**5. Conclusions**

We have successfully validated an 11-oxoaetiocholanolone EIA for measuring FCMs in order to evaluate adrenocortical activity in reindeer. We found a time-lag of approximately seven to eight hours between the ACTH challenge and peak FCM levels. A similar time-lag was observed when samples were taken after human handling and calf marking in the fence. The method proved biologically sensitive and could be of grea<sup>t</sup> value as a tool for welfare assessment of different treatments and handling procedures, and also for evaluating the negative effects of human disturbance in natural pasture areas. As collecting individual faecal samples in a group of housed, semi-free species like reindeer may disturb the animals, combining FCM analysis with genetic data proved useful to overcome the problem of anonymous sampling.

**Author Contributions:** Conceptualization, G.H.M.J., S.M.E., R.P. and ¸S.Ö.G.; Formal analysis, G.H.M.J. and R.P.; Investigation, ¸S.Ö.G., G.H.M.J., R.P., I.H., S.M.E., S.B.H. and I.F.; Methodology, R.P. and ¸S.Ö.G.; Project administration, ¸S.Ö.G., I.H., S.M.E., G.H.M.J., R.P., S.B.H. and I.F.; Supervision, R.P. and ¸S.Ö.G.; Visualization, Rupert Palme; Writing—original draft, ¸S.Ö.G., R.P., G.H.M.J., S.B.H., I.F., I.H. and S.M.E.; Writing—review and editing, ¸S.Ö.G., G.H.M.J. and R.P.

**Funding:** This paper was produced as part of the project "Handling stress in reindeer" funded by grants for development of arctic agriculture, administered by the County Governor of Troms (project number 10035.01). The project had grea<sup>t</sup> synergy effect with the INTERREG Botnia-Atlantica funded project Animal Sense, administered by Nordland County Council.

**Acknowledgments:** Authors would like to thank Benan Gülzari, Roberts Stüritis, Arne Johan Lukkassen and Norvald Ruderaas for the technical and administrative support provided during the trial and processing of samples at NIBIO Tjøtta and Edith Klobetz-Rassam for EIA analysis. We also thank Cecilie Marie Mejdell and Solveig Stubsjøen for their inputs during the project development and gran<sup>t</sup> application. Our utmost gratitude goes to the Reindeer herder Tom Lifjell at Tverrvatnet for giving us access to his animals, and their help with the practical work during the ACTH challenge test. Reindeer herders Stig Rune Smuk, Frode Utsi and the other members of <sup>R</sup>ákkonjárga reindeer district 7 welcomed us into their corrals and made it possible for us to gather faecal samples. Finally, we thank the anonymous reviewers for their valuable comments.

**Conflicts of Interest:** The authors declare no conflicts of interest.
