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Llusia, D., Márquez, R., & Beltrán, J. F. (2010). Non-Selective and Time-Dependent Behavioural Responses of Common Toads (Bufo bufo) to Predator Acoustic Cues. Ethology, 116(12), 1146–1154.
Abstract: Abstract Acoustic predator recognition has rarely been studied in anurans, in spite of the fact that hearing is widespread in these animals and that it has been demonstrated to play an important role in both arthropods and other vertebrates. Using field playback experiments, we tested the hypothesis that adult common toads (Bufo bufo) are capable of recognizing natural vocalizations of a common predator, the Eurasian otter (Lutra lutra), and show antipredator responses. We found that toads exposed to both natural (two types of otter sounds) and synthetic stimuli [white noise (WN) and otter sound-based amplitude modulated WN] increased time allocated to locomotion and escape behaviour. These responses were correlated with time elapsed from sunset to the onset of testing and were independent from the type of acoustic signal, toad features and other environmental factors monitored. We conclude that B. bufo has not developed a selective recognition of predator vocalizations, suggesting that low-frequency or seismic sounds associated with predator movements may provide anurans with better cues about an approaching risk. We propose that the time-dependent response to acoustic stimuli of common toads represents a case of threat-sensitivity and demonstrates that it can occur even when the response to the threat is not predator specific.
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Biondi, L. M., García, G. O., Bó, M. S., & Vassallo, A. I. (2010). Social Learning in the Caracara Chimango, Milvago chimango (Aves: Falconiformes): an Age Comparison. Ethology, 116(8), 722–735.
Abstract: Abstract Milvago chimango is a gregarious raptor showing great ecological plasticity. Their ability to explore new resources has allowed them to survive in areas with increasing human modification. In this study, we evaluated the social learning ability in wild-caught individuals of M. chimango. In particular, we tested whether an ‘observer’ individual could improve the acquisition of a novel behaviour by watching a ‘demonstrator,’ and we examined the effects of age of both observers and demonstrators on social learning. We measured the ability of 18 observers to open an opaque Plexiglas box containing food, and we compared their performance to that of 10 control birds who did not watch a demonstrator solve the task. Prior to watching a demonstrator, only two of the observers and two of the control birds were able to open the box. After watching a demonstrator, 67% of observers were able to open the box, outperforming control birds in speed and success. Juvenile observers were more successful and faster than adults at contacting and opening the box. The age of the demonstrator did not influence the observers’ likelihood of success. These results showed that M. chimango are able to learn a box-opening task with a hidden food reward by observing the behaviour of a conspecific and that this behaviour persisted over several days. Social learning ability in M. chimango might allow certain behavioural patterns, such as those related to novel resource acquisition in modified environments, to be socially transmitted among individuals in a population.
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Dochtermann, N. A., & Jenkins, S. H. (2011). Multivariate Methods and Small Sample Sizes. Ethology, 117(2), 95–101.
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Black, J. M. (1988). Preflight Signalling in Swans: A Mechanism for Group Cohesion and Flock Formation. Ethology, 79(2), 143–157.
Abstract: Abstract The preflight behaviour of whooper swans Cygnus cygnus and Bewick's swans Cygnus columbianus bewickii was examined to determine the adaptive significance of the ritual. Analysis of the preflight sequence revealed that the rate of signalling became significantly faster as the time of takeoff approached. This provides the first quantitative evidence that a threshold of excitability is responsible for triggering synchronised flight in social units. Two ultimate and two proximate factors that affect this threshold were uncovered. They are: 1) Maintaining proximity to partners—flight was delayed by birds with non-attentive mates and signalling lasted on average four times longer than those whose mates showed more interest. 2) Maintaining flock cohesiveness—birds which performed signals for longer periods while swimming among uninterested birds were successful in attracting followers 61% of the time. 3) The bird's feeding performance related to dominance status—less successful feeders (potentially hungry birds), flew after little time and few signals. 4) The type of feeding opportunity at the eventual destination—birds which flew to provided feeds (nutritious barley) spent less time performing preflight signals than when they flew to forage on grass fields.
