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{{short description|
{{for|devices giving alarm signals|Alarm device}}
{{redirect2|Alarm call|Alarmer|the Björk song|Alarm Call|the shoulder dystocia mnemonic|ALARMER}}
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In [[animal communication]], an '''alarm signal''' is an [[antipredator adaptation]] in the form of [[Signalling theory|signal]]s emitted by social animals in response to danger. Many [[primate]]s and [[bird]]s have elaborate '''alarm calls''' for warning [[Biological specificity|conspecifics]] of approaching predators. For example, the alarm call of the [[Common blackbird|blackbird]] is a familiar sound in many gardens. Other animals, like fish and insects, may use non-auditory signals, such as [[Schreckstoff|chemical messages]]. Visual signs such as the white tail flashes of many deer have been suggested as alarm signals; they are less likely to be received by conspecifics, so have tended to be treated as a signal to the [[predator]] instead.
Different calls may be used for predators on the ground or from the air. Often, the animals can tell which member of the group is making the call, so that they can disregard those of little reliability.<ref>[http://rsbl.royalsocietypublishing.org/content/9/5/20130535 Biology Letters. Titi monkey call sequences vary with predator location and type]</ref>
Evidently, alarm signals promote survival by allowing the receivers of the alarm to escape from the source of peril; this can evolve by [[kin selection]], assuming the receivers are related to the signaller. However, alarm calls can increase individual fitness, for example by informing the predator it has been detected.<ref>{{cite journal | doi=10.1046/j.1439-0310.1999.00396.x | volume=105 | issue=6 | title=The Predator Deterrence Function of Primate Alarm Calls | journal=Ethology | pages=477–490| year=1999 | last1=Zuberbühler | first1=Klaus | last2=Jenny | first2=David | last3=Bshary | first3=Redouan | bibcode=1999Ethol.105..477Z | url=http://doc.rero.ch/record/209806/files/Zuberbuhler_K-Predator_detterence-20140416.pdf }}</ref>
Alarm calls are often high-frequency sounds because these sounds are harder to localize.<ref>{{cite web |url=http://mue.music.miami.edu/thesis/robert_hartman/robert_hartman_thesis.pdf |title=Archived copy |
==Selective advantage==
{{
{{main|Signalling theory}}
[[File:Otospermophilus variegatus.webm|thumb|right|Alarm call by a [[rock squirrel]]]]
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=== Altruism ===
{{More citations needed section|date=June 2024}}
Some scientists have used the evidence of alarm-calling behaviour to challenge the theory that "evolution works only/primarily at the level of the [[gene]] and of the gene's
Other researchers, generally those who support the [[selfish gene theory]], question the authenticity of this "altruistic" behaviour. For instance, it has been observed that [[Vervet monkey|vervet]]s sometimes emit calls in the presence of a predator, and sometimes do not. Studies show that these vervets may call more often when they are surrounded by their own offspring and by other relatives who share many of their genes.<ref>{{cite journal|jstor=4534456 |title=Vervet Monkey Alarm Calls: Manipulation through Shared Information? |journal=Behaviour |volume=94 |issue=1/2 |pages=150–166|last1=Cheney |first1=Dorothy L. |last2=Seyfarth |first2=Robert M. |year=1985 |doi=10.1163/156853985X00316 }}</ref> Other researchers have shown that some forms of alarm calling, for example, "aerial predator whistles" produced by [[Belding's ground squirrel]]s, do not increase the chances that a caller will get eaten by a predator; the alarm call is advantageous to both caller and recipient by frightening and warding off the predator.{{Citation needed|date=July 2007}}
=== Predator-directed
Another theory suggests that alarm signals function to attract further predators, which fight over the prey organism, giving it a better chance of escape.<ref>{{cite journal | last1=Chivers | first1=D. P. | last2=Brown | first2=G. E. | last3=Smith | first3=R. J. F. | year=1996 | title=The Evolution of Chemical Alarm Signals: Attracting Predators Benefits Alarm Signal Senders | url=http://spectrum.library.concordia.ca/6740/1/Brown_AmericanNaturalist_1996.pdf| journal=The American Naturalist | volume=148 | issue=4| pages=649–659 | doi=10.1086/285945 | s2cid=53311630 }}</ref> Others still suggest they are a deterrent to predators, communicating the
=== Further research ===
{{Unreferenced section|date=June 2024}}
Considerable research effort continues to be directed toward the purpose and ramifications of alarm-calling behaviour, because, to the extent that this research has the ability to comment on the occurrence or non-occurrence of altruistic behaviour,
