Effect of Racking Systems Versus Enriched Terraria on Fecal Glucocorticoid Metabolites in Four Species of Captive Snakes: A Pilot Study

Fecal glucocorticoid metabolites (FGM) are widely used to assess hypothalamic–pituitary–adrenal (HPA) activity in vertebrates, but their applicability to reptiles, and more specifically to snakes, remains poorly explored. The objective of the present study was to determine how changes in housing conditions, from a standard racking system to enriched terraria, affect fecal glucocorticoid metabolite concentrations as a proxy potentially related to endocrine activity and stress response. A total of 58 fecal samples were collected across three different phases from 12 snakes representing four species: Boa constrictor (BC), Lampropeltis polyzona (LP), Pantherophis guttatus (PG), and Python regius (PR). FGM concentrations ranged from 54.9 to 832.2 ng/g, with a mean value of 298.4 ± 171.6 ng/g (mean ± SD). Data showed marked inter-individual variability, while within-individual concentrations remained relatively stable across experimental phases. PG exhibited the highest FGM concentrations during the study, with LP showing intermediate levels and PR and BC the lowest. The results showed that housing conditions did not have a significant effect on FGM concentrations in the studied population. In conclusion, the present study showed that fecal hormone analysis provides an integrated measure of glucocorticoid metabolites concentrations over time, potentially reflecting physiological differences among snake species.