Animal Cognition最新文献

Scatter hoarding black-capped chickadees use memory to relocate hidden food, often after delays of hours or days. The ability of these birds to maintain accurate memories of the location and current status of many food caches while engaging in other distracting daily activities suggests that their memory may be especially resistant to competing cognitive load. We measured resistance to competing cognitive load during spatial memory tests in black-capped chickadees (Poecile atricapillus) and a non-caching species, dark-eyed juncos (Junco hyemalis). Birds were presented with two types of task. In the Discrimination task, birds learned by trial-and-error to select a target from among 2 distractors. In the Match-to-Sample task, birds viewed a sample which they had to remember in order to correctly select it from among two distractors at test. On two-thirds of trials, the tasks were presented Stand-Alone: after birds initiated a trial, they completed either a Discrimination or a Match-to-Sample task. The remaining trials were Concurrent causing a competing cognitive load: after birds intiated a trial, they saw the sample for the Match-to-Sample task, then completed a Discrimination during the retention interval, and finally completed a Match-to-Sample test. Competing cognitive load reduced accuracy of juncos significantly more than accuracy of chickadees. The need to encode and retain the locations of multiple food caches may have led to the evolution of enhanced cognitive control of memory in black-capped chickadees.

Corvids have long been a target of public fascination and of scientific attention, particularly in the study of animal minds. Using Birch et al.’s (2020) 5-dimensional framework for animal consciousness we ask what it is like to be a corvid and propose a speculative but empirically informed answer. We go on to suggest future directions for research on corvid consciousness and how it can inform ethical treatment and animal welfare legislation.

There have been shifts toward more systematic and standardized methods for studying non-human primate facial signals, thanks to advancements like animalFACS. Additionally, there have been calls to better integrate the study of both facial and gestural communication in terms of theory and methodology. However, few studies have taken this important integrative step. By doing so, researchers could gain greater insight into how the physical flexibility of facial signals affects social flexibility. Our study combines both approaches to examine the relationship between the flexibility of physical form and the social function of chimpanzee facial “gestures”. We used chimpFACS along with established gestural ethograms that provide insights into four key gesture properties and their associated variables documented in chimpanzee gestures. We specifically investigated how the combinatorics (i.e., the different combinations of facial muscle movements) and complexity (measured by the number of discrete facial muscle movements) of chimpanzee facial signals varied based on: (1) how many gesture variables they exhibit; (2) the presence of a specific goal; and (3) the context in which they were produced. Our findings indicate that facial signals produced with vocalizations exhibit fewer gesture variables, rarely align with specific goals, and exhibit reduced contextual flexibility. Furthermore, facial signals that include additional visual movements (such as those of the head) and other visual signals (like manual gestures) exhibit more gestural variables, are frequently aligned with specific goals, and exhibit greater contextual flexibility. Finally, we discovered that facial signals become more morphologically complex when they exhibit a greater number of gesture variables. Our findings indicate that facial “gesturing” significantly enhanced the facial signaling repertoire of chimpanzees, offering insights into the evolution of complex communication systems like human language.

The aim of this study was to investigate the ability of barn swallows (Hirundo rustica) to recognize humans. A field study was conducted in Caoyang Village, Zhanjiang City, Guangdong Province, South China. We assessed the responses of female barn swallows to the recognition of different types of human individuals by measuring their flight initiation distance (FID) when they incubated eggs in the nests. Our results demonstrated that barn swallows can identify the householder where their nest is located, displaying lower FID when the householder approaches, compared to an unfamiliar experimenter. Furthermore, there was no significant difference in FID between swallows reacting to householders who were rarely at home versus those who were frequently present, suggesting that barn swallows may possess the capability to recognize and retain memory of individual humans over time. Our findings provide evidence that barn swallows exhibit remarkable cognitive abilities. The long-standing symbiotic relationship between barn swallows and humans provides a unique model for studying the adaptation of species to environments with close human interactions. Research on their behavior and survival strategies can offer insights into the influence of symbiotic relationships on species adaptability and evolution.

Complex displays that comprise multiple behavioral elements play an essential role in the communication of group-living animals. One of them is a greeting display. Greeting is performed during the reunion after a separation, and is known for maintaining social bonds in mammals and pair bonds in monogamous fish. Greeting displays have been documented in birds, but lack functional studies. Java sparrows (Lonchura oryzivora) are gregarious and long-term monogamous songbird species, exhibiting a complex greeting display consisting of a sequence of four repetitive behavioral elements. We hypothesized that Java sparrow greetings function as between-pair communication in social contexts. In particular, we expected that pair-bonded partners would greet more after experiencing longer separation. In addition, we also predicted that they greet more when other conspecific individuals are nearby; as it is more important for them to confirm and advertise their commitment relationships. To test these ideas, we conducted separation-reunion tests using pair-bonded Java sparrows with different separation times (long vs. short) and different social conditions (with vs. without the presence of conspecifics). We calculated and compared the sequential complexity of the greeting displays. We showed that subject pairs performed a greater number of greeting display bouts after longer separation times. In the presence of conspecifics, greeting displays were more frequent, longer, and more complex. Our finding supports the idea that greeting displays in birds are crucial to pair-bond maintenance, contributing to understanding the evolution of complex communications in birds.

