Primate behavior and diet are the subject of a paper published in the March 2026 edition of the International Journal of Primatology by Jacob Kraus, visiting assistant professof biology at Washington and Lee University.
The paper, “Age–Sex Class Variation in the Activity Budget and Diet of Rhinopithecus bieti in Association with Monthly Temperature,” explores how primate behavior and diet relate to energy and nutritional needs, especially those needs associated with differences in body size, age and sex. The study specifically analyzes the effects these factors have on Asian colobines species when impacted by changes in climate.
Kraus and his co-authors gathered data for more than 32 months on an isolated population of black-and-white snubnosed monkeys at Mount Lasha in the Yunling Provincial Nature Reserve in Yunnan, China. They utilized scan sampling between May 2008 and August 2016 to investigate how temperature affected activity patterns and diet both between and within different age and sex groups of this species.
While the study discovered minimal differences in feeding patterns amongst the monkeys, it did observe significant behavioral differences between the sexes and age groups depending on if the temperatures were warmer or colder. The results suggest that yearly fluctuations in climate increase differences in physical needs among age and sex groups, leading to bigger changes in activity than in diet.
Kraus joined the W&L faculty in 2025 after serving as a visiting assistant professor of biology at Bates College. His research and teaching interests include animal responses to seasonal changes in climate and resource availability, biostatistics, behavioral and wildlife ecology and primatology.
