Funding for this research was provided by:
Stichting voor de Technische Wetenschappen (14723)
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (040.11.573/1798, 040.11.468)
Text and Data Mining valid from 2019-01-01
Received: 2 March 2018
Revised: 13 July 2018
Accepted: 12 November 2018
First Online: 19 January 2019
Compliance with ethical standards
: This study is purely observational and did not involve captive animals or experimental manipulations, only analyses of video material collected for previous studies. The video recordings of the flying flocks and falcons were taken from hundreds of meters distance in an urban environment and did not cause any disturbance to the birds.
: The authors declare that they have no conflict of interest.