Testing the Terrain Hypothesis: Canada Geese See Their World Laterally and Obliquely
The distribution of ganglion cells in the retina determines the specific regions of the visual field with high visual acuity, and thus reflects the perception of a species’ visual environment. The terrain hypothesis proposes that animals living in open areas should have a horizontal visual streak ac...
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2011
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ftunivnebraskali:oai:digitalcommons.unl.edu:icwdm_usdanwrc-2289 2023-11-12T04:15:26+01:00 Testing the Terrain Hypothesis: Canada Geese See Their World Laterally and Obliquely Fernández-Juricic, Esteban Moore, Bret A. Doppler, Megan Freeman, Joseph Blackwelll, Bradley F. Lima, Steven L. DeVault, Travis L. 2011-01-01T08:00:00Z application/pdf https://digitalcommons.unl.edu/icwdm_usdanwrc/1291 https://digitalcommons.unl.edu/context/icwdm_usdanwrc/article/2289/viewcontent/Fernandez_BBE_2011_Testing_the_Terrain_Hypothesis.pdf unknown DigitalCommons@University of Nebraska - Lincoln https://digitalcommons.unl.edu/icwdm_usdanwrc/1291 https://digitalcommons.unl.edu/context/icwdm_usdanwrc/article/2289/viewcontent/Fernandez_BBE_2011_Testing_the_Terrain_Hypothesis.pdf USDA Wildlife Services - Staff Publications Birds Canada goose Ganglion cells Retinal topography Terrain hypothesis Vigilance Visual fields Life Sciences text 2011 ftunivnebraskali 2023-10-30T11:06:02Z The distribution of ganglion cells in the retina determines the specific regions of the visual field with high visual acuity, and thus reflects the perception of a species’ visual environment. The terrain hypothesis proposes that animals living in open areas should have a horizontal visual streak across the retina with high ganglion cell density to increase visual acuity along the horizon. We tested this hypothesis in Canada geese (Branta canadensis) by assessing retinal topography, visual field configuration, and scanning behavior. We found that geese have an oblique rather than a horizontal visual streak across the retina: from a dorsal-nasal to a ventral-temporal position. Geese showed narrow blind areas, which increased the range of their lateral vision, and a relatively large degree of eye movement. Canada geese have relatively wide binocular fields and can see their bill tips. Goose head movement rates were low compared to species with a single fovea, and head movement rates increased in visually obstructed habitats. Canada geese have high acuity across their retina, which would allow them to simultaneously scan the ground and the sky when the head is up and parallel to the ground, as well as align the visual streak with the horizon when the head is tilted downwards. Their visual streak, along with their large eye size, may reduce the need for large amplitude head movements during vigilance bouts in visually unobstructed habitats. Overall, the visual system of geese combines features related to the detection of predators/conspecifics in open areas (visual streak, large lateral field, reduced head movements) as well as visual specializations that would allow for monitoring both the ground and sky (oblique streak) and for extracting and handling of food items (wide binocular fields, visualization of the bill tip). Text Branta canadensis Canada Goose University of Nebraska-Lincoln: DigitalCommons@UNL Canada |
institution |
Open Polar |
collection |
University of Nebraska-Lincoln: DigitalCommons@UNL |
op_collection_id |
ftunivnebraskali |
language |
unknown |
topic |
Birds Canada goose Ganglion cells Retinal topography Terrain hypothesis Vigilance Visual fields Life Sciences |
spellingShingle |
Birds Canada goose Ganglion cells Retinal topography Terrain hypothesis Vigilance Visual fields Life Sciences Fernández-Juricic, Esteban Moore, Bret A. Doppler, Megan Freeman, Joseph Blackwelll, Bradley F. Lima, Steven L. DeVault, Travis L. Testing the Terrain Hypothesis: Canada Geese See Their World Laterally and Obliquely |
topic_facet |
Birds Canada goose Ganglion cells Retinal topography Terrain hypothesis Vigilance Visual fields Life Sciences |
description |
The distribution of ganglion cells in the retina determines the specific regions of the visual field with high visual acuity, and thus reflects the perception of a species’ visual environment. The terrain hypothesis proposes that animals living in open areas should have a horizontal visual streak across the retina with high ganglion cell density to increase visual acuity along the horizon. We tested this hypothesis in Canada geese (Branta canadensis) by assessing retinal topography, visual field configuration, and scanning behavior. We found that geese have an oblique rather than a horizontal visual streak across the retina: from a dorsal-nasal to a ventral-temporal position. Geese showed narrow blind areas, which increased the range of their lateral vision, and a relatively large degree of eye movement. Canada geese have relatively wide binocular fields and can see their bill tips. Goose head movement rates were low compared to species with a single fovea, and head movement rates increased in visually obstructed habitats. Canada geese have high acuity across their retina, which would allow them to simultaneously scan the ground and the sky when the head is up and parallel to the ground, as well as align the visual streak with the horizon when the head is tilted downwards. Their visual streak, along with their large eye size, may reduce the need for large amplitude head movements during vigilance bouts in visually unobstructed habitats. Overall, the visual system of geese combines features related to the detection of predators/conspecifics in open areas (visual streak, large lateral field, reduced head movements) as well as visual specializations that would allow for monitoring both the ground and sky (oblique streak) and for extracting and handling of food items (wide binocular fields, visualization of the bill tip). |
format |
Text |
author |
Fernández-Juricic, Esteban Moore, Bret A. Doppler, Megan Freeman, Joseph Blackwelll, Bradley F. Lima, Steven L. DeVault, Travis L. |
author_facet |
Fernández-Juricic, Esteban Moore, Bret A. Doppler, Megan Freeman, Joseph Blackwelll, Bradley F. Lima, Steven L. DeVault, Travis L. |
author_sort |
Fernández-Juricic, Esteban |
title |
Testing the Terrain Hypothesis: Canada Geese See Their World Laterally and Obliquely |
title_short |
Testing the Terrain Hypothesis: Canada Geese See Their World Laterally and Obliquely |
title_full |
Testing the Terrain Hypothesis: Canada Geese See Their World Laterally and Obliquely |
title_fullStr |
Testing the Terrain Hypothesis: Canada Geese See Their World Laterally and Obliquely |
title_full_unstemmed |
Testing the Terrain Hypothesis: Canada Geese See Their World Laterally and Obliquely |
title_sort |
testing the terrain hypothesis: canada geese see their world laterally and obliquely |
publisher |
DigitalCommons@University of Nebraska - Lincoln |
publishDate |
2011 |
url |
https://digitalcommons.unl.edu/icwdm_usdanwrc/1291 https://digitalcommons.unl.edu/context/icwdm_usdanwrc/article/2289/viewcontent/Fernandez_BBE_2011_Testing_the_Terrain_Hypothesis.pdf |
geographic |
Canada |
geographic_facet |
Canada |
genre |
Branta canadensis Canada Goose |
genre_facet |
Branta canadensis Canada Goose |
op_source |
USDA Wildlife Services - Staff Publications |
op_relation |
https://digitalcommons.unl.edu/icwdm_usdanwrc/1291 https://digitalcommons.unl.edu/context/icwdm_usdanwrc/article/2289/viewcontent/Fernandez_BBE_2011_Testing_the_Terrain_Hypothesis.pdf |
_version_ |
1782332746109026304 |