==Monkeys with alarm calls==
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=== Vervet monkeys ===
[[Vervet monkey]]s (Chlorocebus Pygerythus) are some of the most studied monkeys when it comes to vocalization and alarm calls within the nonhuman primates. They are most known for making alarm calls in the presence of their most common predators ([[leopard]]s, [[eagle]]s, and [[snake]]s). Alarm calls of the vervet monkey are considered arbitrary in relation to the predator that they signify, in the sense that while the calls may be distinct to the threat that the monkeys are perceiving, the calls do not mimic the actual sounds of the predator{{snd}}it is like yelling "Danger!" when seeing an angry dog rather than making barking sounds. This type of alarm calls is seen as the earliest example of symbolic communication (the relationship between signifier and signified is arbitrary and purely conventional) in nonhuman primates.<ref>{{Cite journal|last1=Price|first1=Tabitha|last2=Wadewitz|first2=Philip|last3=Cheney|first3=Dorothy|last4=Seyfarth|first4=Robert|last5=Hammerschmidt|first5=Kurt|last6=Fischer|first6=Julia|date=2015-08-19|title=Vervets revisited: A quantitative analysis of alarm call structure and context specificity|journal=Scientific Reports|language=en|volume=5|issue=1|pages=13220|doi=10.1038/srep13220|pmid=26286236| pmc=4541072 |bibcode=2015NatSR...513220P|issn=2045-2322}}</ref>
However, there is much debate on whether the vervet monkeys alarm calls are actual "words" in the sense of purposely manipulating sounds to communicate specific meaning or are unintentional sounds t hat are made when interacting with an outside stimulus. Like small children who cannot communicate words effectively make random noises when being played with or are stimulated by something in their immediate environment. As children grow and begin learning how to communicate the noises, they make are very broad in relation to their environment. They begin to recognize the things in their environment but there more things than known words or noises so a certain sound may reference multiple things. As children get older, they can become more specific about the noises and words made in relation to the things in their environment. It is thought that as Vervet monkeys get older they are able to learn and break the broad categories into more specific sub categories to a specific context.<ref name=":5">{{Cite book|last=Dorothy|first=Cheney|title=How Monkeys See the World: Inside the Mind of Another Species|publisher=U of Chicago P|year=2018|language=english}}</ref>
In an experiment conducted by Dr. Tabitha Price, they used custom software to gather the acoustic sounds of male and female Vervet monkeys from East Africa and male Vervet monkey from South Africa. The point of the experiment was to gather the acoustic sounds of these monkeys when stimulated by the presence of snakes (mainly [[Pythonidae|Python]]), raptors, terrestrial animals (mostly Leopards), and aggression. Then to determine if the calls could be distinguished with a known context.
The experiment determined that while the Vervet monkeys were able to categorize different predators and members of different social groups, however their ability to communicate specific threats is not proven. The chirps and barks that Vervet monkeys make as an eagle swoops in are the same chirps and barks that are made in moments of high arousal. Similarly, the barks made for leopards are the same that are made during aggressive interactions''. ''The environment that they exist in is too complex for their ability to communicate about everything in their environment specifically.<ref>{{Cite journal|last1=Price|first1=Tabitha|last2=Wadewitz|first2=Philip|last3=Cheney|first3=Dorothy|last4=Seyfarth|first4=Robert|last5=Hammerschmidt|first5=Kurt|last6=Fischer|first6=Julia|date=2015-08-19|title=Vervets revisited: A quantitative analysis of alarm call structure and context specificity|journal=Scientific Reports|language=en|volume=5|issue=1|pages=13220|doi=10.1038/srep13220 |pmid=26286236| pmc=4541072 |bibcode=2015NatSR...513220P|issn=2045-2322}}</ref>
In an experiment conducted by Dr. Julia Fischer, a [[Unmanned aerial vehicle|drone]] was flown over Vervet monkeys and recorded the sounds produced. The Vervet monkeys made alarm calls that were almost identical to the eagle calls of East African Vervets. When a sound recording of the drone was played back a few days later to a monkey that was alone and away from the main group it looked up and scanned the sky. Dr. Fischer concluded that Vervet monkeys can be exposed to a new threat once and understand what it means.
