Received: 3 June 2020
Revised: 9 January 2021
Accepted: 11 January 2021
First Online: 27 January 2021
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: No animal testing was performed during this study.
: All necessary authorization for the observational field study and securing of the area was obtained from the competent authorities. Photographs in Fig. 1 a and b were provided by Bridgid Wickham who has agreed to their inclusion in this publication.
: The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.
: SR conceived the research, wrote the manuscript, and conducted field observations. All authors conducted field observations and read and approved the final manuscript.