Spontaneous tempo production in cockatiels (Nymphicus hollandicus) and jungle crows (Corvus macrorhynchos).

Musical and rhythmical abilities are poorly documented in non-human animals. Most of the existing studies focused on synchronisation performances to external rhythms. In humans, studies demonstrated that rhythmical processing (e. g. rhythm discrimination or synchronisation to external rhythm) is dependent of an individual measure: the individual tempo. It is assessed by asking participants to produce an endogenous isochronous rhythm (known as spontaneous motor tempo) without any specific instructions nor temporal cue. In non-human animal literature, studies describing spontaneous and endogenous production of motor tempo without any temporal clue are rare. This exploratory study aims to describe and compare the spontaneous motor tempo of cockatiels and jungle crows. Data were collected on spontaneous beak drumming behaviours of birds housed in laboratory. Inter beak strokes intervals were calculated from sound tracks of videos. The analyses revealed that inter beak strokes intervals are non-randomly distributed intervals and are isochronous. Recorded spontaneous motor tempos are significantly different among some cockatiels. Since we could only conduct statistical analysis with one corvid, we cannot conclude about this species. Our results suggest that cockatiels and jungle crows have individual tempos, thus encouraging further investigations.

Family first! Influence of parental investment in Guinea pigs (Cavia porcellus) prosocial choices.

Literature often assumed that prosocial behaviours (behaviours that benefit others with or without a cost for the actor) would have evolved many species to improve the effectiveness of parental care (Decety and Cowell 2014). While this hypothesis is rarely questioned at a phylogenetic scale, it was never tested at an individual scale to the best of our knowledge. Therefore, we chose to study the impact of effective parental care on prosociality by comparing the prosocial tendencies of Guinea pigs before mating, during mating and after parturition. We conducted Prosocial Choice Tests on three groups of Guinea pigs (males, multiparous females, and nulliparous females). Subjects had to choose between three options: a prosocial option (subject and recipient being rewarded), a selfish option (only subject was rewarded), and a null option (no reward). Our results showed high prosociality towards their mating partner and their young both in male and in female subjects. Males became selfish towards other males after parturition. Among other interesting results, we found a direct reciprocity phenomenon. We also highlighted an ability in our subjects to consider both the identity and relationship shared with the recipient, such as tolerance (enhancing prosociality), dominance rank (being tested with a dominant recipient increasing selfish responses), and its behaviour (begging calls eliciting prosociality, while threatening ones decreasing it), to choose an option. These findings suggested that prosociality could be modulated by many factors and that the constraints and stakes induced by breeding would highly influence prosocial strategies.

Prosociality and reciprocity according to parental status, communication, and personality in domestic canaries (Serinus canaria).

Prosociality (behaviours that benefit to a recipient without necessarily involving a cost to the actor) has recently been shown to exist in various taxa, including birds. Studies on prosociality in primates found that prosocial tendencies of the subject could be related to sex and parental care, communication from the recipient, cognitive abilities and personality. To investigate the existence of such associations on birds, we conducted a Prosocial Choice Task with domestic canaries (Serinus canaria). In our experiment, the subject could choose between three options: a prosocial, a selfish, and a null option (with no cost for the subject). We also conducted a food sharing experiment and measured several personality traits. Our results highlighted high levels of prosociality and a tendency to reciprocity among reproductive mates. We found a higher propensity to be prosocial in nulliparous individuals than in individuals that have previously been parents, but better sharing abilities in parents than in nulliparous individuals. When they were recipient, parents also used communication more efficiently than nulliparous subjects. Data suggest that parental expertise could enhance subjects' skills in eliciting prosociality. We also highlighted some interaction between prosociality, learning abilities, and some personality traits, proactive individuals being fast learners and more prosocial, while reactive individuals being slow learners and more reciprocal. Our results suggest that prosociality and reciprocity could be linked to personality and cognitive abilities, and that it might be interesting to consider them as parts of individual's cognitive style.

One Function One Tool? A Review on Mutual Exclusivity in Tool Use Learning in Human and Non-human Species.

The goal of this review is twofold: first to explore whether mutual exclusivity and functional fixedness overlap and what might be their respective specificities and second, to investigate whether mutual exclusivity as an inferential principle could be applied in other domains than language and whether it can be found in non-human species. In order to do that, we first give an overview of the representative studies of each phenomenon. We then analyze papers on tool use learning in children that studied or observed one of these phenomena. We argue that, despite their common principle -one tool one function- mutual exclusivity and functional fixedness are two distinct phenomena and need to be addressed separately in order to fully understand the mechanisms underlying social learning and cognition. In addition, mutual exclusivity appears to be applicable in other domains than language learning, namely tool use learning and is also found in non-human species when learning symbols and tools.

