Animal Personality Research Articles

Intersexual differences in the exploratory behaviour of blue tits (Cyanistes caeruleus)

Abstract Breeding performance and survival are mechanisms through which animal personality affects fitness. Exploration behaviour (EB) is an easily obtainable personality trait that correlates to multiple life-history traits, thus it has been widely used in animal personality studies. Through in situ Novel Environment exploration tests, we assessed the exploration behaviour of blue tits (Cyanistes caeruleus) during two breeding seasons. A principal component analysis revealed two behavioural axes regarding the exploration behaviour: slow-fast and timid-daring. We found that male blue tits are significantly slower explorers than female blue tits, suggesting that evolutionary processes act unequally across sexes in our study area. To investigate these processes, we assessed the relationship between exploration behaviour and two fitness aspects: reproduction and survival. Slower-exploring males bred in nests with significantly shorter incubation periods, and timid males had higher local return ratios. Interactions between male and female EB revealed that disassortative pairs were more successful breeders than assortative ones. Further research should explore potential evolutionary implications of intersexual EB differences.

Personality as a Predictor of Time-Activity Budget in Lion-Tailed Macaques (Macaca silenus).

Simple SummaryTime-activity budgets describe how animals divide their day into various behaviours and activities, e.g., time spent foraging or resting. Activity budgets can serve as crucial indicators of energy intake and expenditure, providing better knowledge of a species’ lifestyle. The conventional trend has been to explore group-level time-activity budgets; however, individuals may also vary in their time-activity budgets (e.g., one individual foraging more than another), with the influencing mechanisms still poorly understood. We propose that animal personality, a behavioural and cognitive profile that makes one individual different from another, may explain why individuals vary in their time-activity budgets. We used a multi-method approach comprised of behavioural observations and experiments to assess the personality traits of lion-tailed macaques. The observed traits were used to predict individual time-activity budgets, broadly categorised into food-related, active, and resting behaviours. We then discuss the significance of this novel approach in light of lion-tailed macaque ecology, conservation, and welfare. Time-activity budget, i.e., how a population or an individual divides their day into various behaviours and activities, is an important ecological aspect. Existing research primarily focused on group-level time-activity budgets, while individual variations have only been reported recently. However, little is known about how consistent inter-individual differences or personalities influence time-activity budgets. We examined the personalities of lion-tailed macaques (Macaca silenus) and investigated their influence on individual time-activity budgets. The resulting personality traits, namely persistence, sociability, affiliation, and anxiety, were used to predict the three broad categories of the time-activity budget—food-related, active, and resting behaviours. We found that persistence and sociability positively predicted the time spent being active. Food-related behaviours were positively predicted by persistence, while anxiety was found to influence them negatively. The time spent resting was negatively predicted by persistence. We did not find an effect of affiliation on the time-activity budgets. We discuss these findings in light of the ecology of lion-tailed macaques. Our study highlights the importance of a novel approach that uses animal personality traits as predictors of individual time-activity budgets and offers insights regarding the use of personality assessments in conservation and welfare activities.

Once an optimist, always an optimist? Studying cognitive judgment bias in mice.

Individuals differ in the way they judge ambiguous information: some individuals interpret ambiguous information in a more optimistic, and others in a more pessimistic way. Over the past two decades, such “optimistic” and “pessimistic” cognitive judgment biases (CJBs) have been utilized in animal welfare science as indicators of animals’ emotional states. However, empirical studies on their ecological and evolutionary relevance are still lacking. We, therefore, aimed at transferring the concept of “optimism” and “pessimism” to behavioral ecology and investigated the role of genetic and environmental factors in modulating CJB in mice. In addition, we assessed the temporal stability of individual differences in CJB. We show that the chosen genotypes (C57BL/6J and B6D2F1N) and environments (“scarce” and “complex”) did not have a statistically significant influence on the responses in the CJB test. By contrast, they influenced anxiety-like behavior with C57BL/6J mice and mice from the “complex” environment displaying less anxiety-like behavior than B6D2F1N mice and mice from the “scarce” environment. As the selected genotypes and environments did not explain the existing differences in CJB, future studies might investigate the impact of other genotypes and environmental conditions on CJB, and additionally, elucidate the role of other potential causes like endocrine profiles and epigenetic modifications. Furthermore, we show that individual differences in CJB were repeatable over a period of seven weeks, suggesting that CJB represents a temporally stable trait in laboratory mice. Therefore, we encourage the further study of CJB within an animal personality framework.

