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19 Cards in this Set
- Front
- Back
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Hold phase of head bobbing And thrust phase |
Body moves forward as the bird walks, holds head still Thrust phase the head moves quickly, faster than body and thrusts out |
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Why hold head still |
To stabilize eyes still. Since birds cannot move their eyes they have to stabilize with a still head |
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Movement of head side to side vision benefits |
Better impression of distance |
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Motion parallax |
A depth cue that results from motion of the observer. Since objects that are closer move further across the visual field than distant ones. As the head moves, closer objects appear to move faster and distant more slowly Seen in multiple birds |
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Falcon stoop group a |
Problem is disturbance of the tear film Solution is nictitating membrane which clears the ocular surface of debris |
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How many eyelids do birds have |
3 |
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Group B falcon stoop |
Problem was rapidly drying ocular surface Solution is gland associated with the nictitating membrane. Feather like. Removes debris but secrets viscous fluid to prevent drying |
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In the falcon stoop the fovea and flight pattern are used together to... |
Prey sight and caoture |
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How is the prey image acquired during falconstoop |
They have two fovea, bnasal fovea is deeper which means less light scattering and presumably more cones. Temporal fovea simultaneous image capture (two different points at once. During spiralling flight they use nasal fovea and when they soar they use temporal fovea. Allows better aerodynamics |
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When is the temporal fovea used during flight |
During soaring |
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When is the nasal fovea used |
During spiral |
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Benefits of nasal fovea |
Able to sight prey from high elevation and keep it in sight because of spiral |
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Why fly spiralling if it might potentially take longer |
Deeper fovea has better acuity and the line of sight is 45 degrees |
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Relative receptor density of fovea of birds VS humans |
Acuity of humans due to narrow fovea is much narrower compared to a bird who has a shallow and a deep fovea |
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Conflict between aerodynamics and vision has tow hypotheses |
Either keep head straight and spiral for best vision or shorten path by flying straight but would have to turn head |
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The flight paths recorded by a tracking device of the peregrine falcons found that... |
Falcon begins approach to prey from far away with its deep fovea. When when closer, it can now see prey with shallow fovea. Shallow fovea associated with binocular vision and can leave spiral flight |
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How do UVS and UV vision retinal proteins differ |
6 amino acid substitions in the opsin |
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Deemed ancestral state of bird vision |
VS based on phylogenetics |
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Passeriformes have UVS vision EXCEPT... |
Tyranidae and corvidae |
