Nutrient-specific compensation for seasonal cold stress in a free-ranging temperate colobine monkey

1. Homeostatic responses of animals to environmentally-induced changes in nutrient requirements provide a powerful basis for predictive ecological models, and yet such responses are virtually unstudied in the wild.
2. We tested for macronutrient-specific compensatory feeding responses by free-ranging golden snub-nosed monkeys (Rhinopithecus roxellana) inhabiting high altitude temperate forests where they experience a substantial difference in ambient temperature in cold winters vs. warmer springs. The monkeys had free access to natural foods throughout the year, and to ensure that any seasonal differences in nutrient intake were due to homeostatic compensation and not constraints on food availability, we studied the monkeys during periods in which they were provisioned with the same amount of supplementary foods in winter and spring.
3. Thermoregulatory energy costs in winter and spring were calculated using partitional calorimetric estimations of convective and radiative heat loss ob...