02230nas a2200181   4500008004100000022001300041245012400054210006900178260001600247300001400263490000800277520162600285100002001911700002801931700002401959700002401983856004102007       2019                        eng d  a0003347200aEavesdropping magpies respond to the number of heterospecifics giving alarm calls but not the number of species calling0 aEavesdropping magpies respond to the number of heterospecifics g  cJan-02-2019  a133 - 1430 v1483 a<p>Social information varies in its reliability and relevance, requiring individuals to use rules to avoid inappropriate responses to false information. A simple rule is to respond only when a certain number of individuals provide similar information. Although individuals within social groups can use such numerical rules to assess conspecific information and make consensus decisions, it is unknown whether individuals apply similar rules when assessing the value of heterospecific information. We consider the case of individuals eavesdropping on heterospecific alarm calls. Eavesdroppers may be particularly vulnerable to false alarms because of the large pool of potential callers and variability in the specific threats to which they call. Individuals might therefore value alarm calls more if they come from multiple callers or multiple species than from a single caller or a single species. We tested these predictions using field playback experiments on wild Australian magpies, Gymnorhina tibicen. Magpies responded more strongly to alarm calls coming from two callers versus one caller of the same heterospecific species. However, in contrast to our prediction, magpies responded similarly to alarm calls from two individuals of different species as they did to alarm calls from two individuals of the same species. We conclude that the number of calling individuals does affect response, probably because information from multiple callers is more reliable, but that the value or reliability of information from multiple species may depend on the types of alarm calls and combination of species involved.</p>
1 aIgic, Branislav1 aRatnayake, Chaminda, P.1 aRadford, Andrew, N.1 aMagrath, Robert, D.  uhttps://bio.acousti.ca/ja/node/5353802627nas a2200217   4500008004100000022001300041245009400054210006900148260001600217300001400233490000800247520193000255653002702185653001602212653002702228653002502255653001802280100002102298700002402319856006602343       2017                        eng d  a0003347200aFunctionally referential alarm calls in noisy miners communicate about predator behaviour0 aFunctionally referential alarm calls in noisy miners communicate  cJan-07-2017  a171 - 1790 v1293 a<p>Many vertebrates have alarm calls that warn conspecifics about danger, and some species even communicate about the type of predator or its behaviour, allowing for appropriate responses. However, such &lsquo;functionally referential&rsquo; communication has been shown experimentally in only a handful of species, and requires demonstrating that individuals give acoustically distinct calls to different threats, and that the calls alone are sufficient to prompt listeners to behave as if a specific threat is present. We carried out model presentations, acoustic analyses and a playback experiment to test whether the alarm calls of noisy miners, Manorina melanocephala, are functionally referential. Miners gave different calls to airborne raptor models compared to terrestrial or perched raptor models, and even switched from &lsquo;aerial&rsquo; alarm calls to &lsquo;chur&rsquo; alarm calls when a hawk glider landed on the ground. They also behaved differently to these two types of threats, showing avoidance to aerial threats, including fleeing or freezing, but deterrent behaviour to terrestrial threats, including vigilance, approach and mobbing. The two alarm call types were acoustically distinct, and consistent with calls to live predators. Blind scoring of video revealed that birds responded appropriately to playbacks of alarm calls alone, typically fleeing to aerial alarm calls yet becoming vigilant, approaching and calling to chur calls. Noisy miners produce alarm calls that therefore meet both criteria for functional reference, and thus become one of the few bird species in which such calls have been confirmed. Many birds appear to give different calls to airborne predators compared to during mobbing of terrestrial or stationary predators, so functionally referential alarms are likely to be common and may often categorize predators by their behaviour and not simply their taxonomic type.</p>
10aacoustic communication10aalarm calls10aantipredator behaviour10afunctional reference10amobbing calls1 aCunningham, Sean1 aMagrath, Robert, D.  uhttp://linkinghub.elsevier.com/retrieve/pii/S0003347217301586