Prosociality and reciprocity in capybaras (Hydrochoerus hydrochaeris) in a non-reproductive context.

Prosocial behaviours (providing benefits to a recipient with or without cost for the donor) have been found to be highly influenced by sex and by hierarchy. Rodents, in particular, are good model for studying prosocial responses, as they were found to exhibit intentional prosocial behaviours to reward a conspecific, and are very sensitive to reciprocity. In our study, we conducted a Prosocial Choice Test (PCT) in which four capybaras (Hydrochoerus hydrochaeris) living in a social group could choose between three tokens: choosing the prosocial token rewarded simultaneously the subject and a recipient, while choosing the selfish token only rewarded the subject; and choosing the null token provided no reward to anyone. Dominance within each dyad was also studied, both before and during the PCT experiment. Our results showed an influence of hierarchy: subjects were more prosocial towards the recipient when it was a subordinate than when it was a dominant individual. These results could be interpreted as a desire of strengthening a hierarchical rank regarding the subordinate, of punishing aggressive conspecifics (usually the subject's direct dominant), and of weakening dominant individuals in order to modify the pre-existing hierarchy. Additionally, our results highlighted a direct reciprocity phenomenon, a subject being more likely to be prosocial towards a prosocial recipient. All these findings suggest that prosociality could be well developed in other taxa than Primates and that, in long enough PCT experiments, subtle rules could influence individual prosocial strategies.

Prosociality and reciprocity in bottlenose dolphins (Tursiops truncatus).

Some moral behaviours, often regarded as reflecting high cognitive abilities (such as empathy, cooperation, targeted helping) are known to only be present in very few species, like great apes, elephants and cetaceans. Prosocial behaviours (producing a benefit for the recipient without necessarily involving a cost for the actor) have been mostly found in primates and, more recently, in elephants. Despite dolphins' reputation for helping their conspecifics, experimental studies about their prosocial and empathic abilities are rare. We conducted Prosocial Choice Tests in six bottlenose dolphins. The subjects had to choose between three objects: choosing the prosocial object induced the simultaneous rewarding of both the subject and a recipient individual; choosing the selfish object induced a reward only for the subject; choosing the null one did not reward anyone. We found prosociality and direct reciprocity in our subjects, and our results suggested that bottlenose dolphins might be able to modulate their prosocial and reciprocal tendencies according to partner-specific information. Subjects seemed to be more prosocial towards the other sex and more reciprocal towards same-sex recipients. This reciprocity might be underpinned by the same features that rule their behaviours in the wild (cooperating with same sex conspecifics). Moreover, an audience effect was reported, as the presence of the subject's young increased subjects' likelihood of prosocial response. Our findings highlighted that prosociality could appear in taxa other than primates, suggesting a convergent evolutionary phenomenon.

Emotional responses to conspecific distress calls are modulated by affiliation in cockatiels (Nymphicus hollandicus).

Vocal communication is used across the animal kingdom to transfer information from emitters to receivers, such as size, sex, age, dominance status or even emotional states. The transmission of an emotional state from one individual to another is called "emotional contagion" and is classified as the first level of empathy. Emotional contagion is thought to be stronger between familiar individuals. While affiliation represents a stronger relation between individuals than mere familiarity, it remains understudied whether affiliation modulates emotional reactions as well. Using cockatiels (Nymphicus hollandicus), we played back three types of audio stimuli to individual birds: a partner's distress call (emitted when birds are caught or forcibly restrained), a non-partner's distress call, and a control sound (white noise). The calls were recorded from familiar birds with either low (non-partners) or high levels of affiliation (partners). The subjects' response was scored using four behavioural parameters: the time spent near the loudspeaker, the amount of movements, the number of calls emitted, and the position of the crest. Across all variables, birds were more attentive and active when confronted to distress calls compared to control sounds, particularly when the distress call was emitted from a partner rather than a non-partner. These results raise the possibility that distress calls do not only function as a stimulus-triggering automatic reaction in cockatiels but also transmit emotions. Moreover, affiliation enhanced emotional reactions to conspecific distress calls. Our data provides first insights into the mechanisms of emotional contagion in parrots.

Individual differences in exploratory activity relate to cognitive judgement bias in carpenter ants.

