1 / 30

Avian Sensory Systems

Avian Sensory Systems. Sensory world similar to ours, that of other primates, primarily visual Are some subtle and some significant differences Senses of birds are NOT well understood. Vision is the primary sense, avian eyes are large. Vision.

more
Download Presentation

Avian Sensory Systems

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Avian Sensory Systems • Sensory world similar to ours, that of other primates, primarily visual • Are some subtle and some significant differences • Senses of birds are NOT well understood

  2. Vision is the primary sense, avian eyes are large

  3. Vision • In most species, primary sense used to locate, identify and obtain food • Primary sense in predator detection • Important in flight, displays (communication) • Map of world is visual

  4. Key Structural Components of the Avian Eye • Lens: focuses light on retina • Retina: image-forming region • Pectin: supplies O2, nutrients to retina (a significant difference)

  5. Visual acuity of birds is NOT well understood • Cones more dense: + • Flat eyes: - (some have round eyes) • Each cone has own nerve fiber: + • Steep fovea magnifies image: + • Steep fovea distorts image: - • Guess: most birds slightly better than us, a few much better

  6. Other Features of Avian Vision • Steep fovea enables birds to follow moving objects well (pursuit of prey) • Eyes located on side of head, many birds have only one fovea per eye, lack binocular vision, lack depth perception • Birds have a wide field of view (3000+ common, up to 3600 in Woodcock)

  7. Binocular vision of owls: 2 fovea per eye, eyes located in front

  8. More Features • Species with 2nd fovea (located inside edge of the eye) have binocular vision (raptors, aerial hawkers) • Color vision NOT well understood due to presence of oil droplets • Richer, see ultraviolet • See better through glare, at dawn • Detect polarized light

  9. One more feature: better accommodation due to muscles working on lens and cornea

  10. Hearing: Total range of frequencies heard by birds similar to us, but each bird species has narrower range Species hear best the frequencies of their own calls and song

  11. Ear Structure • No external flap, rim around opening amplifies sound in species hunt by sound • Ear drum separates outer, middle ear (like us), single bone in middle ear transfers sound to inner ear (3 bones in us) • 3 fluid-filled canals for balance next to middle ear • Sound receptors in cochlea of inner ear

  12. Features of Avian Cochlea • More dense sensory hairs suggest more sensitivity (types determine frequencies heard, number stimulated determines intensity perceived) • Tissue as well as fluid above sensory hairs suggests better temporal resolution, ability to detect complexities of song • Experimental tests do not support

  13. Owls and harriers use sound to locate prey • Rims around ear openings amplify sound • Round heads collect sound • Asymmetric ears (both horizontally and vertically) enable localization of sound

  14. Echolocation • Occurs in 2 families, oilbirds and cave swiftlets • Low frequency sounds (clicks) enable orientation in dark caves

  15. Birds have olfactory organ, but sense smell NOT well understood • Turkey vultures, tubenoses, honeyguides use locate food • Some tubenoses use to locate burrows • Kiwis use to detect food underground • Use unknown in most species

  16. Birds have taste buds, but use of sense of taste NOT well understood Birds use vision or touch, not taste, to identify food

  17. Sense of touch (tactile) • Herbst (and other) corpuscles are mechanoreceptors • Located on filoplumes, bristles • Located on bills (especially probers), tongues (woodpeckers) of some species for prey detection

  18. Other senses of birds • Magnetic sense • Sensitive to changes in barometric pressure • Hear infrasound (super-long wavelengths) • All are foreign to us, used in migration

  19. Features of Avian Brain • Large optic lobes, small olfactory lobes • Large cerebellum • Site of higher learning centers, complex neural processing is corpus striatum (middle cerebrum), not cerebral cortex (outer cerebrum) • Left hemisphere dominance

  20. The Control System • Consists of nervous and hormonal systems • Elements of the hormonal system: adrenal, thyroid and pituitary glands and the gonads • Hypothalamus (midbrain) controls the hormonal system • Neurosecretions act on adjacent pituitary • Hormones from pituitary control other glands

  21. Avian “intelligence” • Many birds have complex social memories, aware of relationships to others (cooperative breeders, other social species) • Some birds have well developed spatial memories, can remember thousands of locations (corvids, chickadees; parrots) • Parrots demonstrate cognitive abstract reasoning, semantic signaling (others?)

More Related