Aggressive interactions influence cognitive performance in Western Australian magpies

Extensive research has investigated the relationship between the social environment and cognition, suggesting that social complexity may drive cognitive evolution and development. However, evidence for this relationship remains equivocal. Group size is often used as a measure of social complexity, but this may not capture intraspecific variation in social interactions. Social network analysis can provide insight into the cognitively demanding challenges associated with group living at the individual level. Here, we use social networks to investigate whether the cognitive performance of wild Western Australian magpies (Gymnorhina tibicen dorsalis) is related to group size and individual social connectedness. We quantified social connectedness using four interaction types: proximity, affiliative, agonistic and vocal. Consistent with previous research on this species, individuals in larger groups performed better on an associative learning task. However, social network position was also related to cognitive performance. Individuals receiving aggressive interactions performed better, while those involved in aggressive interactions with more group members performed worse. Overall, this suggests that cognitive performance is related to specific types of social interaction. The findings from this study highlight the value of considering fine-grained metrics of sociality that capture the challenges associated with social life when testing the relationship between the social environment and cognition.

Environmental harshness does not affect the propensity for social learning in great tits, Parus major

According to the harsh environment hypothesis, natural selection should favour cognitive mechanisms to overcome environmental challenges. Tests of this hypothesis to date have largely focused on asocial learning and memory, thus failing to account for the spread of information via social means. Tests in specialized food-hoarding birds have shown strong support for the effects of environmental harshness on both asocial and social learning. Whether the hypothesis applies to non-specialist foraging species remains largely unexplored. We evaluated the relative importance of social learning across a known harshness gradient by testing generalist great tits, Parus major, from high (harsh)- and low (mild)-elevation populations in two social learning tasks. We showed that individuals use social learning to find food in both colour-associative and spatial foraging tasks and that individuals differed consistently in their use of social learning. However, we did not detect a difference in the use or speed of implementing socially observed information across the elevational gradient. Our results do not support predictions of the harsh environment hypothesis suggesting that context-dependent costs and benefits as well as plasticity in the use of social information may play an important role in the use of social learning across environments. Finally, this study adds to the accumulating evidence that the harsh environment hypothesis appears to have more pronounced effects on specialists compared to generalist species.

Contaminant-by-environment interactive effects on animal behavior in the context of global change: Evidence from avian behavioral ecotoxicology

The potential for chemical contaminant exposure to interact with other stressors to affect animal behavioral responses to environmental variability is of mounting concern in the context of anthropogenic environmental change. We systematically reviewed the avian literature to evaluate evidence for contaminant-by-environment interactive effects on animal behavior, as birds are prominent models in behavioral ecotoxicology and global change research. We found that only 17 of 156 (10.9 %) avian behavioral ecotoxicological studies have explored contaminant-by-environment interactions. However, 13 (76.5 %) have found evidence for interactive effects, suggesting that contaminant-by-environment interactive effects on behavior are understudied but important. We draw on our review to develop a conceptual framework to understand such interactive effects from a behavioral reaction norm perspective. Our framework highlights four patterns in reaction norm shapes that can underlie contaminant-by-environment interactive effects on behavior, termed exacerbation, inhibition, mitigation and convergence. First, contamination can render individuals unable to maintain critical behaviors across gradients in additional stressors, exacerbating behavioral change (reaction norms steeper) and generating synergy. Second, contamination can inhibit behavioral adjustment to other stressors, antagonizing behavioral plasticity (reaction norms shallower). Third, a second stressor can mitigate (antagonize) toxicological effects of contamination, causing steeper reaction norms in highly contaminated individuals, with improvement of performance upon exposure to additional stress. Fourth, contamination can limit behavioral plasticity in response to permissive conditions, such that performance of more and less contaminated individuals converges under more stressful conditions. Diverse mechanisms might underlie such shape differences in reaction norms, including combined effects of contaminants and other stressors on endocrinology, energy balance, sensory systems, and physiological and cognitive limits. To encourage more research, we outline how the types of contaminant-by-environment interactive effects proposed in our framework might operate across multiple behavioral domains. We conclude by leveraging our review and framework to suggest priorities for future research.

