The confusion effect—from neural networks to reduced predation risk

Ioannou, Christos C.; Tosh, Colin R.; Neville, Lisa A.; Krause, Jens

doi:10.1093/beheco/arm109

Cited by 97 publications

(73 citation statements)

References 19 publications

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“…1B) (19), allowing us to approximate the time taken to make each targeting decision. Consistent with a confusion effect (26), this decision time increased with the prey target's group size (GLM: LRT 1,67 = 11.32, P = 0.00077). Although this accounts for the targeting of prey in smaller groups, there was no evidence that a prey's tortuosity, either alone or as part of an interaction with group size, had any additional effect [LRT 1,67 = 0.029, P = 0.86; and LRT 1,66 = 0.22, P = 0.64, respectively; see also (7,8)].…”

supporting

confidence: 64%

Predatory Fish Select for Coordinated Collective Motion in Virtual Prey

Ioannou

Guttal

Couzin

2012

Science

306

266

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Movement in animal groups is highly varied and ranges from seemingly disordered motion in swarms to coordinated aligned motion in flocks and schools. These social interactions are often thought to reduce risk from predators, despite a lack of direct evidence. We investigated risk-related selection for collective motion by allowing real predators (bluegill sunfish) to hunt mobile virtual prey. By fusing simulated and real animal behavior, we isolated predator effects while controlling for confounding factors. Prey with a tendency to be attracted toward, and to align direction of travel with, near neighbors tended to form mobile coordinated groups and were rarely attacked. These results demonstrate that collective motion could evolve as a response to predation, without prey being able to detect and respond to predators.

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supporting

confidence: 64%

Predatory Fish Select for Coordinated Collective Motion in Virtual Prey

Ioannou

Guttal

Couzin

2012

Science

306

266

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“…The trade-off between these costs and benefits can be a major strength determining the spatial properties of animal groups (e.g., Parrish and Edelstein-Keshet 1999;Ebensperger et al 2006;Hirsch 2007;Morrell and James 2008). For example, previous studies have demonstrated that two of the most important factors influencing animal group size (the number of individuals in the group) and density are the presence of effective mechanisms for reducing predation (Krause and Ruxton 2002;Ioannou et al 2007), and feeding competition (reviewed in Hirsch 2007). Studies of various species have shown that under conditions of increasing predation risk, animals form larger and denser groups (Spieler 2003;Hoare et al 2004).…”

Section: Discussionmentioning

confidence: 99%

“…Exogenous factors, such as the presence of predators (Hamilton 1971;Beecham and Farnsworth 1999;Krause and Ruxton 2002;Hoare et al 2004;Ioannou et al 2007;Ioannou and Krause 2008) or various conditions (e.g., time of day, season, temperature, the probability of food acquisition, synchronizing activity budgets: Perry 1995a; Parrish and Hamner 1997;Ruckstuhl 1999;Chesson 2000;Gerard et al 2002;Korte 2008b) are common mechanisms that can trigger animal aggregation, increase group size and cohesion and decrease attack success. In several species (e.g.…”

Section: Introductionmentioning

confidence: 99%

Spatial properties of a forest buffalo herd and individual positioning as a response to environmental cues and social behaviour

Melletti

Delgado

Penteriani

et al. 2010

J Ethol

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Many animals aggregate into organized temporary or stable groups under the influence of biotic and abiotic factors, and some studies have shown the influence of habitat features on animal aggregation. This study, conducted from 2002 to 2004 in the Dzanga-Ndoki National Park, Central African Republic, studied a herd of forest buffaloes (Syncerus caffer nanus) to determine whether spatial aggregation patterns varied by season and habitat. Our results show that both habitat structure and season influenced spatial aggregation patterns. In particular, in open habitats such as clearings, the group covered a larger area when resting and was more rounded in shape compared to group properties noted in forest during the wet season. Moreover, forest buffaloes had a more aggregated spatial distribution when resting in clearings than when in the forest, and individual positions within the herd in the clearing habitat varied with age and sex. In the clearings, the adult male (n = 24) was generally, on most occasions, located in the centre of the herd (n = 20), and he was observed at the border only four times. In contrast, females (n = 80) occupied intermediate (n = 57), peripheral (n = 14) and central positions (n = 9) within the group. Juveniles (n = 77) also occurred in intermediate (n = 64) and peripheral positions (n = 13). Based on these results, we concluded that habitat characteristics and social behaviour can have relevant effects on the spatial distribution of animals within a group

