Ontogeny of alarm call responses in meerkats, Suricata suricatta: the roles of age, sex and nearby conspecifics LINDA I. HOLLE ´ N & MARTA B. MANSER Zoologisches Institut, Universita ¨t Zu ¨rich (Received 24 July 2005; initial acceptance 28 September 2005; final acceptance 26 March 2006; published online 6 October 2006; MS. number: 8630R) Given the strong selection on prey animals to escape predation, early development of correct avoidance strategies should be favoured. We studied the development of responses to conspecific alarm calls in a free-ranging population of meerkats in South Africa. Through behavioural observations of naturally oc- curring predator encounters and playback experiments, we monitored responses of young individuals from emergence (3 weeks) to 6 months of age and compared them with those of adults (>12 months). Although the total proportion of responses differing from those of adults was low during the observed period, the probability of responding like adults increased with age. Female young, who remained in closer contact to adults than did male young, were also more likely to show adultlike responses. The largest proportion of non-adultlike responses was shown before reaching independence at 3 months of age, and during this time young commonly ran immediately to a nearby individual when hearing an alarm call. After playbacks of alarm calls, young also reacted more slowly, resumed foraging sooner and spent less time vigilant than did adults. We conclude that young may need experience during early development to associate an alarm call correctly with the type of threat and appropriate response. Older group members may also serve as indirect models, perhaps helping young to form this association. Ó 2006 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. Animals are predisposed to learn about features in their environment that are relevant to their survival, but given the strong selective force that predation exerts on animals, in particular young individuals, one might expect avoid- ance strategies to be fully functional upon a first encoun- ter with a predator. However, if predation risk varies in space and time (Lima & Dill 1990), or if an environmental change causes animals to be exposed to previously unfa- miliar predators (Berger et al. 2001), learning would allow responses to be adjusted to local conditions. Furthermore, the protection of young from predators is an essential component of parental care (Clutton-Brock 1991), so the presence and form of parental care may influence the be- haviour and survival of young. In species where parental care is present, young may rely on their parents to defend them against predators or have the opportunity to learn how to avoid them (e.g. Hodge 2003; Platzen & Magrath 2004), whereas young that do not receive parental care may be under higher pressure to have functional antipredator behaviour from birth (e.g. Impekoven 1976; Miller & Blaich 1986; Go ¨th 2001). Research on the development of alarm call responses in mammals has focused mainly on nonhuman primates (reviewed in Seyfarth & Cheney 1997) and ground squir- rels (Mateo 1996a,b; Hanson & Coss 2001). In both non- human primates and ground squirrels, the appropriate responses to alarm calls seem to develop gradually with age, suggesting that young individuals need experience to associate alarm calls correctly with the type of threat and correct response. For example, infant vervet monkeys, Chlorocebus (formerly Cercopithecus) aethiops, of 3e4 months of age rarely responded like adults, whereas most infants older than 6 months did so (Seyfarth & Che- ney 1986). The need for experience was further supported by Hauser (1988), who found that infant vervet monkeys exposed to superb starling, Spreo superbus, alarm calls at a high rate responded appropriately to these calls at an earlier age than did infants exposed to these calls at a lower rate. Given that learning how to avoid predators might be costly to acquire through individual experience, it is perhaps not surprising that there is substantial evidence for social influences on antipredator behaviour in a wide range of taxa, including fish, birds and mammals Correspondence: L. Holle ´n, Verhaltensbiologie, Zoologisches Institut, Universita ¨t Zu ¨rich, Winterthurerstrasse 190, CH-8057 Zu ¨rich, Switzerland (email: lindah@zool.unizh.ch). 1345 0003e 3472/06/$30.00/0 Ó 2006 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. ANIMAL BEHAVIOUR, 2006, 72, 1345e1353 doi:10.1016/j.anbehav.2006.03.020