Female Java sparrows prefer high exploratory males without assortative mating

A major challenge in behavior and evolutionary ecology is to understand the evolution and maintenance of animal personality. Theory suggests that females can benefit by choosing a high-quality mate, but largely ignores the potential interaction between male and female personality during mate choice. Here, we examined the influence of exploration on mate choice by captive female Java sparrows (Lonchura oryzivora). Females preferred high exploratory males as mates rather than choosing mates according to their own exploration, and thus showed no assortative mating. Our results highlight the role of exploration of males in the mate preference of birds and suggest that mate compatibility plays minor role in the mate preference.

Personality, sperm traits and a test for their combined dependence on male condition in guppies.

There is evidence that animal personality can affect sexual selection, with studies reporting that male behavioural types are associated with success during pre- and post-copulatory sexual selection. Given these links between personality and sexual traits, and the accumulating evidence that their expression can depend on an individual's dietary status (i.e. condition), a novel prediction is that changes in a male's diet should alter both the average expression of personality and sexual traits, and their covariance. We tested these predictions using the guppy Poecilia reticulata, a species previously shown to exhibit strong condition dependence in ejaculate traits and a positive correlation between sperm production and individual variation in boldness. Contrary to expectation, we found that dietary restriction—when administered in mature adult males—did not affect the expression of either behavioural (boldness and activity) or ejaculate traits, although we did find that males subjected to dietary stress exhibited a positive association between sperm velocity and boldness that was not apparent in the unrestricted diet group. This latter finding points to possible context-dependent patterns of covariance between sexually selected traits and personalities, which may have implications for patterns of selection and evolutionary processes under fluctuating environmental conditions.

Toward on-farm measurement of personality traits and their relationships to behavior and productivity of grazing dairy cattle

There is growing evidence that animal personality is linked to a range of productivity traits in farm animals, including dairy cattle. To date, the methodology for assessing personality traits of dairy cattle is time consuming and often requires a test arena, which limits the opportunity for commercial farms to use personality traits of dairy cattle for individualized management. This study investigated whether personality traits of pastured dairy cattle, scored in short behavioral tests, are associated with daily behavioral patterns and milk production. Cows (n = 87) were exposed twice to each of 5 behavioral tests, where their responses to novel or putatively stressful situations were scored on an ordinal scale for investigative and reactive behavior toward a novel object and a novel human after exiting the milking parlor, response to restraint in a crush, avoidance distance from an approaching human in the paddock, and response to milking (step-kick behavior). Most behavior test scores were consistent over the 2 test repeats (using repeatability estimates, Mann-Whitney U test of difference between repeats, and Spearman rank correlation). Behavior test scores were subjected to a principal components analysis that revealed intertest relationships in 3 factors of correlated sets of test scores, interpreted as personality traits (fearful of humans, calm-investigative, and reactive to milking). Regression analyses determined how these traits were associated with daily grazing, ruminating, and lying behaviors, and milk production (after controlling for cow age, breed, lactation status, group, and climate variables). Cows that were more fearful of humans (high avoidance distance, reactive toward the novel human) had reduced lying time compared with cows that scored low on this trait. Cows that were more calm (during restraint) and investigative (toward the novel object) had greater grazing time, which likely contributed to their greater milk production compared with cows that scored low on this trait. Cows that were more reactive to milking produced less milk than cows that scored low on this trait. These results indicate that individual differences in daily behavior patterns and milk production of dairy cattle are associated with personality traits of cows, measured using several short behavioral tests. These methods may be useful for characterizing grazing dairy cattle on commercial farms, which could aid in understanding individual behavior patterns and provide opportunities for individualized management.

Elusive workers are more likely to differentiate into replacement reproductives than aggressive workers in a lower termite.

