Received: 7 June 2020
Accepted: 7 January 2021
First Online: 8 February 2021
Ethics approval and consent to participate
: All the fieldwork was performed using observational, non-invasive techniques which enabled sufficient data for the objectives of the study to be obtained without threatening the welfare of the birds, as they were not manipulated.
: Not applicable.
: The author declares that he has no competing interests.