Ontogenetic and Sex Differences Influence Alarm Call Responses in Mammals: a Meta-Analysis


  • (Invited Review)

Amanda J. Lea, Department of Ecology and Evolutionary Biology, University of California, 621 Young Drive South, Los Angeles, CA 90095-1606, USA.
E-mail: ajlea@ucla.edu


Animals respond to alarm calls by increasing their antipredator behavior; however, responses may consistently differ by age or sex. Although several adaptive explanations have been proposed to account for age-dependent antipredator behavior, similar explanations are rarely extended to sex-specific responses. Furthermore, no attempts have been made to quantitatively estimate the direction or magnitude of these differences across studies. Here, we use meta-analysis to discover overall trends in the literature, as well as differences owing to experimental or population parameters. Across our sample of available studies (unfortunately biased toward rodents and primates), males respond more than females, and young respond more than adults. Furthermore, young of quickly maturing species display more adult-like antipredator behavior than young of slowly maturing species, suggesting that young must develop antipredator behavior at a pace consistent with the length of their ontogenetic period (a.k.a. juvenile/sub-adult period, defined as the time between birth and attainment of sexual maturity). We review previously proposed explanations for such age differences, namely, that longer ontogenetic periods may provide juveniles with time to develop behavior through learning and experience, or, maturation rates may influence age-specific selection pressures and the consequent evolution of age-specific behavioral strategies. We evaluate our results in light of these hypotheses, although our conclusions are limited by the number and taxonomic bias of available studies. We therefore suggest ways in which future studies may tease apart the relative importance of learning and experience vs. age-specific adaptive behavior, and draw attention to opportunities for research on age- and sex-specific alarm call responses.