Many bees, butterflies, birds, bats and primates are known to forage on familiar plant resources by visiting them in a stable and repeatable order called “traplines”. Here we report the existence of trapline foraging in wasps, the Japanese yellow hornets. We monitored the movement patterns of wild individually marked hornets collecting sucrose solution on four artificial flowers placed in their home range. After thirty consecutive foraging bouts, all the hornets had developed a repeatable flower visitation sequence. Using two different arrays of flowers, we also show that hornets consistently increased their foraging efficiency with experience. However, they did not always use the shortest path to visit all the flowers, often favoring movements between nearest-neighbour options rather than minimizing overall travel distance. Our study thus adds nectar-foraging wasps to the list of animals that exhibit trapline foraging, thereby significantly broadening the scope for comparative research in multi-destination route learning and memory.

There have now been many reports of intra-colony differences in how individuals learn on a variety of conditioning tasks in both honey bees and bumble bees. Yet the fundamental mechanistic and adaptive bases for this variation have yet to be fully described. This review summarizes a long series of investigations with the honey bee (Apis mellifera) that had the objective of describing the factors that contribute to this variation. Selection on haploid drones for extremes in learning performance revealed that genotype accounted for much of the variance. Neither age nor behavioral caste consistently accounted for observed variation on different conditioning protocols until genotype was controlled. Two subsequent Quantitative Trait Locus mapping studies identified a locus in the honey bee genome with a significant effect on the learning phenotype. Pharmacological and reverse genetic approaches, combined with neurophysiological analyses, confirmed that a biogenic amine receptor for tyramine affects expression of the trait. This work allowed for development of a hypothetical model of how that receptor functions in the brain to produce broad pleiotropic effects on behavior. Subsequent work used genotype as a treatment condition for evaluation of the variation under quasi-natural conditions, which revealed that individual variation reflects how foragers weigh known and novel resources in decision making. This work, together with other studies of individual differences, suggests a unifying framework for understanding how and why individuals differ in cognitive abilities.

Domestic dogs (Canis familiaris) can recognize basic phonemic information from human speech and respond to commands. Commands are typically presented in isolation with exaggerated prosody known as dog-directed speech (DDS) register. Here, we investigate whether dogs can spontaneously identify meaningful phonemic content in a stream of putatively irrelevant speech spoken in monotonous prosody, without congruent prosodic cues. To test this ability, dogs were played recordings of their owners reading a meaningless text which included a short meaningful or meaningless phrase, either read with unchanged reading prosody or with an exaggerated DDS prosody. We measured the occurrence and duration of dogs’ gaze at their owners. We found that, while dogs were more likely to detect and respond to inclusions that contained meaningful phrases spoken with DDS prosody, they were still able to detect these meaningful inclusions spoken in a neutral reading prosody. Dogs detected and responded to meaningless control phrases in DDS as frequently as to meaningful content in neutral reading prosody, but less often than to meaningful content in DDS. This suggests that, while DDS prosody facilitates the detection of meaningful content in human speech by capturing dogs’ attention, dogs are nevertheless capable of spontaneously recognizing meaningful phonemic content within an unexaggerated stream of speech.

Research examining how cognitive traits evolve in the wild has focussed on finding evidence of the ‘Darwinian holy trinity’– consistent individual variation in cognitive performance that is linked to fitness and has a heritable component. In food-storing birds, there is growing evidence of selection for more accurate spatial memory performance. However, for selection to act on variation in spatial memory performance, it must also have a genetic component. In this study, we used Bayesian animal models to evaluate the heritability of memory performance in a spatial reference memory task in a population of wild toutouwai (North Island robin, Petroica longipes). We also estimated the heritability of variation in measures of the caching behaviour that spatial memory theoretically underpins. We found little evidence of heritability in either spatial memory performance or caching measures, as credible intervals were large with lower bounds close to zero. This result could suggest that individual variation in memory performance and caching behaviour may be primarily due to non-genetic factors. For example, variation in toutouwai spatial memory could be shaped largely by the cognitive demands of altering caching decisions in response to cache theft risk. In this scenario, the underlying mechanisms determining and linking spatial memory and caching behaviour would need to be reconsidered. Alternatively, the large credible intervals for our heritability estimates may be an artefact of small sample size. Therefore, to progress our understanding of how cognition evolves, it is crucial to establish long-term studies in the wild to collect cognitive performance data from as many individuals as possible over successive generations, with the goal of increasing the reliability of heritability estimates.

Detection dogs are trained using limited samples and then expected to generalize this ability to recognize wild samples while maintaining specificity to a target category. Such specificity is critical because dogs are often used to locate targets that are difficult to visually identify. Little is known about how to regain target specificity when false alerts become frequent or established. This case study assessed the training of two conservation dogs that alerted to off-target caracal (Caracal caracal) and leopard (Panthera pardus) scat samples during training to detect cheetah (Acinonyx jubatus) scat. The dogs were trained using an extinction-based differential reinforcement protocol consisting of the non delivery of reinforcement to reduce false alerts to caracal and leopard scats while maintaining sensitivity to cheetah scats. All training was conducted in situ in Samburu County, Kenya, by local handlers under the guidance of trainers. Sessions were filmed and coded for false alerts, true alerts, and where possible, misses and correct dismissals. Within four training sessions, both dogs exhibited an extinction burst demonstrated by an increase and then decrease in both the number and duration of false alerts. They continued to make fewer false alerts for the remainder of the training program. These results demonstrate the ability to reduce false alerts in operational detection dogs via extinction coupled with systematic reinforcement of desired behaviors. This case study highlights the importance of record-keeping and handling protocols for training samples. To our knowledge, this study represents the first publication on an extinction protocol to reduce false alerts in detection dogs.