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The light’s in my eyes: optical modeling demonstrates wind is more important than sea surface-reflected sunlight for foraging herons

Multiple lineages of birds have independently evolved foraging strategies that involve catching aquatic prey by striking at them through the water’s surface. Diurnal, visual predators that hunt across the air-water interface encounter several visual challenges, including sun glint, or reflection of...

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Autores principales: Brown, Holly K.M., Rubega, Margaret, Dierssen, Heidi M.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: PeerJ Inc. 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8485832/
https://www.ncbi.nlm.nih.gov/pubmed/34692240
http://dx.doi.org/10.7717/peerj.12006
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author Brown, Holly K.M.
Rubega, Margaret
Dierssen, Heidi M.
author_facet Brown, Holly K.M.
Rubega, Margaret
Dierssen, Heidi M.
author_sort Brown, Holly K.M.
collection PubMed
description Multiple lineages of birds have independently evolved foraging strategies that involve catching aquatic prey by striking at them through the water’s surface. Diurnal, visual predators that hunt across the air-water interface encounter several visual challenges, including sun glint, or reflection of sunlight by the water surface. Intense sun glint is common at the air-water interface, and it obscures visual cues from submerged prey. Visually-hunting, cross-media predators must therefore solve the problem of glint to hunt effectively. One obvious solution is to turn away from the sun, which would result in reduction of glint effects. However, turning too far will cast shadows over prey, causing them to flee. Therefore, we hypothesized that foraging herons would orient away from, but not directly opposite to the sun. Our ability to understand how predators achieve a solution to glint is limited by our ability to quantify the amount of glint that free-living predators are actually exposed to under different light conditions. Herons (Ardea spp.) are a good model system for answering questions about cross-media hunting because they are conspicuous, widely distributed, and forage throughout a variety of aquatic habitats, on a variety of submerged prey. To test our hypothesis, we employed radiative transfer modeling of water surface reflectance, drawn from optical oceanography, in a novel context to estimate the visual exposure to glint of free-living, actively foraging herons. We found evidence that Ardea spp. do not use body orientation to compensate for sun glint while foraging and therefore they must have some other, not yet understood, means of compensation, either anatomical or behavioral. Instead of facing away from the sun, herons tended to adjust their position to face into the wind at higher wind speeds. We suggest that radiative transfer modeling is a promising tool for elucidating the ecology and evolution of air-to-water foraging systems.
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spelling pubmed-84858322021-10-22 The light’s in my eyes: optical modeling demonstrates wind is more important than sea surface-reflected sunlight for foraging herons Brown, Holly K.M. Rubega, Margaret Dierssen, Heidi M. PeerJ Animal Behavior Multiple lineages of birds have independently evolved foraging strategies that involve catching aquatic prey by striking at them through the water’s surface. Diurnal, visual predators that hunt across the air-water interface encounter several visual challenges, including sun glint, or reflection of sunlight by the water surface. Intense sun glint is common at the air-water interface, and it obscures visual cues from submerged prey. Visually-hunting, cross-media predators must therefore solve the problem of glint to hunt effectively. One obvious solution is to turn away from the sun, which would result in reduction of glint effects. However, turning too far will cast shadows over prey, causing them to flee. Therefore, we hypothesized that foraging herons would orient away from, but not directly opposite to the sun. Our ability to understand how predators achieve a solution to glint is limited by our ability to quantify the amount of glint that free-living predators are actually exposed to under different light conditions. Herons (Ardea spp.) are a good model system for answering questions about cross-media hunting because they are conspicuous, widely distributed, and forage throughout a variety of aquatic habitats, on a variety of submerged prey. To test our hypothesis, we employed radiative transfer modeling of water surface reflectance, drawn from optical oceanography, in a novel context to estimate the visual exposure to glint of free-living, actively foraging herons. We found evidence that Ardea spp. do not use body orientation to compensate for sun glint while foraging and therefore they must have some other, not yet understood, means of compensation, either anatomical or behavioral. Instead of facing away from the sun, herons tended to adjust their position to face into the wind at higher wind speeds. We suggest that radiative transfer modeling is a promising tool for elucidating the ecology and evolution of air-to-water foraging systems. PeerJ Inc. 2021-09-28 /pmc/articles/PMC8485832/ /pubmed/34692240 http://dx.doi.org/10.7717/peerj.12006 Text en ©2021 Milton Brown et al. https://creativecommons.org/licenses/by/4.0/This is an open access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ) and either DOI or URL of the article must be cited.
spellingShingle Animal Behavior
Brown, Holly K.M.
Rubega, Margaret
Dierssen, Heidi M.
The light’s in my eyes: optical modeling demonstrates wind is more important than sea surface-reflected sunlight for foraging herons
title The light’s in my eyes: optical modeling demonstrates wind is more important than sea surface-reflected sunlight for foraging herons
title_full The light’s in my eyes: optical modeling demonstrates wind is more important than sea surface-reflected sunlight for foraging herons
title_fullStr The light’s in my eyes: optical modeling demonstrates wind is more important than sea surface-reflected sunlight for foraging herons
title_full_unstemmed The light’s in my eyes: optical modeling demonstrates wind is more important than sea surface-reflected sunlight for foraging herons
title_short The light’s in my eyes: optical modeling demonstrates wind is more important than sea surface-reflected sunlight for foraging herons
title_sort light’s in my eyes: optical modeling demonstrates wind is more important than sea surface-reflected sunlight for foraging herons
topic Animal Behavior
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8485832/
https://www.ncbi.nlm.nih.gov/pubmed/34692240
http://dx.doi.org/10.7717/peerj.12006
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