Emotional state may influence cognitive processes such as attention and decision-making. A cognitive judgement bias is the propensity to anticipate either positive or negative consequences in response to ambiguous information. Recent work, mainly on vertebrates, showed that the response to ambiguous stimuli might change depending on an individual's affective state, which is influenced by e.g. the social and physical environment. However, the response to ambiguous stimuli could also be affected by the individual's behavioural type (personality), a question that has been under-investigated. We studied the link between individual differences in exploratory activity and the response to an ambiguous stimulus in the ant Camponotus aethiops. Exploratory behaviour, quantified with an open-field test, was variable among individuals but consistent over time within individuals. Individual ants learned to associate a spatial position to a reinforcement and another spatial position to a punishment. Once the ants had acquired this discrimination, cognitive judgement bias was tested with the stimulus in an intermediate position. Fast explorers in the open-field took significantly more time to approach the ambiguous stimulus compared to slow explorers, suggesting a negative judgement bias for fast explorers and a positive bias for slow explorers. This previously unknown link between individual difference in exploratory activity and cognitive bias in a social insect may help understanding the evolution and organization of social life.

You know what? I'm happy. Cognitive bias is not related to personality but is induced by pair-housing in canaries (Serinus canaria).

Recent studies suggest that cognitive bias could constitute a novel and valid measure of animal welfare. Although interest for a link between personality and cognition is growing, no study to date investigated whether a cognitive bias might be related to the personality of the individuals. We trained 43 domestic canaries (Serinus canaria) to discriminate between two sides of a test cage, each side being associated with a different value (attractive or aversive food in a dish). During the test phase, the dish was placed at intermediate locations, representing ambiguous information. Results show evidence of an "optimistic" bias (flying faster to the dish at the ambiguous location) in birds housed in pairs, compared to birds housed singly, suggesting an influence of social context (living conditions) on canaries' emotions when tested individually. We also studied six traits of individuals' personality and found that aggressiveness, neophobia, one sociability index and obstinacy were repeatable across social context and/or day-light schedule, whereas the other sociability index, boldness and locomotion were not. No correlation between the birds' optimism and any of their personality traits was found, suggesting that cognitive bias may be a matter of social context rather than of individual personality.

The perception of self in birds.

The perception of self is an important topic in several disciplines such as ethology, behavioral ecology, psychology, developmental and cognitive neuroscience. Self-perception is investigated by experimentally exposing different species of animals to self-stimuli such as their own image, smell or vocalizations. Here we review more than one hundred studies using these methods in birds, a taxonomic group that exhibits a rich diversity regarding ecology and behavior. Exposure to self-image is the main method for studying self-recognition, while exposing birds to their own smell is generally used for the investigation of homing or odor-based kin discrimination. Self-produced vocalizations - especially in oscine songbirds - are used as stimuli for understanding the mechanisms of vocal coding/decoding both at the neural and at the behavioral levels. With this review, we highlight the necessity to study the perception of self in animals cross-modally and to consider the role of experience and development, aspects that can be easily monitored in captive populations of birds.

On Public Influence on People's Interactions with Ordinary Biodiversity.

Besides direct impacts of urban biodiversity on local ecosystem services, the contact of city dwellers with urban nature in their everyday life could increase their awareness on conservation issues. In this paper, we focused on a particularly common animal urban species, the feral pigeon Columba livia. Through an observational approach, we examined behavioral interactions between city dwellers and this species in the Paris metropolis, France. We found that most people (mean: 81%) do not interact with pigeons. Further, interactions (either positive or negative) are context and age-dependent: children interact more than adults and the elderly, while people in tourist spots interact more than people in urban parks or in railway stations, a result that suggests that people interacting with pigeons are mostly tourists. We discuss these results in terms of public normative pressures on city dwellers' access to and reconnection with urban nature. We call for caution in how urban species are publically portrayed and managed, given the importance of interactions with ordinary biodiversity for the fate of nature conservation.

Intentional gestural communication and discrimination of human attentional states in rhesus macaques (Macaca mulatta).

The present study tested intentionality of a learned begging gesture and attention-reading abilities in rhesus macaques (Macaca mulatta). Subjects were trained to produce a begging gesture towards a hidden food reward that could be delivered by a human experimenter. More specifically, we investigated which attentional cues--body, face and/or eyes orientation of a human partner--were taken into account by the macaques in order to communicate with her. Our results provide strong evidence of intentional communication: the monkeys adjusted their behaviour to that of the partner. The latter's attentional state influenced the monkeys' likelihood of performing begging gestures and showing gaze alternation between the partner and the hidden food. By contrast, we found no evidence of attention-getting behaviours, persistence or elaboration of new communicative behaviours. Our results also showed that rhesus macaques discriminated gross cues including the presence, body and face orientation of the human experimenter but not her eyes. However, the monkeys emitted more gaze alternation and monitored the human's attentional state more closely when she also displayed gaze alternation, suggesting an important role of joint attention in gestural communication.

