Spontaneous innovation in tool manufacture and use in a Goffin's cockatoo

Hooded crows (Corvus cornix) manufacture objects relative to a mental template

It was recently found that not only tool-specialized New Caledonian crows, but also Goffin cockatoos can manufacture physical objects in accordance with a mental template. That is, they can emulate features of existing objects when they manufacture new items. Both species spontaneously ripped pieces of card into large strips if they had previously learned that a large template was rewarded, and small strips when they previously learned that a small template was rewarded. Among New Caledonian crows, this cognitive ability was suggested as a potential mechanism underlying the transmission of natural tool designs. Here, we tested for the same ability in another non-specialised tool user-Hooded crows (Corvus cornix). Crows were exposed to pre-made template objects, varying first in colour and then in size, and were rewarded only if they chose pre-made objects that matched the template. In subsequent tests, birds were given the opportunity to manufacture versions of these objects. All three crows ripped paper pieces from the same colour material as the rewarded template, and, crucially, also manufactured objects that were more similar in size to previously rewarded, than unrewarded, templates, despite the birds being rewarded at random in both tests. Therefore, we found the ability to manufacture physical objects relative to a mental template in yet another bird species not specialized in using or making foraging tools in the wild, but with a high level of brain and cognitive development.

Different ways of evolving tool-using brains in teleosts and amniotes

In mammals and birds, tool-using species are characterized by their relatively large telencephalon containing a higher proportion of total brain neurons compared to other species. Some teleost species in the wrasse family have evolved tool-using abilities. In this study, we compared the brains of tool-using wrasses with various teleost species. We show that in the tool-using wrasses, the telencephalon and the ventral part of the forebrain and midbrain are significantly enlarged compared to other teleost species but do not contain a larger proportion of cells. Instead, this size difference is due to large fiber tracts connecting the dorsal part of the telencephalon (pallium) to the inferior lobe, a ventral mesencephalic structure absent in amniotes. The high degree of connectivity between these structures in tool-using wrasses suggests that the inferior lobe could contribute to higher-order cognitive functions. We conclude that the evolution of non-telencephalic structures might have been key in the emergence of these cognitive functions in teleosts.

Kea, bird of versatility. Kea parrots (Nestor notabilis) show high behavioural flexibility in solving a demonstrated sequence task

Social learning is an important aspect of dealing with the complexity of life. The transmission of information via the observation of other individuals is a cost-effective way of acquiring information. It is widespread within the animal kingdom but may differ strongly in the social learning mechanisms applied by the divergent species. Here we tested eighteen Kea (Nestor notabilis) parrots on their propensity to socially learn, and imitate, a demonstrated sequence of steps necessary to open an apparatus containing food. The demonstration by a conspecific led to more successful openings by observer birds, than control birds without a demonstration. However, all successful individuals showed great variation in their response topography and abandoned faithfully copying the task in favour of exploration. While the results provide little evidence for motor imitation they do provide further evidence for kea's propensity towards exploration and rapidly shifting solving strategies, indicative of behavioural flexibility.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10336-023-02127-y.

Dunking rusk: innovative food soaking behaviour in Goffin's cockatoos (Cacatua goffiniana)

Foraging innovations in animals involving the processing of resources that are already edible in an unprocessed state, yet of improved quality in a processed state, are rare but important to study the evolution of food preparation. Here, we present the first scientific report of food dunking behaviours in parrots by Goffin's cockatoos, a model species for innovative problem solving. Observations during lunch showed seven out of 18 cockatoos placing their food into water and soaking it prior to consumption. This was largely done with dry rusk which was eaten almost exclusively when dunked. Furthermore, their transport effort and waiting times before retrieving food from the water indicate their willingness to invest considerable time to prepare a soaked rusk piece of a higher texture quality. Our present results suggest that the function of this behaviour is to soak the food. Because only some individuals dunked food and dunking has not been observed in the wild, we believe this to be a spontaneous foraging innovation either by one or multiple individuals.

Individual preferences for sound tool design in a parrot

The rarity of tool manufacture in wild parrots is surprising because they share key life-history traits with advanced tool-using species, including large brains, complex sociality and prolonged parental care. When it does occur, tool manufacture in parrots tends to be innovative, spontaneous and individually variable, but most cases have been in captivity. In the wild, only palm cockatoos (Probosciger aterrimus) have been observed using tools regularly. However, they are unusual because they use tools to enhance their displays rather than for foraging or self-maintenance. Males in northern Australia make two types of tool from sticks and seed pods, which they tap rhythmically against a tree during display. We analysed 256 sound tools retrieved from 70 display trees. Drumsticks (89% of tools) were used more often than seed pod tools; most males manufactured only drumsticks, but some made both types. Individual males differed significantly in the design of their drumsticks including the length, width and mass but we found no evidence that neighbours copied each other. We discuss the highly individualized preferences for sound tool design in context of the behavioural predispositions behind the rarity of tool manufacture in wild parrots.

