How great tits respond to urgency-based information in allopatric Southern house wren mobbing calls

Many species of birds use alarm calls to signal information about predators, including the level of threat. Previous playback experiments suggest that the urgency response towards heterospecific calls is phylogenetically conserved, notably in the Paridae family. Using playback experiments conducted on European great tits (Parus major), we tested whether this species perceives information about urgency in mobbing calls produced by an allopatric non-Paridae species, the Southern house wren (Troglodytes aedon bonariae), by broadcasting calls with high-calling rate (high threat) and calls with low-calling rate (low threat). We found that great tits tend to approach the loudspeaker during playbacks of calls with high-calling rate more often than during playbacks of calls with low-calling rate. Female great tits gave more calls during playbacks of calls with high-calling rate than during playbacks of calls with low-calling rate, whereas there was no significant difference in the number of calls given by males between playbacks of calls with high- and low-calling rates. Thus, our results suggested that great tits perceived the urgency message encoded in calls given by an allopatric non-Paridae species.Fil: Dutour, Mylène. University of Western Australia; AustraliaFil: Fernandez, Gustavo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Randler, Christoph. Eberhard Karls Universität Tübingen; Alemani

Communiquer entre espèces pour faire face au prédateur : le cas des cris de harcèlement chez les passereaux

Signaling the presence of a predator most often causes the escape of prey, but it sometimes induces a particular behaviour prompting prey to approach and harass the predator to cause his departure. This mobbing behaviour is associated with the emission of signals leading individuals from different species to come harass the predator. The objective of this thesis is to understand how the transfer of information between several passerine species is organized in mobbing behaviour against predators. My work shows that the mobbing behaviour of passerine birds against a nocturnal raptor depends on the predation risk imposed by this predator. In addition, my results indicate a transfer of information between species and highlight a variable propensity of different species to rally around the harasser. The observed variations in the response to heterospecific calls depended on acoustic similarity, interspecific relationships and seasonality. My results also indicate that prior knowledge of harassment signals is not essential to induce a response, even if an associative learning process promotes its implementation. My work also suggests a convergent evolution in mobbing calls, generating signals with a structure that allows the emitter to be quickly located, an essential parameter to rally potential prey during harassment. My thesis consequently shows that to better understand acoustic communication in passerine birds, it is necessary to consider predation risk, heterospecific interactions and the complexity of acoustic signalsSi le signalement du prédateur provoque le plus souvent la fuite des proies, il induit parfois un comportement particulier incitant la proie à s’approcher du prédateur et le harceler pour provoquer son départ plutôt que de se mettre hors de sa portée. Ce comportement de harcèlement s’accompagne de l’émission d’un signal hétérospécifique conduisant de nombreuses espèces à venir harceler le prédateur. L’objectif de mon travail de thèse est de comprendre comment est régi le transfert d’informations entre plusieurs espèces de passereaux dans le cas du comportement de harcèlement d’un prédateur. Mes travaux montrent que le comportement de harcèlement des passereaux face à un rapace nocturne dépend du risque de prédation posé par ce prédateur. Par ailleurs, les résultats indiquent un transfert d’informations entre les espèces et mettent en évidence une propension variable des différentes espèces à se rallier autour du harceleur. Les variations observées dans la réponse aux cris de harcèlement émis par des individus hétérospécifiques peuvent dépendre de la similarité acoustique, des relations interspécifiques et des variations saisonnières. Mes résultats indiquent aussi que la connaissance préalable des signaux de harcèlement n'est pas indispensable pour induire une réponse, même si un processus d’apprentissage associatif favorise sa mise en place. Mon travail suggère également une évolution convergente des cris de harcèlement, générant des signaux dont la structure permet une localisation rapide de l’émetteur, indispensable pour rameuter des proies potentielles lors du harcèlement. L’ensemble de ces avancées nous oblige désormais à considérer la communication acoustique chez les passereaux en prenant en compte le risque de prédation, les interactions hétérospécifiques et la complexité des signaux acoustique

Mobbing calls: a signal transcending species boundaries

International audienceWhen they detect a predator, some prey exhibit mobbing behaviour and produce mobbing calls that quickly draw a mixed conspecific and heterospecific group against the predator. While the efficiency of this strategy is often linked to interspecific communication, it raises the question of how animals recognize these signals as mobbing calls. It is usually suggested that associative learning about a predator when heterospecific mobbing calls are heard plays a crucial role in communication among species. Alternatively, phylogenetic conservation or evolutionary convergence could also explain this communication process. To determine whether prior experience is required to express a mobbing response, we conducted playback experiments with four European passerine species: great tit, Parus major, blue tit, Cyanistes caeruleus, coal tit, Periparus ater, and common chaffinch, Fringilla coelebs. The aim of the study was to examine whether they would respond to the mobbing signals of several North American passerines. As expected, because natural selection might shape a strong response to conspecific mobbing calls, our focal species reacted more strongly towards their own mobbing calls than towards those of American species. Nevertheless, for the three European species of tit, prior experience of heterospecific mobbing calls was not required to elicit a response. Additionally, for great tit and chaffinch, we found that acoustic similarity could explain behavioural responses to allopatric species. In contrast, such similarity was probably not the main mechanism underlying the response for the other two European species. Heterospecific response to mobbing calls probably involved many different mechanisms. Further studies focusing on each of these should allow us to understand their relative contribution to heterospecific communication

Mobbing behaviour in a passerine community increases with prevalence in predator diet

