Characteristics of Stable Isotope Signature of Diet in Tissues of Captive Japanese Macaques as Revealed by Controlled Feeding

The study investigated the isotopic fractionation of carbon and nitrogen stable isotope ratios between the tissues and diets of captive Japanese macaques through a controlled feeding experiment. The enrichment factors (Δδ13C and Δδ15N) were measured for whole blood, plasma, red blood cells, and hair. The results showed specific Δδ13C and Δδ15N values for each tissue type, with hair showing the highest Δδ13C value. Hair regrown after shaving accurately reflected the δ13C of the diet consumed during hair growth, while naturally grown hair did not show a clear pattern, possibly due to unnatural indoor conditions. The study concluded that further research is needed to clarify the relationships between stable isotope signatures in diet and various body tissues to reconstruct the long-term feeding history of Japanese macaques.