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Huang, S. - P., Yang, S. - Y., & Hsu, Y. (2011). Persistence of Winner and Loser Effects Depends on the Behaviour Measured. Ethology, 117(2), 171–180.
Abstract: Abstract Recent contest experience can influence an individual’s behaviour in subsequent contests. When the probability of winning a subsequent contest is used to quantify experience effects, a loser effect usually lasts longer than a winner effect. This conclusion, however, may be caused by this probability understating the persistence of the influence of a winning experience on contest decisions. Using Kryptolebias marmoratus, a mangrove killifish, as the study organism, we investigated whether different conclusions about the relative persistence of winning and losing experiences would be reached when different aspects of contest behaviour (probability of initiating attacks, probability of winning non-escalated and escalated contests, escalation rate and contest duration) were measured. The results indicated that the apparent persistence of the effect of winning or losing experiences varied with the behaviour studied. When the likelihood to initiate attacks was used, no winner effect was detected while the loser effect lasted for <1 d. When escalation rate was used, the winner effect lasted for 2–4 d, while the loser effect lasted for 1–2 d. When the probability of winning non-escalated contests was used, the winner effect was detectable for <1 d, while the loser effect lasted for 2–4 d. And, when contest duration was used, the winner effect was detectable for 2–4 d, but no loser effect was detectable. These results show that (1) the probability of winning a subsequent contest understated the persistence of the influence of a winning experience on the fish’s contest decisions, (2) the measures most effective at detecting winner effects are different from those most effective at detecting loser effects and (3) in K. marmoratus, both effects can be detected 2 d after the completion of experience training but both dissipate in 4 d.
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Mersmann, D., Tomasello, M., Call, J., Kaminski, J., & Taborsky, M. (2011). Simple Mechanisms Can Explain Social Learning in Domestic Dogs (Canis familiaris). Ethology, 117(8), 675–690.
Abstract: Abstract Recent studies have suggested that domestic dogs (Canis familiaris) engage in highly complex forms of social learning. Here, we critically assess the potential mechanisms underlying social learning in dogs using two problem-solving tasks. In a classical detour task, the test dogs benefited from observing a demonstrator walking around a fence to obtain a reward. However, even inexperienced dogs did not show a preference for passing the fence at the same end as the demonstrator. Furthermore, dogs did not need to observe a complete demonstration by a human demonstrator to pass the task. Instead, they were just as successful in solving the problem after seeing a partial demonstration by an object passing by at the end of the fence. In contrast to earlier findings, our results suggest that stimulus enhancement (or affordance learning) might be a powerful social learning mechanism used by dogs to solve such detour problems. In the second task, we examined whether naïve dogs copy actions to solve an instrumental problem. After controlling for stimulus enhancement and other forms of social influence (e.g. social facilitation and observational conditioning), we found that dogs’ problem solving was not influenced by witnessing a skilful demonstrator (either an unknown human, a conspecific or the dog’s owner). Together, these results add to evidence suggesting that social learning may often be explained by relatively simple (but powerful) mechanisms.
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Noë, R., van Schaik, C. P., & van Hooff, J. A. R. A. M. (1991). The Market Effect: an Explanation for Pay-off Asymmetries among Collaborating Animals. Ethology, 87(1-2), 97–118.
Abstract: Abstract * 1Animals can derive leverage over others from (a) resource holding power, based for instance on fighting ability or dominance, and (b) the possession of commodities, such as special skills and resources that cannot be taken away by force. * 2We contend that power based on the possession of commodities strongly depends on the level of supply and demand for that commodity, a phenomenon we call the ‘market effect’. * 3Several theoretical and empirical examples are given of social systems in which animals belong to two distinct classes that offer two different kinds of commodities. * 4The relative frequency of occurrence of the two classes is shown to determine the relative power of their members. * 5We consider the theoretical properties of bargaining processes by which relative power is converted into corresponding pay-off distributions. * 6We propose coalition games, a class of games with more than two players and in which bargaining is possible, as suitable paradigms for collaboration among members of social units.