It is still debated whether or not Vervet monkeys are actually aware of what the alarm calls mean. One side of the argument is that the monkeys give alarm calls because they are simply excited. The other side of the argument is that the alarm calls create mental representation of predators in the listeners minds. The common middle ground argument is that they give alarm calls because they want others to elicit a certain response, not necessarily because they want the group to think that there is a specific threat near.<ref name=":5" />
Ultimately there is not enough evidence to support whether or not the calls are simply identifying a threat or calling for specific action due to the threat.
=== Campbell's mona monkeys ===
[[Campbell's mona monkey]]s also generate alarm calls, but in a different way than vervet monkeys. Instead of having discrete calls for each predator, Campbell monkeys have two distinct types of calls which contain different calls which consist in an acoustic continuum of affixes which change meaning. It has been suggested that this is a [[:wikt:homologous|homology]] to human [[Morphology (linguistics)|morphology]].<ref>{{Cite journal |doi = 10.1371/journal.pone.0007808|pmid = 19915663|pmc = 2771905|title = Campbell's Monkeys Use Affixation to Alter Call Meaning|journal = PLOS ONE|volume = 4|issue = 11|pages = e7808|year = 2009|last1 = Ouattara|first1 = Karim|last2 = Lemasson|first2 = Alban|last3 = Zuberbühler|first3 = Klaus|bibcode = 2009PLoSO...4.7808O|doi-access = free}}</ref> Similarly, the [[cotton-top tamarin]] is able to use a limited vocal range of alarm calls to distinguish between aerial and land predators.<ref name="Gen22">Neyman, P. F. 1978. Aspects of the ecology and social organization of free-ranging cotton-top tamarins (Saguinus oedipus) and the conservation status of the species. In: The Biology and Conservation of the Callitrichidae (Ed. by D. G. Kleiman), pp. 39e71. Washington, D.C.: [[Smithsonian Institution Press]].</ref> Both the Campbell monkey and the cotton-top tamarin have demonstrated abilities similar to vervet monkeys' ability to distinguish likely direction of predation and appropriate responses.<ref>{{cite journal | doi = 10.1016/j.anbehav.2004.09.020 | title = Alarm calls of white-faced capuchin monkeys: an acoustic analysis | year = 2005 | last1 = Fichtel | first1 = C | last2 = Perry | first2 = S | last3 = Groslouis | first3 = J | s2cid = 53173875 | journal = Animal Behaviour | volume = 70 | pages = 165–176 }}</ref><ref name="AC12">Sproul et al. Cottontop tamarin,'' Saguinus oedipus'', alarm calls contain sufficient information for recognition of individual identity. [[Animal Behaviour (journal)|Animal Behaviour]] (2006) vol. 72 (6) pp. 1379-1385</ref>
That these three [[species]] use vocalizations to warn others of danger has been called by some proof of [[Origin of language|proto-language]] in [[primates]]. However, there is some evidence that this behavior does not refer to the predators themselves but to threat, distinguishing calls from words.<ref>{{cite journal | doi = 10.1006/anbe.1999.1317 | title = Referential labelling in Diana monkeys | year = 2000 | last1 = Zuberbühler | first1 = K | s2cid = 7868715 | journal = Animal Behaviour | volume = 59 | issue = 5 | pages = 917–927 | pmid = 10860519 }}</ref>
=== Barbary macaque ===
Another species that exhibits alarm calls is the [[Barbary macaque]]. Barbary macaque mothers are able to recognize their own offspring's calls and behave accordingly.<ref name="recognition">{{cite journal | last1 = Hammerschmidt | first1 = Kurt | last2 = Todt | first2 = Dietmar | year = 1995 | title = Individual Differences in Vocalisations of Young Barbary Macaques (Macaca Sylvanus): A Multi-Parametric Analysis To Identify Critical Cues in Acoustic Signalling
[[File:Diana Monkey 2.jpg|thumb|[[Diana monkeys]] produce alarm calls that differ based on caller, threat type, and habitat.]]
