Golden snub-nosed monkeys in winter, in China’s Quinling mountains. Credit David Raubenheimer.

University of Sydney researchers have found monkeys living in the wild in cold snowy habitats adjust their nutrient intake to match the elevated costs of thermoregulation.

China’s Quinling mountains, high altitude temperate forests where winter temperatures commonly drop below 0 degrees Celsius and approximately 50 cm of snow covers the ground for several weeks in the winter, was the location of the study.

Published in Functional Ecology, the researchers analysed the nutritional content of all foods the monkeys consumed in order to calculate the nutrient composition of the monkeys’ diets, and then assessed the additional energy the monkeys used to regulate their temperature in winter compared with spring.

Professor David Raubenheimer, the University of Sydney’s Leonard P Ullmann Chair in Nutritional Ecology at the School of Life and Environmental Sciences and Charles Perkins Centre, conducted the study’s nutritional modelling using nutritional geometry, a multidimensional framework that explores how animals balance the ingestion of multiple nutrients.

“To better understand the adaptations that enable these monkeys to live and thrive in such a harsh environment – among the coldest for any primate – we tested how they cope with additional energetic costs of keeping warm in winter,” Professor Raubenheimer said.

“Our study controlled for food availability using supplementary foods to ensure that food was abundant throughout the year and the amounts eaten in winter and spring were due to the animals’ own choices rather than ecological restrictions on what was available to eat.

“The monkeys ate twice as much energy in winter compared to spring. Remarkably, the additional intake in winter came entirely from fats and carbohydrates, with protein intake remaining the same.”