Data from: Cold and hungry: combined effects of low temperature and resource scarcity on an edge-of-range temperate primate, the golden snub-nose monkey

Both biotic and abiotic factors play important roles in influencing
ecological distributions and niche limits. Where biotic and abiotic
stressors co-occur in space and time, homeostatic systems face a different
category of challenge in which stressors compound to impose a challenge
that is greater than the sum of the separate factors. We studied the
homeostatic strategies of the golden snub-nosed monkey (Rhinopithecus
roxellana), a species living in temperate deciduous forests at the edge of
the global distribution range for folivorous primates, to cope with the
co-occurrence of cold temperatures and resource scarcity during winter. We
discovered that in winter the monkeys experience a dietary energy deficit
of 101 kJ/mbm·day-1 compared with calculated needs, despite increased
feeding. This is partly offset by behavioral changes (reduced locomotion
and increased resting) and reducing skin temperature by an average of 3.2
oC through a cutaneous vasoconstriction to decrease heat loss. However,
their major strategy is ingesting surplus energy and accumulating fat
reserves when food was not limiting during summer and autumn. Their 14% of
body mass lost over the winter represented an energy yield of 102
kJ/mbm·day-1, which closely matched the calculated winter energy deficit
of 101 kJ/mbm·day-1. However, the latter value assumes that all the
75.41kJ/mbm·day-1 of protein ingested in winter was available for energy
metabolism. This is almost certainly an over-estimate, suggesting that the
study population was in negative energy balance over the study period. Our
study therefore suggests that despite its suit of integrated homeostatic
responses, the confluence of low temperatures and resource limitation
during winter places this edge-of-range primate close the threshold of
what is energetically viable. It also provides a framework for
quantitative models predicting the vulnerability of temperate primates to
global change.