Two-action task, testing imitative social learning in kea (Nestor notabilis)

Social learning is an adaptive way of dealing with the complexity of life as it reduces the risk of trial-and-error learning. Depending on the type of information acquired, and associations formed, several mechanisms within the larger taxonomy of social learning can be distinguished. Imitation is one such process within this larger taxonomy, it is considered cognitively demanding and is associated with high-fidelity response matching. The present study reproduced a 2002 study conducted by Heyes and Saggerson, which successfully illustrated motor imitation in budgerigars (Melopsittacus undulatus). In our study, eighteen kea (Nestor notabilis) that observed a trained demonstrator remove a stopper from a test box (1) took less time from hopping on the box to feeding (response duration) in session one and (2) were faster in making a vertical removal response on the stopper once they hopped on the box (removal latency) in session one than non-observing control group individuals. In contrast to the budgerigars (Heyes and Saggerson, Ani Behav. 64:851-859, 2002) the present study could not find evidence of motor imitation in kea. The results do illustrate, however, that there were strong social effects on exploration rates indicating motivational and attentional shifts. Furthermore, the results may suggest a propensity toward emulation in contrast to motor imitation or alternatively selectivity in the application of imitation.

Flexible tool set transport in Goffin's cockatoos

The use of tool sets constitutes one of the most elaborate examples of animal technology, and reports of it in nature are limited to chimpanzees and Goffin's cockatoos. Although tool set use in Goffin's was only recently discovered, we know that chimpanzees flexibly transport tool sets, depending on their need. Flexible tool set transport can be considered full evidence for identification of a genuine tool set, as the selection of the second tool is not just a response to the outcomes of the use of the first tool but implies recognizing the need for both tools before using any of them (thus, categorizing both tools together as a tool set). In three controlled experiments, we tested captive Goffin's in tasks inspired by the termite fishing of Goualougo Triangle's chimpanzees. Thereby, we show that some Goffin's can innovate the use and flexibly use and transport a new tool set for immediate future use; therefore, their sequential tool use is more than the sum of its parts. VIDEO ABSTRACT.

The role of climate change and niche shifts in divergent range dynamics of a sister-species pair

Species ranges are set by limitations in factors including climate tolerances, habitat use, and dispersal abilities. Understanding the factors governing species range dynamics remains a challenge that is ever more important in our rapidly changing world. Species ranges can shift if environmental changes affect available habitat, or if the niche or habitat connectivity of a species changes. We tested how changes in habitat availability, niche, or habitat connectivity could contribute to divergent range dynamics in a sister-species pair. The great-tailed grackle (Quiscalus mexicanus) has expanded its range northward from Texas to Nebraska in the past 40 years, while its closest relative, the boattailed grackle (Quiscalus major), has remained tied to the coasts of the Atlantic Ocean and the Gulf of Mexico as well as the interior of Florida. We created species distribution and connectivity models trained on citizen science data from 1970-1979 and 2010-2019 to determine how the availability of habitat, the types of habitat occupied, and range-wide connectivity have changed for both species. We found that the two species occupy distinct habitats and that the great-tailed grackle has shifted to occupy a larger breadth of urban, arid environments farther from natural water sources. Meanwhile, the boattailed grackle has remained limited to warm, wet, coastal environments. We found no evidence that changes in habitat connectivity affected the ranges of either species. Overall, our results suggest that the great-tailed grackle has shifted its realized niche as part of its rapid range expansion, while the range dynamics of the boat-tailed grackle may be shaped more by climate change. The expansion in habitats occupied by the great-tailed grackle is consistent with observations that species with high behavioral flexibility can rapidly expand their geographic range by using human-altered habitat. This investigation identifies how opposite responses to anthropogenic change could drive divergent range dynamics, elucidating the factors that have and will continue to shape species ranges.

Ratcheting up tool innovation in Goffin's cockatoos (Cacatua goffiniana): The effect of contextually diverse prior experience

The ability to gain information from one situation, acquire new skills and/or perfect existing ones, and subsequently apply them to a new situation is a key element in behavioural flexibility and a hallmark of innovation. A flexible agent is expected to store these skills and apply them to contexts different from that in which learning occurred. Goffin's cockatoos (Cacatua goffiniana) are highly innovative parrots renowned for their problem-solving and tool-using skills and are thus excellent candidates to study this phenomenon. We hypothesized that birds allowed to use a tool in a larger variety of contingencies would acquire a broader expertise in handling it, facilitating its transfer to new tasks. In our study, we compared the performance of two groups of captive Goffin's cockatoos (N = 13): A test group received more diverse learning and motor experiences on multiple applications of a hook-type tool, while a control group received intensive, total trial-matched, experience with a single application of the same tool. Then, both groups were tested on two novel tasks to determine whether experience with the tool in multiple contexts would facilitate performance during transfer. While both groups transferred to both novel tasks, group differences in performance were apparent, particularly in the second transfer task, where test birds achieved a higher success rate and reached criteria within fewer trials than control birds. These results provide support for the prediction that experiencing a diverse range of contingencies with a tool appears to allow birds to acquire generalizable knowledge and transferrable skills to tackle an untrained problem more efficiently. In contrast, intensive experience with the tool in a single context might have made control birds less flexible and more fixated on previously learned tool-dependent instances.

Recent developments in parrot cognition: a quadrennial update

Psittacines, along with corvids, are commonly referred to as 'feathered apes' due to their advanced cognitive abilities. Until rather recently, the research effort on parrot cognition was lagging behind that on corvids, however current developments show that the number of parrot studies is steadily increasing. In 2018, M. L. Lambert et al. provided a comprehensive review on the status of the most important work done so far in parrot and corvid cognition. Nevertheless, only a little more than 4 years after this publication, more than 50 new parrot studies have been published, some of them chartering completely new territory. On the 25th anniversary of Animal Cognition we think this warrants a detailed review of parrot cognition research over the last 4 years. We aim to capture recent developments and current trends in this rapidly expanding and diversifying field.

Preliminary evidence of tool use in an Australian magpie?

