Graded or discrete? A quantitative analysis of Campbell's monkey alarm calls

Keenan, Sumir; Lemasson, Alban; Zuberbühler, Klaus

doi:10.1016/j.anbehav.2012.10.014

Cited by 55 publications

(63 citation statements)

References 28 publications

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“…Second, birds can modify a single type of alarm call by altering the repetition rate of the vocal production or by subtly modifying the acoustic structure. Such graded variation is also present in primate communication (Fischer et al 2001;Keenan et al 2013). In some bird species, graded variation is incorporated with discrete variation (Wilson and Evans 2012;Suzuki 2014), which broadens the variety of information that individuals can transmit or provides information about the internal states of the senders (Marler et al 1992;Manser 2001Manser , 2009).…”

Section: Discussionmentioning

confidence: 99%

Semantic communication in birds: evidence from field research over the past two decades

Suzuki

2016

Ecological Research

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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.

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Section: Discussionmentioning

confidence: 99%

Semantic communication in birds: evidence from field research over the past two decades

Suzuki

2016

Ecological Research

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“…Of these calls, boom seems to have a regular syntax, as it usually appears as a single pair of calls at the beginning of sequences. It also seems to have a regular meaning of non-predation -a meaning which is clear enough to be understood by Diana monkeys, which live sympatrically with Campbell's monkeys but do not themselves have booms (specifically, Zuberbühler 2002 shows that Diana 13 As noted in footnote 3, we leave wak out of our discussions because it is not clearly an independent call (Keenan et al 2013 argued on the basis of a clustering analysis that it might be better treated as an instance of hok). We will come back in Section 7.2 to the uses of boom in Campbell's monkeys and in other cercopithecines.…”

Section: Introduction To Campbell's Semanticsmentioning

confidence: 99%

Formal monkey linguistics

Schlenker¹,

Chemla

Schel

et al. 2016

Theoretical Linguistics

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We argue that rich data gathered in experimental primatology in the last 40 years can benefit from analytical methods used in contemporary linguistics. Focusing on the syntactic and especially semantic side, we suggest that these (iii) how are the meanings of individual calls combined? (iv) how do calls or call sequences compete with each other when several are appropriate in a given situation? (v) how did the form and meaning of calls evolve? We address these questions in five case studies pertaining to cercopithecines (Putty-nosed monkeys, Blue monkeys, and Campbell's monkeys), colobinae (Guereza monkeys and King Colobus monkeys), and New World monkeys (Titi monkeys). The morphology mostly involves simple calls, but in at least one case (Campbell's -oo) we find a root-suffix structure, possibly with a compositional semantics. The syntax is in all clear cases simple and finite-state. With respect to meaning, nearly all cases of call concatenation can be analyzed as conjunction. But a key question concerns the division of labor between semantics, pragmatics and the environmental context ('world' knowledge and context change). An apparent case of dialectal variation in the semantics (Campbell's krak) can arguably be analyzed away if one posits sufficiently powerful mechanisms of competition among calls, akin to scalar implicatures. An apparent case of non-compositionality (Putty-nosed pyow-hack sequences) can be analyzed away if one further posits a pragmatic principle of 'urgency', whereby threat-related calls must come early in sequences (another potential case of non-compositionality -Colobus snort-roar sequences -might justify assigning non-compositional meanings to complex calls, but results are tentative). Finally, rich Titi sequences in which two calls are re-arranged in complex ways so as to reflect information about both predator identity and location are argued not to involve a complex syntax/semantics interface, but rather a finegrained interaction between simple call meanings and the environmental context. With respect to call evolution, we suggest that the remarkable preservation of call form and function over millions of years should make it possible to lay the groundwork for an evolutionary monkey linguistics, which we illustrate with cercopithecine booms, and with a comparative analysis of Blue monkey and Putty-nosed monkey repertoires. Throughout, we aim to compare possible theories rather than to fully adjudicate between them, and our claims are correspondingly modest. But we hope that our methods could lay the groundwork for a formal monkey linguistics combining data from primatology with formal techniques from linguistics (from which it does not follow that the calls under study share non-trivial properties, let alone an evolutionary history, with human language).

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“…A particularly interesting example is the Campbell's monkeys' (Cercopithecus campbelli) alarm call system. Here, adult males have a repertoire of three basic alarm calls ('Krak', 'Hok', 'Wak'), which have been termed 'call stems', each of which can occur with an acoustically invariable 'suffix' ('oo') [31]. Here, we use the term 'suffixation' to refer to this phenomenon: the act of adding an acoustically invariable component to different call stems.…”

Section: Introductionmentioning

confidence: 99%

Suffixation influences receivers' behaviour in non-human primates

et al. 2015

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Compared to humans, non-human primates have very little control over their vocal production. Nonetheless, some primates produce various call combinations, which may partially offset their lack of acoustic flexibility. A relevant example is male Campbell's monkeys (Cercopithecus campbelli), which give one call type ('Krak') to leopards, while the suffixed version of the same call stem ('Krak-oo') is given to unspecific danger. To test whether recipients attend to this suffixation pattern, we carried out a playback experiment in which we broadcast naturally and artificially modified suffixed and unsuffixed 'Krak' calls of male Campbell's monkeys to 42 wild groups of Diana monkeys (Cercopithecus diana diana). The two species form mixed-species groups and respond to each other's vocalizations. We analysed the vocal response of male and female Diana monkeys and overall found significantly stronger vocal responses to unsuffixed (leopard) than suffixed (unspecific danger) calls. Although the acoustic structure of the 'Krak' stem of the calls has some additional effects, subject responses were mainly determined by the presence or the absence of the suffix. This study indicates that suffixation is an evolved function in primate communication in contexts where adaptive responses are particularly important.

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Graded or discrete? A quantitative analysis of Campbell's monkey alarm calls

Cited by 55 publications

References 28 publications

Semantic communication in birds: evidence from field research over the past two decades

Semantic communication in birds: evidence from field research over the past two decades

Formal monkey linguistics

Suffixation influences receivers' behaviour in non-human primates

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