Abstract
<title>Abstract</title> <p> We evaluated the post-defecation stability of fecal cortisol concentrations in ocelots ( <italic>Leopardus pardalis</italic> ) and margays ( <italic>Leopardus wiedii</italic> ) under human care during the first 24 h after defecation at the Miguel Álvarez del Toro Zoo (ZooMAT) in Tuxtla Gutiérrez, Chiapas, Mexico. Fecal samples were collected in the quarantine area during August and September 2024 and analyzed using a competitive ELISA assay. Cortisol concentrations were measured at 0.5, 1, 2, 4, 8, 16, and 24 h post-defecation. The four-parameter logistic calibration model showed a good fit (R² = 0.91). No significant variation in fecal cortisol concentrations was detected over time in either species. Significant differences among individuals were detected in margays, and higher fecal cortisol concentrations were observed in the two females than in the single male included in the study, whereas no significant individual differences were detected between the two female ocelots. Post-excretory degradation did not represent a significant source of variation within 24 h under the humid tropical conditions evaluated (maximum temperature: 32.1°C; maximum relative humidity: 95%), supporting the use of fecal cortisol as a reliable biomarker in Neotropical felids under human care. </p>