Spatial position relative to group members affects weight gain in meerkats, Suricata suricatta

Abstract

Social animals often face a trade-off between the costs of foraging competition among group members and the benefits of protection from predators offered by group living. The spatial position of an individual in relation to the other group members during foraging can mediate the effects of this trade-off as individuals at the front or edge may have better access to food resources, but also higher predation risk than individuals near the centre of the group. Using meerkats, Suricata suricatta, as a model species, we investigated the effect of individual spatial position within a group on foraging success. We determined the spatial position of individuals in a meerkat group by fitting the animals with high-resolution GPS loggers. As a proxy of foraging success, we used meerkats' individual body weight differences between the start and the end of daily data collection over foraging periods (3 h). We found significant individual differences in meerkats’ spatial positions within the group. In addition, age-dependent differences in spatial position became obvious, with older meerkats spending less time in the centre of the group and more time in side positions, subordinate females spending less time in the front, and subordinate males spending more time in the back. Younger meerkats who spent more time in the front of the group relative to older meerkats had decreased daily weight gain, indicating less successful foraging. We also found that the dominant females tended to spend more time towards the front of the group, but gained less weight in this position, contrary to the predicted association between front edge of the group and better access to food resources. Our results suggest that the relationship between weight gain and spatial position is highly nuanced and likely to be dependent on more than just trade-offs between foraging success and predation risk.