Publications by year
In Press
Hahn LG, Hooper R, McIvor GE, Thornton A (In Press). Cooperative nest building in wild jackdaw pairs.
Abstract:
Cooperative nest building in wild jackdaw pairs
AbstractAnimals create diverse structures, both individually and cooperatively, using materials from their environment. One striking example are the nests birds build for reproduction, which protect the offspring from external stressors such as predators and temperature, promoting reproductive success. To construct a nest successfully, birds need to make various decisions, for example regarding the nest material and their time budgets. To date, research has focused mainly on species where one sex is primarily responsible for building the nest. In contrast, the cooperative strategies of monogamous species in which both sexes contribute to nest building are poorly understood. Here we investigated the role of both sexes in nest building and fitness correlates of behaviour in wild, monogamous jackdaw pairs (Corvus monedula). We show that both partners contributed to nest building and behaved similarly, with females and males present in the nest box for a comparable duration and transporting material to the nest equally often. However, while females spent more time constructing the nest, males tended to invest more time in vigilance, potentially as a means of coping with competition for nest cavities. These findings suggest a moderate degree of division of labour, which may facilitate cooperation. Moreover, some aspects of behaviour were related to proxies of reproductive success (lay date and egg volume). Females that contributed relatively more to bringing material laid earlier clutches and pairs that spent less time together in the nest box had larger eggs. Thus, selection pressures may act on how nest building pairs spend their time and cooperatively divide the labour. We conclude that cooperative nest building in birds could be associated with monogamy and obligate biparental care, and provides a vital but relatively untapped context through which to study the evolution of cooperation.HighlightsIn wild monogamous jackdaws, mates behaved similarly and cooperated to build their nest.Females built more and called more frequently; males tended to be more vigilant.Females that contributed relatively more to transporting nest material laid earlier clutches.Pairs that spent more time together in the nest box had smaller eggs.Cooperation may be crucial in light of obligate biparental care and nest site competition.
Abstract.
Prentice PM, Mnatzaganian C, Houslay TM, Thornton A, Wilson AJ (In Press). Individual differences in spatial learning are correlated across cognitive tasks but not associated with stress response behaviour in the Trinidadian guppy.
Abstract:
Individual differences in spatial learning are correlated across cognitive tasks but not associated with stress response behaviour in the Trinidadian guppy
AbstractCognition is vital for carrying out behaviours required for survival and reproduction. In animals, we now know that cognitive performance varies not just among species, but also among individuals within populations. While this variation is a prerequisite for contemporary natural selection, it is also true that selection does not act on traits in isolation. The extent to which cognitive traits covary with other aspects of phenotype (e.g. personality traits) is therefore expected to be an important factor in shaping evolutionary dynamics. Here we adopt a multivariate approach to test for spatial learning ability in a captive population of male Trinidadian guppies (Poecilia reticulata), and ask whether differences in cognitive performance are associated with (repeatable) differences in stress response behaviour. We focus on stress response for two reasons. First, functional links between cognitive traits and ‘stress coping style’ have been hypothesised. Second, individual-level studies of cognitive performance typically rely on multiple testing paradigms that may themselves be a stressor. Thus, there is a risk that variation in stress responsiveness is itself a cause of apparent, but artefactual variance in cognitive ability. Using a set of fish exposed repeatedly to two distinct spatial learning tasks (maze layouts), and an acute stress response test (open field trial), we find differences among-individuals in task performance that are repeatable within- and across maze layouts. On average performance improves with experience in the first maze, consistent with spatial learning, but not in the second. In both mazes, there is among-individual variation in the trajectory of mean performance with trial number suggesting individuals differ in ‘learning rate’. Acute stress response behaviour is repeatable but predicts neither average time to solve the maze nor learning rate. We thus find no support for among-individual correlation between acute stress response and cognitive performance. However, we highlight the possibility that cumulative, chronic stress effects may nonetheless cause observed declines in performance across repeats for some individuals (leading to lack of improvement in mean time to solve the second maze). If so, this may represent a pervasive but difficult challenge for our ability to robustly estimate learning rates in studies of animal cognition.
Abstract.
Prentice P, mnatzaganian C, Houslay T, Thornton A, Wilson A (In Press). Individual differences in spatial learning are correlated across tasks but not with stress response behaviour in guppies. Animal Behaviour
Hooper R, Brett B, Thornton A (In Press). Problems with comparative analyses of avian brain size.
Abstract:
Problems with comparative analyses of avian brain size
AbstractThere are multiple hypotheses for the evolution of cognition. The most prominent hypotheses are the Social Intelligence Hypothesis (SIH) and the Ecological Intelligence Hypothesis (EIH), which are often pitted against one another. These hypotheses tend to be tested using broad-scale comparative studies of brain size, where brain size is used as a proxy of cognitive ability, and various social and/or ecological variables are included as predictors. Here, we test how methodologically robust such analyses are. First, we investigate variation in brain and body size measurements across >1000 species of bird. We demonstrate that there is substantial variation in brain and body size estimates across datasets, indicating that conclusions drawn from comparative brain size models are likely to differ depending on the source of the data. Following this, we subset our data to the Corvides infraorder and interrogate how modelling decisions impact results. We show that model results change substantially depending on variable inclusion, source and classification. Indeed, we could have drawn multiple contradictory conclusions about the principal drivers of brain size evolution. These results reflect recent concerns that current methods in comparative brain size studies are not robust. We add our voices to a growing community of researchers suggesting that we move on from using such methods to investigate cognitive evolution. We suggest that a more fruitful way forward is to instead use direct measures of cognitive performance to interrogate why variation in cognition arises within species and between closely related taxa.
Abstract.
Kings M, Arbon J, McIvor G, Whitaker M, Radford A, Lerner J, Thornton A (In Press). Selective adjustment of social associations and its influence on social networks in wild corvids.
Abstract:
Selective adjustment of social associations and its influence on social networks in wild corvids
Abstract
. The adjustment of social associations by individuals in response to changes in their social environment is a core principle of influential theories on the evolution of cognition1,2 and cooperation3,4. Selectively adjusting associations with others is thought to allow individuals to maximise short-term rewards from social interactions, thus re-shaping social networks to better favour connections between compatible group members5–8. Crucially, this has yet to be tested in natural populations, where the need to maintain long-term, fitness-enhancing relationships may limit social plasticity9,10. Using a novel social-network-manipulation experiment, we show that wild jackdaws (Corvus monedula) learned to favour social associations with compatible group members (individuals that provided greater returns from social foraging interactions). Consequently, the overall frequency of associations between compatible social partners increased as the experiment progressed. This resulted in clustering of compatible individuals within the social network, but the magnitude of this effect was small, likely due to the preservation of pre-existing long-term relationships. These results provide critical field evidence that learning to adjust social associations is beneficial whilst highlighting trade-offs with the need to maintain valuable long-term relationships. Our findings therefore provide important insights into the cognitive and behavioural basis of social network plasticity and the interplay between individual behaviour and social network structure in natural populations.
Abstract.
2023
Thornton A, Mesoudi A (2023). Untenable propositions and alternative avenues.: Comment to "Blind alleys and fruitful pathways in the comparative study of cultural cognition" by Andrew Whiten.
Phys Life Rev,
44, 51-53.
Author URL.
2022
Ashton BJ, Thornton A, Speechley EM, Ridley AR (2022). Does trappability and self-selection influence cognitive performance?.
Royal Society open science,
9(9).
Abstract:
Does trappability and self-selection influence cognitive performance?
Recent research has highlighted how trappability and self-selection-the processes by which individuals with particular traits may be more likely to be caught or to participate in experiments-may be sources of bias in studies of animal behaviour and cognition. It is crucial to determine whether such biases exist, and if they do, what effect they have on results. In this study, we investigated if trappability (quantified through 'ringing status'-whether or not a bird had been trapped for ringing) and self-selection are sources of bias in a series of associative learning experiments spanning 5 years in the Western Australian magpie (Gymnorhina tibicen dorsalis). We found no evidence of self-selection, with no biases in task participation associated with sex, age, group size or ringing status. In addition, we found that there was no effect of trappability on cognitive performance. These findings give us confidence in the results generated in the animal cognition literature and add to a growing body of literature seeking to determine potential sources of bias in studies of animal behaviour, and how they influence the generalizability and reproducibility of findings.
Abstract.
Driscoll I, Manser M, Thornton A (2022). Function of meerkats' mobbing-like response to secondary predator cues: recruitment not teaching. Animal Behaviour, 194, 111-126.
Soravia C, Ashton BJ, Thornton A, Ridley AR (2022). General cognitive performance declines with female age and is negatively related to fledging success in a wild bird.
Soravia C, Ashton BJ, Thornton A, Ridley AR (2022). General cognitive performance declines with female age and is negatively related to fledging success in a wild bird.
Proc Biol Sci,
289(1989).
Abstract:
General cognitive performance declines with female age and is negatively related to fledging success in a wild bird.
Identifying the causes and fitness consequences of intraspecific variation in cognitive performance is fundamental to understand how cognition evolves. Selection may act on different cognitive traits separately or jointly as part of the general cognitive performance (GCP) of the individual. To date, few studies have examined simultaneously whether individual cognitive performance covaries across different cognitive tasks, the relative importance of individual and social attributes in determining cognitive variation, and its fitness consequences in the wild. Here, we tested 38 wild southern pied babblers (Turdoides bicolor) on a cognitive test battery targeting associative learning, reversal learning and inhibitory control. We found that a single factor explained 59.5% of the variation in individual cognitive performance across tasks, suggestive of a general cognitive factor. GCP varied by age and sex; declining with age in females but not males. Older females also tended to produce a higher average number of fledglings per year compared to younger females. Analysing over 10 years of breeding data, we found that individuals with lower general cognitive performance produced more fledglings per year. Collectively, our findings support the existence of a trade-off between cognitive performance and reproductive success in a wild bird.
Abstract.
Author URL.
Blackburn G, Broom E, Ashton BJ, Thornton A, Ridley AR (2022). Heat stress inhibits cognitive performance in wild Western Australian magpies, Cracticus tibicen dorsalis.
Animal Behaviour,
188, 1-11.
Abstract:
Heat stress inhibits cognitive performance in wild Western Australian magpies, Cracticus tibicen dorsalis
Cognition enables animals to respond and adapt to environmental changes and has been linked to fitness in multiple species. Identifying the potential impact of a warming climate on cognition is therefore crucial. We quantified individual performance in an ecologically relevant cognitive trait, associative learning, to investigate the relationship between heat stress and cognition in wild Western Australian magpies over 2 consecutive years. We found that heat stress had a significant negative effect on performance in both years, with individual pass rates much lower under heat stress than under nonheat stress conditions. The long-term repeatability of cognitive performance within temperature conditions was high (i.e. consistent fails under heat stress and consistent passes under nonheat stress conditions between years), but repeatability between conditions was low. This suggests that the observed effect could not be attributed solely to natural fluctuation in cognitive performance. This study is one of the first to reveal the negative influence of heat stress on cognitive performance in a wild animal, drawing attention to the potential cognitive consequences of rising temperatures.
Abstract.
Ashton BJ, Thornton A, Cauchoix M, Ridley AR (2022). Long-term repeatability of cognitive performance.
R Soc Open Sci,
9(5).
Abstract:
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.
Abstract.
Author URL.
McIvor GE, Lee VE, Thornton A (2022). Nesting jackdaws’ responses to human voices vary with local disturbance levels and the gender of the speaker. Animal Behaviour, 192, 119-132.
Hooper R, Brett B, Thornton A (2022). Problems with using comparative analyses of avian brain size to test hypotheses of cognitive evolution.
PLOS ONE,
17(7), e0270771-e0270771.
