In the summer of 2019, the third last stage of the relocation of the European sousliks from an endangered colony near Sliven to the last remaining colony of the Zapadna Strandzha Special Protection Area was completed.
The stress caused by the release into the new habitat may impede adaptation and threaten the survival of the animals after translocation. To minimize these risks, the species conservation experts for the LIFE project "LAND for LIFE" studied the stress levels in the displaced and local individuals in the colony in Zapadna Strandzha Special Protection Area. Gentle non-invasive methods were used, namely, detection of cortisol metabolite concentrations in fecal samples. The analyses were performed in the laboratories of the University of Vienna with the support of the Program for Support of Young Scientists and Doctoral Students at the Bulgarian Academy of Sciences. The results showed that the relocated animals adapted quickly and did not suffer from chronic stress as a result of the relocation. The distances they travel, as well as changes in their weight, remain unaffected by stress. Surprisingly, their levels of cortisol (a stress hormone) are lower than those found in local individuals. This is probably caused by the new higher density of the colony, to which they are not accustomed.
Evidence that the activities to strengthen the colony are successful is provided by the annual monitoring carried out by the team. During the visit to the reinforced colony in May 2020, 17 animals were caught, for comparison in 2019 they were 14, and in 2018 - 10. There was a significant increase in active sousliks holes - 180 were counted, while in the same transect in 2019 they were 117, in 2018 - 121, and in 2017 - 36. The area of the colony has also increased.
The results are published in the prestigious scientific journal Mammalian biology by Springer Nature.
The activities on reinforcing the colony of European sousliks in Zapadna Strandzha Special Protection Area are carried out by Dr. Yordan Koshev (from IBEI - BAS), who is also the leader of the activities on the protection of the Souslik within the BSPB LIFE project "LAND for LIFE" and Maria Kachamakova , who is a PhD student at IBEI - BAS and a collaborator on the project.