Responses to intruder scents in the cooperatively breeding meerkat: sex and social status differences and temporal variation

Although sex-specific responses to intruder scent marks have been described in many mammal species, less is known about variation in responses in cooperatively breeding species where differential access to breeding opportunities exists within groups. When reproductive skew is high, strong responses to extragroup breeding rivals would be expected mainly from dominant individuals, with levels of investment depending on female receptiveness. However, evidence from controlled experiments on cooperative breeders for sex and social status differences in responses to intruder scent marks is limited. Here, we investigated responses to intruder scent marks in cooperatively breeding meerkats (Suricata suricatta), where a single dominant pair largely monopolizes within-group reproduction. A series of experimental presentations using feces were used to test first, whether meerkats discriminate between resident and extragroup male scent marks; second, whether sex and social status affect the response to intruding male scents; and third, whether dominant males increase their level of response when dominant females are most receptive. Our results suggest that meerkats are able to discriminate between resident and intruding male scent marks and show that dominant males have the strongest overall response to intruder scent marks, which does not increase with female receptiveness. We suggest that, although all group members may be affected by the presence of intruders, reproductive conflict may be the main reason for the stronger response of dominant males to extragroup male scent marks in this cooperatively breeding species with high reproductive skew. Copyright 2011, Oxford University Press.