We investigated tool use in twelve wild-caught Australian magpies. When presented with a tool use apparatus consisting of two transparent walls with a food reward placed in-between, seven magpies pulled the stick out of the apparatus acquiring the food within. On one occasion, one magpie manipulated the removed stick, carried it back to the apparatus, dropped it between the two walls and proceeded to rake out the food within reach of its beak. We believe this observation is important for the field of comparative cognition as it (1) is the first study to report stick tool use in Australian magpies, and (2) shows a novel behaviour in a ground foraging bird that, as far as we know, do not naturally use tools for food extraction. This study provides preliminary evidence that Australian magpies may be added to the list of bird species that can use tools.

Training of Motion Control May Not Improve Tool-Manipulation Ability in Rats (Rattus norvegicus)

In recent times, previous studies have reported the manipulation of tools by rats and degus in controlled experimental settings. However, a previous study reported that only one out of eight experimentally naïve rats could manipulate a rake-shaped tool according to the position of a food reward without prior experience of obtaining the reward with the tool before the test. The present study aimed to improve the training of rats and investigate rodents’ ability to manipulate tools according to food position. Stricter criteria were employed when training the rats to promote the rats’ monitoring of their own tool manipulation. Additional training was introduced to give them the opportunity to learn that the reward moved closer to them by pulling an object connected to the reward. The present study showed that only one of eight rats could manipulate a tool according to the position of the reward without prior experience of obtaining the reward with the tool or perceiving that part of the tool came in contact with the reward, as the previous study showed. The change in training did not enhance the rats’ tool-manipulation ability according to the food position. These procedures should be conducted in a wider variety of animals to investigate whether the training in motion control can promote the subjects’ effective tool-use behavior.

How to behave when marooned: the behavioural component of the island syndrome remains underexplored

Animals on islands typically depart from their mainland relatives in assorted aspects of their biology. Because they seem to occur in concert, and to some extent evolve convergently in disparate taxa, these changes are referred to as the ‘island syndrome’. While morphological, physiological and life-history components of the island syndrome have received considerable attention, much less is known about how insularity affects behaviour. In this paper, we argue why changes in personality traits and cognitive abilities can be expected to form part of the island syndrome. We provide an overview of studies that have compared personality traits and cognitive abilities between island and mainland populations, or among islands. Overall, the pickings are remarkably slim. There is evidence that animals on islands tend to be bolder than on the mainland, but effects on other personality traits go either way. The evidence for effects of insularity on cognitive abilities or style is highly circumstantial and very mixed. Finally, we consider the ecological drivers that may induce such changes, and the mechanisms through which they might occur. We conclude that our knowledge of the behavioural and cognitive responses to island environments remains limited, and we encourage behavioural biologists to make more use of these ‘natural laboratories for evolution’.

Innovative composite tool use by Goffin's cockatoos (Cacatua goffiniana)

Composite tool use (using more than one tool simultaneously to achieve an end) has played a significant role in the development of human technology. Typically, it depends on a number of specific and often complex spatial relations and there are thus very few reported cases in non-human animals (e.g., specific nut-cracking techniques in chimpanzees and capuchin monkeys). The innovative strategies underlying the innovation and spread of tool manufacture and associative tool use (using > 1 tools) across tool using animals is an important milestone towards a better understanding of the evolution of human technology. We tested Goffin's cockatoos on a composite tool problem, the 'Golf Club Task', that requires the use of two objects in combination (one used to control the free movement of a second) to get a reward. We demonstrate that these parrots can innovate composite tool use by actively controlling the position of the end effector and movement of both objects involved in a goal directed manner. The consistent use of different techniques by different subjects highlights the innovative nature of the individual solutions. To test whether the solution could be socially transmitted, we conducted a second study, which provided only tentative evidence for emulative learning. To our knowledge, this indicates that the cognitive preconditions for composite tool use have also evolved outside the primate lineage.

Do sex differences in construction behavior relate to differences in physical cognitive abilities?

Nest-building behaviour in birds may be particularly relevant to investigating the evolution of physical cognition, as nest building engages cognitive mechanisms for the use and manipulation of materials. We hypothesized that nest-building ecology may be related to physical cognitive abilities. To test our hypothesis, we used zebra finches, which have sex-differentiated roles in nest building. We tested 16 male and 16 female zebra finches on three discrimination tasks in the following order: length discrimination, flexibility discrimination, and color discrimination, using different types of string. We predicted that male zebra finches, which select and deposit the majority of nesting material and are the primary nest builders in this species, would learn to discriminate string length and flexibility-structural traits relevant to nest building-in fewer trials compared to females, but that the sexes would learn color discrimination (not structurally relevant to nest building) in a similar number of trials. Contrary to these predictions, male and female zebra finches did not differ in their speed to learn any of the three tasks. There was, however, consistent among-individual variation in performance: learning speed was positively correlated across the tasks. Our findings suggest that male and female zebra finches either (1) do not differ in their physical cognitive abilities, or (2) any cognitive sex differences in zebra finches are more specific to tasks more closely associated with nest building. Our experiment is the first to examine the potential evolutionary relationship between nest building and physical cognitive abilities.

Animal tool use: Many tools make light work for wild parrots

Tool set use is rare in the animal kingdom. Previously, only primates were known to use multiple tools with different functions to achieve a single goal. New research now reveals the convergent evolution of tool set use in wild parrots.

