Variation In Risk-taking Behavior Research Articles

Drivers of within- and among-individual variation in risk-taking behaviour during reproduction in a long-lived bird.

Plastic and selective mechanisms govern parental investment adjustments to predation threat. We investigated the relative importance of plasticity and selection in risk-taking propensity of incubating female common eiders Somateria mollissima facing unprecedented predation in SW Finland, Baltic Sea. Using a 12-year individual-based dataset, we examined within- and among-individual variation in flight initiation distance (FID), in relation to predation risk, nest detectability, individual traits and reproductive investment (NFID = 1009; Nindividual = 559). We expected females nesting in riskier environments (higher predation risk, lower nest concealment) to mitigate environmentally imposed risk by exhibiting longer FIDs, and females investing more in current reproduction (older, in better condition or laying larger clutches) to display shorter FIDs. The target of predation-adult or offspring-affected the mechanisms adapting risk-taking propensity; females plastically increased their FID under higher adult predation risk, while risk-avoiding breeders were predominant on islands with higher nest predation risk. Risk-taking females selected thicker nest cover, consistent with personality-matching habitat choice. Females plastically attenuated their anti-predator response (shorter FIDs) with advancing age, and females in better body condition were more risk-taking, a result explained by selection processes. Future research should consider predator type when investigating the fitness consequences of risk-taking strategies.

Suppression of personality variation in boldness during foraging in three-spined sticklebacks

Consistent inter-individual variation in behaviour within a population, widely referred to as personality variation, can be affected by environmental context. Feedbacks between an individual’s behaviour and state can strengthen (positive feedback) or weaken (negative feedback) individual differences when experiences such as predator encounters or winning contests are dependent on behavioural type. We examined the influence of foraging on individual-level consistency in refuge use (a measure of risk-taking, i.e. boldness) in three-spined sticklebacks, Gasterosteus aculeatus, and particularly whether changes in refuge use depended on boldness measured under control conditions. In the control treatment trials with no food, individuals were repeatable in refuge use across repeated trials, and this behavioural consistency did not differ between the start and end of these trials. In contrast, when food was available, individuals showed a higher degree of consistency in refuge use at the start of the trials versus controls but this consistency significantly reduced by the end of the trials. The effect of the opportunity to forage was dependent on behavioural type, with bolder fish varying more in their refuge use between the start and the end of the feeding trials than shyer fish, and boldness positively predicted the likelihood of feeding at the start but not at the end of the trials. This suggests a state-behaviour feedback, but there was no overall trend in how bolder individuals changed their behaviour. Our study shows that personality variation can be suppressed in foraging contexts and a potential but unpredictable role of feedbacks between state and behaviour.Significance statementIn this experimental study, we examined how foraging influences consistency in risk-taking in individual three-spined sticklebacks. We show that bolder individuals become less consistent in their risk-taking behaviour than shyer individuals during foraging. Some bolder individuals reinforce their risk-taking behaviour, suggesting a positive feedback between state and behaviour, while others converge on the behaviour of shyer individuals, suggesting a negative feedback. In support of a role of satiation in driving negative feedback effects, we found that bolder individuals were more likely to feed at the start but not at the end of the trials. Overall, our findings suggest that foraging can influence personality variation in risk-taking behaviour; however, the role of feedbacks may be unpredictable.

Relative deprivation as a cause of risky behaviors

Combining a standard measure of concern about low relative wealth and a standard measure of relative risk aversion leads to a novel explanation of variation in risk-taking behavior identified and d...

Relative deprivation as a cause of risky behaviors

ABSTRACTCombining a standard measure of concern about low relative wealth and a standard measure of relative risk aversion leads to a novel explanation of variation in risk-taking behavior identified and documented by social psychologists and economists. We obtain two results: (1) Holding individual i’s wealth and his rank in the wealth distribution constant, the individual’s relative risk aversion decreases when he becomes more relatively deprived as a result of an increase in the average wealth of the individuals who are wealthier than he is. (2) If relative deprivation enters the individual’s utility function approximately linearly then, holding constant individual i’s wealth and the average wealth of the individuals who are wealthier than he is, the individual’s relative risk aversion decreases when he becomes more relatively deprived as a result of a decline in his rank. Our findings provide a theoretical support for evidence about the propensity of relatively deprived individuals to gamble and resort to other risky behaviors.

