpress.com/doi/pdf/10.1139/juvs-2016-0004

A small rotary-winged unmanned aerial vehicle (UAV) was flown above the nests of four raptor species: osprey (Pandion haliaetus), bald eagle (Haliaeetus leucocephalus), ferruginous hawk (Buteo regalis), and red-tailed hawk (B. jamaicensis) to document the parental nest defense response to the aircraft. Adult behaviour was documented with a voice recorder and an ethogram, starting ~100 m distant from the nest and continuing until the base of the nest was reached, the survey completed, and the nest area exited. All adult movements and vocalizations were recorded with distance of bird and researchers from the nest when a given behaviour occurred. Ospreys showed the strongest nest defense response followed by ferruginous hawks and red-tailed hawks with bald eagles showing the least aggressive response. Ospreys showed no greater response to the UAV in the air near the nest than to researchers simply standing at the base of the nest structure, while bald eagles showed a significantly higher response to the aircraft than researchers at the nest base. Although aggression varied, no species showed aggression at levels that would discourage the use of UAVs to survey raptor nests. When a proper flight technique is adopted, UAVs can offer a useful tool for surveying raptor nests.