An anecdotal observation of anti-predatory tool use in a New Zealand parrot

I observed a wild kākā (Nestor meridionalis) excavate a piece of deadwood from the branch it was perched on and carry it to a new position immediately above a perched predatory falcon (Falco novaeseelandiae). It then raised its head upwards, and in a single downward motion with its head, released the piece of wood towards the falcon below. The piece of wood stuck the falcon in the back, which immediately took flight and disappeared from view. I conclude my description of this anecdotal observation of anti-predatory tool use with caveats and alternative interpretations.

Extending the Reach of Tooling Theory: A Neurocognitive and Phylogenetic Perspective

Tool use research has suffered from a lack of consistent theoretical frameworks. There is a plethora of tool use definitions and the most widespread ones are so inclusive that the behaviors that fall under them arguably do not have much in common. The situation is aggravated by the prevalence of anecdotes, which have played an undue role in the literature. In order to provide a more rigorous foundation for research and to advance our understanding of the interrelation between tool use and cognition, we suggest the adoption of Fragaszy and Mangalam's (2018) tooling framework, which is characterized by the creation of a body-plus-object system that manages a mechanical interface between tool and surface. Tooling is limited to a narrower suite of behaviors than tool use, which might facilitate its neurocognitive investigation. Indeed, evidence in the literature indicates that tooling has distinct neurocognitive underpinnings not shared by other activities typically classified as tool use, at least in primates. In order to understand the extent of tooling incidences in previous research, we systematically surveyed the comprehensive tool use catalog by Shumaker et al. (2011). We identified 201 tool use submodes, of which only 81 could be classified as tooling, and the majority of the tool use examples across species were poorly supported by evidence. Furthermore, tooling appears to be phylogenetically less widespread than tool use, with the greatest variability found in the primate order. However, in order to confirm these findings and to understand the evolution and neurocognitive mechanisms of tooling, more systematic research will be required in the future, particularly with currently underrepresented taxa.

Self-care tooling innovation in a disabled kea (Nestor notabilis)

Tooling is associated with complex cognitive abilities, occurring most regularly in large-brained mammals and birds. Among birds, self-care tooling is seemingly rare in the wild, despite several anecdotal reports of this behaviour in captive parrots. Here, we show that Bruce, a disabled parrot lacking his top mandible, deliberately uses pebbles to preen himself. Evidence for this behaviour comes from five lines of evidence: (i) in over 90% of instances where Bruce picked up a pebble, he then used it to preen; (ii) in 95% of instances where Bruce dropped a pebble, he retrieved this pebble, or replaced it, in order to resume preening; (iii) Bruce selected pebbles of a specific size for preening rather than randomly sampling available pebbles in his environment; (iv) no other kea in his environment used pebbles for preening; and (v) when other individuals did interact with stones, they used stones of different sizes to those Bruce preened with. Our study provides novel and empirical evidence for deliberate self-care tooling in a bird species where tooling is not a species-specific behaviour. It also supports claims that tooling can be innovated based on ecological necessity by species with sufficiently domain-general cognition.

Novel neuroanatomical integration and scaling define avian brain shape evolution and development

How do large and unique brains evolve? Historically, comparative neuroanatomical studies have attributed the evolutionary genesis of highly encephalized brains to deviations along, as well as from, conserved scaling relationships among brain regions. However, the relative contributions of these concerted (integrated) and mosaic (modular) processes as drivers of brain evolution remain unclear, especially in non-mammalian groups. While proportional brain sizes have been the predominant metric used to characterize brain morphology to date, we perform a high-density geometric morphometric analysis on the encephalized brains of crown birds (Neornithes or Aves) compared to their stem taxa—the non-avialan coelurosaurian dinosaurs and Archaeopteryx. When analyzed together with developmental neuroanatomical data of model archosaurs (Gallus, Alligator), crown birds exhibit a distinct allometric relationship that dictates their brain evolution and development. Furthermore, analyses by neuroanatomical regions reveal that the acquisition of this derived shape-to-size scaling relationship occurred in a mosaic pattern, where the avian-grade optic lobe and cerebellum evolved first among non-avialan dinosaurs, followed by major changes to the evolutionary and developmental dynamics of cerebrum shape after the origin of Avialae. Notably, the brain of crown birds is a more integrated structure than non-avialan archosaurs, implying that diversification of brain morphologies within Neornithes proceeded in a more coordinated manner, perhaps due to spatial constraints and abbreviated growth period. Collectively, these patterns demonstrate a plurality in evolutionary processes that generate encephalized brains in archosaurs and across vertebrates.

Goffin's Cockatoos (Cacatua goffiniana) Can Solve a Novel Problem After Conflicting Past Experiences

Novel problems often partially overlap with familiar ones. Some features match the qualities of previous situations stored in long-term memory and therefore trigger their retrieval. Using relevant, while inhibiting irrelevant, memories to solve novel problems is a hallmark of behavioral flexibility in humans and has recently been demonstrated in great apes. This capacity has been proposed to promote technical innovativeness and thus warrants investigations of such a mechanism in other innovative species. Here, we show that proficient tool-users among Goffin's cockatoos-an innovative tool-using species-could use a relevant previous experience to solve a novel, partially overlapping problem, even despite a conflicting, potentially misleading, experience. This suggests that selecting relevant experiences over irrelevant experiences guides problem solving at least in some Goffin's cockatoos. Our result supports the hypothesis that flexible memory functions may promote technical innovations.