Pure rank preferences and variation in risk-taking behavior

Assuming that an individual’s rank in the wealth distribution is the only factor determining the individual’s wellbeing, we analyze the individual’s risk preferences in relation to gaining or losing rank, rather than the individual’s risk preferences towards gaining or losing absolute wealth. We show that in this characterization of preferences, a high-ranked individual is more willing than a low-ranked individual to take risks that can provide him with a rise in rank: relative risk aversion with respect to rank in the wealth distribution is a decreasing function of rank. This result is robust to incorporating (the level of) absolute wealth in the individual’s utility function.

Relative Deprivation as a Cause of Risky Behaviors

Combining a standard measure of concern about low relative wealth and a standard measure of relative risk aversion leads to a novel explanation of variation in risk-taking behavior identified and documented by social psychologists and economists. We obtain two results: (1) Holding individual i's wealth and his rank in the wealth distribution constant, the individual's relative risk aversion decreases when he becomes more relatively deprived as a result of an increase in the average wealth of the individuals who are wealthier than he is. (2) If relative deprivation enters the individual's utility function approximately linearly then, holding constant individual i's wealth and the average wealth of the individuals who are wealthier than he is, the individual's relative risk aversion decreases when he becomes more relatively deprived as a result of a decline in his rank. Our findings provide a theoretical support for evidence about the propensity of relatively deprived individuals to gamble and resort to other risky behaviors.

Pure Rank Preferences and Variation in Risk-Taking Behavior

Assuming that an individual’s rank in the wealth distribution is the only factor determining the individual’s well-being, we analyze the individual’s risk preferences in relation to gaining or losing rank, rather than the individual’s risk preferences towards gaining or losing absolute wealth. We show that in this characterization of preferences, a high-ranked individual is more willing than a low-ranked individual to take risks that can provide him with a rise in rank: relative risk aversion with respect to rank in the wealth distribution is a decreasing function of rank. This result is robust to incorporating (the level of) absolute wealth in the individual’s utility function.

Pure Rank Preferences and Variation in Risk-Taking Behavior

Assuming that an individual's rank in the wealth distribution is the only factor determining the individual's wellbeing, we analyze the individual's risk preferences in relation to gaining or losing rank, rather than the individual's risk preferences towards gaining or losing absolute wealth. We show that in this characterization of preferences, a high-ranked individual is more willing than a low-ranked individual to take risks that can provide him with a rise in rank: relative risk aversion with respect to rank in the wealth distribution is a decreasing function of rank. This result is robust to incorporating (the level of) absolute wealth in the individual's utility function.

Relative Deprivation as a Cause of Risky Behaviors

Combining a standard measure of concern about low relative wealth and a standard measure of relative risk aversion leads to a novel explanation of variation in risk-taking behavior identified and documented by social psychologists and economists. We obtain two results: (1) Holding individual i’s wealth and his rank in the wealth distribution constant, the individual’s relative risk aversion decreases when he becomes more relatively deprived as a result of an increase in the average wealth of the individuals who are wealthier than he is. (2) If relative deprivation enters the individual’s utility function approximately linearly then, holding constant individual i’s wealth and the average wealth of the individuals who are wealthier than he is, the individual’s relative risk aversion decreases when he becomes more relatively deprived as a result of a decline in his rank. Our findings provide a theoretical support for evidence about the propensity of relatively deprived individuals to gamble and resort to other risky behaviors.

