Lions (Panthera leo) solve, learn, and remember a novel resource acquisition problem

Long-term memory in wild falcons

Long-term memory - information retention over long timescales - can allow animals to retain foraging skills and efficiently respond to seasonally available resources and changing environments1. Most long-term memory research is with captive species, focusing on spatial, individual or object recognition, with less known about wild species and the retention of motor task abilities, as in the case of complex foraging skills2,3. We have examined whether wild striated caracaras (Phalcoboenus australis), recently shown to rapidly and flexibly innovate with an eight-task puzzle box4, retain task memories one year later. We found that, despite no reinforcement, caracaras repeated motor techniques that led to their most recent success on tasks the year prior, solving nearly twice as fast as a naïve control group and four times faster than when naïve. Our results suggest long-term memory may be important for non-migratory opportunistic generalists, particularly in remote island environments with seasonally available resources, and further highlight how striated caracaras are promising candidates for avian cognitive studies.

Cooperation increases bottlenose dolphins' (Tursiops truncatus) social affiliation

Dolphins live in a fission-fusion society, where strong social bonds and alliances can last for decades. However, the mechanism that allows dolphins to form such strong social bonds is still unclear. Here, we hypothesized the existence of a positive feedback mechanism in which social affiliation promotes dolphins' cooperation, which in turn promotes their social affiliation. To test it, we stimulated the cooperation of the 11 dolphins studied by providing a cooperative enrichment tool based on a rope-pulling task to access a resource. Then we measured the social affiliation [simple ratio index (SRI)] of each possible pair of dolphins and evaluated whether it increased after cooperation. We also evaluated whether, before cooperation, pairs that cooperated had a higher SRI than those that did not cooperate. Our findings showed that the 11 cooperating pairs had significantly stronger social affiliation before cooperation than the 15 non-cooperating pairs. Furthermore, cooperating pairs significantly increased their social affiliation after cooperation, while non-cooperating pairs did not. As a result, our findings provide support to our hypothesis, and suggest that the previous social affiliation between dolphins facilitates cooperation, which in turn promotes their social affiliation.

The current state of carnivore cognition

The field of animal cognition has advanced rapidly in the last 25 years. Through careful and creative studies of animals in captivity and in the wild, we have gained critical insights into the evolution of intelligence, the cognitive capacities of a diverse array of taxa, and the importance of ecological and social environments, as well as individual variation, in the expression of cognitive abilities. The field of animal cognition, however, is still being influenced by some historical tendencies. For example, primates and birds are still the majority of study species in the field of animal cognition. Studies of diverse taxa improve the generalizability of our results, are critical for testing evolutionary hypotheses, and open new paths for understanding cognition in species with vastly different morphologies. In this paper, we review the current state of knowledge of cognition in mammalian carnivores. We discuss the advantages of studying cognition in Carnivorans and the immense progress that has been made across many cognitive domains in both lab and field studies of carnivores. We also discuss the current constraints that are associated with studying carnivores. Finally, we explore new directions for future research in studies of carnivore cognition.

Both age and experience are important for successful problem solving in juvenile fawn-footed mosaic-tailed rats Melomys cervinipes

Problem solving ability is affected by many factors, including physiology, personality, and cognition. However, how age and experience influence problem-solving ability during development is harder to untangle. We tested how age and experience affected problem solving in a native Australian rodent, the fawn-footed mosaic-tailed rat Melomys cervinipes. Juveniles were divided into two groups (different ages at start of testing) and then received a food-baited cardboard matchbox every 10 days for a total of three tests. We compared the problem-solving ability of individuals from both groups, which allowed us to separate the effects of age and experience. Juveniles with more experience solved the task faster than juveniles with less experience. Furthermore, inexperienced older juveniles interacted with the problems more than inexperienced younger juveniles. Previous solving experience may be important for short-term solving success, while age, in the absence of experience, might be associated with increased exploration, leading to increased investigation of novel problems. Previous experience at manipulating objects generally may also be important for problem-solving success, which likely provides an advantage as resources and habitats change seasonally and annually.