Convergent evolution of complex cognition: Insights from the field of avian cognition into the study of self-awareness

Pioneering research on avian behaviour and cognitive neuroscience have highlighted that avian species, mainly corvids and parrots, have a cognitive tool kit comparable with apes and other large-brained mammals, despite conspicuous differences in their neuroarchitecture. This cognitive tool kit is driven by convergent evolution, and consists of complex processes such as casual reasoning, behavioural flexibility, imagination, and prospection. Here, we review experimental studies in corvids and parrots that tested complex cognitive processes within this tool kit. We then provide experimental examples for the potential involvement of metacognitive skills in the expression of the cognitive tool kit. We further expand the discussion of cognitive and metacognitive abilities in avian species, suggesting that an integrated assessment of these processes, together with revised and multiple tasks of mirror self-recognition, might shed light on one of the most highly debated topics in the literature-self-awareness in animals. Comparing the use of multiple assessments of self-awareness within species and across taxa will provide a more informative, richer picture of the level of consciousness in different organisms.

String-pulling in the Goffin's cockatoo (Cacatua goffiniana)

Goffin’s cockatoos, a parrot species endemic to the Tanimbar Islands in Indonesia, demonstrate remarkable cognitive skills across various technical tasks. These neophilic extractive foragers explore objects with their beak and feet, and are skilled in several modes of tool use. In this study, we confronted the animals for the first time with a vertical string-pulling setup, including a set of classic and novel controls. Nine of the 12 subjects, two of which were subadults, immediately interacted with the single-string task, with seven individuals successfully obtaining the reward on their very first attempt. Four different double string discrimination tests with varying spatial relations were used to assess the Goffin’s cockatoos’ apprehension of basic physical task properties. We found significant differences in performance between the respective experimental conditions, as well as the development of side biases. The results suggest that while the birds seem to consider simple cause–effect relationships, there is no evidence for a mental representation of the causal mechanisms underlying the string-pulling tasks, as subjects failed the crossed strings condition out of immediate sight. Finally, we provide suggestions on improving the methodology, and discuss our findings in regard to the Goffin’s cockatoo’s ecology.

Problem-solving performance in wild Steller’s jays using a string-pulling task

Animals that exploit resources from human-modified environments may encounter unique problems when searching for food. Pulling a string tied to a food reward (string-pulling task) is one of the most widespread methods of testing a species’ problem-solving performance in non-human animals. Performance in problem-solving tasks may be influenced by an individual’s characteristics and social interactions, especially in its natural habitat. We examined problem solving by free-ranging Steller’s jays (Cyanocitta stelleri) when extracting food from a string-pulling task presented in their natural habitat. During the study, seven of 50 jays successfully solved the task on their first to eighteenth experimental opportunity; solvers differed from nonsolvers by showing higher levels of persistence by pulling the string in more trials. Of the successful jays, five birds solved without observing others, while two birds were present during successful trials and subsequently completed the task. All seven jays demonstrated improvement in the task by using less string pulls over additional successful trials. Nineteen other jays in the population interacted with the apparatus and pulled the string, but not enough to acquire the food. These 19 jays were significantly bolder (shorter latencies to approach), more explorative (contacted more parts of the apparatus), and had observed solvers more than the 24 individuals that did not pull the string. These results indicate a broad spectrum of individual differences in propensity for solving novel tasks in our population of Steller’s jays.

Innovative problem solving in macaws

Behavioural innovations with tool-like objects in non-habitually tool-using species are thought to require complex physical understanding, but the underlying cognitive processes remain poorly understood. A few parrot species are capable of innovating tool-use and borderline tool-use behaviours. We tested this capacity in two species of macaw (Ara ambiguus, n = 9; Ara glaucogularis, n = 8) to investigate if they could solve a problem-solving task through manufacture of a multi-stone construction. Specifically, after having functional experience with a pre-inserted stick tool to push a reward out of a horizontal tube, the subjects were required to insert five stones consecutively from one side to perform the same function as the stick tool with the resulting multi-component construction. One Ara glaucogularis solved the task and innovated the stone construction after the experience with the stick tool. Two more subjects (one of each species) did so after having further functional experience of a single stone pushing a reward out of a shortened tube. These subjects were able to consistently solve the task, but often made errors, for example counter-productive stone insertions from the opposing end, even in some of the successful trials. Conversely, multiple trials without errors also suggested a strong goal direction. Their performance in the follow-up tasks was inconclusive since they sometimes inserted stones into un-baited or blocked ‘dummy tubes’, but this could have been an attention-deficit behaviour as subjects had not encountered these ‘dummy tubes’ before. Overall, the successful subjects’ performance was so erratic that it proved difficult to conclude whether they had functional understanding of their multi-stone constructions.

Neural Processes Underlying Tool Use in Humans, Macaques, and Corvids

It was thought that tool use in animals is an adaptive specialization. Recent studies, however, have shown that some non-tool-users, such as rooks and jays, can use and manufacture tools in laboratory settings. Despite the abundant evidence of tool use in corvids, little is known about the neural mechanisms underlying tool use in this family of birds. This review summarizes the current knowledge on the neural processes underlying tool use in humans, macaques and corvids. We suggest a possible neural network for tool use in macaques and hope this might inspire research to discover a similar brain network in corvids. We hope to establish a framework to elucidate the neural mechanisms that supported the convergent evolution of tool use in birds and mammals.

