Leadership Under Risk: Male Vervet Monkeys' ( <i>Chlorocebus pygerythrus</i> ) Roles in Group Progression Across Potentially High‐Risk Terrain

ABSTRACT The evolution of cooperative behaviour among unrelated individuals is still incompletely understood. One example is the provision of costly services by males in primate societies, which is difficult to explain by traditional reciprocity‐based models. Here, we investigated group progressions in wild vervet monkeys ( Chlorocebus pygerythrus ) to test two main hypotheses for male‐biased positioning in potentially risky contexts: paternal care and reputation‐based partner choice. Over more than 2 years, we recorded the order and timing of individual crossings in five neighbouring groups of vervet monkeys across two terrain types differing in presumed risk (rivers and dirt roads). Adult males, particularly dominant males, were more likely to occupy leading positions than females or juveniles, and this tendency was stronger during river crossings. When leading, males often crossed alone, whereas non‐leading males usually crossed within subgroups. Leadership was most pronounced in dominant males without likely offspring. Males who did not lead did not preferentially cross with infants based on their paternal status, and higher leading rates did not predict subsequent mating success or short‐term changes in dominance rank. These findings provide no support for paternal care or direct mating benefits. Instead, male leadership in these contexts likely reflects a combination of ecological conditions, and dominance‐ and paternity‐related differences in behaviour. We conclude that male‐biased positioning in group movement is context‐dependent and may arise from multiple, potentially overlapping processes rather than a single cooperative function. Our results highlight the role of dominance and reproductive status in shaping male service provisioning and underscore its potential flexible function in primate social organisation.