=== Diana monkeys ===
[[Diana monkey
Diana monkeys emit different alarm calls as a result of their sex. Male alarm calls are primarily used for resource defence, male–male competition, and communication between groups of conspecifics.<ref>{{Cite journal|last1=ZUBERBÜHLER|first1=KLAUS|last2=NOË|first2=RONALD|last3=SEYFARTH|first3=ROBERT M|date= March 1997 |title=Diana monkey long-distance calls: messages for conspecifics and predators|journal=Animal Behaviour|volume=53|issue=3|pages=589–604|doi=10.1006/anbe.1996.0334|s2cid=39349789|issn=0003-3472|url=http://doc.rero.ch/record/278333/files/Zuberbuhler_K.-Diana_monkey_20170113150113-DW.pdf}}</ref> Female alarm calls are mainly used for communication within groups of conspecifics to avoid predation.<ref>{{Cite journal|last1=Zuberbühler|first1=Klaus|last2=Uster|first2=Dana|date=2001|journal=Behaviour|volume=138|issue=6|pages=741–756|doi=10.1163/156853901752233389|issn=0005-7959|title=The Functional Significance of Diana Monkey 'clear' Calls|url=http://doc.rero.ch/record/278361/files/Uster_D.-The_functional_20170118170901-RA.pdf}}</ref>
Alarm calls are also predator-specific. In [[Taï National Park]], [[Côte d'Ivoire]], Diana monkeys are preyed on by leopards, eagles, and chimpanzees, but only emit alarm calls for leopards and eagles.<ref name=":6" /><ref name=":7" /> When threatened by chimpanzees, they use silent, cryptic behaviour and when threatened by leopards or eagles, they emit predator-specific alarm signals.<ref name=":7" /> When researchers play recordings of alarm calls produced by chimpanzees in response to predation by leopards, about fifty per cent of nearby Diana monkeys switch from a chimpanzee antipredator response to a leopard antipredator response.<ref name=":7" /> The tendency to switch responses is especially prominent among Diana monkey populations that live within the main range of the chimpanzee community.<ref name=":7" /> This shift in antipredator response suggests that the monkeys interpret chimpanzee-produced, leopard-induced alarm calls as evidence for the presence of a leopard.<ref name=":7" /> When the same monkeys are then played recordings of leopard growls, their reactions confirm that they had anticipated the presence of a leopard.<ref name=":7" /> There are three possible cognitive mechanisms explaining how Diana monkeys recognize chimpanzee-produced, leopard-induced alarm calls as evidence for a nearby leopard: [[associative learning]], [[causal reasoning]], or a specialized learning programme driven by adaptive antipredator behaviour necessary for survival.<ref name=":7" />
In Taï National Park and [[Tiwai Island]], [[Sierra Leone]], specific acoustic markers in the alarm calls of Diana monkeys convey both threat type and caller familiarity information to a receiver. In Taï National Park, males respond to eagle alarm signals based on predator type and caller familiarity. When the caller is unfamiliar to the receiver, the response call is a 'standard' eagle alarm call, characterized by a lack of frequency transition at the onset of the call.<ref name=":6" /> When the caller is familiar, the response call is an atypical eagle alarm call, characterized by a frequency transition at onset, and the response is faster than to that of an unfamiliar caller.<ref name=":6" /> On Tiwai Island, males respond in the opposite way to eagle alarm signals.<ref name=":6" /> When the caller is familiar, the response call is a 'standard' eagle alarm call, without a frequency transition at onset. When the caller is unfamiliar, the response call is an atypical eagle alarm call, with a frequency transition at onset.<ref name=":6" />