Long-term repeatability of cognitive performance

Measures of cognitive performance, derived from psychometric tasks, have yielded important insights into the factors governing cognitive variation. However, concerns remain over the robustness of these measures, which may be susceptible to non-cognitive factors such as motivation and persistence. Efforts to quantify short-term repeatability of cognitive performance have gone some way to address this, but crucially the long-term repeatability of cognitive performance has been largely overlooked. Quantifying the long-term repeatability of cognitive performance provides the opportunity to determine the stability of cognitive phenotypes and the potential for selection to act on them. To this end, we quantified long-term repeatability of cognitive performance in wild Australian magpies over a three-year period. Cognitive performance was repeatable in two out of four cognitive tasks-associative learning and reversal-learning performance was repeatable, but spatial memory and inhibitory control performance, although trending toward significance, was not. Measures of general cognitive performance, obtained from principal components analyses carried out on each cognitive test battery, were highly repeatable. Together, these findings provide evidence that at least some cognitive phenotypes are stable, which in turn has important implications for our understanding of cognitive evolution.

Slow-Fast Cognitive Phenotypes and Their Significance for Social Behavior: What Can We Learn From Honeybees?

Cognitive variation is proposed to be the fundamental underlying factor that drives behavioral variation, yet it is still to be fully integrated with the observed variation at other phenotypic levels that has recently been unified under the common pace-of-life framework. This cognitive and the resulting behavioral diversity is especially significant in the context of a social group, the performance of which is a collective outcome of this diversity. In this review, we argue about the utility of classifying cognitive traits along a slow-fast continuum in the larger context of the pace-of-life framework. Using Tinbergen’s explanatory framework for different levels of analyses and drawing from the large body of knowledge about honeybee behavior, we discuss the observed interindividual variation in cognitive traits and slow-fast cognitive phenotypes from an adaptive, evolutionary, mechanistic and developmental perspective. We discuss the challenges in this endeavor and suggest possible next steps in terms of methodological, statistical and theoretical approaches to move the field forward for an integrative understanding of how slow-fast cognitive differences, by influencing collective behavior, impact social evolution.

Ecophysiology of egg rejection in hosts of avian brood parasites: new insights and perspectives

Egg rejection is the most effective and widespread defense used by host species to counteract the extreme fitness costs frequently imposed by obligate avian brood parasites. Yet, the proximate mechanisms underlying between- and within-individual variation in host responses remain poorly explored. Emerging evidence suggests that egg rejection is dependent on individual physiological states, and draws attention to the role of hormones as mediators of flexible antiparasitic responses. In this perspective article, I outline recent advances in our understanding of the proximate factors that mediate egg rejection. I also point out some areas where knowledge remains still lacking, especially those related to the development and maintenance of effective cognitive functions, the potential role of oxidative stress, immunological state, and developmental stressors. I propose new hypotheses that stimulate future research on behavioral host responses toward brood parasitism.

Inhibitory control, exploration behaviour and manipulated ecological context are associated with foraging flexibility in the great tit

Organisms are constantly under selection to respond effectively to diverse, sometimes rapid, changes in their environment, but not all individuals are equally plastic in their behaviour. Although cognitive processes and personality are expected to influence individual behavioural plasticity, the effects reported are highly inconsistent, which we hypothesise is because ecological context is usually not considered. We explored how one type of behavioural plasticity, foraging flexibility, was associated with inhibitory control (assayed using a detour-reaching task) and exploration behaviour in a novel environment (a trait closely linked to the fast-slow personality axis). We investigated how these effects varied across two experimentally manipulated ecological contexts-food value and predation risk. In the first phase of the experiment, we trained great tits Parus major to retrieve high value (preferred) food that was hidden in sand so that this became the familiar food source. In the second phase, we offered them the same familiar hidden food at the same time as a new alternative option that was visible on the surface, which was either high or low value, and under either high or low perceived predation risk. Foraging flexibility was defined as the proportion of choices made during 4-min trials that were for the new alternative food source. Our assays captured consistent differences among individuals in foraging flexibility. Inhibitory control was associated with foraging flexibility-birds with high inhibitory control were more flexible when the alternative food was of high value, suggesting they inhibited the urge to select the familiar food and instead selected the new food option. Exploration behaviour also predicted flexibility-fast explorers were more flexible, supporting the information-gathering hypothesis. This tendency was especially strong under high predation risk, suggesting risk aversion also influenced the observed flexibility because fast explorers are risk prone and the new unfamiliar food was perceived to be the risky option. Thus, both behaviours predicted flexibility, and these links were at least partly dependent on ecological conditions. Our results demonstrate that an executive cognitive function (inhibitory control) and a behavioural assay of a well-known personality axis are both associated with individual variation in the plasticity of a key functional behaviour. That their effects on foraging flexibility were primarily observed as interactions with food value or predation risk treatments also suggest that the population-level consequences of some behavioural mechanisms may only be revealed across key ecological conditions.