Abstract:
Problems with using comparative analyses of avian brain size to test hypotheses of cognitive evolution
There are multiple hypotheses for the evolution of cognition. The most prominent hypotheses are the Social Intelligence Hypothesis (SIH) and the Ecological Intelligence Hypothesis (EIH), which are often pitted against one another. These hypotheses tend to be tested using broad-scale comparative studies of brain size, where brain size is used as a proxy of cognitive ability, and various social and/or ecological variables are included as predictors. Here, we test how robust conclusions drawn from such analyses may be. First, we investigate variation in brain and body size measurements across >1000 bird species. We demonstrate that there is substantial variation in brain and body size estimates across datasets, indicating that conclusions drawn from comparative brain size models are likely to differ depending on the source of the data. Following this, we subset our data to the Corvides infraorder and interrogate how modelling decisions impact results. We show that model results change substantially depending on variable inclusion, source and classification. Indeed, we could have drawn multiple contradictory conclusions about the principal drivers of brain size evolution. These results reflect concerns from a growing number of researchers that conclusions drawn from comparative brain size studies may not be robust. We suggest that to interrogate hypotheses of cognitive evolution, a fruitful way forward is to focus on testing cognitive performance within and between closely related taxa, with an emphasis on understanding the relationship between informational uncertainty and cognitive evolution.
Abstract.
Cuff E, Thornton A, Boogert N (2022). Prospecting Behaviour in Wild Jackdaws.
Abstract:
Prospecting Behaviour in Wild Jackdaws
Habitat suitability must be carefully considered when an animal is trying to locate a potential breeding site. Acquiring information on the quality of potential nest sites helps an individual to reduce their environmental uncertainty and to better respond to the fluctuating environmental changes. Decisions on where and when to breed are critical determinants of an animals’ reproductive success and can directly affect individuals’ fitness. It is therefore expected that animals will invest considerable time and energy into collecting information. Prospecting behaviour, whereby an animal gathers information about possible future breeding sites, helps individuals to reduce environmental certainty and make better and more informed decisions on where to breed. When assessing prospecting behaviour, it is important to consider the societal structures which may affect the propensity of prospecting to occur. Some individuals, such as those with greater dominance, commonly have higher reproductive success as their fitness affords them greater access to, or monopolization of, essential resources such as breeding sites. Yet, prospecting has received limited attention, despite its important role in breeding success. To understand this more, this study assesses wild jackdaws (Corvus monedula), who prospect breeding sites prior to breeding and who live in a hierarchical society. Investigation of how individuals and pair-bonded pairs gather information throughout the breeding season revealed that prospecting frequency did not significantly change throughout the breeding season. Prospecting did not occur more often at nest boxes with higher breeding success, nor do successfully breeding prospectors gather more information after their chicks have fledged. Pair-bonded individuals were not more likely to prospect with their partner. Yet, when they prospected together, the trips were longer. Dominance, however, had no effect on who prospected and for how long. Yet, a non-significant trend suggests that females prospect for longer than males. How information is gathered from prospecting trips, whether alone or with a breeding partner, and its role in individual decision-making processes may influence breeding habitat selection and is likely to affect dispersal and population dynamics of not just an individual but the species.
Abstract.
Reynolds AM, McIvor GE, Thornton A, Yang P, Ouellette NT (2022). Stochastic modelling of bird flocks: accounting for the cohesiveness of collective motion.
J R Soc Interface,
19(189).
Abstract:
Stochastic modelling of bird flocks: accounting for the cohesiveness of collective motion.
Collective behaviour can be difficult to discern because it is not limited to animal aggregations such as flocks of birds and schools of fish wherein individuals spontaneously move in the same way despite the absence of leadership. Insect swarms are, for example, a form of collective behaviour, albeit one lacking the global order seen in bird flocks and fish schools. Their collective behaviour is evident in their emergent macroscopic properties. These properties are predicted by close relatives of Okubo's 1986 [Adv. Biophys.22, 1-94. (doi:10.1016/0065-227X(86)90003-1)] stochastic model. Here, we argue that Okubo's stochastic model also encapsulates the cohesiveness mechanism at play in bird flocks, namely the fact that birds within a flock behave on average as if they are trapped in an elastic potential well. That is, each bird effectively behaves as if it is bound to the flock by a force that on average increases linearly as the distance from the flock centre increases. We uncover this key, but until now overlooked, feature of flocking in empirical data. This gives us a means of identifying what makes a given system collective. We show how the model can be extended to account for intrinsic velocity correlations and differentiated social relationships.
Abstract.
Author URL.
Thornton A, Truskanov N (2022). The role of natural history in animal cognition.
Current Opinion in Behavioral Sciences,
46Abstract:
The role of natural history in animal cognition
Animals’ cognitive processes are shaped by the challenges they face in their environments over developmental and evolutionary time, but cognitive studies are often disconnected from these challenges. Here, we argue that a failure to ground research in natural history can inadvertently misdirect research efforts and make results difficult to interpret. We highlight these potential pitfalls using a series of case studies and consider how field research, ecologically informed lab studies and formal theory can offer potential solutions. Animal cognition research is entering an exciting new phase, with technological advances providing opportunities to tackle previously intractable questions, both in the lab and in the wild, while mathematical models are increasingly helping to strengthen the field's theoretical foundations. Placing natural history at the centre of this work will be crucial to ensure that we capitalise on these advances to build a robust understanding of the proximate and ultimate basis of animal cognition.
Abstract.
O'Coin D, Mclvor GE, Thornton A, Ouellette NT, Ling H (2022). Velocity correlations in jackdaw flocks in different ecological contexts.
Phys Biol,
20(1).
Abstract:
Velocity correlations in jackdaw flocks in different ecological contexts.
Velocity correlation is an important feature for animal groups performing collective motions. Previous studies have mostly focused on the velocity correlation in a single ecological context. It is unclear whether correlation characteristics vary in a single species in different contexts. Here, we studied the velocity correlations in jackdaw flocks in two different contexts: transit flocks where birds travel from one location to another, and mobbing flocks where birds respond to an external stimulus. We found that in both contexts, although the interaction rules are different, the velocity correlations remain scale-free, i.e. the correlation length (the distance over which the velocity of two individuals is similar) increases linearly with the group size. Furthermore, we found that the correlation length is independent of the group density for transit flocks, but increases with increasing group density in mobbing flocks. This result confirms a previous observation that birds obey topological interactions in transit flocks, but switch to metric interactions in mobbing flocks. Finally, in both contexts, the impact of group polarization on correlation length is not significant. Our results suggest that wild animals are always able to respond coherently to perturbations regardless of context.
Abstract.
Author URL.
Dibnah AJ, Herbert-Read JE, Boogert NJ, McIvor GE, Jolles JW, Thornton A (2022). Vocally mediated consensus decisions govern mass departures from jackdaw roosts.
Curr Biol,
32(10), R455-R456.
Abstract:
Vocally mediated consensus decisions govern mass departures from jackdaw roosts.
In the early morning, large groups of up to hundreds or even thousands of roosting birds, sometimes comprising the entire roost population, often take off together in sudden mass departures. These departures commonly occur in low-light conditions and structurally complex habitats where access to visual cues is likely to be restricted. Roosting birds are often highly vocal, leading us to hypothesise that vocalisations, which can propagate over large distances, could provide a means of enabling individuals to agree on when to depart - that is to establish a consensus1 - and thus coordinate the timing of mass movements. Investigations of the role of acoustic signals in coordinating collective decisions have been limited to honeybees2 and relatively small vertebrate groups (
Abstract.
Author URL.
2021
Brakes P, Carroll EL, Dall SRX, Keith SA, McGregor PK, Mesnick SL, Noad MJ, Rendell L, Robbins MM, Rutz C, et al (2021). A deepening understanding of animal culture suggests lessons for conservation.
Proceedings of the Royal Society B: Biological Sciences,
288(1949).
Abstract:
A deepening understanding of animal culture suggests lessons for conservation
A key goal of conservation is to protect biodiversity by supporting the long-term persistence of viable, natural populations of wild species. Conservation practice has long been guided by genetic, ecological and demographic indicators of risk. Emerging evidence of animal culture across diverse taxa and its role as a driver of evolutionary diversification, population structure and demographic processes may be essential for augmenting these conventional conservation approaches and decision-making. Animal culture was the focus of a ground-breaking resolution under the Convention on the Conservation of Migratory Species of Wild Animals (CMS), an international treaty operating under the UN Environment Programme. Here, we synthesize existing evidence to demonstrate how social learning and animal culture interact with processes important to conservation management. Specifically, we explore how social learning might influence population viability and be an important resource in response to anthropogenic change, and provide examples of how it can result in phenotypically distinct units with different, socially learnt behavioural strategies. While identifying culture and social learning can be challenging, indirect identification and parsimonious inferences may be informative. Finally, we identify relevant methodologies and provide a framework for viewing behavioural data through a cultural lens which might provide new insights for conservation management.
Abstract.
Lee VE, Thornton A (2021). Animal Cognition in an Urbanised World.
Frontiers in Ecology and Evolution,
9Abstract:
Animal Cognition in an Urbanised World
Explaining how animals respond to an increasingly urbanised world is a major challenge for evolutionary biologists. Urban environments often present animals with novel problems that differ from those encountered in their evolutionary past. To navigate these rapidly changing habitats successfully, animals may need to adjust their behaviour flexibly over relatively short timescales. These behavioural changes, in turn, may be facilitated by an ability to acquire, store, and process information from the environment. The question of how cognitive abilities allow animals to avoid threats and exploit resources (or constrain their ability to do so) is attracting increasing research interest, with a growing number of studies investigating cognitive and behavioural differences between urban-dwelling animals and their non-urban counterparts. In this review we consider why such differences might arise, focusing on the informational challenges faced by animals living in urban environments, and how different cognitive abilities can assist in overcoming these challenges. We focus largely on birds, as avian taxa have been the subject of most research to date, but discuss work in other species where relevant. We also address the potential consequences of cognitive variation at the individual and species level. For instance, do urban environments select for, or influence the development of, particular cognitive abilities? Are individuals or species with particular cognitive phenotypes more likely to become established in urban habitats? How do other factors, such as social behaviour and individual personality, interact with cognition to influence behaviour in urban environments? the aim of this review is to synthesise current knowledge and identify key avenues for future research, in order to improve our understanding of the ecological and evolutionary consequences of urbanisation.
Abstract.
Dibnah A (2021). Collective decision-making in jackdaw winter roosts.
Abstract:
Collective decision-making in jackdaw winter roosts
Animals living in groups must often make decisions collectively to maintain the benefits of group cohesion. Collective movement decisions require group members to reach a consensus before departure so that individuals can coordinate and synchronise their movement timing and direction. Therefore, behavioural mechanisms must be utilised that can efficiently transfer social information and integrate a variety of individual decision preferences. Some groups use quorum mechanisms to optimise both decision-making speed and accuracy, whereby the likelihood of the group performing an action increases sharply and non-linearly after a threshold number of individuals have indicated support. Quorum decisions have been well studied in eusocial insects, but empirical evidence is lacking that they play a role in large groups of vertebrates. Acoustic cues, such as vocalisations, may provide an efficient means for individuals to indicate support and reach a consensus when many individuals are dispersed or visually obscured. In this thesis, I investigated the potential for vocally-mediated quorum decisions to coordinate collective departures in jackdaw winter roosts. Here, many hundreds of birds often perform synchronised mass take-offs around sunrise that are preceded by high levels of vocalisations. Firstly, using audio and video recordings, I found that when calling intensity increased at faster rates, departures occurred earlier and greater proportions of the roost population departed together. Similarly, greater absolute calling intensities immediately prior to departure were associated with greater proportions departing cohesively, but calling intensity was unrelated to roost group size. Secondly, I used playback experiments to test whether artificially simulating an earlier onset of consensus through greater calling intensities just before departure would cause earlier departures. Experimental calling playbacks caused departures to occur on average 5-6 minutes earlier compared to control playbacks. In contrast, departure times under natural conditions (no treatment trials) showed no clear differences with those of control trials. This indicates that jackdaws were responding specifically to conspecific calls and that calling has a causal effect on departure timing. Overall, my thesis provides the first empirical and experimental evidence for collective movements being coordinated by vocally-mediated quorum decisions in large vertebrate groups.
