Herring schooling manoeuvres in response to killer whale attacks

Nøttestad, Leif; Axelsen, Bjørn Erik

doi:10.1139/cjz-77-10-1540

Cited by 51 publications

(75 citation statements)

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“…7 and 8) or antipredator tactics of schooling fish or of ungulate or other types of "selfish" herds (refs. [43][44][45][46][47][48]]. Foraging and predation tradeoffs may also be important to the colonial orb-weaving spiders.…”

Section: Discussionmentioning

confidence: 99%

Cooperative capture of large prey solves scaling challenge faced by spider societies

Yip

Powers

Avilés

2008

Proc. Natl. Acad. Sci. U.S.A.

165

145

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A decrease in the surface area per unit volume is a well known constraint setting limits to the size of organisms at both the cellular and whole-organismal levels. Similar constraints may apply to social groups as they grow in size. The communal three-dimensional webs that social spiders build function ecologically as single units that intercept prey through their surface and should thus be subject to this constraint. Accordingly, we show that web prey capture area per spider, and thus number of insects captured per capita, decreases with colony size in a neotropical social spider. Prey biomass intake per capita, however, peaks at intermediate colony sizes because the spiders forage cooperatively and larger colonies capture increasingly large insects. A peaked prey biomass intake function would explain not only why these spiders live in groups and cooperate but also why they disperse only at large colony sizes, thus addressing both sociality and colony size range in this social spider. These findings may also explain the conspicuous absence of social spiders from higher latitudes and higher elevations, areas that we have previously shown to harbor considerably fewer insects of the largest size classes than the lowland tropical rainforests where social spiders thrive. Our findings thus illustrate the relevance of scaling laws to the size and functioning of levels of organization above the individual.Anelosimus ͉ cooperation ͉ group foraging ͉ sociality ͉ allometry

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Section: Discussionmentioning

confidence: 99%

Cooperative capture of large prey solves scaling challenge faced by spider societies

Yip

Powers

Avilés

2008

Proc. Natl. Acad. Sci. U.S.A.

165

145

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“…Prey can actively defend themselves through predator mobbing (Krebs and Davies, 1993), more vigilant scanning for predators (Mooring et al, 2004) or confusion effect when schooling (Nottestad and Axelsen, 1999). Passive defence (the dilution effect) is characterized by per-capita predation probability declining with increasing prey density and corresponds to a type II functional response (Gascoigne and Lipcius, 2004).…”

Section: Introductionmentioning

confidence: 99%

Caught between two Allee effects: Trade-off between reproduction and predation risk

Pavlová

Berec

Boukal

2010

Journal of Theoretical Biology

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Abstract:Reproductive activities are often associated with conspicuous morphology or behaviour that could be exploited by predators. Individuals can therefore face a trade-off between reproduction and predation risk. Here we use simple models to explore population-dynamical consequences of such a trade-off for populations subject to a mate-finding Allee effect and an Allee effect due to predation. We present our results in the light of populations that belong to endangered species or pests and study their viability and resilience. We distinguish several qualitative scenarios characterized by the shape and strength of the trade-off and, in particular, identify conditions for which the populations survive or go extinct. Reproduction can be so costly that the population always goes extinct. In other cases, the population goes extinct only over a certain range of low, intermediate or high levels of reproductive activities. Moreover, we show that predator removal (e.g. in an attempt to save an endangered prey species) has the least effect on populations with low cost of reproduction in terms of predation and, conversely, predator addition (e.g. to eradicate a pest) is most effective for populations with high predation cost of reproduction. Our results indicate that a detailed knowledge of the trade-off can be crucial in applications: for some trade-off shapes, only intermediate levels of reproductive activities might guarantee population survival, while they can lead to extinction for others. We therefore suggest that the fate of populations subject to the two antagonistic Allee effects should be evaluated on a case-by-case basis. Although the literature offers no quantitative data on possible trade-off shapes in any taxa, indirect evidence suggests that the trade-off and both Allee effects can occur simultaneously, e.g. in the golden egg bug Phyllomorpha laciniata.

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“…Anti-predator resp herring have been documented (Nøttestad & Axelsen, 1999) and it is probable that herring take advantage of momentary breaks in orca group formation to disperse laterally and dive, rendering their geometry and vertical position more challenging for tail slapping. In addition, certain fish densities and quantities may be insufficient to merit further shoa leading the orcas to abort their efforts prematurely (Nøttestad et al, 2002).…”

Section: Oo06_327smentioning

confidence: 99%

“…Once the herring have been gathered at the surface, the orcas further corral them into a small, compact and circular ball by swimming around the fish, flashing their white ventral sides and releasing bubbles (Similä & Ugarte, 1993;Nøttestad & Axelsen, 1999).…”

Section: Introductionmentioning

confidence: 99%

Orchestration : the movement and vocal behavior of free-ranging Norwegian killer whales (Orcinus orca)

Shapiro¹

2008

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Studying the social and cultural transmission of behavior among animals helps to identify patterns of interaction and information content flowing between individuals. Killer whales are likely to acquire traits culturally based on their population-specific feeding behaviors and group-distinctive vocal repertoires. I used digital tags to explore the contributions of individual Norwegian killer whales to group carousel feeding and the relationships between vocal and non-vocal activity.Periods of tail slapping to incapacitate herring during feeding were characterized by elevated movement variability, heightened vocal activity and call types containing additional orientation cues. Tail slaps produced by tagged animals were identified using a rapid pitch change and occurred primarily within 20m of the surface. Two simultaneously tagged animals maneuvered similarly when tail slapping within 60s of one another, indicating that the position and composition of the herring ball influenced their behavior.Two types of behavioral sequence preceding the tight circling of carousel feeding were apparent. First, the animals engaged in periods of directional swimming. They were silent in 2 of 3 instances, suggesting they may have located other foraging groups by eavesdropping. Second, tagged animals made broad horizontal loops as they dove in a manner consistent with corralling. All 4 of these occasions were accompanied by vocal activity, indicating that this and tail slapping may benefit from social communication. No significant relationship between the call types and the actual movement measurements was found.Killer whale vocalizations traditionally have been classified into discrete call types. Using human speech processing techniques, I considered that calls are alternatively comprised of shared segments that can be recombined to form the stereotyped and variable repertoire. In a classification experiment, the characterization of calls using the whole call, a set of unshared segments, or a set of shared segments yielded equivalent performance. The shared segments required less information to parse the same vocalizations, suggesting a more parsimonious system of representation.This closer examination of the movements and vocalizations of Norwegian killer 3 whales, combined with future work on ontogeny and transmission, will inform our understanding of whether and how culture plays a role in achieving population-specific behaviors in this species. 4 ACKNOWLEDGEMENTS

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Herring schooling manoeuvres in response to killer whale attacks

Cited by 51 publications

References 0 publications

Cooperative capture of large prey solves scaling challenge faced by spider societies

Cooperative capture of large prey solves scaling challenge faced by spider societies

Caught between two Allee effects: Trade-off between reproduction and predation risk

Orchestration : the movement and vocal behavior of free-ranging Norwegian killer whales (Orcinus orca)

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