The impact of environmental and social factors on learning abilities: a meta-analysis

Since the 1950s, researchers have examined how differences in the social and asocial environment affect learning in rats, mice, and, more recently, a variety of other species. Despite this large body of research, little has been done to synthesize these findings and to examine if social and asocial environmental factors have consistent effects on cognitive abilities, and if so, what aspects of these factors have greater or lesser impact. Here, we conducted a systematic review and meta-analysis examining how different external environmental features, including the social environment, impact learning (both speed of acquisition and performance). Using 531 mean-differences from 176 published articles across 27 species (with studies on rats and mice being most prominent) we conducted phylogenetically corrected mixed-effects models that reveal: (i) an average absolute effect size |d| = 0.55 and directional effect size d = 0.34; (ii) interventions manipulating the asocial environment result in larger effects than social interventions alone; and (iii) the length of the intervention is a significant predictor of effect size, with longer interventions resulting in larger effects. Additionally, much of the variation in effect size remained unexplained, possibly suggesting that species differ widely in how they are affected by environmental interventions due to varying ecological and evolutionary histories. Overall our results suggest that social and asocial environmental factors do significantly affect learning, but these effects are highly variable and perhaps not always as predicted. Most notably, the type (social or asocial) and length of interventions are important in determining the strength of the effect.

Wild jackdaws respond to their partner's distress, but not with consolation

Individuals are expected to manage their social relationships to maximize fitness returns. For example, reports of some mammals and birds offering unsolicited affiliation to distressed social partners (commonly termed 'consolation') are argued to illustrate convergent evolution of prosocial traits across divergent taxa. However, most studies cannot discriminate between consolation and alternative explanations such as self-soothing. Crucially, no study that controls for key confounds has examined consolation in the wild, where individuals face more complex and dangerous environments than in captivity. Controlling for common confounds, we find that male jackdaws (Corvus monedula) respond to their mate's stress-states, but not with consolation. Instead, they tended to decrease affiliation and partner visit rate in both experimental and natural contexts. This is striking because jackdaws have long-term monogamous relationships with highly interdependent fitness outcomes, which is precisely where theory predicts consolation should occur. Our findings challenge common conceptions about where consolation should evolve, and chime with concerns that current theory may be influenced by anthropomorphic expectations of how social relationships should be managed. To further our understanding of the evolution of such traits, we highlight the need for our current predictive frameworks to incorporate the behavioural trade-offs inherent to life in the wild.

Innovative problem-solving in wild hyenas is reliable across time and contexts

Individual differences in behavior are the raw material upon which natural selection acts, but despite increasing recognition of the value of considering individual differences in the behavior of wild animals to test evolutionary hypotheses, this approach has only recently become popular for testing cognitive abilities. In order for the intraspecific approach with wild animals to be useful for testing evolutionary hypotheses about cognition, researchers must provide evidence that measures of cognitive ability obtained from wild subjects reflect stable, general traits. Here, we used a multi-access box paradigm to investigate the intra-individual reliability of innovative problem-solving ability across time and contexts in wild spotted hyenas (Crocuta crocuta). We also asked whether estimates of reliability were affected by factors such as age-sex class, the length of the interval between tests, or the number of times subjects were tested. We found significant contextual and temporal reliability for problem-solving. However, problem-solving was not reliable for adult subjects, when trials were separated by more than 17 days, or when fewer than seven trials were conducted per subject. In general, the estimates of reliability for problem-solving were comparable to estimates from the literature for other animal behaviors, which suggests that problem-solving is a stable, general trait in wild spotted hyenas.