Abstract.
Greggor AL, Thornton A (2021). Convergent Evolution of Intelligence. In (Ed) Encyclopedia of Evolutionary Psychological Science, 1427-1434.
Hahn LG, Hooper R, McIvor GE, Thornton A (2021). Cooperative nest building in wild jackdaw pairs. Animal Behaviour, 178, 149-163.
Lee VE, Greggor AL, Thornton A (2021). Social Learning in Birds. In (Ed) The Cambridge Handbook of Animal Cognition, 503-533.
Gwynn A (2021). The Effects of Forest Fires on the Behaviour and Health of Bornean Orang-utans in Sebangau Peat-Swamp Forest.
Abstract:
The Effects of Forest Fires on the Behaviour and Health of Bornean Orang-utans in Sebangau Peat-Swamp Forest
Forest fires are one of the greatest threats to endangered species in tropical peat-swamp forests. Over the last two decades, it has become evident that forest fires are increasing in frequency and severity at an alarming rate as a result of increasing anthropogenic land modification and climate change. Once considered a depauperate habitat type, peat-swamp forests have now been shown to contain considerable diversity and endemism. of particular attention is the importance of peat-swamp forests for the critically endangered Bornean orang-utan (Pongo pygmaeus). Peat-swamp forests contain high densities and some of the last remaining strongholds of orang-utans in the world. The way in which fire affects orang-utans, in terms of their individual fitness, ability to survive and reproductive success may provide an early warning system and key insights into future fire-induced population trajectories. This study investigates variation in orang-utan activity budgets, physiological condition and gastrointestinal parasite infection before and after major fire events. I analysed 8056.8 hours of behavioural observations collected between 2011 and 2019 using generalised linear mixed models to assess if a major fire event in 2015 impacted the amount of time orang-utans allocate to daily activities. I revealed that orang-utans decrease their active period and allocate less time to resting over the long-term, four years post-fire, but increase their time allocation to resting in the short-term, up to nine months post-fire. I did not detect any decline in physiological condition after the 2015 fire event from analysis of ketones and specific gravity in 262 urine samples collected between 2009 and 2019. I employed the use of the Mini-FLOTAC faecal analysis technique to investigate changes in gastrointestinal parasite prevalence and load after a major fire event 2019. I collected 77 faecal samples between March and December 2019 from which I identified and counted the presence of gastrointestinal nematode eggs and larvae. Using zero-inflated negative binomial models and Fisher’s exact tests, I revealed that overall nematode intensity was greater post-fire but detected no significant change in parasitic prevalence. From these findings, I suggest that orang-utans may have been employing energy conserving behavioural strategies to cope with fire disturbance, but this was unlikely due to a negative energy balance. The findings of a greater nematode intensity warrants further investigation into alternative physiological markers and the impact of forest fires on wildlife health. Understanding how orang-utans are affected by forest fires will considerably improve the ability to manage and conserve remaining populations in forests prone to fire.
Abstract.
Soravia C, Ashton BJ, Thornton A, Ridley AR (2021). The impacts of heat stress on animal cognition: Implications for adaptation to a changing climate.
WILEY INTERDISCIPLINARY REVIEWS-CLIMATE CHANGE,
12(4).
Author URL.
Hooper R, Meekins E, McIvor GE, Thornton A (2021). Wild jackdaws respond to their partner's distress, but not with consolation.
R Soc Open Sci,
8(6).
Abstract:
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.
Abstract.
Author URL.
2020
Lee V (2020). Avian cognition in a changing world.
Abstract:
Avian cognition in a changing world
Humans are altering the natural environment at an unprecedented rate, with profound consequences for non-human animals. However, species differ in how they respond to these ecological changes. Understanding the responses of wildlife to environmental change is vital to conserve biodiversity and mitigate anthropogenic impacts. Behaviour can often act as a rapid adaptation to ecological change, and is influenced by an organism’s ability to acquire and process information from their environment. Despite the importance of cognition in shaping behaviour, little is known about the role of cognition in allowing some species to thrive in human-dominated habitats. In this thesis, I examine how the cognitive abilities of wild jackdaws allow these birds to cope with the challenges of a rapidly changing world. Specifically, I focus on the need to navigate a dynamic social environment, and the need to learn about anthropogenic threats. Firstly, I investigate how jackdaws track their social environment by recognising conspecifics and their relationships. In Chapter 3, I demonstrate that jackdaws individually recognise the contact calls of their breeding partner, but I find no evidence of vocal discrimination beyond the pair bond. In Chapter 4, I use infidelity simulations to investigate whether jackdaws track changes to prevailing social relationships, although I find no evidence that jackdaws respond to relationship information in this experimental context. Secondly, I investigate how jackdaws’ cognitive abilities shape their behaviour during encounters with people, allowing birds to avoid danger whilst exploiting anthropogenic resources. I test the commonly-held preconception that jackdaws identify people carrying shotguns as dangerous (Chapter 5), but find no evidence that jackdaws use objects being carried by people to inform their escape decisions in this case. I also demonstrate that jackdaws learn socially about dangerous people (Chapter 6). Throughout these experiments, jackdaws differed considerably in their behaviour, which may influence individual success in anthropogenic habitats. In Chapter 7, I find that individual jackdaws differ consistently in their responses to human disturbance, but that these differences do not appear to impact reproductive success. Together, my findings highlight the importance of fundamental behavioural and cognitive research in predicting animals’ responses to environmental change.
Abstract.
Driscoll I, Manser M, Thornton A (2020). Mobbing-like response to secondary predator cues informs group behaviour in wild meerkats.
Driscoll I, Manser M, Thornton A (2020). Mobbing-like response to secondary predator cues is not a form of teaching in meerkats.
Thornton A, Happé F, Caldwell CA (2020). Supporting the weight of the elephant in the room: Technical intelligence propped up by social cognition and language.
Behav Brain Sci,
43Abstract:
Supporting the weight of the elephant in the room: Technical intelligence propped up by social cognition and language.
We consider the evolutionary plausibility of Osiurak and Reynaud's (O&R) arguments. We argue that technical reasoning is not quite the magic bullet that O&R assume, and instead propose a co-evolutionary account of the interplay between technical reasoning and social learning, with language emerging as a vital issue neglected in O&R's account.
Abstract.
Author URL.
Goumas M, Lee VE, Boogert NJ, Kelley LA, Thornton A (2020). The Role of Animal Cognition in Human-Wildlife Interactions. Frontiers in Psychology, 11
Driscoll I (2020). The function of the mobbing-like response to secondary predator cues in wild meerkats.
Abstract:
The function of the mobbing-like response to secondary predator cues in wild meerkats
Early detection of predators greatly improves prey escape and survival chances. By investigating cues left behind by predators, such as fur, urine, faeces, feathers (known as secondary predator cues, SPCs) prey may gain vital information about predators in the vicinity. This can inform defensive behaviours without the need for dangerous direct contact with a potential predator. Meerkats (Suricata suricatta) display an unusual mobbing-like response upon encountering SPCs, not reported in any other species. The function of this behaviour is unclear because, unlike mobbing of a live predator, this response does not yield the primary benefit of driving the threat away. An additional suggested benefit of predator mobbing is cultural transmission of information. The mobbing-like response in meerkats may function similarly in transferring information about cues associated with threats. I first investigated whether this mobbing-like response constituted a form of teaching, experimentally testing whether adults increase response intensity to promote learning in naïve pups. The results suggested that the mobbing-like response is not a form of teaching, with the presence and/or number of pups reducing response intensity. I then analysed long-term data to examine how the response to natural SPC encounters differs from predator encounters, comparing rate of animal mobbing vs mobbing-like response to SPCs. Additionally, I used the long-term data to investigate changes in behaviour (alarm calling, guarding, distance travelled and pup provisioning) in the hour before and after a SPC encounter. I also investigated the effect of pup presence on both of these responses. Again there was no evidence for teaching, with the presence and/or number of pups reducing response rate to SPCs. The presence of pups increased guarding rate generally but did not affect behavioural changes following an SPC encounter. Alarm calling rate was increased and distance travelled decreased following a SPC encounter but was not affected by the presence of pups, suggesting these are direct responses to encountering SPCs. Overall, the results suggest that the role of the mobbing-like response is not teaching, but instead functions in informing defensive group behaviour.
Abstract.
Thornton A, Lucas A, Kings M, Whittle D, Davey E (2020). The value of teaching increases with tool complexity in cumulative cultural evolution.
Proceedings of the Royal Society B: Biological Sciences,
287, 20201885-20201885.
Abstract:
The value of teaching increases with tool complexity in cumulative cultural evolution
Human cumulative cultural evolution (CCE) is recognized as a powerful ecological and evolutionary force, but its origins are poorly understood. The long-standing view that CCE requires specialized social learning processes such as teaching has recently come under question, and cannot explain why such processes evolved in the first place. An alternative, but largely untested, hypothesis is that these processes gradually coevolved with an increasing reliance on complex tools. To address this, we used large-scale transmission chain experiments (624 participants), to examine the role of different learning processes in generating cumulative improvements in two tool types of differing complexity. Both tool types increased in efficacy across experimental generations, but teaching only provided an advantage for the more complex tools. Moreover, while the simple tools tended to converge on a common design, the more complex tools maintained a diversity of designs. These findings indicate that the emergence of cumulative culture is not strictly dependent on, but may generate selection for, teaching. As reliance on increasingly complex tools grew, so too would selection for teaching, facilitating the increasingly open-ended evolution of cultural artefacts.
Abstract.
2019
Thornton A, Boogert NJ (2019). Animal Cognition: the Benefits of Remembering.
Current Biology,
29(9), R324-R327.
Abstract:
Animal Cognition: the Benefits of Remembering
How cognitive abilities evolve through natural selection is poorly understood. Two new studies show that a good spatial memory helps birds that hide their food to survive and produce more offspring.
Abstract.
Brakes P, Dall SRX, Aplin LM, Bearhop S, Carroll EL, Ciucci P, Fishlock V, Ford JKB, Garland EC, Keith SA, et al (2019). Animal cultures matter for conservation. Science
Ling H, Mclvor GE, Westley J, van der Vaart K, Vaughan RT, Thornton A, Ouellette NT (2019). Behavioural plasticity and the transition to order in jackdaw flocks.
Nature Communications,
10(1).
Abstract:
Behavioural plasticity and the transition to order in jackdaw flocks
AbstractCollective behaviour is typically thought to arise from individuals following fixed interaction rules. The possibility that interaction rules may change under different circumstances has thus only rarely been investigated. Here we show that local interactions in flocks of wild jackdaws (Corvus monedula) vary drastically in different contexts, leading to distinct group-level properties. Jackdaws interact with a fixed number of neighbours (topological interactions) when traveling to roosts, but coordinate with neighbours based on spatial distance (metric interactions) during collective anti-predator mobbing events. Consequently, mobbing flocks exhibit a dramatic transition from disordered aggregations to ordered motion as group density increases, unlike transit flocks where order is independent of density. The relationship between group density and group order during this transition agrees well with a generic self-propelled particle model. Our results demonstrate plasticity in local interaction rules and have implications for both natural and artificial collective systems.
Abstract.
Ling H, Mclvor GE, Westley J, van der Vaart K, Yin J, Vaughan RT, Thornton A, Ouellette NT (2019). Collective turns in jackdaw flocks: kinematics and information transfer.
Journal of the Royal Society Interface,
16(159), 20190450-20190450.
