Avian Senses: Vision, Hearing, and Beyond

1. Chapter 7 – senses, brains and intelligence Lecture Wednesday and Friday, during lab we may go out birding if no one needs help with projects.

2. Avian Senses • Avian experience of the world not like mammalian experience • Vision much richer and better developed than mammals • Able to detect (possibly via vision) things mammals cannot • Like humans birds possess language, tool making ability, and culture (learning and passing it on) Woodpecker Finch (Camarhynchus pallidus) New Caledonia Crow (Corvus moneduloides)

3. Avian Senses • Birds are extremely visual • Eyes are a significant portion of the head • Up to 15% of the head mass • Greater distance resolution than mammals • 2.5-3x that of humans • Both monocular and binocular vision (varies with eye location)

4. Avian Senses

5. Avian Senses Fovea are areas of acute vision where the retina is arranged in a pit-like structure. This may allow for enhanced visual acuity.

6. Avian Senses Raptors like the Zoned-tailed Hawk (Buteo albonotatus) above can have multiple fovea possibly for greater visual acuity during flight and hunting

7. Avian Senses • Avian pecten • Unique structure • Large and darkly pigmented, seems not to interfere with vision • May be a source of nutrition and oxygen for the retina Pecten location

8. Avian Senses • Avian color vision different from ours • Birds possess 4 color cones • With cones are oils that limit the portion of spectrum responded to • One cone responds to UV light • “Birds see colors we don’t even have names for or can even imagine!” UV light is integrated with the visible portion of the spectrum, we have no idea how this is done

9. Avian Senses • Birds can perceive magnetic fields • Used in navigation during migration by many • Magnetite can be found in bird skulls, particularly in the eye area • Rhodopsin may have a role

10. Avian Senses • Hearing • Externally, birds have no structures like mammals • Only a single bone in the ear – the stapes • Ear structure simpler than mammals and hearing not any better than mammals Location of ear opening

11. Avian Senses • Species of particular note – the owls • Feather ruff or disk around face focuses sound • Can hear sounds inaudible to humans • Asymmetrical ear location facilitates greater sound location

12. Avian Senses Herbst corpuscle for mechanoreception Semi-circular canals for equilibrium

13. Avian Senses • Chemical senses: • Birds do possess taste buds, can taste basic tastes • Question, do vultures possess tastebuds? If so, why? • Birds possess the sense of smell • Small olfactory bulbs gave sense of smell a bad rap • Scent used for food and navigation (again, messing with the Pigeons) • Growing interest in use of scent during reproduction and mate choice • Gonadotropin-releasing hormone neurohormones originate from olfactory placode (mammals, perhaps birds too), may influence sex and scent

14. Avian Senses Dark-eyed Juncos (Junco hyemalis) Crested Auklets (Aethia cristatella)

15. Avian Senses • Bird brains • Brains large in size given body size • ‘Bird brain’ not an insult

16. Avian senses Things to note, the eyes are huge! The brain (the pink stuff you can see through the skull) is large too

17. Avian Senses

18. Avian Senses

19. Avian Senses • In birds spatial memory and cognitive memory is well developed • Foraging, caching, territorial boundaries • Friend and foe, predators • Food storing species have been shown to experience neuron death and neurogenesis • Seasonal change over in the brain • Song control system (SCS) experiences this also

20. Spring Northern Cardinal (Cardinalis cardinalis) high vocal center (HVC), impacts song learning and production Seasonal and sex differences observed in many species Male Female

21. Avian Senses Cognition and intelligence Blue Jays learn all sorts of stuff, both good and bad for researchers