Object manufacture based on a memorized template: Goffin's cockatoos attend to different model features

Although several nonhuman animals have the ability to recognize and match templates in computerized tasks, we know little about their ability to recall and then physically manufacture specific features of mental templates. Across three experiments, Goffin cockatoos (Cacatua goffiniana), a species that can use tools in captivity, were exposed to two pre-made template objects, varying in either colour, size (long or short) or shape (I or L-shaped), where only one template was rewarded. Birds were then given the opportunity to manufacture versions of these objects themselves. We found that all birds carved paper strips from the same colour material as the rewarded template, and half were also able to match the size of a template (long and short). This occurred despite the template being absent at test and birds being rewarded at random. However, we found no evidence that cockatoos could carve L-shaped pieces after learning that L-shaped templates were rewarded, though their manufactured strips were wider than in previous tests. Overall, our results show that Goffin cockatoos possess the ability to physically adjust at least the size dimension of manufactured objects relative to a mental template. This ability has previously only been shown in New Caledonian crows, where template matching was suggested as a potential mechanism allowing for the cumulative cultural transmission of tool designs. Our results show that within avian tool users, the ability to recreate a physical template from memory does not seem to be restricted to species that have cumulative tool cultures.

Exploring the role of individual learning in animal tool-use

The notion that tool-use is unique to humans has long been refuted by the growing number of observations of animals using tools across various contexts. Yet, the mechanisms behind the emergence and sustenance of these tool-use repertoires are still heavily debated. We argue that the current animal behaviour literature is biased towards a social learning approach, in which animal, and in particular primate, tool-use repertoires are thought to require social learning mechanisms (copying variants of social learning are most often invoked). However, concrete evidence for a widespread dependency on social learning is still lacking. On the other hand, a growing body of observational and experimental data demonstrates that various animal species are capable of acquiring the forms of their tool-use behaviours via individual learning, with (non-copying) social learning regulating the frequencies of the behavioural forms within (and, indirectly, between) groups. As a first outline of the extent of the role of individual learning in animal tool-use, a literature review of reports of the spontaneous acquisition of animal tool-use behaviours was carried out across observational and experimental studies. The results of this review suggest that perhaps due to the pervasive focus on social learning in the literature, accounts of the individual learning of tool-use forms by naïve animals may have been largely overlooked, and their importance under-examined.

Macphail’s Null Hypothesis of Vertebrate Intelligence: Insights From Avian Cognition

Macphail famously criticized two foundational assumptions that underlie the evolutionary approach to comparative psychology: that there are differences in intelligence across species, and that intelligent behavior in animals is based on more than associative learning. Here, we provide evidence from recent work in avian cognition that supports both these assumptions: intelligence across species varies, and animals can perform intelligent behaviors that are not guided solely by associative learning mechanisms. Finally, we reflect on the limitations of comparative psychology that led to Macphail’s claims and suggest strategies researchers can use to make more advances in the field.

Decision-making flexibility in New Caledonian crows, young children and adult humans in a multi-dimensional tool-use task

The ability to make profitable decisions in natural foraging contexts may be influenced by an additional requirement of tool-use, due to increased levels of relational complexity and additional work-effort imposed by tool-use, compared with simply choosing between an immediate and delayed food item. We examined the flexibility for making the most profitable decisions in a multi-dimensional tool-use task, involving different apparatuses, tools and rewards of varying quality, in 3-5-year-old children, adult humans and tool-making New Caledonian crows (Corvus moneduloides). We also compared our results to previous studies on habitually tool-making orangutans (Pongo abelii) and non-tool-making Goffin's cockatoos (Cacatua goffiniana). Adult humans, cockatoos and crows, but not children and orangutans, did not select a tool when it was not necessary, which was the more profitable choice in this situation. Adult humans, orangutans and cockatoos, but not crows and children, were able to refrain from selecting non-functional tools. By contrast, the birds, but not the primates tested, struggled to attend to multiple variables-where two apparatuses, two tools and two reward qualities were presented simultaneously-without extended experience. These findings indicate: (1) in a similar manner to humans and orangutans, New Caledonian crows and Goffin's cockatoos can flexibly make profitable decisions in some decision-making tool-use tasks, though the birds may struggle when tasks become more complex; (2) children and orangutans may have a bias to use tools in situations where adults and other tool-making species do not.

Kea show three signatures of domain-general statistical inference

One key aspect of domain-general thought is the ability to integrate information across different cognitive domains. Here, we tested whether kea (Nestor notabilis) can use relative quantities when predicting sampling outcomes, and then integrate both physical information about the presence of a barrier, and social information about the biased sampling of an experimenter, into their predictions. Our results show that kea exhibit three signatures of statistical inference, and therefore can integrate knowledge across different cognitive domains to flexibly adjust their predictions of sampling events. This result provides evidence that true statistical inference is found outside of the great apes, and that aspects of domain-general thinking can convergently evolve in brains with a highly different structure from primates. This has important implications not only for our understanding of how intelligence evolves, but also for research focused on how to create artificial domain-general thought processes.

Self-control in crows, parrots and nonhuman primates

Self-control is critical for both humans and nonhuman animals because it underlies complex cognitive abilities, such as decision-making and future planning, enabling goal-directed behavior. For instance, it is positively associated with social competence and life success measures in humans. We present the first review of delay of gratification as a measure of self-control in nonhuman primates, corvids (crow family) and psittacines (parrot order): disparate groups that show comparable advanced cognitive abilities and similar socio-ecological factors. We compare delay of gratification performance and identify key issues and outstanding areas for future research, including finding the best measures and drivers of delayed gratification. Our review therefore contributes to our understanding of both delayed gratification as a measure of self-control and of complex cognition in animals. This article is categorized under: Cognitive Biology > Evolutionary Roots of Cognition Psychology > Comparative Psychology.

