One of the core features of human speech is that words cause listeners to retrieve corresponding visual mental images. However, whether vocalizations similarly evoke mental images in animal ...communication systems is surprisingly unknown. Japanese tits (Parus minor) produce specific alarm calls when and only when encountering a predatory snake. Here, I show that simply hearing these calls causes tits to become more visually perceptive to objects resembling snakes. During playback of snake-specific alarm calls, tits approach a wooden stick being moved in a snake-like fashion. However, tits do not respond to the same stick when hearing other call types or if the stick’s movement is dissimilar to that of a snake. Thus, before detecting a real snake, tits retrieve its visual image from snake-specific alarm calls and use this to search out snakes. This study provides evidence for a call-evoked visual search image in a nonhuman animal, offering a paradigm to explore the cognitive basis for animal vocal communication in the wild.
Many animals use variation in their alarm calls to warn conspecifics about different predatory threats. Information about predators can be encoded by producing discrete types of alarm calls and/or ...through graded variation in a single call type (i.e. calling rate or note repetitions). Another way to encode predator information is to combine different types of calls or notes into longer structured sequences. However, few studies have examined how individuals use discrete, graded and combinatorial variation in alarm calls to denote specific risks. I investigated the acoustic structure and information content of alarm calls in Japanese great tits, Parus major minor, by exposing their nests to three predator species (snakes, crows and martens) and a nonpredator species (doves). Great tits produced acoustically discrete alarm calls for the different nest predators: ‘jar’ calls for snakes and ‘chicka’ calls for crows and martens. The adults further discriminated between crows and martens by altering the calling rate and note number of the ‘chicka’ calls. A total of 175 types of note combinations were observed in the ‘chicka’ calls, and the tits used these combination types differently for the crows and martens. These results provide the first demonstration that birds can encode information about predator type by using production specificity, graded features and note combinations of discrete alarm calls. Previous studies have shown that parent and nestling Japanese great tits can respond in different, adaptive ways to discrete alarm calls. However, further playback studies are required to determine whether and how conspecifics can extract predator information from graded and combinatorial variation in alarm calls.
•I investigated alarm calls of Japanese great tits for different nest predators.•Great tits produced ‘jar’ calls for snakes, ‘chicka’ calls for crows and martens.•The number of notes in ‘chicka’ calls varied between crows and martens.•The note combination types of ‘chicka’ calls varied between crows and martens.
Human language can express limitless meanings from a finite set of words based on combinatorial rules (i.e., compositional syntax). Although animal vocalizations may be comprised of different basic ...elements (notes), it remains unknown whether compositional syntax has also evolved in animals. Here we report the first experimental evidence for compositional syntax in a wild animal species, the Japanese great tit (Parus minor). Tits have over ten different notes in their vocal repertoire and use them either solely or in combination with other notes. Experiments reveal that receivers extract different meanings from 'ABC' (scan for danger) and 'D' notes (approach the caller), and a compound meaning from 'ABC-D' combinations. However, receivers rarely scan and approach when note ordering is artificially reversed ('D-ABC'). Thus, compositional syntax is not unique to human language but may have evolved independently in animals as one of the basic mechanisms of information transmission.
Many animals produce vocal alarm signals when they detect a predator, and heterospecific species sharing predators often eavesdrop on and respond to these calls 1. Despite the widespread occurrence ...of interspecific eavesdropping in animals, its underlying cognitive process remains to be elucidated. If alarm calls, like human referential words, denote a specific predator type (e.g., “snake!”), then receivers may retrieve a mental image of the predator when hearing these calls 2–4. Here, using a recently developed experimental paradigm 5, I test whether heterospecific alarm calls evoke a predator-specific visual search image in wild birds. During playback of snake-specific alarm calls produced by Japanese tits (Parus minor), coal tits (Periparus ater) approach a wooden stick being moved in a snake-like manner. However, coal tits do not approach the same stick when hearing other call types or if the stick’s movement is dissimilar to that of a snake. Thus, Japanese tit snake alarms cause coal tits to specifically enhance visual attention to snakelike objects. These results provide experimental evidence for the evocation of visual search images by heterospecific alarm calls, highlighting the importance of integrating cross-modal information in interspecific eavesdropping.