Abstract:
Collective turns in jackdaw flocks: kinematics and information transfer
The rapid, cohesive turns of bird flocks are one of the most vivid examples of collective behaviour in nature, and have attracted much research. Three-dimensional imaging techniques now allow us to characterize the kinematics of turning and their group-level consequences in precise detail. We measured the kinematics of flocks of wild jackdaws executing collective turns in two contexts: during transit to roosts and anti-predator mobbing. All flocks reduced their speed during turns, probably because of constraints on individual flight capability. Turn rates increased with the angle of the turn so that the time to complete turns remained constant. We also find that context may alter where turns are initiated in the flocks: for transit flocks in the absence of predators, initiators were located throughout the flocks, but for mobbing flocks with a fixed ground-based predator, they were always located at the front. Moreover, in some transit flocks, initiators were far apart from each other, potentially because of the existence of subgroups and variation in individual interaction ranges. Finally, we find that as the group size increased the information transfer speed initially increased, but rapidly saturated to a constant value. Our results highlight previously unrecognized complexity in turning kinematics and information transfer in social animals.
Abstract.
Nagy G, Thornton A, Ling H, McIvor G, Ouellette NT, Vaughan R (2019). Computational and Structural Advantages of Pairwise Flocking.
Abstract:
Computational and Structural Advantages of Pairwise Flocking
Abstract.
Coomes JR, McIvor GE, Thornton A (2019). Correction to ‘Evidence for individual discrimination and numerical assessment in collective antipredator behaviour in wild jackdaws (. <i>Corvus monedula</i>. )’. Biology Letters, 15(11), 20190740-20190740.
Ling H, McIvor GE, van der Vaart K, Vaughan RT, Thornton A, Ouellette NT (2019). Costs and benefits of social relationships in the collective motion of bird flocks. Nature Ecology and Evolution
Coomes JR, McIvor GE, Thornton A (2019). Evidence for individual discrimination and numerical assessment in collective antipredator behaviour in wild jackdaws (Corvus monedula).
Biology Letters,
15(10).
Abstract:
Evidence for individual discrimination and numerical assessment in collective antipredator behaviour in wild jackdaws (Corvus monedula)
Collective responses to threats occur throughout the animal kingdom but little is known about the cognitive processes underpinning them. Antipredator mobbing is one such response. Approaching a predator may be highly risky, but the individual risk declines and the likelihood of repelling the predator increases in larger mobbing groups. The ability to appraise the number of conspecifics involved in a mobbing event could therefore facilitate strategic decisions about whether to join. Mobs are commonly initiated by recruitment calls, which may provide valuable information to guide decision-making. We tested whether the number of wild jackdaws responding to recruitment calls was influenced by the number of callers. As predicted, playbacks simulating three or five callers tended to recruit more individuals than playbacks of one caller. Recruitment also substantially increased if recruits themselves produced calls. These results suggest that jackdaws use individual vocal discrimination to assess the number of conspecifics involved in initiating mobbing events, and use this information to guide their responses. Our results show support for the use of numerical assessment in antipredator mobbing responses and highlight the need for a greater understanding of the cognitive processes involved in collective behaviour.
Abstract.
Ashton BJ, Thornton A, Ridley AR (2019). Larger group sizes facilitate the emergence and spread of innovations in a group-living bird.
Animal Behaviour,
158, 1-7.
Abstract:
Larger group sizes facilitate the emergence and spread of innovations in a group-living bird
The benefits of group living have traditionally been attributed to risk dilution or the efficient exploitation of resources; individuals in social groups may therefore benefit from access to valuable information. If sociality facilitates access to information, then individuals in larger groups may be predicted to solve novel problems faster than individuals in smaller groups. Additionally, larger group sizes may facilitate the subsequent spread of innovations within animal groups, as has been proposed for human societies. We presented a novel foraging task (where a food reward could be accessed by pushing a self-shutting sliding door) to 16 groups of wild, cooperatively breeding Australian magpies, Cracticus tibicen dorsalis, ranging in size from two to 11 individuals. We found a nonlinear decline in the time taken for the innovative behaviour to emerge with increasing group size, and social information use facilitated the transmission of novel behaviour, with it spreading more quickly in larger than smaller groups. This study provides important evidence for a nonlinear relationship between group size and the emergence of innovation (and its subsequent transmission) in a wild population of animals. Further work investigating the scope and strength of group size–innovation relationships, and the mechanisms underpinning them, will help us understand the potential advantages of living in larger social groups.
Abstract.
Ling H, McIvor GE, van der Vaart K, Vaughan RT, Thornton A, Ouellette NT (2019). Local interactions and their group-level consequences in flocking jackdaws.
Proceedings of the Royal Society B: Biological Sciences,
286, 20190865-20190865.
Abstract:
Local interactions and their group-level consequences in flocking jackdaws
As one of nature's most striking examples of collective behaviour, bird flocks have attracted extensive research. However, we still lack an understanding of the attractive and repulsive forces that govern interactions between individuals within flocks and how these forces influence neighbours' relative positions and ultimately determine the shape of flocks. We address these issues by analysing the three-dimensional movements of wild jackdaws (Corvus monedula) in flocks containing 2–338 individuals. We quantify the social interaction forces in large, airborne flocks and find that these forces are highly anisotropic. The long-range attraction in the direction perpendicular to the movement direction is stronger than that along it, and the short-range repulsion is generated mainly by turning rather than changing speed. We explain this phenomenon by considering wingbeat frequency and the change in kinetic and gravitational potential energy during flight, and find that changing the direction of movement is less energetically costly than adjusting speed for birds. Furthermore, our data show that collision avoidance by turning can alter local neighbour distributions and ultimately change the group shape. Our results illustrate the macroscopic consequences of anisotropic interaction forces in bird flocks, and help to draw links between group structure, local interactions and the biophysics of animal locomotion.
Abstract.
Ashton BJ, Ridley AR, Thornton A (2019). Smarter through group living: a response to Smulders.
Learn Behav,
47(4), 277-279.
Abstract:
Smarter through group living: a response to Smulders.
We recently identified a strong, positive relationship between group size and individual cognitive performance, and a strong, positive relationship between female cognitive performance and reproductive success (Ashton, Ridley, Edwards, & Thornton in Nature, 554, 364-367, 2018). An opinion piece by Smulders (Learning & Behavior, https://doi.org/10.3758/s13420-018-0335-0, 2018) raised the interesting notion that these patterns may be underlined by motivational factors. In this commentary, we highlight why none of the available data are consistent with this explanation, but instead support the argument that the demands of group living influence cognitive development, with knock-on consequences for fitness.
Abstract.
Author URL.
Lee VE, Régli N, McIvor GE, Thornton A (2019). Social learning about dangerous people by wild jackdaws.
Royal Society Open Science,
6(9), 191031-191031.
Abstract:
Social learning about dangerous people by wild jackdaws
. For animals that live alongside humans, people can present both an opportunity and a threat. Previous studies have shown that several species can learn to discriminate between individual people and assess risk based on prior experience. To avoid potentially costly encounters, it may also pay individuals to learn about dangerous people based on information from others. Social learning about anthropogenic threats is likely to be beneficial in habitats dominated by human activity, but experimental evidence is limited. Here, we tested whether wild jackdaws (
. Corvus monedula
. ) use social learning to recognize dangerous people. Using a within-subjects design, we presented breeding jackdaws with an unfamiliar person near their nest, combined with conspecific alarm calls. Subjects that heard alarm calls showed a heightened fear response in subsequent encounters with the person compared to a control group, reducing their latency to return to the nest. This study provides important evidence that animals use social learning to assess the level of risk posed by individual humans.
.
Abstract.
Lee VE, McIvor GE, Thornton A (2019). Testing relationship recognition in wild jackdaws (Corvus monedula).
Sci Rep,
9(1).
Abstract:
Testing relationship recognition in wild jackdaws (Corvus monedula).
According to the social intelligence hypothesis, understanding the challenges faced by social animals is key to understanding the evolution of cognition. In structured social groups, recognising the relationships of others is often important for predicting the outcomes of interactions. Third-party relationship recognition has been widely investigated in primates, but studies of other species are limited. Furthermore, few studies test for third-party relationship recognition in the wild, where cognitive abilities are deployed in response to natural socio-ecological pressures. Here, we used playback experiments to investigate whether wild jackdaws (Corvus monedula) track changes in their own relationships and the relationships of others. Females were presented with 'infidelity simulations': playbacks of their male partner copulating with a neighbouring female, and their male neighbour copulating with another female, against a congruent control. Our results showed substantial inter-individual variation in responses, but females did not respond more strongly to infidelity playbacks, indicating that jackdaws may not attend and/or respond to relationship information in this experimental context. Our results highlight the need for further study of relationship recognition and other cognitive traits that facilitate group-living in the wild, particularly in non-primates and in a wider range of social systems.
Abstract.
Author URL.
Thornton A, Boogert NJ (2019). The nature and nurturing of animal minds. In Hosken DJ, Hunt J, Wedell N (Eds.) Genes and Behaviour Beyond Nature-Nurture, Wiley, 181-201.
2018
Ashton BJ, Thornton A, Ridley AR (2018). An intraspecific appraisal of the social intelligence hypothesis.
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES,
373(1756).
Author URL.
Woods RD, Kings M, McIvor GE, Thornton A (2018). Caller characteristics influence recruitment to collective antipredator events in jackdaws.
Scientific Reports,
8, 7343-7343.
Abstract:
Caller characteristics influence recruitment to collective antipredator events in jackdaws
Across the animal kingdom, examples abound of individuals coming together to repel external threats. When such collective actions are initiated by recruitment signals, individuals may benefit from being selective in whom they join, so the identity of the initiator may determine the magnitude of the group response. However, the role of signaller discrimination in coordinating group-level responses has yet to be tested. Here we show that in wild jackdaws, a colonial corvid species, collective responses to anti-predator recruitment calls are mediated by caller characteristics. In playbacks next to nestboxes, the calls of nestbox residents attracted most recruits, followed in turn by other colony members, non-colony members and rooks (a sympatric corvid). Playbacks in fields outside nestbox colonies, where the immediate threat to broods was lower, showed similar results, with highest recruitment to nearby colony members’ calls. Responses were further influenced by caller sex: calls from non-colony member females were less likely to elicit responsive scolding by recruits than other calls, potentially reflecting social rank associated with sex and colony membership. These results show that vocal discrimination mediates jackdaws’ collective responses and highlight the need for further research into the cognitive basis of collective actions in animal groups.
Abstract.
Ashton BJ, Ridley AR, Edwards EK, Thornton A (2018). Cognitive performance is linked to group size and affects fitness in Australian magpies. Nature, 554, pages 364-367.
Street SE, Morgan TH, Thornton A, Brown GR, Laland KN, Cross CP (2018). Human mate-choice copying is domain-general social learning. Scientific Reports, 8, 1715-1715.
Boogert NJ, Madden JR, Morand-Ferron J, Thornton A (2018). Measuring and understanding individual differences in cognition.
Philos Trans R Soc Lond B Biol Sci,
373(1756).
Abstract:
Measuring and understanding individual differences in cognition.
Individuals vary in their cognitive performance. While this variation forms the foundation of the study of human psychometrics, its broader importance is only recently being recognized. Explicitly acknowledging this individual variation found in both humans and non-human animals provides a novel opportunity to understand the mechanisms, development and evolution of cognition. The papers in this special issue highlight the growing emphasis on individual cognitive differences from fields as diverse as neurobiology, experimental psychology and evolutionary biology. Here, we synthesize this body of work. We consider the distinct challenges in quantifying individual differences in cognition and provide concrete methodological recommendations. In particular, future studies would benefit from using multiple task variants to ensure they target specific, clearly defined cognitive traits and from conducting repeated testing to assess individual consistency. We then consider how neural, genetic, developmental and behavioural factors may generate individual differences in cognition. Finally, we discuss the potential fitness consequences of individual cognitive variation and place these into an evolutionary framework with testable hypotheses. We intend for this special issue to stimulate researchers to position individual variation at the centre of the cognitive sciences.This article is part of the theme issue 'Causes and consequences of individual differences in cognitive abilities'.