One of the most intriguing questions in eusocial insects is to understand how the overt reproductive conflict in the colony appears limited when queens or kings are senescent or lost because the morphologically similar individuals in the colony are reproductively totipotent. Whether there are some individuals who preferentially differentiate into replacement reproductives or not has received little attention. The consistent individual behavioral differences (also termed "animal personality") of individuals from the colony can shape cunningly their task and consequently affect the colony fitness but have been rarely investigated in eusocial insects. Here, we used the termite Reticulitermes labralis to investigate if variations in individual personalities (elusiveness and aggressiveness) may predict which individuals will perform reproductive differentiation within colonies. We observed that when we separately reared elusive and aggressive workers, elusive workers differentiate into reproductives significantly earlier than aggressive workers. When we reared them together in the proportions 12:3, 10:5, and 8:7 (aggressive workers: elusive workers), the first reproductives mostly differentiated from the elusive workers, and the reproductives differentiated from the elusive workers significantly earlier than from aggressive workers. Furthermore, we found that the number of workers participating in reproductive differentiation was significantly lower in the groups of both types of workers than in groups containing only elusive workers. Our results demonstrate that the elusiveness trait was a strong predictor of workers' differentiation into replacement reproductives in R. labralis. Moreover, our results suggest that individual personalities within the insect society could play a key role in resolving the overt reproductive conflict.

Self-Domestication Underground? Testing for Social and Morphological Correlates of Animal Personality in Cooperatively-Breeding Ansell’s Mole-Rats (Fukomys anselli)

Ansell’s mole-rats (Fukomys anselli) are sexually dimorphic subterranean rodents that live in families consisting of a single breeding pair and their late-dispersing non-breeding offspring. Most individuals exhibit a conspicuous white head patch, which results from integumental depigmentation. Alongside other morphological, physiological, and social characteristics, skin depigmentation in these social rodents mirrors traits that presumably evolved as byproducts from selection against aggression in domestic animals, making them a potential candidate species for a self-domesticated wild mammal. Here we explored whether the expression of the white head patch, sexual dimorphism, and reproductive division of labor are reflected by different personalities in Ansell’s mole-rats. We tested locomotory activity and risk-taking as well as aggression and affiliative behavior in 51 individuals originating from nine captive families in various experimental set-ups. In line with the concept of animal personality, we recovered consistent individual responses over time. While sex had no influence on any tested variable, reproductive status was found to affect risk-taking behavior but not other personality dimensions. Discriminant function analysis revealed that family members clustered more closely together than expected by chance, suggesting that group affiliation rather than sex or social status determines behavioral profiles in this species. Finally, we failed to recover any consistent correlation between head patch expression and behavior, which conflicts with predictions of the self-domestication hypothesis. We argue that many domestication-like traits in Ansell’s mole-rat and its congeners evolved in the framework of subterranean adaptation and call for a cautious application of the self-domestication concept to wild mammals.

Transcriptomic profiles of consistent risk-taking behaviour across time and contexts in European sea bass.

Bolder individuals have greater access to food sources and reproductive partners but are also at increased risk of predation. Boldness is believed to be consistent across time and contexts, but few studies have investigated the stability of this trait across variable environments, such as varying stress loads or long periods of time. Moreover, the underlying molecular components of boldness are poorly studied. Here, we report that boldness of 1154 European sea bass, evaluated using group risk-taking tests, is consistent over seven months and for individuals subjected to multiple environments, including a chronically stressful environment. Differences in risk-taking behaviour were further supported by differences observed in the responses to a novel environment test: shy individuals displayed more group dispersion, more thigmotaxic behaviour and lower activity levels. Transcriptomic analyses performed on extreme phenotypes revealed that bold individuals display greater expression for genes involved in social and exploration behaviours, and memory in the pituitary, and genes involved in immunity and responses to stimuli in the head kidney. This study demonstrates that personality traits come with an underpinning molecular signature, especially in organs involved in the endocrine and immune systems. As such, our results help to depict state-behaviour feedback mechanisms, previously proposed as key in shaping animal personality.

Adult exploration predicts parental responsiveness to juvenile songs in zebra finch parent–juvenile interactions

Recent research has established the importance of animal personality traits in behavioural ecology, encompassing domains such as mate choice, cognition and social interactions. However, less is known about how personality traits predict parental behaviour. In the current study, we investigate these relationships in the zebra finch, Taeniopygia gutatta, a species that provides biparental care and in which social feedback from parents shapes juvenile song learning. Adults were first assessed on exploratory tendency in a novel environment, then allowed to pair and rear cross-fostered young. Birds were housed in single-family cages within the colony, allowing for visual and auditory interaction between families. We examined foster parent–juvenile interactions over the course of song learning (35–65 days posthatch), recording parental responsiveness (responses contingent on juvenile songs) as these responses are known to influence song learning outcomes. Exploration scores predicted parental responsiveness in contrasting ways: low-exploring males provided more contingent responses to the immature song of juveniles, while high-exploring females increased their responsiveness to a greater degree over the course of juvenile song development. Over the period of offspring song development, females were more responsive to changes in juvenile vocal production, increasing the number of responses provided as juveniles increased their rate of singing. In contrast, males were less variable in their response rate across development; their contingent singing was not sensitive to changes in the rate of juvenile singing. The importance of exploration as a predictor of parental responsiveness to offspring behaviour demonstrates the possible significance of previous findings that adults pair based on the trait of exploration.