The differences in alarm call responses are due to differences in habitat. In Taï National Park, there is a low predation risk from eagles, high primate abundance, strong intergroup competition, and a tendency for group encounters to result in high levels of aggression.<ref name=":6" /> Therefore, even familiar males are a threat to whom males respond with aggression and an atypical eagle alarm call.<ref name=":6" /> Only unfamiliar males, who are likely to be solitary and non-threatening, do not receive an aggressive response and receive only a typical alarm call.<ref name=":6" /> On Tiwai Island, there is a high predation risk from eagles, low primate abundance, a tendency for group encounters to result in peaceful retreats, low resource competition, and frequent sharing of foraging areas.<ref name=":6" /> Therefore, there is a lack of aggression towards familiar conspecifics to whom receivers respond with a 'standard' eagle call.<ref name=":6" /> There is only aggression towards unfamiliar conspecifics, to whom receivers respond with an atypical call.<ref name=":6" /> Simply put, a response with a typical eagle alarm call prioritizes the risk of predation, while a response with an atypical alarm call prioritizes social aggression.<ref name=":6" />
Diana monkeys also display a predisposition for flexibility in acoustic variation of alarm call assembly related to caller [[Ontogeny|ontogenetic]] or lifetime predator experience. In Taï National Park and on Tiwai Island, monkeys have a predisposition to threat-specific alarm signals.<ref name=":8">{{Cite journal|last1=Stephan|first1=Claudia|last2=Zuberbühler|first2=Klaus|date=2008-09-25|title=Predation increases acoustic complexity in primate alarm calls|journal=Biology Letters|volume=4|issue=6|pages=641–644|doi=10.1098/rsbl.2008.0488|pmid=18818146|pmc=2614181|issn=1744-9561}}</ref> In Taï National Park, males produce three threat-specific calls in response to three threats: eagles, leopards, and general disturbances.<ref name=":8" /> On Tiwai Island, males produce two threat-specific calls in response to two groups of threats: eagles, and leopards or general disturbances.<ref name=":8" /> The latter are likely grouped together because leopards have not been present on the island for at least 30 years.<ref name=":8" /> Other primates, such as Guereza monkeys and [[
=== Sexual selection for predator-specific alarm signals ===
In [[
=== Controversy over the semantic properties of alarm calls ===
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==Chimpanzees with alarm calls==
[[File:Chimpanzee (150887903).jpeg|alt=|thumb|200x200px|[[Chimpanzees]] produce alarm calls in response to threats.]]
[[Chimpanzee]]s emit alarm calls in response to predators, such as leopards and snakes.<ref name=":7">{{Cite journal|last=Zuberbühler|first=Klaus|s2cid=20767860|date= January 2000 |title=Causal knowledge of predators' behaviour in wild Diana monkeys|journal=Animal Behaviour|volume=59|issue=1|pages=209–220|doi=10.1006/anbe.1999.1296|pmid=10640383|issn=0003-3472}}</ref><ref>{{Cite journal|last1=Crockford|first1=Catherine|last2=Boesch|first2=Christophe|s2cid=53151685|date= July 2003 |title=Context-specific calls in wild chimpanzees, Pan troglodytes verus: analysis of barks|journal=Animal Behaviour|volume=66|issue=1|pages=115–125|doi=10.1006/anbe.2003.2166|issn=0003-3472}}</ref> They produce three types of alarm calls: acoustically-variable 'hoos', 'barks', and 'SOS screams'.<ref name=":0">{{Cite journal|last1=Schel|first1=Anne Marijke|last2=Townsend|first2=Simon W.|last3=Machanda|first3=Zarin|last4=Zuberbühler|first4=Klaus|last5=Slocombe|first5=Katie E.|date=2013-10-16|title=Chimpanzee Alarm Call Production Meets Key Criteria for Intentionality|journal=PLOS ONE|volume=8|issue=10|pages=e76674|doi=10.1371/journal.pone.0076674|pmid=24146908|pmc=3797826|issn=1932-6203|bibcode=2013PLoSO...876674S|doi-access=free}}</ref> Alarm signalling is impacted by receiver knowledge and caller age, can be coupled with receiver monitoring, and is important to the understanding of the evolution of [[hominoid]] communication.