Abstract.
Author URL.
Lokuciejewski E (2018). Post-release behaviour of reintroduced Orangutans (Pongo pygmaeus wurmbii) in Bukit Baka Bukit Raya National Park and Bukit Batikap Conservation Forest, Central Kalimantan, Indonesia.
Abstract:
Post-release behaviour of reintroduced Orangutans (Pongo pygmaeus wurmbii) in Bukit Baka Bukit Raya National Park and Bukit Batikap Conservation Forest, Central Kalimantan, Indonesia.
Rescue, rehabilitation and reintroduction programmes are a vital conservation tool used to protect individuals under immediate threat, and then re-establish viable populations in protected habitats. The critically endangered orangutan (Pongo spp.) has experienced significant population decline, primarily due to deforestation and hunting, therefore a considerable number of individuals are rescued from fragmented forests or the illegal pet trade. Whilst the protection of the remaining wild populations remains paramount, the substantial number of individuals currently residing in rescue centres means reintroduction is a crucial strategy for reducing the threat of extinction.
Previously, many reintroductions have been ineffective, primarily attributed to inadequate project management, the introduction of unregulated tourism, or due to the individuals’ failure to acquire vital survival skills. Furthermore, the lack of post-release monitoring often inhibits analyses of the post-release progress, survival rates, and the long-term effects of human-facilitated rehabilitation. Therefore, the reintroduction of Bornean orangutans (Pongo pygmaeus wurmbii) into two protected forests, Bukit Baka Bukit Raya National Park and Bukit Batikap Conservation Forest, Central Kalimantan, provided vital opportunities for understanding how early life experiences and rehabilitation shapes post-release behaviour, ultimately aiding the improvement of reintroduction protocols.
Mixed model analyses of data from consistent post-release monitoring revealed that across the first three months post-release, orangutans displayed behavioural irregularities when compared to their fully-wild counterparts. Temporarily, significantly elevated levels of resting and travelling counteracted reduced levels of feeding, attributed to recovery from transportation and stress from reintroduction into a novel habitat. After approximately three months post-release, behaviour stabilised and closely resembled that of wild orangutans, revealing the robust behavioural flexibility of the species.
Evidence is also provided for distinct dispersal strategies following reintroduction, most notably flanged males were more likely to disperse out of the study site, whilst females often displayed site fidelity and established their home range surrounding their release location. Reintroduced individuals often displayed larger home ranges, when compared to wild individuals, likely in response to substantial overlaps between individuals around release locations, and subsequent resource competition.
Overall, reintroductions were deemed successful, however, differences in dietary composition were discovered, most notably, lower fruit consumption, and a subsequent increased reliance on fall-back foods. Dietary differences are likely attributed to insufficient foraging skills, therefore improvements to rehabilitation protocols are provided, vital for increasing post-release success. Ultimately, the success of this reintroduction programme, and the establishment of new populations reinforces the value of reintroduction as an effective tool for conservation.
Abstract.
Ling H, Mclvor GE, Nagy G, MohaimenianPour S, Vaughan RT, Thornton A, Ouellette NT (2018). Simultaneous measurements of three-dimensional trajectories and wingbeat frequencies of birds in the field.
J R Soc Interface,
15(147).
Abstract:
Simultaneous measurements of three-dimensional trajectories and wingbeat frequencies of birds in the field.
Tracking the movements of birds in three dimensions is integral to a wide range of problems in animal ecology, behaviour and cognition. Multi-camera stereo-imaging has been used to track the three-dimensional (3D) motion of birds in dense flocks, but precise localization of birds remains a challenge due to imaging resolution in the depth direction and optical occlusion. This paper introduces a portable stereo-imaging system with improved accuracy and a simple stereo-matching algorithm that can resolve optical occlusion. This system allows us to decouple body and wing motion, and thus measure not only velocities and accelerations but also wingbeat frequencies along the 3D trajectories of birds. We demonstrate these new methods by analysing six flocking events consisting of 50 to 360 jackdaws (Corvus monedula) and rooks (Corvus frugilegus) as well as 32 jackdaws and 6 rooks flying in isolated pairs or alone. Our method allows us to (i) measure flight speed and wingbeat frequency in different flying modes; (ii) characterize the U-shaped flight performance curve of birds in the wild, showing that wingbeat frequency reaches its minimum at moderate flight speeds; (iii) examine group effects on individual flight performance, showing that birds have a higher wingbeat frequency when flying in a group than when flying alone and when flying in dense regions than when flying in sparse regions; and (iv) provide a potential avenue for automated discrimination of bird species. We argue that the experimental method developed in this paper opens new opportunities for understanding flight kinematics and collective behaviour in natural environments.
Abstract.
Author URL.
McIvor GE, Lee VE, Thornton A (2018). Testing social learning of anti-predator responses in juvenile jackdaws: the importance of accounting for levels of agitation.
Royal Society Open Science,
5, 171571-171571.
Abstract:
Testing social learning of anti-predator responses in juvenile jackdaws: the importance of accounting for levels of agitation
Social learning is often assumed to help young animals
respond appropriately to potential threats in the environment.
We brought wild, juvenile jackdaws briefly into captivity
to test whether short exposures to conspecific vocalizations
are sufficient to promote anti-predator learning. Individuals
were presented with one of two models—a stuffed fox
representing a genuine threat, or a toy elephant simulating
a novel predator. Following an initial baseline presentation,
juveniles were trained by pairing models with either adult
mobbing calls, indicating danger, or contact calls suggesting
no danger. In a final test phase with no playbacks, birds
appeared to have habituated to the elephant, regardless of
training, but responses to the fox remained high throughout,
suggesting juveniles already recognized it as a predator before
the experiment began. Training with mobbing calls did seem
to generate elevated escape responses, but this was likely to
be a carry-over effect of the playback in the previous trial.
Overall, we found little evidence for social learning. Instead,
individuals’ responses were mainly driven by their level
of agitation immediately preceding each presentation. These
results highlight the importance of accounting for agitation in
studies of anti-predator learning, and whenever animals are
held in captivity for short periods.
Abstract.
Mesoudi AA, Thornton A (2018). What is cumulative cultural evolution?. Proceedings of the Royal Society B: Biological Sciences
Greggor AL, McIvor GE, Clayton NS, Thornton A (2018). Wild jackdaws are wary of objects that violate expectations of animacy.
Royal Society Open Science,
5(10).
Abstract:
Wild jackdaws are wary of objects that violate expectations of animacy
Nature is composed of self-propelled, animate agents and inanimate objects. Laboratory studies have shown that human infants and a few species discriminate between animate and inanimate objects. This ability is assumed to have evolved to support social cognition and filial imprinting, but its ecological role for wild animals has never been examined. An alternative, functional explanation is that discriminating stimuli based on their potential for animacy helps animals distinguish between harmless and threatening stimuli. Using remote-controlled experimental stimulus presentations, we tested if wild jackdaws (Corvus monedula) respond fearfully to stimuli that violate expectations for movement. Breeding pairs (N ¼ 27) were presented at their nests with moving and non-moving models of ecologically relevant stimuli (birds, snakes and sticks) that differed in threat level and propensity for independent motion. Jackdaws were startled by movement regardless of stimulus type and produced more alarm calls when faced with animate objects. However, they delayed longest in entering their nest-box after encountering a stimulus that should not move independently, suggesting they recognized the movement as unexpected. How jackdaws develop expectations about object movement is not clear, but our results suggest that discriminating between animate and inanimate stimuli may trigger information gathering about potential threats.
Abstract.
2017
Valletta J, Torney C, Kings M, Thornton A, Madden J (2017). Applications of machine learning in animal behaviour studies. Animal Behaviour
Davidson GL, Thornton A, Clayton NS (2017). Evolution of iris colour in relation to cavity nesting and parental care in passerine birds. Biology Letters, 13, 20160783-20160783.
2016
Greggor AL, McIvor GE, Clayton NS, Thornton A (2016). Contagious risk taking: social information and context influence wild jackdaws' responses to novelty and risk.
Sci Rep,
6Abstract:
Contagious risk taking: social information and context influence wild jackdaws' responses to novelty and risk.
Although wild animals increasingly encounter human-produced food and objects, it is unknown how they learn to discriminate beneficial from dangerous novelty. Since social learning allows animals to capitalize on the risk-taking of others, and avoid endangering themselves, social learning should be used around novel and unpredictable stimuli. However, it is unclear whether animals use social cues equally around all types of novelty and at all times of year. We assessed whether wild, individually marked jackdaws-a highly neophobic, yet adaptable species-are equally influenced by social cues to consume novel, palatable foods and to approach a startling object. We conducted these tests across two seasons, and found that in both seasons observers were more likely to consume novel foods after seeing a demonstrator do so. In contrast, observers only followed the demonstrator in foraging next to the object during breeding season. Throughout the year more birds were wary of consuming novel foods than wary of approaching the object, potentially leading to jackdaws' greater reliance on social information about food. Jackdaws' dynamic social cue usage demonstrates the importance of context in predicting how social information is used around novelty, and potentially indicates the conditions that facilitate animals' adjustment to anthropogenic disturbance.
Abstract.
Author URL.
Greggor AL, Thornton A (2016). Convergent evolution of animal intelligence. In Shackleford TA, Weekes-Shackleford VA (Eds.) Encyclopedia of Evolutionary Psychological Science, Springer International Publishing, 1-7.
Thornton A, McAuliffe K, Dall SRX, Fernandez-Duque E, Garber PA, Young AJ (2016). Fundamental Problems with the Cooperative Breeding Hypothesis. A reply to Burkart & Van Schaik. Journal of Zoology, 299(2), 84-88.
Greggor AL, Thornton A, Clayton NS (2016). Harnessing learning biases is essential for applying social learning in conservation. Behavioral Ecology and Sociobiology, 71, 16-16.
Greggor AL, Jolles JW, Thornton A, Clayton NS (2016). Seasonal changes in neophobia and its consistency in rooks: the effect of novelty type and dominance position. Animal Behaviour, 121, 11-20.
Greggor AL, Clayton NS, Fulford AJC, Thornton A (2016). Street smart: faster approach towards litter in urban areas by highly neophobic corvids and less fearful birds. Animal Behaviour, 117, 123-133.
Mesoudi A, Chang L, Dall SRX, Thornton A (2016). The evolution of individual and cultural variation in social learning. Trends in Ecology and Evolution, 31(3), 215-225.
Greggor AL, Spencer KA, Clayton NS, Thornton A (2016). Wild jackdaws’ reproductive success and their offspring’s stress hormones are connected to provisioning rate and brood size, not to parental neophobia. General and Comparative Endocrinology, 243, 70-77.
2015
Thornton A, Mcauliffe K (2015). Cognitive consequences of cooperative breeding? a critical appraisal.
Journal of Zoology,
295(1), 12-22.
Abstract:
Cognitive consequences of cooperative breeding? a critical appraisal
The social intelligence hypothesis, which posits that the challenges of life in complex social environments drive cognitive evolution, enjoys widespread theoretical and empirical support. Recent years have seen the emergence of a novel variant of this hypothesis, suggesting that cooperative breeding is associated with the elaboration of socio-cognitive abilities. With this cooperative breeding hypothesis (CBH) rapidly gaining currency, the time is ripe for a critical appraisal. Proponents of the CBH argue that cooperative breeding leads to increased cognitive performance, calling upon cognitive and motivational processes including spontaneous prosocial tendencies, attending to and learning from conspecifics, teaching and coordinating activities. We review the literature on the natural history and cognitive abilities of cooperative breeders and other social animals and conclude that there is no compelling evidence that these processes are either unique to cooperative breeders or particularly cognitively demanding. Thus, there is currently no reason to suppose that cooperative breeding has major cognitive consequences.
Abstract.
Zwirner E, Thornton A (2015). Cognitive requirements of cumulative culture: teaching is useful but not essential.