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McFarland, R., & Majolo, B. (2011). Reconciliation and the Costs of Aggression in Wild Barbary Macaques (Macaca sylvanus): A Test of the Integrated Hypothesis. Ethology, , no-no.
Abstract: The ‘integrated hypothesis’ predicts that reconciliation (the post-conflict friendly interaction between former opponents observed in various group-living species) functions to reduce anxiety and the risk of aggression from the former opponent or a bystander in the aftermath of a conflict. It also predicts that relationship quality between opponents affects the occurrence of reconciliation and modulates the anxious response of the opponents after a conflict. Because of the asymmetric nature of aggressive interactions, the cost of aggression is likely to differ between the victim and the aggressor. The aim of this study was to test the predictions of the ‘integrated hypothesis’ independently for the victim and the aggressor of a conflict. We collected data on two wild groups of Barbary macaques. This study represents, to our knowledge, the first systematic test of the integrated hypothesis on wild, non-provisioned animals. Victims of aggression were at a greater risk of receiving aggression from the former opponent or a bystander after a conflict and showed elevated anxiety. We found no such costs for the aggressor. Reconciliation reduced anxiety in the victim but did not reduce their risk of receiving aggression. Finally, relationship quality affected the occurrence of reconciliation but did not modulate post-conflict anxiety. The results of our study show that the costs of aggression are asymmetrically distributed between the victim and the aggressor. Such differences are likely to lead to different social tactics used by the victim and the aggressor in the aftermath of a conflict.
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Cain, K. E., Rich, M. S., Ainsworth, K., & Ketterson, E. D. (2011). Two Sides of the Same Coin? Consistency in Aggression to Conspecifics and Predators in a Female Songbird. Ethology, 117(9), 786–795.
Abstract: Different forms of aggression have traditionally been treated separately according to function or context (e.g., aggression towards a conspecific vs. a predator). However, recent work on individual consistency in behavior predicts that different forms of aggression may be correlated across contexts, suggesting a lack of independence. For nesting birds, aggression towards both conspecifics and nest predators can affect reproductive success, yet the relationship between these behaviors, especially in females, is not known. Here, we examine free-living female dark-eyed juncos (Junco hyemalis) and compare their aggressive responses towards three types of simulated intruders near the nest: a same-sex conspecific, an opposite-sex conspecific, and a nest predator. We also examine differences in the strength of response that might relate to the immediacy of the perceived threat the intruder poses for the female or her offspring. We found greater aggression directed towards a predator than a same-sex intruder and towards a same-sex than an opposite-sex intruder, consistent with a predator being a more immediate threat than a same-sex intruder, followed by an opposite-sex intruder. We also found positive relationships across individuals between responses to a same-sex intruder and a simulated predator, and between responses to a same-sex and an opposite-sex intruder, indicating that individual females are consistent in their relative level of aggression across contexts. If correlated behaviors are mediated by related mechanisms, then different forms of aggression may be expressions of the same behavioral tendency and constrained from evolving independently.
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Pays, O., Sirot, E., & Fritz, H. (2011). Collective Vigilance in the Greater Kudu: Towards a Better Understanding of Synchronization Patterns. Ethology, , no-no.
Abstract: Collective detection of predators is one of the main advantages of living in groups in prey species. However, the mechanisms linking individual and collective vigilance remain largely unknown. Here, we investigated individual and collective vigilance in a natural population of greater kudu (Tragelaphus strepsiceros), a gregarious ruminant living under high predation risk. Controlling for environmental, individual and group factors, we show that the proportion of time during which at least one individual was vigilant increased with group size, whereas individual investment in vigilance decreased. We also show that individuals tended to synchronize both vigilance and feeding activities. More generally, and whatever the considered group size, we demonstrate how the independent scanning assumption underestimated both the proportion of time during which no individual was vigilant and the proportion of time during which all individuals were simultaneously vigilant, but overestimated the proportion of time during which one vigilant individual only was present. Our results thus contrast with the point of view that the alternative to independent vigilance is coordinated vigilance and plead for a better description of the processes whereby reciprocal influences between individuals shape collective patterns of vigilance.
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