Exploring innovative problem-solving in African lions (Panthera leo) and snow leopards (Panthera uncia)

Cognitive ability is likely linked to adaptive ability; animals use cognition to innovate and problem-solve in their physical and social environments. We investigated innovative problem-solving in two species of high conservation importance: African lions (Panthera leo; n = 6) and snow leopards (Panthera uncia; n = 9). We designed a custom multi-access puzzle box (MAB) to present a simple and effective behavioral test for the cats to explore. We measured Repeated Innovation, Persistence, Success, Contact Latency, and the Exploration Diversity of individuals interacting with the MAB. Of the six African lions, three (50%) solved one door to the box, one solved two doors (16.67%), and one solved three doors (16.67%). Of the nine snow leopards, one solved one door (11.11%), three solved two doors (33.33%), and none solved all three doors (0%). Persistence was a significant predictor of Success in African lions and snow leopards; more Persistent individuals were more likely to open a door. We also observed significant individual variation in Persistence for both species, but only snow leopards also exhibited differences in Contact Latency and Exploration Diversity. These results suggest individuals vary in their problem-solving approaches. Our findings support both species as successful, repeated innovators. Carnivores face ecological and social challenges and, presumably, benefit from cognitive abilities facilitating the successful navigation of these challenges in captivity and the wild.

Memory enhances problem solving in the fawn-footed mosaic-tailed rat Melomys cervinipes

Problem solving is important for survival, allowing animals to access novel food resources or escape from predators. It was originally thought to rely on an animal's intelligence; however, studies examining the relationship between individual cognitive ability and problem solving performance show mixed results, and studies are often restricted to only one cognitive and one problem solving task. We investigated the relationship between general cognitive ability and problem solving across multiple tasks in the fawn-footed mosaic-tailed rat Melomys cervinipes. We measured general cognitive ability across different domains (memory in an odour learning association task, recognition in a novel object recognition task, size discrimination using different sized pieces of food, and learning across multiple presentations of a food-baited activity board). We also measured problem solving across different contexts (food-baited puzzle boxes in home cage, obstruction task, and food-baited activity board in a novel arena). Mosaic-tailed rats showed a general cognitive ability, with average problem solving latency, memory ability, and learning in the tile task being correlated. As such, individuals that were able to remember an association and learned to solve the tile task solved the problems faster than individuals that could not remember or learn. Our results suggest that problem solving in mosaic-tailed rats likely relies on some forms of simple cognition, particularly memory, but could also depend on other traits, such as an individual's persistence.

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

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

Long-term memory for a learned behaviour in a wild bird

Long-term memory is a crucial adaptation for long-lived species. However, there have been few tests of the long-term retention of learned behaviours in free living, wild animals. Here, we demonstrate that the North Island robin (Petroica longipes; hereafter toutouwai) can recall a learned foraging behaviour for close to 2 years, with no intervening reinforcement. Birds that had been trained to peck open lids to retrieve a concealed food reward spontaneously solved a lid opening task between 10 and 22 months since they had last encountered the lid opening apparatus. By contrast, naive individuals could not solve the task. This long-term retention of a learned skill with no reinforcement, spanning over a quarter of the median age for wild toutouwai in our population, suggests that this threatened species may be an ideal candidate for conservation management strategies aimed at teaching individuals about novel threats and resources.

Innovation in a native Australian rodent, the fawn-footed mosaic-tailed rat (Melomys cervinipes)

Innovation is the ability to use a new behaviour, or use an existing behaviour in a new context. Innovation, as an aspect of behavioural flexibility, could be important for allowing animals to cope with rapid environmental changes. Surprisingly, few studies have focused on how innovation ability is affected by task complexity. We investigated innovation ability across multiple tasks of varying complexity in a native Australian rodent, the fawn-footed mosaic-tailed rat (Melomys cervinipes). We predicted that mosaic-tailed rats would be capable of innovating because they live in complex habitats and can exploit disturbed and changing environments. However, we also predicted that the success rate of innovating would decrease as task complexity increased. Mosaic-tailed rats were exposed to six novel problems: cylinder, matchbox, obstruction test, pillar, tile and lever (the last three presented in a Trixie dog activity board), which represented increasing complexity. We counted the number of individuals that could solve at least one task, compared individuals for solving efficiency and latency to solve, and compared the solving success of each task. All mosaic-tailed rats could innovate. However, solving success differed between individuals, with some solving every task and others only solving one. Solving success rate was significantly higher in the simplest task (pillar) compared to the most complicated task (lever). There was no effect of sex or sampling condition on innovation. This study is the first to demonstrate innovation ability across task complexity in an Australian rodent and provides promising avenues for future studies of innovation.

