The 'after you' gesture in a bird.

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). While displays of body parts have been described in many animals, their functional similarity to human gestures has primarily been explored in great apes, with little research attention given to other animal groups. To date, only a few studies have provided evidence for deictic gestures in birds and fish, 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 gestures.

Experimental evidence for core-Merge in the vocal communication system of a wild passerine.

One of the cognitive capacities underlying language is core-Merge, which allows senders to combine two words into a sequence and receivers to recognize it as a single unit. Recent field studies suggest intriguing parallels in non-human animals, e.g.

Other Species' Alarm Calls Evoke a Predator-Specific Search Image in Birds.

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.

The syntax-semantics interface in animal vocal communication.

Syntax (rules for combining words or elements) and semantics (meaning of expressions) are two pivotal features of human language, and interaction between them allows us to generate a limitless number of meaningful expressions. While both features were traditionally thought to be unique to human language, research over the past four decades has revealed intriguing parallels in animal communication systems. Many birds and mammals produce specific calls with distinct meanings, and some species combine multiple meaningful calls into syntactically ordered sequences.

Animal syntax.

Toshitaka Suzuki and Klaus Zuberbühler introduce the syntactical features found in the communication systems of non-human animals.

Imagery in wild birds: Retrieval of visual information from referential alarm calls.

Japanese tits (Parus minor) produce specific alarm calls when they encounter a predatory snake. A recent field experiment showed that receiver tits became visually perceptive to an object resembling a snake when hearing these calls. However, the tits did not respond to the same object when hearing other call types or when the object was dissimilar to a snake.

Call combinations in birds and the evolution of compositional syntax.

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.

Alarm calls evoke a visual search image of a predator in birds.

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 () produce specific alarm calls when and only when encountering a predatory snake.

Wild Birds Use an Ordering Rule to Decode Novel Call Sequences.

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.

Foraging intention affects whether willow tits call to attract members of mixed-species flocks.

Understanding how individual behaviour influences the spatial and temporal distribution of other species is necessary to resolve the complex structure of species assemblages. Mixed-species bird flocks provide an ideal opportunity to investigate this issue, because members of the flocks are involved in a variety of behavioural interactions between species. Willow tits () often produce loud calls when visiting a new foraging patch to recruit other members of mixed-species flocks.

Naive Juveniles Are More Likely to Become Breeders after Witnessing Predator Mobbing.

Responding appropriately during the first predatory attack in life is often critical for survival. In many social species, naive juveniles acquire this skill from conspecifics, but its fitness consequences remain virtually unknown. Here we experimentally demonstrate how naive juvenile Siberian jays (Perisoreus infaustus) derive a long-term fitness benefit from witnessing knowledgeable adults mobbing their principal predator, the goshawk (Accipiter gentilis).

Referential calls coordinate multi-species mobbing in a forest bird community.

Japanese great tits () use a sophisticated system of anti-predator communication when defending their offspring: they produce different mobbing calls for different nest predators (snake versus non-snake predators) and thereby convey this information to conspecifics (i.e. functionally referential call system).

Occasional cooperative breeding in birds and the robustness of comparative analyses concerning the evolution of cooperative breeding.

Cooperative breeding is a widespread and intense form of cooperation, in which individuals help raise offspring that are not their own. This behaviour is particularly well studied in birds, using both long-term and comparative studies that have provided insights into the evolution of reproductive altruism. In most cooperatively breeding species, helpers are offspring that remain with their parents beyond independency and help in the raising of younger siblings.

Experimental evidence for compositional syntax in bird calls.

Human language can express limitless meanings from a finite set of words based on combinatorial rules (i.e., compositional syntax).

Mass-based condition measures and their relationship with fitness: in what condition is condition?

Mass or body-size measures of 'condition' are of central importance to the study of ecology and evolution, and it is often assumed that differences in condition measures are positively and linearly related to fitness. Using examples drawn from ecological studies, we show that indices of condition frequently are unlikely to be related to fitness in a linear fashion. Researchers need to be more explicit in acknowledging the limitations of mass-based condition measures and accept that, under some circumstances, they may not relate to fitness as traditionally assumed.

Assessment of predation risk through referential communication in incubating birds.

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.