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Resident European ground squirrels exhibit higher stress levels than translocated individuals after conservation reinforcement

Abstract

The European ground squirrel (Spermophilus citellus) is a rodent inhabiting the open grasslands of central and southeastern Europe. The species is endangered, and various conservation activities are being conducted to preserve and improve the populations’ status, especially during the recent years including translocations of individuals. The success of these measures has varied and is potentially strongly influenced by the chronic and acute stress associated with the translocation process itself. This stress load, however, has rarely been investigated in the framework of such conservation projects, neither in translocated nor in resident individuals. To fill this gap, we investigated glucocorticoid metabolite concentrations in translocated ground squirrels and compared these with concentrations in resident animals of a reinforced colony in southeastern Bulgaria. Between 2017 and 2019, we sampled a total of 252 individuals for faecal cortisol metabolite concentrations (FCM). The results showed that FCM decreased after the release in translocated individuals and that the time span after the translocation event was the key variable explaining the decrease. Surprisingly, the FCM levels were higher in the resident ground squirrels than in the translocated individuals throughout the active season and in the following spring. Furthermore, we found no effect of FCM concentrations on dispersal distances or body mass gain in translocated individuals.

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Acknowledgements

The study was supported by the Program for Support of Young Researchers and PhD Students at the Bulgarian Academy of Sciences (Grant no 17-110). The Western Strandzha translocation activities were funded by LAND for LIFE project (LIFE14 NAT/BG/001119, co-ordinated by the BSPB) (www.landforlife.org). Special thanks are due to Dimitra-Lida Rammou for her valuable assistance during the field work. We warmly thank Svetoslav Spasov and Dimitar Gradinarov (BSPB), without whom the translocation would not have been possible. We are grateful to Elisabeth Pschernig (University of Vienna) for sample analysis and to Yasen Mutafchiev for the review and the advice. We also thank Anton Sokolov, Svetla Todorova (Sofia University), Dimitar Ragyov (IBER-BAS) and Kristina Yonkova for their participation in the sampling process.

Funding

The study was supported by the Program for Support of Young Researchers and Ph.D. Students at the Bulgarian Academy of Sciences (Grant no. 17-110). The Western Strandzha translocation activities were funded by LAND for LIFE project (LIFE14 NAT/BG/001119, co-ordinated by the BSPB) (www.landforlife.org).

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Correspondence to Maria Kachamakova.

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Kachamakova, M., Koshev, Y. & Millesi, E. Resident European ground squirrels exhibit higher stress levels than translocated individuals after conservation reinforcement. Mamm Biol 101, 127–136 (2021). https://doi.org/10.1007/s42991-020-00066-2

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Keywords

  • Spermophilus citellus
  • Translocation
  • FCM
  • Stress
  • Conservation