Use of abandoned structures by Przewalski's wild horses and other wildlife in the Chernobyl Exclusion Zone

Przewalski's wild horses (Equus ferus przewalski) are an endangered species and current conservation efforts aim to maintain genetic diversity and reintroduce wild populations. From 1998 to 2004, 36 Przewalski's horses were introduced in the Chernobyl Exclusion Zone (CEZ) with no subsequent direct management, and current population size and genetic diversity are unknown. We used remote cameras positioned at the entrance of abandoned structures within the CEZ to elucidate visitation of these structures by Przewalski's horses and other large mammals to assess the use of this method for monitoring the horse population within the CEZ. We estimated frequency of structure use in winter (Nov 2016-Feb 2017) and summer (Mar 2018-Oct 2018) periods and estimated basic group characteristics such as group type (all male vs. mixed sex), group size, and number of foals. Przewalski's horses were detected 35 times at 9 of 10 monitored structures in winter and 149 times at all 8 monitored structures in summer. Eight other mammalian species were documented using abandoned structures. Mixed sex groups of horses contained 5.30 +/- 0.25 adults and 1.00 +/- 0.12 foals (mean +/- S.E.). All-male groups contained 1.59 +/- 0.15 individuals. Our data suggest Przewalski's horses routinely use abandoned structures in the CEZ with visitation patterns tending to be nocturnal in winter and crepuscular in summer. Congregation of horses in these structures could have implications for future monitoring of the population by providing detailed information on demographics, population size, and genetic diversity which would benefit management plans for this population and provide a baseline for future work.