Sci Rep,
5Abstract:
Cognitive requirements of cumulative culture: teaching is useful but not essential.
The cumulative nature of human culture is unique in the animal kingdom. Progressive improvements in tools and technologies have facilitated humanity's spread across the globe and shaped human evolution, but the cognitive mechanisms enabling cultural change remain unclear. Here we show that, contrary to theoretical predictions, cumulative improvements in tools are not dependent on specialised, high-fidelity social learning mechanisms. Participants were tasked with building a basket to carry as much rice as possible using a set of everyday materials and divided into treatment groups with differing opportunities to learn asocially, imitate, receive teaching or emulate by examining baskets made by previous chain members. Teaching chains produced more robust baskets, but neither teaching nor imitation were strictly necessary for cumulative improvements; emulation chains generated equivalent increases in efficacy despite exhibiting relatively low copying fidelity. People used social information strategically, choosing different materials to make their baskets if the previous basket in the chain performed poorly. Together, these results suggest that cumulative culture does not rest on high-fidelity social learning mechanisms alone. Instead, the roots of human cultural prowess may lie in the interplay of strategic social learning with other cognitive traits including the ability to reverse engineer artefacts through causal reasoning.
Abstract.
Author URL.
Aplin LM, Farine DR, Morand-Ferron J, Cockburn A, Thornton A, Sheldon BC (2015). Counting conformity: evaluating the units of information in frequency-dependent social learning.
ANIMAL BEHAVIOUR,
110, E5-E8.
Author URL.
Duffield C, Wilson AJ, Thornton A (2015). Desperate Prawns: Drivers of Behavioural Innovation Vary across Social Contexts in Rock Pool Crustaceans.
PLoS One,
10(10).
Abstract:
Desperate Prawns: Drivers of Behavioural Innovation Vary across Social Contexts in Rock Pool Crustaceans.
Innovative behaviour may allow animals to cope with changes in their environment. Innovative propensities are known to vary widely both between and within species, and a growing body of research has begun to examine the factors that drive individuals to innovate. Evidence suggests that individuals are commonly driven to innovate by necessity; for instance by hunger or because they are physically unable to outcompete others for access to resources. However, it is not known whether the factors that drive individuals to innovate are stable across contexts. We examined contextual variation in the drivers of innovation in rock pool prawns (Palaemon spp), invertebrates that face widely fluctuating environments and may, through the actions of tides and waves, find themselves isolated or in groups. Using two novel foraging tasks, we examined the effects of body size and hunger in prawns tested in solitary and group contexts. When tested alone, small prawns were significantly more likely to succeed in a spatial task, and faster to reach the food in a manipulation task, while hunger state had no effect. In contrast, size had no effect when prawns were tested in groups, but food-deprived individuals were disproportionately likely to innovate in both tasks. We suggest that contextual variation in the drivers of innovation is likely to be common in animals living in variable environments, and may best be understood by considering variation in the perception of relative risks and rewards under different conditions.
Abstract.
Author URL.
Aplin LM, Farine DR, Morand-Ferron J, Cockburn A, Thornton A, Sheldon BC (2015). Experimentally induced innovations lead to persistent culture via conformity in wild birds.
Nature,
518(7540), 538-541.
Abstract:
Experimentally induced innovations lead to persistent culture via conformity in wild birds.
In human societies, cultural norms arise when behaviours are transmitted through social networks via high-fidelity social learning. However, a paucity of experimental studies has meant that there is no comparable understanding of the process by which socially transmitted behaviours might spread and persist in animal populations. Here we show experimental evidence of the establishment of foraging traditions in a wild bird population. We introduced alternative novel foraging techniques into replicated wild sub-populations of great tits (Parus major) and used automated tracking to map the diffusion, establishment and long-term persistence of the seeded innovations. Furthermore, we used social network analysis to examine the social factors that influenced diffusion dynamics. From only two trained birds in each sub-population, the information spread rapidly through social network ties, to reach an average of 75% of individuals, with a total of 414 knowledgeable individuals performing 57,909 solutions over all replicates. The sub-populations were heavily biased towards using the technique that was originally introduced, resulting in established local traditions that were stable over two generations, despite a high population turnover. Finally, we demonstrate a strong effect of social conformity, with individuals disproportionately adopting the most frequent local variant when first acquiring an innovation, and continuing to favour social information over personal information. Cultural conformity is thought to be a key factor in the evolution of complex culture in humans. In providing the first experimental demonstration of conformity in a wild non-primate, and of cultural norms in foraging techniques in any wild animal, our results suggest a much broader taxonomic occurrence of such an apparently complex cultural behaviour.
Abstract.
Author URL.
Thornton A, Wilson AJ (2015). In search of the Darwinian Holy Trinity in cognitive evolution: a comment on Croston et al. Behavioral Ecology, 26(6), 1460-1461.
Greggor AL, Thornton A, Clayton NS (2015). Neophobia is not only avoidance: Improving neophobia tests by combining cognition and ecology.
Current Opinion in Behavioral Sciences,
6, 82-89.
Abstract:
Neophobia is not only avoidance: Improving neophobia tests by combining cognition and ecology
Psychologists and behavioural ecologists use neophobia tests to measure behaviours ranging from anxiety to predatory wariness. Psychologists typically focus on underlying cognitive mechanisms at the expense of ecological validity, while behavioural ecologists generally examine adaptive function but ignore cognition. However, neophobia is an ecologically relevant fear behaviour that arises through a cognitive assessment of novel stimuli. Both fields have accrued conflicting results using various testing protocols, making it unclear what neophobia tests measure and what correlations between neophobia and other traits mean. Developing cognitively and ecologically informed tests allows neophobia to be empirically evaluated where appropriate and controlled for where it interferes with other behavioural measures. We offer guidelines for designing tests and stress the need for interdisciplinary dialogue to better explore neophobia's proximate causes and ecological consequences.
Abstract.
Thornton A, Raihani NJ (2015). The proximate-ultimate confusion in teaching and cooperation.
Behavioral and Brain Sciences,
38Abstract:
The proximate-ultimate confusion in teaching and cooperation
Kline does an admirable job of extending the functionalist framework developed by comparative researchers to help understand the function and form of human teaching. Functionalist approaches consider the adaptive value and underlying mechanisms of behaviour as separate but complementary questions, avoiding the conflation of ultimate and proximate explanations that has long hindered research on teaching and other forms of cooperation.
Abstract.
Mcauliffe K, Thornton A (2015). The psychology of cooperation in animals: an ecological approach.
Journal of Zoology,
295(1), 23-35.
Abstract:
The psychology of cooperation in animals: an ecological approach
There has been a recent push to study the psychological processes supporting cooperation in nonhuman animals. However, progress has been limited thus far due to differences in approaches between psychologists and behavioral ecologists. Although the former tend to use controlled experiments to pinpoint precise cognitive mechanisms, these experiments often lack ecological validity. In contrast, behavioral ecologists seek to understand the adaptive function of cooperative behavior of animals in the wild but typically neglect the underlying psychological mechanisms. Here we appraise and integrate evidence from these two approaches to understand the potential cognitive solutions to four fundamental challenges that animals face during cooperative interactions under natural conditions: (1) when to cooperate; (2) with whom to cooperate; (3) what to do in cooperative interactions; (4) how much to contribute to cooperation. We argue that an ecologically motivated approach is critical to understanding the psychological mechanisms of cooperation and how these mechanisms evolve.
Abstract.
Davidson GL, Clayton NS, Thornton A (2015). Wild jackdaws, Corvus monedula, recognize individual humans and may respond to gaze direction with defensive behaviour.
Animal Behaviour,
108, 17-24.
Abstract:
Wild jackdaws, Corvus monedula, recognize individual humans and may respond to gaze direction with defensive behaviour
Predator recognition is a prerequisite for antipredator behaviour. Although species level predator recognition is well documented, there is emerging evidence that some birds, including corvids, can differentiate between individual humans that pose different levels of threat. Other predator cues such as gaze direction may offer additional important information regarding the likelihood of an attack, but it is unknown whether wild animals can integrate information about the individual identity and gaze direction of a predator when perceiving threat levels. Here we measured wild jackdaws' responses to human head orientation, directed towards or away from their nestbox containing chicks. To test whether aversive responses to gaze direction were integrated with information about human identity, the human presenting gaze cues wore one of two masks: a 'threatening' mask that had previously been worn when handling the jackdaws' chicks and a 'neutral mask' that had previously been worn when walking by, but not disturbing the nest. Latency to return to the nestbox was significantly higher when the threatening mask rather than the neutral mask was worn, but it was not influenced by head direction. However, once a jackdaw landed outside the nestbox, there was a nonsignificant trend for it to be quicker to enter the box when the human was gazing towards, rather than away from the box. These results indicate that wild jackdaws can recognize different individual humans and thus differentiate between those wearing a threatening and a neutral mask, and respond defensively by guarding their chicks from potential threat. Jackdaws may integrate both predator identity and gaze cues; however, predation risk is primarily perceived through individual human recognition.
Abstract.
2014
Greggor AL, Clayton NS, Phalan B, Thornton A (2014). Comparative cognition for conservationists.
Trends Ecol Evol,
29(9), 489-495.
Abstract:
Comparative cognition for conservationists.
Every animal occupies a unique cognitive world based on its sensory capacities, and attentional and learning biases. Behaviour results from the interaction of this cognitive world with the environment. As humans alter environments, cognitive processes ranging from perceptual processes to learned behaviour govern animals' reactions. By harnessing animals' perceptual biases and applying insights from cognitive theory, we can purposefully alter cues to reduce maladaptive responses and shape behaviour. Despite the fundamental connection between cognition and behaviour, the breadth of cognitive theory is underutilised in conservation practice. Bridging these disciplines could augment existing conservation efforts targeting animal behaviour. We outline relevant principles of perception and learning, and develop a step-by-step process for applying aspects of cognition towards specific conservation issues.
Abstract.
Author URL.
Davidson GL, Butler S, Fernández-Juricic E, Thornton A, Clayton NS (2014). Gaze sensitivity: Function and mechanisms from sensory and cognitive perspectives.
Animal Behaviour,
87(C), 3-15.
Abstract:
Gaze sensitivity: Function and mechanisms from sensory and cognitive perspectives
Sensitivity to the gaze of other individuals has long been a primary focus in sociocognitive research on humans and other animals. Information about where others are looking may often be of adaptive value in social interactions and predator avoidance, but studies across a range of taxa indicate there are substantial differences in the extent to which animals obtain and use information about other individuals' gaze direction. As the literature expands, it is becoming increasingly difficult to make comparisons across taxa as experiments adopt and adjust different methodologies to account for differences between species in their socioecology, sensory systems and possibly also their underlying cognitive mechanisms. Furthermore, as more species are found to exhibit gaze sensitivity, more terminology arises to describe the behaviours. To clarify the field, we propose a restricted nomenclature that defines gaze sensitivity in terms of observable behaviour, independent of the underlying mechanisms. This is particularly useful in nonhuman animal studies where cognitive interpretations are ambiguous. We then describe how socioecological factors may influence whether species will attend to gaze cues, and suggest links between ultimate factors and proximate mechanisms such as cognition and perception. In particular, we argue that variation in sensory systems, such as retinal specializations and the position of the eyes, will determine whether gaze cues (e.g. head movement) are perceivable during visual fixation. We end by making methodological recommendations on how to apply these variations in socioecology and visual systems to advance the field of gaze research.
Abstract.
Thornton A (2014). How and why are some species so smart? a comment on Rowe and Healy. Behavioral Ecology, 25(6), 1294-1295.
Zandberg L, Jolles JW, Boogert NJ, Thornton A (2014). Jackdaw nestlings can discriminate between conspecific calls but do not beg specifically to their parents.
Behavioral Ecology,
25(3), 565-573.
