Methodological Considerations for Using Fecal Glucocorticoid Metabolite Concentrations as an Indicator of Physiological Stress in the Brown Bear (Ursus arctos)

• Published in: Physiological and Biochemical Zoology
• Main Authors: Dalerum, Fredrik, Ganswindt, André, Palme, Rupert, Bettega, Chiara, Delgado, María del Mar, Dehnhard, Martin, Freire, Susana, García-González, Ricardo, Marcos, Jaime, Miranda, María, Vázquez, Víctor M., Sánchez Corominas, Teresa, Tuñón Huerta, José, Zedrosser, Andreas, Ordiz, Andrés, Penteriani, Vincenzo
• Other Authors: Ministerio de Ciencia, Innovación y Universidades (España), Principado de Asturias
• Format: Article in Journal/Newspaper
• Language: English
• Published: University of Chicago Press 2020
• Subjects: Stress; ACTH challenge; Noninvasive hormone monitoring; Steroid stability; Bears; Ursus; Carnivore; Eia; Ursus arctos
• Online Access: http://hdl.handle.net/10261/228316; https://doi.org/10.1086/708630; https://doi.org/10.13039/100011941

Reliable methods to measure stress-related glucocorticoid responses in free-ranging animals are important for wildlife management and conservation. Such methods are also paramount for our ability to improve our knowledge of the ecological consequences of physiological processes. The brown bear (Ursus arctos) is a large carnivore of ecological and cultural importance and is important for management. Here, we provide a physiological validation for an enzyme immunoassay (EIA) to quantify glucocorticoid metabolites in brown bear feces. We also provide an evaluation of the effects of sample exposure to ambient temperature on measured fecal glucocorticoid metabolite (fGCM) concentrations. We evaluated three EIA systems: a cortisol assay, an 11-oxoetiocholanolone assay, and an 11β-hydroxyetiocholanolone assay. Of these, the cortisol assay provided the best discrimination between peak fGCM concentrations detected 1–4 d after injections of synthetic adrenocorticotrophic hormone and preinjection baseline concentrations in four individual brown bears. The time of exposure to ambient temperature had substantial but variable effects on measured fGCM concentrations, including variation both between samples from the same individual and among samples from different bears. We propose that the validated EIA system for measuring fGCM concentrations in the brown bear could be a useful noninvasive method to monitor stress in this species. However, we highlight that this method requires that fecal samples be frozen immediately after defecation, which could be a limitation in many field situations. This research project has been partially funded by FOA, Fundación Biodiversidad, and the Servicio de Medio Natural, Consejería de Desarrollo Rural, Agroganadería y Pesca del Principado de Asturias to M.M.D. In addition, F.D. was financially supported by a Spanish Ramon y Cajal grant funded by the Spanish Ministry of Economy and Competitiveness (RYC-2013-16263); V.P. was supported by a Grupos de Investigación (GRUPIN) research grant from ...