Emergence of personality in weaning-age kittens of the domestic cat?

Individual differences in behavior (animal personality) have recently received much attention although less so in young mammals. We tested 74 preweaning-age kittens from 16 litters of domestic cats in five everyday contexts repeated three times each across a 3-week period: a handling test where an experimenter held the kitten, a test where a piece of raw beef was given to the kitten and gradually withdrawn, a test where the kitten was presented with a live mouse in a jar, a test where the kitten was briefly confined in a pet carrier, and an encounter with an unfamiliar human who first remained passive and then attempted to stroke the kitten. We found consistent individual differences in behavior in all tests except with the mouse, although less marked than in equivalent tests with adult cats. Differences in behavior were unrelated to sex, body mass, litter size, or maternal identity. We found only weak correlations in results among the tests (behavioral syndromes), again unlike findings in adult cats. We conclude that weanling kittens show consistent individual differences in behavior but in a different manner to adults. If and how the pattern of such differences changes across development remains to be studied.

Personality and social environment predict cognitive performance in common marmosets (Callithrix jacchus).

Consistent inter-individual variation in cognition has been increasingly explored in recent years in terms of its patterns, causes and consequences. One of its possible causes are consistent inter-individual differences in behaviour, also referred to as animal personalities, which are shaped by both the physical and the social environment. The latter is particularly relevant for group-living species like common marmosets (Callithrix jacchus), apt learners that display substantial variation in both their personality and cognitive performance, yet no study to date has interlinked these with marmosets’ social environment. Here we investigated (i) consistency of learning speed, and (ii) whether the PCA-derived personality traits Exploration-Avoidance and Boldness-Shyness as well as the social environment (i.e., family group membership) are linked with marmosets’ speed of learning. We tested 22 individuals in series of personality and learning-focused cognitive tests, including simple motor tasks and discrimination learning tasks. We found that these marmosets showed significant inter-individual consistency in learning across the different tasks, and that females learned faster than males. Further, bolder individuals, and particularly those belonging to certain family groups, learned faster. These findings indicate that both personality and social environment affect learning speed in marmosets and could be important factors driving individual variation in cognition.

The effects of intra- and interspecific competitions on personality and individual plasticity in two sympatric brown frogs

We studied how individuals modify their behavior in response to inter- and intraspecific competitors and how these changes affected the pattern of variation between populations and species. As study models, we used tadpoles of two brown frogs, Rana latastei and R. dalmatina. Since R. latastei is always sympatric to R. dalmatina, whereas R. dalmatina is sympatric to R. latastei only in the periphery of its range, we predicted a stronger response to heterospecifics in R. latastei than in R. dalmatina and, within each species, in syntopic than in allotopic populations. To test these predictions, we raised tadpoles, from either syntopic or allotopic populations, in either syntopy or allotopy and repeatedly tested them in open field trials in the presence of a caged conspecific, a caged heterospecific, or an empty cage. As predicted, we found that, on average, R. latastei tadpoles modified their behavior across treatments more than R. dalmatina tadpoles and individuals from the syntopic population changed more than their conspecifics from the allotopic population. In both species, the pattern of variation at the individual level mirrored that at the population and species levels providing no evidence for an individual-by-environment interaction (Itimes E). Besides these differences, however, individuals of the two species also showed unpredicted and context-independent behavioral differences, suggesting that there might be more to interspecific behavioral variation than the effect of selection by heterospecific competitors.Significance statementDoes the distribution range of a species influence the evolution of plastic behaviors to heterospecific competitors? And how do differences in plasticity affect animal personality? To answer these questions, we raised tadpoles of two brown frog species, Rana dalmatina and R. latastei, and studied how the amount and the type of their swimming varied with the presence of the other species. R. latastei, whose small distribution range fully overlaps with that of R. dalmatina, plastically responds to it, whereas R. dalmatina, which is sympatric to R. latastei only in the periphery of its broader range, does not. These interspecific differences mirrored those among individuals: tadpoles of both species show repeatable behaviors, but only those of R. latastei plastically changed their behavior with the presence of the other species; however, neither R. latastei nor R. dalmatina show among-individual variation in plasticity.