Do Tonkean macaques (Macaca tonkeana) tailor their gestural and visual signals to fit the attentional states of a human partner?

We tested here whether Tonkean macaques (Macaca tonkeana), trained to produce a pointing gesture, modify their behaviour in response to different human's attentional states. More specifically, we investigated the macaque's ability to communicate intentionally about the location of an unreachable hidden food reward in several contexts which differ by the human partner's attentional state. The experimenter displayed seven attentional states differing on the basis of body, head and gaze orientation. Our study validates several criteria of an intentional communication. We showed that macaques produce more pointing gestures when an audience, i.e. the human partner, is present than absent. We also revealed an adjustment of gaze alternation between the face of the experimenter and the hidden food reward according to several experimental conditions. However, in our study, macaques did not produce auditory attention-getting behaviours when the human partner was inattentive. Finally, only rough cues, i.e. presence, body and face orientation of the observer, seem to be taken into account by macaques. However, our results also supposed the importance of joint attention for macaques since they display more gaze alternation when the head and/or eyes of the human partner are mobile.

Motivation and manipulation capacities of the blue and yellow macaw and the tufted capuchin: a comparative approach.

This study compared the motivation of the blue and yellow macaw (n=8) and the tufted capuchin (n=3) to manipulate objects that presented different features, their manipulative repertoires, and their ability to solve complex manipulation tasks. Results show that both species seem to be more motivated to manipulate objects that look like food items and that manipulative behavior may be considered as play behavior in the blue and yellow macaws, and would improve foraging motor skills. The tufted capuchins performed more different action styles than the macaws when manipulating objects, and performed substrate-use behavior - the object is put in relationship with a substrate - while the macaws did not. This is an interesting difference because these characteristics are supposed to be precursory of tool-use, behavior never observed in this macaw species. It may be due to the arboreal lifestyle of the macaw and its neophobic character that do not allow it to easily contact objects. Following the same method and using more individuals, further comparative studies should be conducted in order to test these hypotheses. Both species were able to solve complex manipulation tasks.

A study of sharing and reciprocity in grey parrots (Psittacus erithacus).

Demonstrations of nonhuman ability to share resources and reciprocate such sharing seem contingent upon the experimental paradigm used (note Horner et al. in PNAS 108:13847-13851, 2011). Here, such behaviour in Grey parrots (Psittacus erithacus) was tested in two experiments, both designed to avoid possible issues involving apparatus complexity, visible reward options, and physical competition and/or limited communication between subjects. In both studies, two birds, working in dyads, took turns in choosing one of four different coloured cups with differing outcomes: empty (null, nonrewarding), selfish (keeping reward for oneself), share (sharing a divisible reward), or giving (donating reward to other). In Experiment 1, each bird alternated choices with a conspecific; in Experiment 2, each bird alternated with the three humans with different specific intentions (selfish, giving, or copying bird's behaviour). In both experiments, birds could learn to cooperatively reward a partner at little cost to themselves-by sharing-and potentially maximize overall reward by reciprocating such sharing. Experiment 1 results differed depending upon which bird began a session: Only our dominant bird, as follower, was willing to share. In Experiment 2, birds' responses tended towards consistency with human behaviour. Our dominant bird was willing to share a reward with a human who was willing to give up her reward, was selfish with the selfish human, and tended towards sharing with the copycat human; our subordinate bird tended slightly towards increased sharing with the generous human and selfishness with the selfish human, but did not change behaviour with the copycat.

Training large macaws for artificial insemination procedures.

For some endangered parrot species, captive breeding may be the only insurance for their survival. However, many individuals in captivity do not reproduce. Artificial insemination (AI) may help overcome reproductive failures or geographic distance. For semen collection in birds, massage is the most commonly used method. However, this process, which usually requires capture and restraint, involves risk of stress and injuries. The aim of this experiment was to train large macaws to accept the physical manipulations of their body parts needed for the artificial insemination process. Within 15 weeks, a male and a female Buffon's macaw (Ara ambiguus) learned to accept handling without apparent stress. A pair of green-winged macaws (Ara chloropterus) progressed more slowly and displayed some signs of stress. This stress highlights the need to monitor the birds' possible signs of discomfort during the training in order to adapt the working protocol. These results demonstrate that it is possible to train the AI behaviors, thus avoiding the capture, restraint, and anesthesia. An added benefit to this is the potential for the training to provide a form of behavioral enrichment.

Pigeons discriminate between human feeders.