Abstract:
Jackdaw nestlings can discriminate between conspecific calls but do not beg specifically to their parents
The ability to recognize other individuals may provide substantial benefits to young birds, allowing them to target their begging efforts appropriately, follow caregivers after fledging, and establish social relationships later in life. Individual recognition using vocal cues is likely to play an important role in the social lives of birds such as corvids that provision their young postfledging and form stable social bonds, but the early development of vocal recognition has received little attention. We used playback experiments on jackdaws, a colonial corvid species, to test whether nestlings begin to recognize their parents' calls before fledging. Although the food calls made by adults when provisioning nestlings were individually distinctive, nestlings did not beg preferentially to their parents' calls. Ten-day-old nestlings not only responded equally to the calls of their parents, neighboring jackdaws whose calls they were likely to overhear regularly and unfamiliar jackdaws from distant nest boxes, but also to the calls of rooks, a sympatric corvid species. Responses to rooks declined substantially with age, but 20- and 28-day-old nestlings were still equally likely to produce vocal and postural begging responses to parental and nonparental calls. This is unlikely to be due to an inability to discriminate between calls, as older nestlings did respond more quickly and with greater vocal intensity to familiar calls, with some indication of discrimination between parents and neighbors. These results suggest that jackdaws develop the perceptual and cognitive resources to discriminate between conspecific calls before fledging but may not benefit from selective begging responses. © the Author 2014.
Abstract.
Davidson GL, Clayton NS, Thornton A (2014). Salient eyes deter conspecific nest intruders in wild jackdaws (Corvus monedula).
Biol Lett,
10(2).
Abstract:
Salient eyes deter conspecific nest intruders in wild jackdaws (Corvus monedula).
Animals often respond fearfully when encountering eyes or eye-like shapes. Although gaze aversion has been documented in mammals when avoiding group-member conflict, the importance of eye coloration during interactions between conspecifics has yet to be examined in non-primate species. Jackdaws (Corvus monedula) have near-white irides, which are conspicuous against their dark feathers and visible when seen from outside the cavities where they nest. Because jackdaws compete for nest sites, their conspicuous eyes may act as a warning signal to indicate that a nest is occupied and deter intrusions by conspecifics. We tested whether jackdaws' pale irides serve as a deterrent to prospecting conspecifics by comparing prospectors' behaviour towards nest-boxes displaying images with bright eyes (BEs) only, a jackdaw face with natural BEs, or a jackdaw face with dark eyes. The jackdaw face with BEs was most effective in deterring birds from making contact with nest-boxes, whereas both BE conditions reduced the amount of time jackdaws spent in proximity to the image. We suggest BEs in jackdaws may function to prevent conspecific competitors from approaching occupied nest sites.
Abstract.
Author URL.
Thornton A, Isden J, Madden JR (2014). Toward wild psychometrics: Linking individual cognitive differences to fitness.
Behavioral Ecology,
25(6), 1299-1301.
Abstract:
Toward wild psychometrics: Linking individual cognitive differences to fitness
Our understanding of the processes underlying animal cognition has improved dramatically in recent years, but we still know little about how cognitive traits evolve. Following Darwinian logic, to understand how selection acts on such traits we must determine whether they vary between individuals, influence fitness, and are heritable. A handful of recent studies have begun to explore the relationship between variation in individual cognitive performance and fitness under natural conditions. Such work holds great promise, but its success is contingent on accurate characterization and quantification of the cognitive differences between individuals. Existing research has typically adopted a "problem-solving" approach, assuming that individuals that complete novel tasks have greater cognitive prowess than those that do not. We argue that this approach is incapable of determining that individual differences are due to cognitive factors. We propose the adoption of psychologically grounded psychometric testing and discuss the criteria necessary to examine the fitness consequences of cognitive variation in the wild.
Abstract.
Greggor AL, Clayton NS, Phalan B, Thornton A (2014). Translating cognitive insights into effective conservation programs: reply to Schakner et al.
Trends Ecol Evol,
29(12), 652-653.
Author URL.
2013
Jolles JW, King AJ, Manica A, Thornton A (2013). Heterogeneous structure in mixed-species corvid flocks in flight.
Animal Behaviour,
85(4), 743-750.
Abstract:
Heterogeneous structure in mixed-species corvid flocks in flight
Flocks of birds in flight represent a striking example of collective behaviour. Models of self-organization suggest that repeated interactions among individuals following simple rules can generate the complex patterns and coordinated movements exhibited by flocks. However, such models often assume that individuals are identical and interchangeable, and fail to account for individual differences and social relationships among group members. Here, we show that heterogeneity resulting from species differences and social structure can affect flock spatial dynamics. Using high-resolution photographs of mixed flocks of jackdaws, Corvus monedula, and rooks, Corvus frugilegus, we show that birds preferentially associated with conspecifics and that, like high-ranking members of single-species groups, the larger and more socially dominant rooks positioned themselves near the leading edge of flocks. Neighbouring birds showed closer directional alignment if they were of the same species, and neighbouring jackdaws in particular flew very close to one another. Moreover, birds of both species often flew especially close to a single same-species neighbour, probably reflecting the monogamous pair bonds that characterize these corvid social systems. Together, our findings demonstrate that the characteristics of individuals and their social systems are likely to result in preferential associations that critically influence flock structure. © 2013 the Association for the Study of Animal Behaviour.
Abstract.
2012
Thornton A, Clayton NS, Grodzinski U (2012). Animal minds: from computation to evolution.
Philos Trans R Soc Lond B Biol Sci,
367(1603), 2670-2676.
Author URL.
McAuliffe K, Thornton A (2012). How do banded mongooses locate and select anvils for cracking encased food items?.
BEHAVIOURAL PROCESSES,
90(3), 350-356.
Author URL.
Hoppitt W, Samson J, Laland KN, Thornton A (2012). Identification of Learning Mechanisms in a Wild Meerkat Population.
PLOS ONE,
7(8).
Author URL.
Thornton A, Lukas D (2012). Individual variation in cognitive performance: developmental and evolutionary perspectives.
Philos Trans R Soc Lond B Biol Sci,
367(1603), 2773-2783.
Abstract:
Individual variation in cognitive performance: developmental and evolutionary perspectives.
Animal cognition experiments frequently reveal striking individual variation but rarely consider its causes and largely ignore its potential consequences. Studies often focus on a subset of high-performing subjects, sometimes viewing evidence from a single individual as sufficient to demonstrate the cognitive capacity of a species. We argue that the emphasis on demonstrating species-level cognitive capacities detracts from the value of individual variation in understanding cognitive development and evolution. We consider developmental and evolutionary interpretations of individual variation and use meta-analyses of data from published studies to examine predictors of individual performance. We show that reliance on small sample sizes precludes robust conclusions about individual abilities as well as inter- and intraspecific differences. We advocate standardization of experimental protocols and pooling of data between laboratories to improve statistical rigour. Our analyses show that cognitive performance is influenced by age, sex, rearing conditions and previous experience. These effects limit the validity of comparative analyses unless developmental histories are taken into account, and complicate attempts to understand how cognitive traits are expressed and selected under natural conditions. Further understanding of cognitive evolution requires efforts to elucidate the heritability of cognitive traits and establish whether elevated cognitive performance confers fitness advantages in nature.
Abstract.
Author URL.
Thornton A, Samson J (2012). Innovative problem solving in wild meerkats.
Animal Behaviour,
83(6), 1459-1468.
Abstract:
Innovative problem solving in wild meerkats
Behavioural innovations may have far-reaching evolutionary and ecological consequences, allowing individuals to obtain new resources and cope with environmental change. However, as innovations are rarely observed in nature, their emergence is poorly understood. What drives individuals to innovate, and what psychological mechanisms allow them to do so? We used three novel food extraction tasks to address these questions in groups of wild meerkats, Suricata suricatta. Innovatory tendencies were unrelated to body condition and foraging success, but were affected by age, rank and sex. Juvenile individuals were most likely to interact with tasks, but seldom solved them, perhaps owing to their small size or lack of dexterity. Instead, adult subordinates made up the bulk of the innovators. In cooperatively breeding societies, the inability of subordinate helpers to compete physically with dominant breeders may drive them to seek out solutions to novel problems. Most innovators were males, which, as the dispersing sex, may be particularly prone to solve novel problems, and innovators virtually always persisted longer than other group members when interacting with tasks. Most successful individuals solved tasks more than once, and learned to inhibit ineffective prepotent responses across successive presentations of the same task. They did not learn to manipulate functional parts of the apparatus more efficiently, however, nor did they extract general rules allowing them to solve novel tasks faster. Contrary to recent suggestions that innovation may be cognitively demanding, these results suggest that simple, conserved learning processes and dogged perseverance may suffice to generate solutions to novel problems. © 2012 the Association for the Study of Animal Behaviour.
Abstract.
Raihani NJ, Thornton A, Bshary R (2012). Punishment and cooperation in nature.
Trends in Ecology and Evolution,
27(5), 288-295.
Abstract:
Punishment and cooperation in nature
Humans use punishment to promote cooperation in laboratory experiments but evidence that punishment plays a similar role in non-human animals is comparatively rare. In this article, we examine why this may be the case by reviewing evidence from both laboratory experiments on humans and ecologically relevant studies on non-human animals. Generally, punishment appears to be most probable if players differ in strength or strategic options. Although these conditions are common in nature, punishment (unlike other forms of aggression) involves immediate payoff reductions to both punisher and target, with net benefits to punishers contingent on cheats behaving more cooperatively in future interactions. In many cases, aggression yielding immediate benefits may suffice to deter cheats and might explain the relative scarcity of punishment in nature. © 2012 Elsevier Ltd.
Abstract.
Thornton A, Clutton-Brock T (2012). Social learning and the development of individual and group behaviour in mammal societies. In Whiten A, Hinde RA, Stringer CB, Laland KN (Eds.) Culture Evolves, Oxford University Press, USA, 71-87.
Thornton A, McAuliffe K (2012). Teaching can teach us a lot. Animal Behaviour, 83(4).
2011
Thornton A, Clutton-Brock T (2011). Social learning and the development of individual and group behaviour in mammal societies.
Philos Trans R Soc Lond B Biol Sci,
366(1567), 978-987.
Abstract:
Social learning and the development of individual and group behaviour in mammal societies.
As in human societies, social learning may play an important role in shaping individual and group characteristics in other mammals. Here, we review research on non-primate mammals, concentrating on work at our long-term meerkat study site, where longitudinal data and field experiments have generated important insights into the role of social learning under natural conditions. Meerkats live under high predation pressure and occupy a difficult foraging niche. Accordingly, pups make extensive use of social information in learning to avoid predation and obtain food. Where individual learning is costly or opportunities are lacking, as in the acquisition of prey-handling skills, adults play an active role in promoting learning through teaching. Social learning can also cause information to spread through groups, but our data suggest that this does not necessarily result in homogeneous, group-wide traditions. Moreover, traditions are commonly eroded by individual learning. We suggest that traditions will only persist where there are high costs of deviating from the group norm or where skill development requires extensive time and effort. Persistent traditions could, theoretically, modify selection pressures and influence genetic evolution. Further empirical studies of social learning in natural populations are now urgently needed to substantiate theoretical claims.
Abstract.
Author URL.
2010
Thornton A, Raihani NJ (2010). Identifying teaching in wild animals.
LEARNING & BEHAVIOR,
38(3), 297-309.
Author URL.
Thornton A, Samson J, Clutton-Brock T (2010). Multi-generational persistence of traditions in neighbouring meerkat groups.
Proc Biol Sci,
277(1700), 3623-3629.
Abstract:
Multi-generational persistence of traditions in neighbouring meerkat groups.
