Funding for this research was provided by:
Russian Science Foundation (19-14-00037)
Received: 29 May 2019
Accepted: 10 October 2019
First Online: 22 October 2019
Ethics approval and consent to participate
: This study was the part of the research program of the Scientific Research Department of Moscow Zoo. Three authors, who collected material, are zoo staff members, so no special permission was required for them to work with animals in Moscow Zoo. All study animals belonged to the laboratory collection of Moscow Zoo. The experimental procedure has been approved by the Committee of Bio-ethics of Lomonosov Moscow State University, research protocol # 2011-36. We adhered to the ‘Guidelines for the treatment of animals in behavioural research and teaching’ (Anim. Behav., 2006, 71, 245–253) and to the laws on animal welfare for scientific research of the Russian Federation, where the study was conducted. No one single animal suffered due to data collection.
: Not applicable.
: The authors declare that they have no competing interests.