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Aerial attack strategies of hawks hunting bats, and the adaptive benefits of swarming

Aggregation can reduce an individual’s predation risk, by decreasing predator hunting efficiency or displacing predation onto others. Here, we explore how the behaviors of predator and prey influence catch success and predation risk in Swainson’s hawks Buteo swainsoni attacking swarming Brazilian fr...

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Autores principales: Brighton, Caroline H, Zusi, Lillias, McGowan, Kathryn A, Kinniry, Morgan, Kloepper, Laura N, Taylor, Graham K
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Oxford University Press 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8177810/
https://www.ncbi.nlm.nih.gov/pubmed/34104109
http://dx.doi.org/10.1093/beheco/araa145
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author Brighton, Caroline H
Zusi, Lillias
McGowan, Kathryn A
Kinniry, Morgan
Kloepper, Laura N
Taylor, Graham K
author_facet Brighton, Caroline H
Zusi, Lillias
McGowan, Kathryn A
Kinniry, Morgan
Kloepper, Laura N
Taylor, Graham K
author_sort Brighton, Caroline H
collection PubMed
description Aggregation can reduce an individual’s predation risk, by decreasing predator hunting efficiency or displacing predation onto others. Here, we explore how the behaviors of predator and prey influence catch success and predation risk in Swainson’s hawks Buteo swainsoni attacking swarming Brazilian free-tailed bats Tadarida brasiliensis on emergence. Lone bats including stragglers have a high relative risk of predation, representing ~5% of the catch but ~0.2% of the population. Attacks on the column were no less successful than attacks on lone bats, so hunting efficiency is not decreased by group vigilance or confusion. Instead, lone bats were attacked disproportionately often, representing ~10% of all attacks. Swarming therefore displaces the burden of predation onto bats outside the column—whether as isolated wanderers not benefitting from dilution through attack abatement, or as peripheral stragglers suffering marginal predation and possible selfish herd effects. In contrast, the hawks’ catch success depended only on the attack maneuvers that they employed, with the odds of success being more than trebled in attacks involving a high-speed stoop or rolling grab. Most attacks involved one of these two maneuvers, which therefore represent alternative rather than complementary tactics. Hence, whereas a bat’s survival depends on maintaining column formation, a hawk’s success does not depend on attacking lone bats—even though their tendency to do so is sufficient to explain the adaptive benefits of their prey’s aggregation behavior. A hawk’s success instead depends on the flight maneuvers it deploys, including the high-speed stoop that is characteristic of many raptors. Swarming bats emerging from a massive desert roost reduce their predation risk by maintaining tight column formation, because the hawks that predate them attack peripheral stragglers and isolated wanderers disproportionately. Whereas a bat’s predation risk depends on maintaining its position within the column, the catch success of a hawk depends on how it maneuvers itself to attack, and is maximized by executing a high-speed dive or rolling grab maneuver.
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spelling pubmed-81778102021-06-07 Aerial attack strategies of hawks hunting bats, and the adaptive benefits of swarming Brighton, Caroline H Zusi, Lillias McGowan, Kathryn A Kinniry, Morgan Kloepper, Laura N Taylor, Graham K Behav Ecol Original Articles Aggregation can reduce an individual’s predation risk, by decreasing predator hunting efficiency or displacing predation onto others. Here, we explore how the behaviors of predator and prey influence catch success and predation risk in Swainson’s hawks Buteo swainsoni attacking swarming Brazilian free-tailed bats Tadarida brasiliensis on emergence. Lone bats including stragglers have a high relative risk of predation, representing ~5% of the catch but ~0.2% of the population. Attacks on the column were no less successful than attacks on lone bats, so hunting efficiency is not decreased by group vigilance or confusion. Instead, lone bats were attacked disproportionately often, representing ~10% of all attacks. Swarming therefore displaces the burden of predation onto bats outside the column—whether as isolated wanderers not benefitting from dilution through attack abatement, or as peripheral stragglers suffering marginal predation and possible selfish herd effects. In contrast, the hawks’ catch success depended only on the attack maneuvers that they employed, with the odds of success being more than trebled in attacks involving a high-speed stoop or rolling grab. Most attacks involved one of these two maneuvers, which therefore represent alternative rather than complementary tactics. Hence, whereas a bat’s survival depends on maintaining column formation, a hawk’s success does not depend on attacking lone bats—even though their tendency to do so is sufficient to explain the adaptive benefits of their prey’s aggregation behavior. A hawk’s success instead depends on the flight maneuvers it deploys, including the high-speed stoop that is characteristic of many raptors. Swarming bats emerging from a massive desert roost reduce their predation risk by maintaining tight column formation, because the hawks that predate them attack peripheral stragglers and isolated wanderers disproportionately. Whereas a bat’s predation risk depends on maintaining its position within the column, the catch success of a hawk depends on how it maneuvers itself to attack, and is maximized by executing a high-speed dive or rolling grab maneuver. Oxford University Press 2021-03-31 /pmc/articles/PMC8177810/ /pubmed/34104109 http://dx.doi.org/10.1093/beheco/araa145 Text en © The Author(s) 2021. Published by Oxford University Press on behalf of the International Society for Behavioral Ecology. https://creativecommons.org/licenses/by/4.0/This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) ), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Original Articles
Brighton, Caroline H
Zusi, Lillias
McGowan, Kathryn A
Kinniry, Morgan
Kloepper, Laura N
Taylor, Graham K
Aerial attack strategies of hawks hunting bats, and the adaptive benefits of swarming
title Aerial attack strategies of hawks hunting bats, and the adaptive benefits of swarming
title_full Aerial attack strategies of hawks hunting bats, and the adaptive benefits of swarming
title_fullStr Aerial attack strategies of hawks hunting bats, and the adaptive benefits of swarming
title_full_unstemmed Aerial attack strategies of hawks hunting bats, and the adaptive benefits of swarming
title_short Aerial attack strategies of hawks hunting bats, and the adaptive benefits of swarming
title_sort aerial attack strategies of hawks hunting bats, and the adaptive benefits of swarming
topic Original Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8177810/
https://www.ncbi.nlm.nih.gov/pubmed/34104109
http://dx.doi.org/10.1093/beheco/araa145
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