Extraction without tooling around — The first comprehensive description of the foraging- and socio-ecology of wild Goffin’s cockatoos (Cacatua goffiniana)

When tested under laboratory conditions, Goffin’s cockatoos (Cacatua goffiniana) demonstrate numerous sophisticated cognitive skills. Most importantly, this species has shown the ability to manufacture and use tools. However, little is known about the ecology of these cockatoos, endemic to the Tanimbar Islands in Indonesia. Here we provide first insights into the feeding- and socio-ecology of the wild Goffin’s cockatoos and propose potential links between their behaviour in natural settings and their advanced problem-solving capacities shown in captivity. Observational data suggests that Goffin’s cockatoos rely on a large variety of partially seasonal resources. Furthermore, several food types require different extraction techniques. These ecological and behavioural characteristics fall in line with current hypotheses regarding the evolution of complex cognition and innovativeness. We discuss how the efficiency of (extractive) foraging may preclude tool use in wild Goffin’s cockatoos, even though the corresponding cognitive and ecological prerequisites seem to be present.

Prospective but not retrospective tool selection in the Goffin’s cockatoo (Cacatua goffiniana)

The ability to select the necessary means for a familiar task while the task itself or the respective tools are out of sight suggests a rudimentary form of planning. Here we investigated if and how a non-specialized tool using bird, the Goffin’s cockatoo, can prospectively or retrospectively select the functional tool in a decision-making task featuring two different types of apparatuses and their corresponding tools. Each apparatus could only be employed with one specific type of tool. Either the apparatus was presented and occluded prior to the presentation of the tools (prospective condition) or the tools were presented and occluded prior to the presentation of the apparatus (retrospective condition). Our results suggest the birds can prospectively but not retrospectively select the correct tool, paralleling previous research in tool using apes, and indicate at least simple forms of prospective selection in the tool use of a species distantly related to primates.

Tool making cockatoos adjust the lengths but not the widths of their tools to function

The ability to innovatively use or even manufacture different tools depending on a current situation can be silhouetted against examples of stereotyped, inborn tool use/manufacture and is thus often associated to advanced cognitive processing. In this study we confronted non-specialized, yet innovative tool making birds, Goffin's cockatoos (Cacatua goffiniana), with an apparatus featuring an out-of-reach food reward that could be placed at different distances from a tool opening. Alternatively, the food stayed at a constant distance but the tool opening in the front of the apparatus had different diameters. We used a novel material for tool manufacture (cardboard) that demanded an incrementally increased manufacturing effort from the actor, depending on the length of the tool required. We found that our subjects used two strategies to succeed in this tasks: either by making carboard-stripe tools using the full length of the material sheets originally offered or by adjusting the lengths of their tools to different goal distances. Subjects also discarded cardboard stripes that were too short to reach the goal prior to use and discarded longer pieces when the goal was further away than when it was close. Nevertheless, likely due to morphological constraints, the birds failed to adjust the widths of their tools depending on the diameter of the tool opening.

Compound tool construction by New Caledonian crows

The construction of novel compound tools through assemblage of otherwise non-functional elements involves anticipation of the affordances of the tools to be built. Except for few observations in captive great apes, compound tool construction is unknown outside humans, and tool innovation appears late in human ontogeny. We report that habitually tool-using New Caledonian crows (Corvus moneduloides) can combine objects to construct novel compound tools. We presented 8 naïve crows with combinable elements too short to retrieve food targets. Four crows spontaneously combined elements to make functional tools, and did so conditionally on the position of food. One of them made 3- and 4-piece tools when required. In humans, individual innovation in compound tool construction is often claimed to be evolutionarily and mechanistically related to planning, complex task coordination, executive control, and even language. Our results are not accountable by direct reinforcement learning but corroborate that these crows possess highly flexible abilities that allow them to solve novel problems rapidly. The underlying cognitive processes however remain opaque for now. They probably include the species' typical propensity to use tools, their ability to judge affordances that make some objects usable as tools, and an ability to innovate perhaps through virtual, cognitive simulations.

Habitual tool use innovated by free-living New Zealand kea

The emergence of flexible tool use is rare in the animal kingdom and thought to be largely constrained by either cognitive ability or ecological factors. That mostly birds with a high level of intelligence innovate tool use in captivity is consistent with the former hypothesis. We report here the first documented case of habitual tool use innovated in the wild by a bird species only known to have used tools in captivity. Trap-boxes containing food-bait and snap-trap(s) were installed in the remote Murchison Mountains, New Zealand, from 2002 to catch introduced stoats. Kea tampered with the trap-boxes in various ways. Over approximately 2.5 years, sticks were found inserted into at least 227 different trap-boxes that were up to 27 km apart. Video footage confirmed that the stick insertion was kea tool use. Trap-boxes are unlikely to have provided the only possibility for kea tool use in their habitat given their extractive foraging and skilled object manipulation. We argue that they instead greatly facilitated the opportunity for tool use, thus increasing the chance that kea would invent the behaviour. The innovation of tool use by kea in response to facilitation provides rare field support for the cognitive constraints hypothesis.