Limitations and challenges of adapting subjective keeper questionnaires to non-Western sanctuary settings

In the past decade, there has been substantial growth in the number of animal personality studies published, however relatively little work has been conducted on different species of bears. Personality structure can provide insight into individual differences in behavioural responses, and in the context of captive management, may be valuable for improving welfare through individualised monitoring and care. The goal of this study was to assess the relationship between personality and welfare in Asiatic black bears (‘moon bear’, Ursus thibetanus) and sun bears (Helarctos malayanus). In collaboration with bear behaviour specialists, we adapted existing personality, subjective well-being, and welfare surveys originally designed for other captive mammal species to be appropriate and specific for bears. Surveys were written in English and translated to Khmer, with backtranslation checked for retention of the original meaning. The surveys were delivered verbally to 16 experienced bear keepers working within a bear rescue centre in Cambodia. In total, 36 Asiatic black bears and 41 sun bears were rated. Each bear was assessed by two keepers who were familiar with the individual animal. Although this approach has been successfully used with an array of captive species, in the current study, observer agreement was found to be very low as determined by intraclass correlations of rating scores. Because of this, we were unable to determine the personality structures in these species and thus could not examine the relationship between personality and welfare. The cause of this low agreement is unclear however in this paper we discuss potential cross-cultural or logistical reasons, and suggest that future studies using questionnaires to assess animal personality, welfare, or subjective well-being may benefit from consideration of these challenges in their study design.

Small mammal personalities generate context dependence in the seed dispersal mutualism

Mutualisms are foundational components of ecosystems with the capacity to generate biodiversity through adaptation and coevolution and give rise to essential services such as pollination and seed dispersal. To understand how mutualistic interactions shape communities and ecosystems, we must identify the mechanisms that underlie their functioning. One mechanism that may drive mutualisms to vary in space and time is the unique behavioral types, or personalities, of the individuals involved. Here, our goal was to examine interindividual variation in the seed dispersal mutualism and identify the role that different personalities play. In a field experiment, we observed individual deer mice (Peromyscus maniculatus) with known personality traits predating and dispersing seeds in a natural environment and classified all observed interactions made by individuals as either positive or negative. We then scored mice on a continuum from antagonistic to mutualistic and found that within a population of scatter hoarders, some individuals are more mutualistic than others and that one factor driving this distinction is animal personality. Through this empirical work, we provide a conceptual advancement to the study of mutualism by integrating it with the study of intraspecific behavioral variation. These findings indicate that animal personality is a previously overlooked mechanism generating context dependence in plant–animal interactions and suggest that behavioral diversity may have important consequences for the functioning of mutualisms.

Repeatability and Predictability of Calf Feeding Behaviors-Quantifying Between- and Within-Individual Variation for Precision Livestock Farming.

Individual calves show substantial between- and within-individual variation in their feeding behavior, the existence and extent of which are not fully researched. In this study, 57,196 feeding records, collected by a computerized milk feeder from 48 pre-weaned calves over 5 weeks, were collated and analyzed for individual differences in three different feeding behaviors using a multi-level modeling approach. For each feeding behavior, we quantified behavioral variation by calculating repeatability and the coefficient of variation in predictability. Our results indicate that calves differed from each other in their average behavioral expression (behavioral type) and in their residual, within individual variation around their behavioral type (predictability). Feeding rate and total meals had the highest repeatability (>0.4) indicating that substantial, temporally stable between-individual differences exist for these behaviors. Additionally, for some behaviors (e.g., feeding rate) calves varied from more to less predictable whereas for other behaviors (e.g., meal size) calves were more homogenous in their within-individual variation around their behavioral type. Finally, we show that for individual calves, behavioral types for feeding rate and total meals were positively correlated which may suggest the existence of an underlying factor responsible for driving the (co)expression of these two behaviors. Our results highlight how the application of methods from the behavioral ecology literature can assist in improving our understanding of individual differences in calf feeding behavior. Furthermore, by uncovering consistencies between individual behavioral differences in calves, our results indicate that animal personality may play a role in driving variability in calf feeding behavior.

