The space use by Przewalski's horses of the semi-free population during first years after their reintroduction to Orenburg State Nature Reserve, Russia

Abstract

In 2015, the Joint Directorate of State Nature Reserves «Orenburg» and «Shaitan-Tau» (FSFI «Orenburg Reserves») launched the Programme on establishing a semi-free population of the Przewalski's horse Equus ferus przewalskii in the 165 km2 Pre-Urals Steppe site of Orenburg State Nature Reserve (Russia). The aim of this study is to analyse the space use by two harem groups of the Przewalski's horse during the first years after release from acclimatisation enclosures. The study conducted from October 2016 to March 2019 and started when the first group of horses had been released from the acclimatisation enclosure to the main territory of Pre-Urals Steppe. Locations of harems were analysed separately for two periods: winter and snow-free. We compared location points in preferred areas (assessed by Kernel Density Estimation 50%) and other (random locations) with regard distance to acclimatisation enclosures, to a local zoo, and to ponds (only for snow-free period). The horses preferred to be closer to the acclimatisation enclosures and the local zoo during the winter period, but tended to avoid the zoo during the snow-free period. The distance between free-ranging harem groups was shorter during the winter than in the snow-free period. We also found a higher tendency of one group to be closer to the acclimatisation enclosures and the zoo. The presence of other horses within the area of release is an obvious attraction factor for free-ranging individuals and groups. We are of the opinion that it is due to needs to occasionally interact with horses of other groups regardless of whether it is aggression or attachment. Females seemed to contribute significantly in interband relationships of Przewalski's horses in Pre-Urals Steppe. Such social needs may facilitate a whole population's integrity, as acclimatisation enclosures with groups of horses inside will be an anchor that holds free-ranging horses within the site of reintroduction. On the other hand, free-ranging Przewalski's horses will leave an unfenced protected area with no guarantee to come back as soon as they detect other horses outside the reserve border. The difference in the distance between groups and the lower association needs in the snow-free period indicates the necessity for proper planning of a suitable area for free-ranging populations of Przewalski's horses.

Keywords

• distribution
• Equus ferus przewalskii
• Kernel Density Estimation
• Pre-Urals Steppe
• space use