In recent years, evidence for interindividual variation in ''personality'' within animal populations has been accumulating. Personality is defined as consistency in an individual's behavioral responses over time and/or across situations. One personality trait that has potentially far-reaching implications for behavioral ecology, and may provide insight into the mechanisms by which consistent behavioral correlations arise, is that of boldness. Boldness is defined as the tendency of an individual to take risks and be exploratory in novel contexts. Using the framework of behavioral syndromes, we tested for individual differences in boldness in the laboratory among field-caught juvenile bluegill sunfish (Lepomis macrochirus) within and across the contexts of exploratory behavior, activity, and risk taking (e.g., antipredator) behavior. After such testing, individuals were tagged and returned to their lake of origin as part of a mark-recapture study testing for the repeatability of individual differences in boldness. Here, we report strong and consistent individual differences in boldness within and across all 3 behavioral contexts. Additionally, we observed that at least some boldness behaviors were repeatable after a 1-3 month recapture period. This study provides novel evidence for a boldness syndrome in sunfish, as well as insight into how behavioral types (e.g., shy/bold) may evolve and be maintained in natural populations.

No abstract

Size-selective harvesting associated with commercial and recreational fishing practices has been shown to alter life history traits through a phenomenon known as fishing-induced evolution. This phenomenon may be a result of selection pathways targeting life-history traits directly or indirectly through correlations with behavioral traits. Here, we report on the relationship between individual differences in behavior and capture technique (beach seining versus angling) in wild-caught juvenile bluegill sunfish ( Lepomis macrochirus ). Both fish caught by using a seine net (seined) and fish caught by using a lure (angled) were individually tested under standardized laboratory conditions for their boldness, water-column use, and general activity. Observed inter-individual differences in boldness were strongly correlated with method of capture in the wild. Fish caught by angling were more timid and had fewer ectoparasites than fish caught using a seine net. However, this relationship did not carry over to an experiment in a large outdoor pool with seine-caught, individually tagged wild fish, where bolder individuals were more likely to be angled in open water away from refuges than more timid individuals, based on their previously assessed boldness scores. Our study is both novel and important, as it describes the relationship between capture technique and boldness in a natural population and underscores the potential risk of sampling biases associated with method of animal capture for behavioral, population, and conservation biologists.

The istiophorid family of billfishes is characterized by an extended rostrum or 'bill'. While various functions (e.g. foraging and hydrodynamic benefits) have been proposed for this structure, until now no study has directly investigated the mechanisms by which billfishes use their rostrum to feed on prey. Here, we present the first unequivocal evidence of how the bill is used by Atlantic sailfish (Istiophorus albicans) to attack schooling sardines in the open ocean. Using high-speed video-analysis, we show that (i) sailfish manage to insert their bill into sardine schools without eliciting an evasive response and (ii) subsequently use their bill to either tap on individual prey targets or to slash through the school with powerful lateral motions characterized by one of the highest accelerations ever recorded in an aquatic vertebrate. Our results demonstrate that the combination of stealth and rapid motion make the sailfish bill an extremely effective feeding adaptation for capturing schooling prey.

One of the main challenges in the study of social networks in vertebrates is to close the gap between group patterns and dynamics. Usually scan samples or transect data are recorded to provide information about social patterns of animals, but these techniques themselves do not shed much light on the underlying dynamics of such groups. Here we show an approach which captures the fission-fusion dynamics of a fish population in the wild and demonstrates how the gap between pattern and dynamics may be closed. Our analysis revealed that guppies have complex association patterns that are characterised by close strong connections between individuals of similar behavioural type. Intriguingly, the preference for particular social partners is not expressed in the length of associations but in their frequency. Finally, we show that the observed association preferences could have important consequences for transmission processes in animal social networks, thus moving the emphasis of network research from descriptive mechanistic studies to functional and predictive ones.

In recent years, animal social interactions have received much attention in terms of personality research (e.g. aggressive or cooperative interactions). However, other components of social behaviour such as those describing the intensity, frequency, directedness and individual repeatability of interactions in animal groups have largely been neglected. Network analysis offers a valuable opportunity to characterize individual consistency of traits in labile social groups and therein provide novel insights to personality research in ways previously not possible using traditional techniques. Should individual network positions be consistently different between individuals under changing conditions, they might reflect expressions of an individual's personality. Here, we discuss a conceptual framework for Communicated by D. P. Croft

Recently emerged brook charr foraging in still-water pools along the sides of streams tend to be either sedentary, feeding from the lower portion of the water column (a sit-and-wait tactic) near the stream bank, or very active, feeding from the upper portion of the water column (an active search tactic) away from the bank. We tested whether the search tactics used by charr in the field represent behavioural syndromes related to activity and space use. After quantifying the behaviour of fish in the field, focal individuals were captured and their behaviour quantified in novel environment experiments in the laboratory. In an aquarium, individuals that used an active search tactic in the field spent a higher proportion of time moving, spent less time near the aquarium bottom, and took less time to find their way out of an erect glass jar, on average, than did individuals that used a sit-and-wait tactic in the field. When presented with near-bank and open-water conditions over 6 days in the laboratory, individuals that used an active search tactic in the field remained active and altered their activity less, on average, than individuals that used a sit-and-wait tactic in the field. Immediate responses to a pebble dropped in the aquarium (simulated risk from above) were not correlated with field behaviour. The search tactics used by brook charr in the field reflect part of a behavioural syndrome related to general activity and space use, but not to startle responses. These initial, individual differences in behaviour provide important raw material for the initial stages of resource polymorphism.

Understanding the manner by which individual differences in personality arise and are maintained in animal populations is currently a topic of considerable research interest. This is particularly the case when it comes to developmental processes and understanding how behaviors change over ontogeny. Such developmental perspectives are essential given that the vast majority of animal species possess complex life cycles or undergo some form of metamorphosis. Yet, in spite of the broad taxonomic relevance and the obvious potential importance of metamorphosis for understanding the basis of consistency in personality over ontogeny, almost no research has been done on this topic. Using the lake frog (Rana ridibunda) as a study organism, we tested whether individual-level differences in personality (activity, exploration and boldness) were consistent within both larval and juvenile frog life-history stages and across metamorphosis. We found that most behaviors of interest were highly consistent within a given life-history stage and at least some traits were consistent across metamorphosis (e.g., activity and exploration). Generally, more active, exploratory individuals in novel experimental arenas were also bolder and more likely to spend time in more risky open areas of a familiar environment. To our knowledge, our study is the first to both characterize personality traits across anuran development and provide evidence of consistency in behavior across metamorphosis in a vertebrate species.