=== Receiver knowledge ===
Alarm signalling varies depending on the receiver's knowledge of a certain threat. Chimpanzees are significantly more likely to produce an alarm call when conspecifics are unaware of a potential threat or were not nearby when a previous alarm call was emitted.<ref name=":1">{{Cite journal|last1=Crockford|first1=Catherine|last2=Wittig|first2=Roman M.|last3=Mundry|first3=Roger|last4=Zuberbühler|first4=Klaus|date= January 2012 |title=Wild Chimpanzees Inform Ignorant Group Members of Danger|journal=Current Biology|volume=22|issue=2|pages=142–146|doi=10.1016/j.cub.2011.11.053|pmid=22209531|issn=0960-9822|doi-access=free|hdl=10023/4314|hdl-access=free}}</ref>
=== Caller age ===
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=== Evolution of hominoid communication ===
The evolution of hominoid communication is evident through chimpanzee 'hoo' vocalizations and alarm calls. Researchers propose that communication evolved as [[natural selection]] diversified 'hoo' vocalizations into context-dependent 'hoos' for travel, rest, and threats.<ref name=":4">{{Cite journal|last1=Crockford|first1=Catherine|last2=Gruber|first2=Thibaud|last3=Zuberbühler|first3=Klaus|date= May 2018 |title=Chimpanzee quiet hoo variants differ according to context|journal=Royal Society Open Science|volume=5|issue=5|pages=172066|doi=10.1098/rsos.172066|pmid=29892396|pmc=5990785|issn=2054-5703|bibcode=2018RSOS....572066C}}</ref> Context-dependent communication is beneficial and likely maintained by selection as it facilities cooperative activities and social cohesion between signallers and receivers that can increase the likelihood of survival.<ref name=":4" /> Alarm calls in chimpanzees also point to the evolution of hominoid language. Callers assess conspecifics' knowledge of threats, fill their need for information, and, in doing so, use social cues and intentionality to inform communication.<ref name=":0" /><ref name=":2" /> Filling a gap in information and incorporating social cues and intentionality into communication are all components of human language.<ref name=":0" /><ref name=":2" /> These shared elements between chimpanzee and human communication suggest an evolutionary basis, most likely that
==False alarm calls==
[[Image:Barn Swallow-Mindaugas Urbonas.jpg|right|thumb|200px|Deceptive vocalizations are given by male [[barn swallow]]s.]]
[[Deception|Deceptive]] alarm calls are used by male swallows (''[[Hirundo rustica]]'').<ref>{{cite journal | last1 = Møller | first1 = A. P. | year = 1990 | title = Deceptive use of alarm calls by male swallows ''Hirundo rustica'': A new paternity guard
Counterfeit alarm calls are also used by [[Thrush (bird)|thrushes]] to avoid [[intraspecific competition]]. By sounding a bogus alarm call normally used to warn of aerial predators, they can frighten other birds away, allowing them to eat undisturbed.<ref>Wickler, W. (1968) ''Mimicry in Plants and Animals'' (Translated from the German) McGraw-Hill, New York. {{ISBN|0-07-070100-8}}. p. 108.</ref>
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==Alarm pheromones==
Alarm signals need not be communicated only by [[Hearing (sense)|auditory]] means. For example, many animals may use [[Chemoreception|chemosensory]] alarm signals, communicated by chemicals known as [[pheromone]]s. Minnows and catfish release alarm pheromones (''[[Schreckstoff]]'') when injured, which cause nearby fish to hide in dense schools near the bottom.<ref>Campbell, N. & Reece, J. 2004. ''Biology'' 7th Edition - Benjamin Cummings {{ISBN|0-8053-7146-X}}</ref>
==See also==
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{{evo ecol}}
{{Signalling theory}}
[[Category:Signalling theory]]
[[Category:Animal communication]]
[[Category:Antipredator adaptations]]
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[[Category:Survival skills]]
[[Category:Articles containing video clips]]
[[Category:Chemical ecology]]
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