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“…The difference in the strength of the observed responses to the vessel noise between the low-and high-density shoals can potentially be interpreted as a differential assessment of predation risk. Shoaling is commonly presented as an adaptive strategy that enhances fish safety through the action of several antipredatory mechanisms, which include a numerical dilution of risk (Pitcher and Parrish 1993), collective predator detection (Magurran et al 1985), a confusion effect (Landeau and Terborgh 1986;Ioannou et al 2008), or coordinated escape maneuvers (Pitcher and Parrish 1993). The safety of prey is expected to increase with aggregation size; fish in larger shoals may enjoy reduced predation risk compared with fish in smaller shoals (Pitcher and Parrish 1993;Krause and Ruxton 2002).…”

Section: Discussionmentioning

confidence: 99%

The reaction of a captive herring school to playbacks of a noise-reduced and a conventional research vessel

Handegard

Robertis

Rieucau

et al. 2015

Can. J. Fish. Aquat. Sci.

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Fish avoidance of vessels can bias fisheries-independent surveys. To understand these biases, recordings of underwater radiated vessel noise from a noise-reduced and a conventional research vessel were played back at the same sound pressure levels (SPL) as experienced in situ to Atlantic herring (Clupea harengus) in a net pen at two different densities. The noise-reduced vessel recording was also scaled to the same SPL as the conventional vessel to test if characteristics other than SPL affected the reactions. Overall, only weak reactions were observed, but reactions were stronger in the low-density school, in the middle of the pen, and for the scaled silent vessel compared with the conventional vessel. These observations may be attributable to the lack of low frequencies (<50 Hz) in the playbacks, differential motivation for reaction driven by fish density, higher low-frequency noise in the middle of the pen (but lower overall SPL), and characteristics other than SPL. These results call into question the use of SPL as a proxy for fish reaction to vessels as used in standards for construction of research vessels. Résumé :Les réactions d'évitement de poissons face à des navires peuvent biaiser les inventaires indépendants de pêche. Afin d'évaluer l'étendue de tels biais, une expérience de repasses de séquences sonores a été effectuée sur des bancs de harengs atlantique (Clupea harengus), de densités différentes, placés dans des enclos en filet. Les séquences sonores utilisées comprenaient des enregistrements d'un navire conventionnel et d'un navire à niveaux sonores réduits, « navire silencieux », toutes présentées aux mêmes niveaux de pression acoustique (NPA) que ceux auxquels les harengs sont généralement soumis in situ. Le navire à niveaux sonores réduits a également été rehaussé aux mêmes NPA que ceux produits par le navire conventionnel afin de déterminer si des facteurs autres que les NPA peuvent affecter les réactions d'évitement des harengs. En général, seules de faibles réactions aux séquences sonores ont été observées. Cependant, de plus fortes réactions ont été observées pour le banc de faible densité comparées au banc de forte densité, ainsi que de plus fortes réactions lors de repasses de séquences sonores rehaussées du navire silencieux comparées au navire conventionnel. De telles observations peuvent être expliquées soit par l'absence de basses fréquences (<50 Hz) dans les repasses sonores, soit par différents niveaux de motivation à répondre aux repasses en lien avec les différences de densité entre les bancs, soit par l'effet de basses fréquences acoustiques plus élevées au milieu de l'enclos en filet (malgré de plus faibles NPA), ou soit par des facteurs autres que les NPA. Par conséquent, les résultats obtenus lors de notre expérience questionnent la justesse de l'utilisation des NPA comme un indice de réactions de poissons face à des navires; comme il est pratique courante lors de la construction de navires de recherche.

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The confusion effect—from neural networks to reduced predation risk

Cited by 97 publications

References 19 publications

Predatory Fish Select for Coordinated Collective Motion in Virtual Prey

Predatory Fish Select for Coordinated Collective Motion in Virtual Prey

Spatial properties of a forest buffalo herd and individual positioning as a response to environmental cues and social behaviour

The reaction of a captive herring school to playbacks of a noise-reduced and a conventional research vessel

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