Translocation in relict shy-selected animal populations: Program success versus prevention of wildlife-human conflict

Past human persecution of wildlife has acted as a major selection agent shaping many animal features including behaviour. A major component of behaviour with diverse consequences for conservation is the shyness/boldness continuum. Shyer individuals are often geographically restricted, less prone to wander out of their ecological refuges but, on the contrary, less likely to experience human-induced mortality and lead to human-wildlife conflict. In this essay we discuss how the success of translocations may interact both positively and negatively with animal personalities, based on several case studies of re-introductions and reinforcements involving remnant mammal and bird populations. Although shyness may be inconvenient to conservationists when dealing with raptor translocations in which eventual dispersal may be a desired trait in the long run, a trade-off may emerge between boldness and prevention of human-wildlife conflict when dealing with large carnivores. Some other trade-offs may also occur, such as that between boldness and desired philopatry at the initial stage of re-introductions.

Among-individual variation of risk-taking behaviour in group and solitary context is uncorrelated but independently repeatable in a juvenile Arctic charr (Salvelinus alpinus) aquaculture strain

Behavioural traits have been shown to have implications in fish welfare and growth performances in aquaculture. If several studies have demonstrated the existence of repeatable and heritable behavioural traits (i.e., animal personality), the methodology to assess personality in fishes is often carried out in solitary context, which appears to somewhat limit their use from a selective breeding perspective because these tests are too time consuming. To address this drawback, group-based tests have been developed. In Nordic country, Arctic charr (Salvelinus alpinus) is widely used in aquaculture, but no selection effort on behavioural traits has yet been carried out. Specifically, in this study we examined if risk-taking behaviour was repeatable and correlated in group and solitary context and if the early influences of physical environment affect the among-individual variation of behavioural trait across time in order to verify whether a group risk-taking test could be used as a selective breeding tool. Here, we found that in both contexts and treatments, the risk-taking behaviour was repeatable across 7 days. However, no cross-context consistency was found between group and solitary, which indicates that individual Arctic charr express different behavioural trait in group and solitary.

Bold or shy? Examining the risk–taking behavior and neophobia of invasive and non–invasive house sparrows

Behavior provides a useful framework for understanding specialization, with animal personality aiding our understanding of the invasiveness of birds. Invasions imply dispersion into unknown areas and could require changes in behavior or spatial clustering based on personality. Reduced neophobia and increased exploring behavior could allow individuals to colonize new areas as they test and use non–familiar resources. Here, we hypothesized that house sparrow (Passer domesticus) individuals from invasive populations would exhibit bolder behavior than in non–invasive populations. We assessed risk taking and neophobia in male house sparrows in Barcelona (where it is considered native) and in Mexico City (where it has become widely invasive), captured in two different habitats, urban and non–urban. We assessed latency to enter an experimental cage and to explore it, and latency to feed and feeding time in the presence of a novel object. We found that sparrows from Mexico City, both from urban and non–urban areas, were quicker to enter the experimental cage than the sparrows from Barcelona. The time it took the birds to start exploring the cage gave a similar result. We found no differences between cities or habitats in the latency to feed and feeding time while exposed to a novel object. Our results partially support the view that the invader populations from Mexico City are bolder than those from Barcelona. Behavior is an important component of plasticity and its variability may have an important effect on adaptation to local situations. Future studies should disentangle the underlying mechanisms that explain the different personalities found in populations of different regions, contrasting populations of different densities, and taking different food availability scenarios into account.

Sex and Population Drive Interindividual Variations in a Cognitive Task Across Three Populations of Wild Zebrafish

Animal personality refers to the consistency of variation in behavior among individuals which may be the driving force behind variations in complex behaviors as well. Individual personality could predict how well an organism would perform in behavior and cognition related tasks, as well as survive and thrive in its environment. Therefore, we would expect inter-individual variations in many behaviors, which would persist even if habituation to the experimental setup occurs, which generally results in convergence of behavior (i.e., the difference between individuals becomes less pronounced). Our study used wild-caught zebrafish (Danio rerio) from three natural habitats with differing ecological regimes, to understand how consistency and repeatability in specific traits such as boldness, exploration, and spatial ability varies across and within populations even when habituation causes change in behavior. We found that the extent of individual variation differs between populations, with dynamic habitats showing similar repeatability. This indicates that habitat conditions are important drivers of individual variation in addition to other factors, such as sex or size of individuals within populations. Although we found that sex and size played an important role within some populations for some behaviors, in others, the variation was likely caused by other factors (for example, ecological factors such as vegetation and/or resource availability), for which we have not accounted. This study underlines the importance of studying inter-individual differences as the phenomenon that underpins multiple behavioral traits and explains the possible role of environmental and inherent factors that drive these differences.