Physiological health benchmarks in free-ranging Fosa ( <i>Cryptoprocta ferox</i> ): establishing reference intervals to assess the impact of anthropogenic disturbance on an endemic apex predator

Abstract Anthropogenic changes are impacting biodiversity at multiple levels. However, the effects of environmental stressors on physiological function and health of individual organisms are not well understood. Population-specific benchmark data are crucial for evaluating the health of populations over time, and for comparisons between different wild populations and captive animals. The Fosa (Cryptoprocta ferox), the largest extant member of the Eupleridae, is endemic to Madagascar. As an apex predator, the Fosa faces increasing anthropogenic disturbance. It therefore is vital to establish reference intervals for hematological and biochemical parameters in free-ranging Fosa to monitor their health and to conserve the species in both wild and captive environments. Through a sequence of blood tests, we aimed to provide information on the physiological health of free-ranging Fosa and in comparison with captive Fosa. A total of 71 Fosa from 3 sites across their geographic range were captured and sampled for hematological and serum biochemical analysis for health evaluation. Our analysis indicates that many wild Fosa have blood values outside the RI established from captive individuals, which may reflect stress and pathological conditions of individuals and underscores the importance of establishing population-specific reference intervals because those derived from captive individuals may not accurately reflect the health status of wild populations. The reference intervals obtained through our study have the potential to serve as valuable benchmarks for future evaluations of hematologic and serum biochemistry values in wild Fosa, contributing to future research and conservation efforts.