Display omitted
•Many animals eavesdrop on and respond to alarm calls produced by other species•I tested if other species’ alarm calls evoke a search image of a predator in birds•Coal tits approached snake-like objects when hearing Japanese tit snake alarm calls•Other species’ alarm calls can evoke a visual search image of a specific predator
Eavesdropping on other species’ alarm calls is widespread in animals, but its underlying cognitive process is unclear. Suzuki shows that a wild bird species enhances visual attention to snake-like objects when hearing snake-specific alarm calls of other species, providing evidence for call-evoked visual search images in interspecific eavesdropping.
Syntax is the set of rules for combining words into phrases, providing the basis for the generative power of linguistic expressions. In human language, the principle of compositionality governs how ...words are combined into a larger unit, the meaning of which depends on both the meanings of the words and the way in which they are combined. This linguistic capability, i.e., compositional syntax, has long been considered a trait unique to human language. Here, we review recent studies on call combinations in a passerine bird, the Japanese tit (Parus minor), that provide the first firm evidence for compositional syntax in a nonhuman animal. While it has been suggested that the findings of these studies fail to provide evidence for compositionality in Japanese tits, this criticism is based on misunderstanding of experimental design, misrepresentation of the importance of word order in human syntax, and necessitating linguistic capabilities beyond those given by the standard definition of compositionality. We argue that research on avian call combinations has provided the first steps in elucidating how compositional expressions could have emerged in animal communication systems.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Animal communication signals can contain surprisingly complex information, which plays a vital role in a variety of social interactions. For example, many species of birds and mammals produce vocal ...alarm signals when encountering a predator 1,2, and these calls often serve to communicate the type of predator and/or the degree of danger to members of a social group 3–5. Similarly, signals used in parent–offspring interactions can encode sophisticated information such as the type and immediacy of threat to the offspring 6–8. Here, I show that differential use of parental alarm calls in great tits (Parus major) functions to elicit different predator-avoidance behaviors in altricial nestlings: great tit parents produce acoustically distinctive alarm calls for the two main nest predators, the jungle crow (Corvus macrorhynchos) and the Japanese rat snake (Elaphe climacophora). Nestlings crouched down inside their nest cavity in response to alarm calls given for a crow, while they fled the cavity in response to alarm calls given for a snake. The two responses help nestlings to selectively evade those predators, because crows snatch nestlings from the nest entrance, whereas snakes invade the nest cavity. While chicks of some species have been shown to recognize and respond appropriately to parental alarm calls 7–10, the present findings demonstrate that nest predation by multiple predator species can drive evolution of complex parent–offspring communication in altricial species.
What do animal signals mean? This is a central question in studies on animal communication. Research into the semantics of animal signals began in 1980, with evidence that alarm calls of a non-human ...primate designated predators as external referents. These studies have challenged the historical assumption that such referential signaling is a unique feature of human language and produced a paradigm shift in animal communication research. Over the past two decades, an increasing number of field studies have revealed similar complexity in anti-predator communication of birds. The acoustic structures of avian alarm calls show a high degree of variation in pitch, duration, shape, and repetition rate. In addition to such distinct and graded variations, several birds combine discrete types of notes or calls into higher complex sequences. These variations in alarm calls are typically associated with the predator’s attributes, such as predator type and distance, and receivers respond to them with appropriate anti-predator behaviors. Although alarm calls of several bird species, as well as those of monkeys, appear to denote predator attributes, almost nothing is known about the cognitive processes that underlie the production and perception of these signals. In this review, I explore the existing evidence for referential signaling in birds and highlight the importance of the cognitive approach to animal communication research. I hope this review will promote further investigations of alarm-calling behavior in birds and will help enhance our understanding of the ecology and evolution of semantic communication.