Within-group relationships and lack of social enhancement during object manipulation in captive Goffin's cockatoos (Cacatua goffiniana)

Different types of social relationships can influence individual learning strategies in structured groups of animals. Studies on a number of avian species have suggested that local and/or stimulus enhancement are important ingredients of the respective species’ exploration modes. Our aim was to identify the role of enhancement during object manipulation in different social contexts. We used focal observations to identify a linear dominance hierarchy as well as affiliative relationships between individuals in a group of 14 Goffin’s cockatoos (Cacatua goffiniana, formerly goffini). Thereafter, in an unrewarded object choice task, several pairs of subjects were tested for a possible influence of social enhancement (local vs. stimulus) in three conditions: dominance, affiliation, and kinship. Our results suggest strong individual biases. Whereas previous studies on ravens and kea had indicated that enhancement in a non-food-related task was influenced by the social relationship between a demonstrator and an observer (affiliated – nonaffiliated), we found no such effects in our study group. In this context, Goffin’s cockatoos’ object learning seems to take place more on an individual level, despite their generally high motivation to manipulate nonfood items.

Serial reversal learning and cognitive flexibility in two species of Neotropical parrots (Diopsittaca nobilis and Pionites melanocephala)

Serial reversal learning of colour discriminations was assessed as an index of cognitive flexibility in two captive species of Neotropical parrots. Both species showed similar performances across serial reversals and no between species differences were observed. In a second task subjects' performances were assessed after they experienced either a low or high pre-reversal learning criterion. If reversal performances improve through processes of associative learning, a high pre-reversal criterion is expected to strengthen previously learned associations and hence impede post-reversal performances. Conversely, highly reinforced associations may facilitate the use of conditional rules that can be generalised across reversals and improve post-reversal performances. We found that high criterion subjects made fewer post-reversal errors and required fewer trials to reach criterion, than low criterion subjects. Red-shouldered macaws and black-headed caiques may therefore demonstrate capacities for solving serial reversal problems by applying conditional rules, rather than learning solely by associative processes. Such performances coincide with findings in great apes, but contrast with findings in monkeys and prosimians, which generally show impaired reversal performances when trained to a highly rigorous pre-reversal criterion. Overall, these findings suggest an evolutionary convergence of cognitive flexibility between parrots and non-human great apes.

The keybox: Shape-frame fitting during tool use in Goffin's cockatoos (Cacatua goffiniana)

The ability to move an object in alignment to a surface develops early in human ontogeny. However, aligning not just your own body but also the object itself in relation to a surface with a specific shape requires using landmarks rather than the own body as a frame of reference for orientation. The ability to do so is considered important in the development of tool use behaviour in human and non-human animals. Aside from humans, with the exception of a single study on habitually tool using primates, shape-frame matching abilities remain largely unstudied. The Goffin's cockatoo is a generalist parrot, and not a specialised tool user but has shown the capacity to innovate and use different types of tools under controlled settings. We tested these parrots in a tool selection and tool use task featuring objects and their corresponding substrate grooves in a number of shapes with different levels of symmetry. Subjects had to choose the correct 'key' to insert into a box, and align its shape to fit into the corresponding 'keyhole' in the box. The parrots were able to select the correct key above chance level from early on in the experiment. Despite their lack of hands, they required fewer placement attempts than primates to insert simple object shapes into corresponding grooves. For complex shapes, they reduced their insertion effort by rotating shapes in their beak while avoiding as many protrusions as possible. Unrewarded play experience with similar object shapes was provided to some of the subjects previously to testing, but did not seem to have an effect on the number of correct choices or on insertion effort.

Goffin's cockatoos make the same tool type from different materials

Innovative tool manufacture is rare and hard to isolate in animals. We show that an Indonesian generalist parrot, the Goffin's cockatoo, can flexibly and spontaneously transfer the manufacture of stick-type tools across three different materials. Each material required different manipulation patterns, including substrates that required active sculpting for achieving a functional, elongated shape.

Can hook-bending be let off the hook? Bending/unbending of pliant tools by cockatoos

The spontaneous crafting of hook-tools from bendable material to lift a basket out of a vertical tube in corvids has widely been used as one of the prime examples of animal tool innovation. However, it was recently suggested that the animals' solution was hardly innovative but strongly influenced by predispositions from habitual tool use and nest building. We tested Goffin's cockatoo, which is neither a specialized tool user nor a nest builder, on a similar task set-up. Three birds individually learned to bend hook tools from straight wire to retrieve food from vertical tubes and four subjects unbent wire to retrieve food from horizontal tubes. Pre-experience with ready-made hooks had some effect but was not necessary for success. Our results indicate that the ability to represent and manufacture tools according to a current need does not require genetically hardwired behavioural routines, but can indeed arise innovatively from domain general cognitive processing.

Function and flexibility of object exploration in kea and New Caledonian crows

A range of non-human animals frequently manipulate and explore objects in their environment, which may enable them to learn about physical properties and potentially form more abstract concepts of properties such as weight and rigidity. Whether animals can apply the information learned during their exploration to solve novel problems, however, and whether they actually change their exploratory behaviour to seek functional information about objects have not been fully explored. We allowed kea (Nestor notabilis) and New Caledonian crows (Corvus moneduloides) to explore sets of novel objects both before and after encountering a task in which some of the objects could function as tools. Following this, subjects were given test trials in which they could choose among the objects they had explored to solve a tool-use task. Several individuals from both species performed above chance on these test trials, and only did so after exploring the objects, compared with a control experiment with no prior exploration phase. These results suggest that selection of functional tools may be guided by information acquired during exploration. Neither kea nor crows changed the duration or quality of their exploration after learning that the objects had a functional relevance, suggesting that birds do not adjust their behaviour to explicitly seek this information.