Funding for this research was provided by:
Narodowe Centrum Nauki (2017/27/B/NZ8/00465)
Received: 6 November 2019
Revised: 1 May 2020
Accepted: 19 July 2020
First Online: 17 September 2020
Compliance with ethical standards
: The analyses and procedures of this research conformed to the current laws of Poland. Permits to conduct the analysis of nest-card data were not required as we analysed previously collected breeding data. The fielwork in the nature reserve “Stawy Milickie” in 2018–19 was conducted under the permit of the Regional Directorate for Nature Protection in Wrocław (ExternalRef removed.2).
: The authors declare that they have no conflict of interest.