Nutritional and Physiological Markers Are Mediated by Seasonality and Forest Access in Captive Coquerel's Sifakas
Primates today live along a continuum of conditions in the wild and in captivity, providing diverse settings to study ecological flexibility. The western sifakas, a clade of endangered lemurs endemic to Madagascar, live in diverse ecosystems, including dry, spiny, and montane forests, and persist even in small forest fragments across their native ranges. A colony of the Coquerel's sifakas (Propithecus coquereli) is also housed at the Duke Lemur Center (DLC) in Durham, NC, where select groups gain access to forest enclosures, a setup that blends human management with an experimental introduction to non-native habitats. To better understand how sifakas adjust to local conditions, we profiled a suite of circulating nutritional and physiological markers collected from DLC sifakas with and without forest access in two seasons. In spring compared to summer, the sifakas had elevated concentrations of many amino acids, which may reflect the seasonal consumption of proteinaceous young leaves. Sifakas with forest access, compared to peers in stall enclosures, had elevated glucose, hippuric acid, the liver enzyme ALT, and a marker of muscle protein turnover—3-methylhistidine. These results likely differentially reflect freely foraged diets and the energy required for locomotion and thermoregulation under more naturalistic conditions. Calcium concentrations were well above values published for wild sifakas in Madagascar. Whereas some markers, like ALT, highlight how sifakas adjust to environmental heterogeneity seemingly without detrimental health effects, others, like calcium, may point to the potential consequences of a mismatch between the environments where species evolved to live and the conditions they now face. Our results can inform husbandry management and dietary optimization for this endangered species in captivity. More broadly, we advocate for research of captive wildlife under ecologically relevant conditions to inform understanding of how wild kin persist under diverse, novel, and local conditions, with implications for conservation management and monitoring in the wild.