In what sense are dogs special? Canine cognition in comparative context

The great increase in the study of dog cognition in the current century has yielded insights into canine cognition in a variety of domains. In this review, we seek to place our enhanced understanding of canine cognition into context. We argue that in order to assess dog cognition, we need to regard dogs from three different perspectives: phylogenetically, as carnivoran and specifically a canid; ecologically, as social, cursorial hunters; and anthropogenically, as a domestic animal. A principled understanding of canine cognition should therefore involve comparing dogs' cognition with that of other carnivorans, other social hunters, and other domestic animals. This paper contrasts dog cognition with what is known about cognition in species that fit into these three categories, with a particular emphasis on wolves, cats, spotted hyenas, chimpanzees, dolphins, horses, and pigeons. We cover sensory cognition, physical cognition, spatial cognition, social cognition, and self-awareness. Although the comparisons are incomplete, because of the limited range of studies of some of the other relevant species, we conclude that dog cognition is influenced by the membership of all three of these groups, and taking all three groups into account, dog cognition does not look exceptional.

Proactive behavior, but not inhibitory control, predicts repeated innovation by spotted hyenas tested with a multi-access box

Innovation is widely linked to cognitive ability, brain size, and adaptation to novel conditions. However, successful innovation appears to be influenced by both cognitive factors, such as inhibitory control, and non-cognitive behavioral traits. We used a multi-access box (MAB) paradigm to measure repeated innovation, the number of unique innovations learned across trials, by 10 captive spotted hyenas (Crocuta crocuta). Spotted hyenas are highly innovative in captivity and also display striking variation in behavioral traits, making them good model organisms for examining the relationship between innovation and other behavioral traits. We measured persistence, motor diversity, motivation, activity, efficiency, inhibitory control, and neophobia demonstrated by hyenas while interacting with the MAB. We also independently assessed inhibitory control with a detour cylinder task. Most hyenas were able to solve the MAB at least once, but only four hyenas satisfied learning criteria for all four possible solutions. Interestingly, neither measure of inhibitory control predicted repeated innovation. Instead, repeated innovation was predicted by a proactive syndrome of behavioral traits that included high persistence, high motor diversity, high activity and low neophobia. Our results suggest that this proactive behavioral syndrome may be more important than inhibitory control for successful innovation with the MAB by members of this species.

How to stay perfect: the role of memory and behavioural traits in an experienced problem and a similar problem

When animals encounter a task they have solved previously, or the same problem appears in a different apparatus, how does memory, alongside behavioural traits such as persistence, selectivity and flexibility, enhance problem-solving efficiency? We examined this question by first presenting grey squirrels with a puzzle 22 months after their last experience of it (the recall task). Squirrels were then given the same problem presented in a physically different apparatus (the generalisation task) to test whether they would apply the previously learnt tactics to solve the same problem but in a different apparatus. The mean latency to success in the first trial of the recall task was significantly different from the first exposure but not different from the last exposure of the original task, showing retention of the task. A neophobia test in the generalisation task suggested squirrels perceived the different apparatus as a different problem, but they quickly came to apply the same effective tactics as before to solve the task. Greater selectivity (the proportion of effective behaviours) and flexibility (the rate of switching between tactics) both enhanced efficiency in the recall task, but only selectivity enhanced efficiency in the generalisation task. These results support the interaction between memory and behavioural traits in problem-solving, in particular memory of task-specific tactics that could enhance efficiency. Squirrels remembered and emitted task-effective tactics more than ineffective tactics. As a result, they consistently changed from ineffective to effective behaviours after failed attempts at problem-solving.

Big cats as a model system for the study of the evolution of intelligence

Currently, carnivores, and felids in particular, are vastly underrepresented in cognitive literature, despite being an ideal model system for tests of social and ecological intelligence hypotheses. Within Felidae, big cats (Panthera) are uniquely suited to studies investigating the evolutionary links between social, ecological, and cognitive complexity. Intelligence likely did not evolve in a unitary way but instead evolved as the result of mutually reinforcing feedback loops within the physical and social environments. The domain-specific social intelligence hypothesis proposes that social complexity drives only the evolution of cognitive abilities adapted only to social domains. The domain-general hypothesis proposes that the unique demands of social life serve as a bootstrap for the evolution of superior general cognition. Big cats are one of the few systems in which we can directly address conflicting predictions of the domain-general and domain-specific hypothesis by comparing cognition among closely related species that face roughly equivalent ecological complexity but vary considerably in social complexity.