Reports of socially transmitted traditions based on behavioural differences between geographically separated groups of conspecifics are contentious because they cannot exclude genetic or environmental causes. Here, we report persistent differences between neighbouring groups of meerkats (Suricata suricatta) where extensive gene flow precludes genetic differentiation. Over 11 years, some groups consistently emerged later from their sleeping burrows in the morning than others, despite complete turnovers in group membership and the influx of immigrants. Group territories overlapped and, in many cases, the same sleeping burrows were used by different groups. Differences persisted even after accounting for effects of group size, weather and burrow characteristics, and were unrelated to food availability within territories. These results provide compelling evidence that the emergence times of meerkat groups represent conservative traditions.
Abstract.
Author URL.
2009
Thornton A, Malapert A (2009). Experimental evidence for social transmission of food acquisition techniques in wild meerkats.
Animal Behaviour,
78(2), 255-264.
Abstract:
Experimental evidence for social transmission of food acquisition techniques in wild meerkats
Despite major evolutionary implications, patterns of social information transmission in natural populations remain poorly understood. We used an experiment to examine the spread of novel food acquisition techniques through groups of wild meerkats, Suricata suricatta. We trained individual 'demonstrators' in six groups to obtain food from an apparatus using one of two techniques. A further three control groups had no demonstrators. We found evidence for social learning on two levels. First, a greater proportion of individuals in experimental than control groups interacted with the apparatus and obtained food from it. Second, a number of individuals in experimental groups adopted demonstrators' techniques following interactions with demonstrators or other group members that had already learned from demonstrators. Scrounging appeared to be the primary driver of technique acquisition, with naïve individuals being more likely to learn a technique if they had scrounged from an individual performing that technique. Among individuals that never scrounged, observing successful performance of a technique also had a positive effect on technique adoption. Young individuals were more likely than adults to join and scrounge from demonstrators and were consequently more likely to learn. A number of individuals also learned without observing or scrounging from demonstrators, and there was some indication that their techniques subsequently spread to others, leading to the existence of alternative socially learned techniques within groups. These results shed light on patterns of social learning in nature and suggest that a lack of behavioural uniformity within groups need not imply a lack of socially transmitted behaviour. © 2009 the Association for the Study of Animal Behaviour.
Abstract.
Hodge SJ, Thornton A, Flower TP, Clutton-Brock TH (2009). Food limitation increases aggression in juvenile meerkats.
BEHAVIORAL ECOLOGY,
20(5), 930-935.
Author URL.
Thornton A, Hodge SJ (2009). The development of foraging microhabitat preferences in meerkats.
BEHAVIORAL ECOLOGY,
20(1), 103-110.
Author URL.
Thornton A, Malapert A (2009). The rise and fall of an arbitrary tradition: an experiment with wild meerkats.
Proceedings of the Royal Society B: Biological Sciences,
276(1660), 1269-1276.
Abstract:
The rise and fall of an arbitrary tradition: an experiment with wild meerkats
Humans often follow the choices of others, even when profitable alternatives exist, leading to the maintenance of arbitrary traditions. Arbitrary traditions have also been shown to persist in captive groups of other animals, but it is unclear whether they do so in the wild where there are ample opportunities for exploring alternatives. We conducted the first experiment examining the maintenance of arbitrary traditions in wild mammal groups. We trained 'demonstrators' in seven meerkat groups to obtain rewards from one out of the two distinctive landmarks. Two control groups had no trained demonstrators. Naive individuals initially ignored the landmarks, but were more likely to approach them and obtain rewards following encounters with demonstrators. Individuals in control groups were less likely to obtain rewards. While control groups showed no landmark preference, experimental groups initially preferred the landmark chosen by demonstrators, even though an equally rewarding alternative was nearby, leading to the establishment of local traditions. However, individuals that learned that one landmark was profitable began to explore the other rather than conforming to the majority behaviour, so traditions collapsed over time. This suggests that where conformist tendencies are lacking, the maintenance of traditions in natural populations depends on the relative influence of social and individual learning. © 2009 the Royal Society.
Abstract.
Thornton A, Malapert A (2009). The rise and fall of an arbitrary tradition: an experiment with wild meerkats.
Proc Biol Sci,
276(1660), 1269-1276.
Abstract:
The rise and fall of an arbitrary tradition: an experiment with wild meerkats.
Humans often follow the choices of others, even when profitable alternatives exist, leading to the maintenance of arbitrary traditions. Arbitrary traditions have also been shown to persist in captive groups of other animals, but it is unclear whether they do so in the wild where there are ample opportunities for exploring alternatives. We conducted the first experiment examining the maintenance of arbitrary traditions in wild mammal groups. We trained 'demonstrators' in seven meerkat groups to obtain rewards from one out of the two distinctive landmarks. Two control groups had no trained demonstrators. Naive individuals initially ignored the landmarks, but were more likely to approach them and obtain rewards following encounters with demonstrators. Individuals in control groups were less likely to obtain rewards. While control groups showed no landmark preference, experimental groups initially preferred the landmark chosen by demonstrators, even though an equally rewarding alternative was nearby, leading to the establishment of local traditions. However, individuals that learned that one landmark was profitable began to explore the other rather than conforming to the majority behaviour, so traditions collapsed over time. This suggests that where conformist tendencies are lacking, the maintenance of traditions in natural populations depends on the relative influence of social and individual learning.
Abstract.
Author URL.
2008
Thornton A (2008). Early body condition, time budgets and the acquisition of foraging skills in meerkats.
Animal Behaviour,
75(3), 951-962.
Abstract:
Early body condition, time budgets and the acquisition of foraging skills in meerkats
Early body condition commonly has important downstream effects on fitness. One, as yet unexplored, mechanism behind these effects may be that condition in early life affects time budgets and hence opportunities to learn critical skills. Meerkat, Suricata suricatta, pups must choose between begging for food from helpers and foraging for themselves. I found that pups in good condition early in life invested more time in foraging than individuals in poor condition and subsequently developed greater foraging efficiency, which was maintained in later life. Young pups spent an average of 18% of their time foraging, even though all pups were initially incompetent foragers and gained few direct benefits from their attempts. Pups whose hunger was reduced through experimental provisioning increased their investment in foraging. This suggests that investment in foraging is mediated by available energy reserves and raises the possibility that, although foraging is energetically costly, pups may gain long-term benefits by practising. Surprisingly, manipulating body weight through long-term experimental provisioning did not result in increased investment in foraging or improved foraging efficiency. Possible explanations for this result are considered. The findings presented here provide some support for the hypothesis that high body condition allows individuals to invest time in costly foraging practice, leading to the development of skills. These effects, acting in tandem with other processes such as differential neural development, may help to explain common links between early condition and future fitness. © 2007 the Association for the Study of Animal Behaviour.
Abstract.
Hoppitt WJE, Brown GR, Kendal R, Rendell L, Thornton A, Webster MM, Laland KN (2008). Lessons from animal teaching.
Trends in Ecology and Evolution,
23(9), 486-493.
Abstract:
Lessons from animal teaching
Many species are known to acquire valuable life skills and information from others, but until recently it was widely believed that animals did not actively facilitate learning in others. Teaching was regarded as a uniquely human faculty. However, recent studies suggest that teaching might be more common in animals than previously thought. Teaching is present in bees, ants, babblers, meerkats and other carnivores but is absent in chimpanzees, a bizarre taxonomic distribution that makes sense if teaching is treated as a form of altruism. Drawing on both mechanistic and functional arguments, we integrate teaching with the broader field of animal social learning, and show how this aids understanding of how and why teaching evolved, and the diversity of teaching mechanisms. © 2008 Elsevier Ltd. All rights reserved.
Abstract.
Thornton A (2008). Social learning about novel foods in young meerkats.
Animal Behaviour,
76(4), 1411-1421.
Abstract:
Social learning about novel foods in young meerkats
Animals are often neophobic towards novel foods, but will incorporate them into their diet after interacting with experienced conspecifics. Such social learning is likely to be particularly important for young animals, for which most foods are unfamiliar. It has been suggested that in some species adults actively promote learning about unfamiliar foods by teaching offspring, although firm evidence is lacking. I examined social influences on learning about novel foods among wild meerkats, Suricata suricatta, a species where older group members teach pups prey-handling skills. In two experiments, naïve pups were significantly more likely to eat hardboiled egg, a food item not normally present in the diet, and scorpions, a common prey type, if they had interacted with experienced conspecifics. I then investigated whether helpers teach pups to eat unfamiliar prey by preferentially feeding rare items and through direct feeding, where food items are transferred mouth to mouth. Rare prey items were fed more frequently than common items, although this may reflect nutritional characteristics. Direct feeding was most commonly used by juvenile helpers, which typically contribute relatively little to cooperative activities, and was more frequent if other helpers were nearby. This suggests that direct feeding may be a means of reducing the costs of feeding by improving the efficiency of energy transfer and minimizing the risks of kleptoparasitism. I conclude that learning about novel foods is likely to occur as a by-product of provisioning by helpers. There was little evidence that helpers actively teach pups what to eat. © 2008 the Association for the Study of Animal Behaviour.
Abstract.
Thornton A, Raihani NJ (2008). The evolution of teaching.
Animal Behaviour,
75(6), 1823-1836.
Abstract:
The evolution of teaching
Teaching has long been a neglected area in animal behaviour, despite its relevance for a wide range of topics. In light of recent evidence for teaching in nonhuman animals, research can begin to examine the conditions under which it may evolve. Here, we make the case for an evolutionary perspective that treats teaching as a form of cooperative behaviour which functions to promote learning in others. We outline its key characteristics and discuss the selection pressures that may favour its evolution. Teaching will be favoured by selection only where the costs to teachers of facilitating learning are outweighed by the long-term fitness benefits they accrue once pupils have learned, and these benefits will be scaled by the ease with which pupils could learn without teaching. This perspective allows us to make predictions as to the distribution of teaching, the forms it may take, and the relation between teaching in humans and other species. We conclude by considering how teaching may best be categorized. We suggest that natural selection is likely to favour different forms of teaching, depending on whether it serves to promote learning of procedural or declarative information. © 2008 the Association for the Study of Animal Behaviour.
Abstract.
Thornton A (2008). Variation in contributions to teaching by meerkats.
Proc Biol Sci,
275(1644), 1745-1751.
Abstract:
Variation in contributions to teaching by meerkats.
Recent evidence from cooperative insect, bird and mammal societies has challenged the assumption that teaching is restricted to humans. However, little is known about the factors affecting the degree to which individuals in such societies contribute to teaching. Here, I examine variation in contributions to teaching in meerkats, where older group members teach pups to handle difficult prey. I show that investment in teaching varies with characteristics of pups, helpers, groups and ecological conditions. Although prior experience in caring for pups did not significantly influence teaching behaviour, younger helpers, which were still investing in growth, contributed less to teaching than older individuals. This suggests that, in common with other cooperative activities, contributions to teaching vary with the costs experienced by individual group members. However, in contrast to other forms of helping in meerkats, I detected no effects of nutritional state on teaching, suggesting that it carries relatively low costs. In species where individuals can potentially gain direct or indirect fitness benefits from facilitating learning in others, low costs divided among multiple group members may help tip the balance towards selection for teaching.
Abstract.
Author URL.
2007
Thornton A, Raihani NJ, Radford AN (2007). Teachers in the wild: some clarification.
TRENDS IN COGNITIVE SCIENCES,
11(7), 272-273.
Author URL.
2006
Thornton A, McAuliffe K (2006). Kalahari classrooms: How meerkats teach pups to hunt.
Planet Earth(WINTER 2006), 20-21.
Abstract:
Kalahari classrooms: How meerkats teach pups to hunt
A team of scientists set out to find put how meerkat pups learn their hunting skills. The group spent about two years living at a field site run by the University of Cambridge deep in the Kalahari desert. The progress of over 100 pups from birth into adulthood was followed thus making it possible to investigate how they become efficient killers. Results confirm that pups' skills improve as a result of exposure to live prey.
Abstract.
Thornton A, McAuliffe K (2006). Teaching in wild meerkats.
SCIENCE,
313(5784), 227-229.
Author URL.