Considered as plague in many cities, pigeons in urban areas live close to human activities and exploit this proximity to find food which is often directly delivered by people. In this study, we explored the capacity of feral pigeons to take advantage of this human-based food resource and discriminate between friendly and hostile people. Our study was conducted in an urban park. Pigeons were fed by two experimenters of approximately the same age and skin colour but wearing coats of different colours. During the training sessions, the two human feeders displayed different attitudes: one of the feeders was neutral and the second was hostile and chased away the pigeons. During the two test phases subsequent to the training phase, both feeders became neutral. Two experiments were conducted, one with one male and one female feeder and the second with two female feeders. In both experiments, the pigeons learned to quickly (six to nine sessions) discriminate between the feeders and maintained this discrimination during the test phases. The pigeons avoided the hostile feeder even when the two feeders exchanged their coats, suggesting that they used stable individual characteristics to differentiate between the experimenter feeders. Thus, pigeons are able to learn quickly from their interactions with human feeders and use this knowledge to maximize the profitability of the urban environment. This study provides the first experimental evidence in feral pigeons for this level of human discrimination.

Finding good acoustic features for parrot vocalizations: the feature generation approach.

A crucial step in the understanding of vocal behavior of birds is to be able to classify calls in the repertoire into meaningful types. Methods developed to this aim are limited either because of human subjectivity or because of methodological issues. The present study investigated whether a feature generation system could categorize vocalizations of a bird species automatically and effectively. This procedure was applied to vocalizations of African gray parrots, known for their capacity to reproduce almost any sound of their environment. Outcomes of the feature generation approach agreed well with a much more labor-intensive process of a human expert classifying based on spectrographic representation, while clearly out-performing other automated methods. The method brings significant improvements in precision over commonly used bioacoustical analyses. As such, the method enlarges the scope of automated, acoustics-based sound classification.

Referential learning of French and Czech labels in African grey parrots (Psittacus erithacus): different methods yield contrasting results.

Some African grey parrots (Psittacus erithacus), the most famous being Pepperberg's parrot Alex, are able to imitate human speech and produce labels referentially. In this study, the aim was to teach ten African grey parrots from two laboratories to label items. Training three parrots from the first laboratory for several months with the Model/Rival method, developed by Pepperberg, in which two humans interact in front of the subject to demonstrate the use of a label, led to disappointing results. Similarly, seven parrots from the second laboratory, having been trained with several variants of Model/Rival attained little success. After the informal observation of the efficiency of other methods (i.e. learning to imitate labels either spontaneously or with specific learning methods and use of these labels referentially), four different teaching methods were tested with two birds: the Model/Rival; Repetition/Association which consisted of repeating a label and presenting the item only when the parrot produced the label; Intuitive in which the experimenter handled an item and repeated its name in front of the subject; Diffusion in which labels with either variable or flat intonation were played back daily to parrots. One bird learned three labels, one of which was used referentially, with the Repetition/Association method. He learned one label non-referentially with the Model/Rival but no labels were acquired using the other methods. The second bird did not learn any labels. This study demonstrates that different methods can be efficient to teach labels referentially and it suggests that rearing conditions and interindividual variability are important features when assessing learning ability of African grey parrots.

How do African grey parrots (Psittacus erithacus) perform on a delay of gratification task?

Humans and other animals often find it difficult to choose a delayed reward over an immediate one, even when the delay leads to increased pay-offs. Using a visible incremental reward procedure, we tested the ability of three grey parrots to maintain delay of gratification for an increasingly valuable food pay-off. Up to five sunflower seeds were placed within the parrot's reach, one at a time, at a rate of one seed per second. When the parrot took a seed the trial was ended and the birds consumed the accumulated seeds. Parrots were first tested in daily sessions of ten trials and then with single daily trials. For multiple trial sessions, all three parrots showed some limited improvement across 30 sessions. For single trial sessions, only one parrot showed any increase in seed acquisition across trials. This parrot was also able to consistently obtain two or more seeds per trial (across both multiple and single trial conditions) but was unable to able to wait 5 s to obtain the maximum number of seeds. This parrot was also tested on a slower rate of seed presentation, and this significantly reduced her mean seed acquisition in both multiple and single trial conditions, suggesting that both value of reward available and delay duration impact upon self-control. Further manipulation of both the visibility and proximity of seeds during delay maintenance had little impact upon tolerance of delays for both parrots tested in this condition. This task demanded not just a choice of delayed reward but the maintenance of delayed gratification and was clearly difficult for the parrots to learn; additional training or alternative paradigms are required to better understand the capacity for self-control in this and other species.