Ontogenetic changes in alarm-call production and usage in meerkats (Suricata suricatta): adaptations or constraints?

Abstract

In many species, individuals suffer major mortality in their first year because of predation. Behaviours that facilitate successful escape are therefore under strong selection, but anti-predator skills often emerge gradually during an individual's early development. Using long-term data and acoustic recordings of alarm calls collected during natural predator encounters, we aimed to elucidate two largely unsolved issues in anti-predator ontogeny: (1) whether incorrect predator assignment is adaptively ageappropriate, given that vulnerability often changes during development, or whether age-related differences reflect true mistakes made by immature individuals; and (2) the extent to which the development of adult-like competence in alarm-call production and usage is simply a function of maturational processes or dependent upon experience. We found that young meerkats (Suricata suricatta) were less likely to give alarm calls than adults, but alarmed more in response to non-threatening species compared to adults. However, stimuli that pose a greater threat to young than adults did not elicit more calling from young; this argues against age-related changes in vulnerability as the sole explanation for developmental changes in calling. Young in small groups, who were more likely to watch out for predators, alarmed more than less vigilant young in larger groups. Moreover, despite similarities in acoustic structure between alarm call types, calls appeared in the repertoire at different rates, and those that were associated with frequently encountered predators were produced relatively early on. These results indicate that experience is a more plausible explanation for such developmental trajectories than maturation.

On the Meaning of Alarm Calls: A Review of Functional Reference in Avian Alarm Calling

“…During playbacks of adult calls, moreover, infants do not respond as specifically as adults, looking down for example instead of up when eagle alarm calls are played. In meerkats, which have functionally referential alarm calls that also denote level of urgency (Manser 2001), young (<1 year) and adults produce alarm calls in different contexts and respond differently to playbacks of them (Holl en & Manser 2006;Holl en et al 2008). Interestingly, young meerkats tend to respond with an appropriate level of urgency, even while producing inappropriate calls more often than adults, suggesting that the ability to respond appropriately to predation risk develops earlier than functional reference (Holl en & Manser 2007).…”

Social learning and the development of individual and group behaviour in mammal societies

“…Differences in pup and adult call use are not adaptive responses to age-related differences in vulnerability, as predators that are more threatening to pups than adults do not elicit more alarm calling from pups. Rather, pups begin responding appropriately to common predators at an earlier age than to rarer predators, suggesting that alarm call usage improves with experience [23]. Given that adults' responses provide the only means for pups to learn associations between predators and call types, social learning is likely to be important.…”

Honest error, precaution or alertness advertisement? Reactions to vertebrate pseudopredators in red‐nosed cuxiús (Chiropotes albinasus),a high‐canopy neotropical primate

“…Under such circumstances, the cautious interpretation of a pseudopredators’ shape by a potential prey species simply cuts into the time available for foraging or other activities and so merely delays dinner, rather than risking becoming it. Lastly, there is also ontogeny to correct species identification, with the frequency of appropriately given alarm calls increasing as individuals get older (e.g., baboon and vervet monkeys: Fischer, dwarf mongoose, Helogale parvula : Rasa, ; and meerkat, Suricata suricatta : Hollén, Clutton‐Brock, & Manser, ).…”