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Mobbing behaviour varies according to predator dangerousness and occurrence

International audienceAnimals possess various antipredator behaviours to reduce their risk of predation. Whereas most prey make considerable effort to avoid their predators, sometimes individuals approach and mob predators as a group. Among the types of predators that elicit mobbing, raptors such as hawks and owls are one of the more consistent targets. We conducted playback experiments to investigate the strength of mobbing behaviour according to the perceived risk associated with either predator dangerousness or local pre- dation pressure. We ␣rst determined whether mobbing is speci␣c to dangerous predators or more broadly directed at predatory species. We experimentally investigated whether prey can discriminate the level of dangerousness of two owl species. Our results indicate that prey adjusted the strength of their mobbing behaviour according to the perceived risk: passerine birds mobbed the Eurasian pygmy owl, Glaucidium passerinum (i.e. a dangerous predator) but not the boreal owl, Aegolius funereus (i.e. a far less dangerous species). Second, we compared mobbing behaviour in similar habitats differing in predation pressure (with or without pygmy owls). Working on identical bird communities, we revealed that mobbing varied in relation to the local presence of the predator. Where the pygmy owl was absent, calls of this dangerous predator failed to elicit mobbing among passerine birds although they responded strongly to a playback of a mobbing chorus. This study provides experimental evidence that intense predation increases the expression of cooperative mobbing in passerine birds

Syntax manipulation changes perception of mobbing call sequences across passerine species

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Seasonal variation in mobbing behaviour of passerine birds

International audienceWhen they detect a predator, many birds exhibit mobbing behaviour and produce mobbing calls that quickly draw other prey against the predator. This anti-predator strategy often involves several species and, therefore, implies heterospecific communication. As fledging and nestling stages could be particularly targeted by predators, a high mobbing intensity is to be expected during the breeding season. While recognizing other species’ mobbing calls is critical to setting up this behav- iour, to date, we have no information about the perception of these calls with regard to the season. Here, we used playbacks of mobbing calls to study the variation in response of the Great Tit (Parus major) and the Blue Tit (Cyanistes caeruleus) exposed to the mobbing calls of two heterospecific species, the Eurasian Nuthatch (Sitta europaea), and the Eurasian Wren (Troglodytes troglodytes). To investigate mobbing response seasonality, we conducted playback experiments during spring (breeding season) and autumn (non-breeding season). Contrary to most previous studies, we found that mobbing intensity was greater in autumn than in spring. Additionally, although neither Nuthatch nor Wren is related to the Tit family, we found that both Tit species responded more to the former than the latter species. At the heterospecific communication level, this study demonstrates a previously unsuspected level of complexity in the use of mobbing calls

Biological conclusions about importance of order in mobbing calls vary with the reproductive context in Great Tits ( Parus major )

International audienceCurrently, there is considerable debate surrounding the presence of some human language-specific characteristics in non-human animals, such as the use of compositional syntax (i.e. meaning of a sequence determined both by meaning of its individual parts and in the way they are combined). Compositional syntax has been investigated in mobbing calls of two closely related tit species, the Japanese Tit Parus minor and the Great Tit Parus major, but with one contrasting result: hearing calls in the reversed order diminished the behavioural responses of Japanese Tits but only partially those of Great Tits. This difference may have been due to an external factor such as the season in which the experiment was undertaken, as the Japanese Tits were tested in winter and Great Tits in spring. Here, we studied the responses of Great Tits towards natural and reversed mobbing sequences during spring and winter by investigating two behaviours: approaching and vigilance behaviours. We found that sensitivity to syntax reversal was impacted by the season. The birds were vigilant but less likely to approach reversed calls in winter. However, the opposite occurred in spring, with the birds scanning less but still approaching. This study suggests that the perception of combinatorial calls in Great Tits is influenced by the season, emphasizing the importance of context in studies investigating complex cognitive processing in animals

Effects of domestication on responses of chickens and red junglefowl to conspecific calls: A pilot study.

Beyond physical and zootechnical characteristics, the process of animal domestication has also altered how domesticated individuals, compared to their wild counterparts, perceive, process, and interact with their environment. Little is known, however, on whether and how domestication altered the perception of conspecific calls on both domesticated and wild breeds. In the present work, we compared the vigilance behavior of domestic and captive-born wild fowl following the playback of chicken alarm calls and contentment calls (control). The playback tests were performed on four different breeds/lines. We first compared the behavioral reaction of domesticated White Leghorn (WL, a breed selected for egg production) and Red Junglefowl (RJF) hens (ancestor of domestic chickens). We also compared the behavior of Red Junglefowl hens selected for high or low fear of humans (RJF HF and RJF LF, respectively), a proxy to investigate early effects of domestication. Contrary to our expectations, no breed/line reacted accordingly to the calls, as the increase in vigilance behavior after the playback calls was similar for both alarm and contentment calls. Although no call discrimination differences were found, breeds did differ on how they reacted/habituated to the calls. Overall, WL were more vigilant than RJF, and birds from the RJF LF line decreased their vigilance over testing days, while this was not the case for the RJF HF line. These results suggest that birds under commercial-like conditions are unable to discriminate between alarm and contentment calls. Interestingly, domestication and selection for low fear of humans may have altered how birds react to vocal stimuli. It is important to consider that farmed animals may interpret and be affected by the vocalizations of their conspecifics in unexpected ways, which warrants further investigation

The role of associative learning process on the response of fledgling great tits (Parus major) to mobbing calls

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