Seasonal and Social Correlates of Changes in Hair, Skin, and Scrotal Condition in Vervet Monkeys (Cercopithecus Aethiops) of Amboseli National Park, Kenya

In a 20-month study of six groups of vervet monkeys in Amboseli National Park, Kenya, researchers observed seasonal hair loss in all individuals and changes in scrotal color and hyperpigmentation in all adult males. Hair loss was more significant in low-ranking individuals, particularly males, and was associated with changes in scrotal color and the presence of scrotal hyperpigmentation. A strong negative correlation was found between scrotal color and hyperpigmentation. The study proposed three potential explanations for these observations: nutrition, stress from competition, or a combination of both. These findings suggest that such physical changes could serve as indicators of physical or emotional stress in free-ranging vervet monkeys.