Parents of many bird species produce alarm calls when they approach and deter a nest predator in order to defend their offspring. Alarm calls have been shown to warn nestlings about predatory ...threats, but parents also face a similar risk of predation when incubating eggs in their nests. Here, I show that incubating female Japanese great tits, Parus minor, assess predation risk by conspecific alarm calls given outside the nest cavity. Tits produce acoustically discrete alarm calls for different nest predators: "jar" calls for snakes and "chicka" calls for other predators such as crows and martens. Playback experiments revealed that incubating females responded to "jar" calls by leaving their nest, whereas they responded to "chicka" calls by looking out of the nest entrance. Since snakes invade the nest cavity, escaping from the nest helps females avoid snake predation. In contrast, "chicka" calls are used for a variety of predator types, and therefore, looking out of the nest entrance helps females gather information about the type and location of approaching predators. These results show that incubating females derive information about predator type from different types of alarm calls, providing a novel example of functionally referential communication.
The ‘after you’ gesture in a bird Suzuki, Toshitaka N.; Sugita, Norimasa
Current biology,
03/2024, Letnik:
34, Številka:
6
Journal Article
Recenzirano
Gestures are ubiquitous in human communication, involving movements of body parts produced for a variety of purposes, such as pointing out objects (deictic gestures) or conveying messages (symbolic ...gestures)1. While displays of body parts have been described in many animals2, their functional similarity to human gestures has primarily been explored in great apes3,4, with little research attention given to other animal groups. To date, only a few studies have provided evidence for deictic gestures in birds and fish5,6,7, but it is unclear whether non-primate animals can employ symbolic gestures, such as waving to mean ‘goodbye’, which are, in humans, more cognitively demanding than deictic gestures1. Here, we report that the Japanese tit (Parus minor), a socially monogamous bird, uses wing-fluttering to prompt their mated partner to enter the nest first, and that wing-fluttering functions as a symbolic gesture conveying a specific message (‘after you’). Our findings encourage further research on animal gestures, which may help in understanding the evolution of complex communication, including language.
Suzuki et al. show that a wild bird species uses wing movements as a gesture to prompt their mate to enter the nest cavity first. This discovery challenges the notion that gestures are exclusive to humans and great apes, opening new avenues for exploring the meanings of visual displays in a range of animal taxa.
The generative power of human language depends on grammatical rules, such as word ordering, that allow us to produce and comprehend even novel combinations of words 1–3. Several species of birds and ...mammals produce sequences of calls 4–6, and, like words in human sentences, their order may influence receiver responses 7. However, it is unknown whether animals use call ordering to extract meaning from truly novel sequences. Here, we use a novel experimental approach to test this in a wild bird species, the Japanese tit (Parus minor). Japanese tits are attracted to mobbing a predator when they hear conspecific alert and recruitment calls ordered as alert-recruitment sequences 7. They also approach in response to recruitment calls of heterospecific individuals in mixed-species flocks 8, 9. Using experimental playbacks, we assess their responses to artificial sequences in which their own alert calls are combined into different orderings with heterospecific recruitment calls. We find that Japanese tits respond similarly to mixed-species alert-recruitment call sequences and to their own alert-recruitment sequences. Importantly, however, tits rarely respond to mixed-species sequences in which the call order is reversed. Thus, Japanese tits extract a compound meaning from novel call sequences using an ordering rule. These results demonstrate a new parallel between animal communication systems and human language, opening new avenues for exploring the evolution of ordering rules and compositionality in animal vocal sequences.
Display omitted
•Grammatical rules allow us to produce and understand novel combinations of words•Japanese tits discriminate between different orderings of novel call sequences•Japanese tits extract a compound meaning when sequences follow a specific ordering•Compositional expressions can be driven by ordering rules in non-human animals
Japanese tits often combine different calls into ordered sequences to generate compound messages. Suzuki et al. show experimentally that this bird species uses an ordering rule when responding to truly novel vocal sequences, demonstrating that this communicative capacity is not unique to humans but has also evolved in animal communication systems.
PDF