State-dependent changes in risk-taking behaviour as a result of age and residual reproductive value

Animals are able to modify their behaviour in response to changes in their internal and environmental state. The asset protection principle predicts that an animal's risk-taking behaviour should vary as a result of its residual reproductive value (RRV); animals with greater RRV would incur a greater cost if injured or killed and should therefore take fewer risks than those with low RRV. Despite the intuitive appeal of this hypothesis, few studies have effectively separated the effects of RRV on behaviour from those of age. We addressed this weakness in the widely invoked hypothesis by measuring the risk-taking behaviour of female Australian field crickets, Teleogryllus oceanicus, at various points in the animal's lifetime. We found significant effects of age on risk-taking behaviour: older females emerged from a shelter sooner after a simulated predation threat and exhibited greater mobility in an open arena. Importantly, there was also a significant marginal effect of RRV on risk-taking behaviour. Females with lower RRV displayed greater levels of risk taking than females with high RRV. Our results thereby offer support for the asset protection principle as an explanation for state-dependent variation in risk-taking behaviour.

Escape ability and risk-taking behaviour in a Hungarian population of the collared flycatcher (Ficedula albicollis)

Risk-taking decisions in front of a predator are crucial for the fitness of the animals. Risk-taking behaviour can be hypothesised to depend on escape ability, which is difficult to study in the wild. In this field study, we investigated whether escape ability (i) is a consistent individual-specific characteristic and (ii) can explain between-individual variation in risk-taking behaviour in male collared flycatchers (Ficedula albicollis). We estimated escape ability by the time that was needed to capture individuals by hand in an outdoor aviary during both the courtship and the nestling feeding phases. We estimated risk-taking by human-induced flight initiation distance (FID) and parental nest-defence behaviour. We also measured variables that reflect individual quality and condition to assess how these affect escape ability. Time to capture was weakly repeatable in the within- and between-season contexts, but was considerably repeatable within a day. We found that time to capture decreased between courtship and nestling feeding phases, probably due to parallel changes in body condition (as shown by the systematic decline of individual body mass between phases correlating with within-individual changes in time to capture). Overall, time to capture was not significantly related to risk-taking behaviour, but we found a negative correlation between time to capture and FID in yearlings. In conclusion, escape ability in flycatchers seems to be a condition-dependent plastic trait, and it has the potential to affect immediate risk-taking decisions. We investigated the proximate determinants of escape ability in collared flycatcher males and whether this trait can be a potential driver of risk-taking behaviour, which is a rarely considered issue. We measured escape ability as time needed to capture birds in an outdoor aviary by hand. We found that escape ability was repeatable only in a short-term context, and differed between the courtship and chick-feeding periods, probably due to parallel changes in body condition. Furthermore, escape ability in yearlings (but not in adults) correlated with an estimate of risk-taking in the wild indicating that males with better ability to escape take higher risk. Our findings highlight that individual decisions about risk-taking might partially rely on how individuals assess their potential escape success.

Between individual variation in risk-taking behavior and its life history consequences

Flight initiation distances (FIDs) of animals approached by a potential predator provide information about the risk that individuals are willing to take given their state and the environment. Species differ in mean and variance in FID, suggesting that species with a large variance in FID have individuals that take either small or great risks, whereas species with a small variance are composed of individuals that are homogeneous in their risk-taking behavior. Here, we investigate the correlations between interspecific variance in risk-taking behavior and habitat selection, breeding range and population size, dispersal, and life history. Greater between individual variation in risk-taking behavior for a given average level of risk taking would imply that more different habitats could be exploited, resulting in larger local and global population sizes and larger ranges. There should be a link between dispersal distances and FID because individuals of risk-averse species should encounter greater difficulties of finding suitable breeding habitats. High local and global population sizes should select for fast life histories with early age at first reproduction, high annual fecundity, low juvenile survival, and fast rates of senescence in species with variable FIDs. Finally, a greater diversity of habitat use should select for a longer reproductive season in species with more variable FIDs. Analyses of FIDs for 133 species of birds revealed results largely consistent with these predictions. Because risk taking correlates with other kinds of behavior that constitute a syndrome behavioral syndromes can play an important role in producing ecological syndromes (i.e., correlations between ecological traits).

Natural Selection, the Costs of Reproduction, and a Refinement of Lack's Principle

Natural Selection, the Costs of Reproduction, and a Refinement of Lack's Principle