Intraspecific variation in boldness and exploration shapes behavioral responses to stress in Galápagos sea lion pups

Abstract: Behavioral plasticity allows individual organisms to alter behavioral traits in response to environmental or state-dependent conditions. Structured animal personality traits often influence the degree of between-individual variation in plasticity within a population, especially as it relates to an individual’s behavioral coping style towards disturbances. Here, we investigated whether boldness and exploration measured during novel object tests in young Galápagos sea lion pups were associated with individual behavioral responses towards capture. We found that only state-related traits, such as sex and body condition, and not personality affected baseline capture responses (struggle and escape responses after release). Male pups and those that maintained good body condition tended to show initially low struggle and escape behavior. These responses, however, were not highly repeatable within individuals during the study period. Different personality types greatly differed in how they modulated their behavior over time, and few sea lions utilized fixed strategies. Unexpectedly, bolder but less explorative individuals habituated quickest to capture, while shy and explorative pups increased responses over time. Pups found to be bolder but less explorative in novel object tests also moved between fewer sites within their habitat based on observational data. This may suggest that these individuals may be less sensitive to disturbances by increasing familiarity within a limited home range. Our results illustrate that individual pups may differentially assess risk and adjust behavior to cope with disturbance within their early life environment. Significance statement: Galápagos sea lions are an endangered pinniped species which live within a habitat characterized by a large degree of environmental uncertainty. We hypothesized that, depending on their personality, Galápagos sea lion pups may show varying degrees of behavioral plasticity in response to a dynamic early life environment. We show that bold pups and those that were less explorative during novel object tests and within their natural habitat were more likely to habituate quickly to stressful experiences (i.e., a capture and handling regime). We postulate that a familiarity with the physical and social environment in addition to personality traits may play an important role in how individual sea lion pups assess and cope with early life risks.