Funding for this research was provided by:
Narodowe Centrum Nauki (2017/26/D/NZ8/01063)
British Ornithologists’ Union
Received: 1 June 2020
Revised: 1 September 2020
Accepted: 9 September 2020
First Online: 23 September 2020
Compliance with ethical standards
: The authors declare that they have no conflicts of interest.
: Ethical approval from national and/or institutional committees for the use of animals was not required for this study. The study complied with the current laws of Poland and was conducted under relevant study access permits issued by the Director of Białowieża National Park. All applicable international, national, and/or institutional guidelines for the ethical use of animals were followed.
: All authors gave consent to participate in the study.
: All authors consent to publication.
: Not applicable.