Bird Anatomy

1. Bird Anatomy

2. Circulatory System • Separate systemic, pulmonary circulations • 4-chambered heart • Same in mammals - homeotherms

3. Hearts • 1.5-2 X larger than in comparable mammals • Maintain higher metabolism • Smaller birds have relatively larger hearts than larger birds • Heart size increases with latitude, altitude for same species

4. Heart Beat • Heart beat slower than in mammals • Smaller birds have faster heartbeats than larger birds

5. Blood Pressure • Slightly higher than mammals • Bordering on safety • Heart, aortic ruptures can occur

6. Respiratory System • Most efficient among vertebrates • Unique design • Complex flow-through system of sacs & interconnecting tubes

7. Respiratory System • Small lungs (2% of body volume) connected to large air sacs (~10X larger) • 4 pairs of sacs plus 1 unpaired sac (some variation)

8. Respiratory System • Tiny, inelastic lungs filled with tubular air capillaries - parabronchi • Unidirectional movement of air through parabronchi compared to dead-end structure of mammalian alveoli

9. Respiratory System

10. Respiratory System • Process - 2-cycle pump • 2 inhalation/exhalation cycles required to move each breath totally through respiratory system • Posterior air sacs to lungs to anterior air sacs

11. Respiratory System

12. Respiratory System • Unidirectional air flow through lungs • Oxygenated air during both inhalation and exhalation • Blood flows in opposite direction

13. Air Sacs • May also aid in: • Cooling • Buoyancy • Defecation/egg-laying muscle assistance • Courtship

14. Accessory Things • Syrinx - voicebox • Where trachea splits into bronchi • Various types, but generally are complex arrangements of muscles, membranes

15. Accessory Things • Sounds (songs) produced in several ways • Vibrating membranes • Changing size of openings • Changing air movement patterns

16. Excretion • Kidneys and salt glands • Kidneys similar to mammal kidneys • 2X as large (relative) • More rapid metabolism • Not as efficient at removing salt • Need for salt glands

17. Excretion • Kidneys produce primarily uric acid rather than urea • Requires less water (not as toxic as urea) • Holdover from embryo (egg)

18. Excretion • Uric acid works well in dry climates, conserves weight • Water not needed in large quantities • Wastes dumped into cloaca (no urinary bladder), mixed with feces, forms white paste with dark lumps

19. Excretion • Salt glands in head • Concentrate salt 3-5X that in blood • Discharge through nostrils • Especially active in marine birds

20. Reproductive Anatomy - Male • Paired testes • Grow during breeding season, shrink otherwise • Up to 200-300X difference in size between seasons

21. Reproductive Anatomy - Male

22. Reproductive Anatomy - Male • Left testis slightly larger than right • Related to female - left side only?

23. Reproductive Anatomy - Male • Vas deferens - wavy tubes • Mature sperm collect until transferred • End nearest cloaca may swell to serve as storage sac

24. Reproductive Anatomy - Male • Copulatory organ - present in more primitive birds • E.g., flightless ratites, Galliformes, ducks & geese • Erectile, grooved structure used to guide sperm into female’s cloaca during copulation • Birds lacking feature just press cloacal openings together

25. Sperm Development • High body temperature causes problems • Sperm cells can’t develop at normal body temperatures

26. Sperm Development • Alternatives: • Develop at night when body temperature may drop • Delay final development until storage in cooler sac or pouch near cloaca

27. Sperm Output • Millions to billions per copulation

28. Sperm in Female • Sperm may be stored in female temporarily in lower oviduct pouch • Stored sperm may remain viable for up to several months before eggs are laid • Highly variable among species

29. Fertilization • One to many copulations may be required for fertilization • Parthenogenesis possible in some species (e.g., turkeys)

30. Reproductive Anatomy - Female • Left side only • Ovary, oviduct • Right ovary, oviduct whither away • Weight reduction? • But paired systems (abnormal) have been observed in dozens of species

31. Reproductive Anatomy - Female • Enlarge during breeding season, shrink after

32. Reproductive Anatomy - Female • Ovary may contain thousands of ovarian follicles • Only few per year mature into ova • Rapid growth through addition of fat, protein food (yolk) probably from liver

33. Reproductive Anatomy - Female • Oviduct responsible for adding albumen, shell membranes, shell, pigment to ova • Five regions

34. Reproductive Anatomy - Female • Infundibulum - funnels, captures released ova • 2 ova released simultaneously produce “double-yolked” egg • Ovum spends ~18 minutes here in chicken

35. Reproductive Anatomy - Female • Magnum - largest region • Secretes layers of albumen (egg-white) • Moisture and cushioning • Ovum spends ~4 hrs here in chicken

36. Reproductive Anatomy - Female • Isthmus • Produces shell membranes • Flexible keratin • Ovum spends ~1.25 hrs here in chicken

37. Reproductive Anatomy - Female • Uterus • Shell gland produces the calcium carbonate shell • Pigment glands apply color(s) • Ovum spends ~18-20 hrs here in chicken

38. Reproductive Anatomy - Female • Vagina • Lined with mucous glands and muscular to aid egg-laying • Ovum spends very brief time here in chicken - just passing through!

39. Calcium Sources for Eggs • Diet most important source for most birds • Bones serve as a secondary source

40. Bird Songs & Calls • Calls are brief sounds with simple acoustic structure • Usually 1 or 2 notes, rarely 4 or 5 • Used for behavior coordination • Non-sexual • Flocking, feeding, migration, predator reaction • Some innate, others learned

41. Bird Songs & Calls • Songs are complex sounds • Groups of notes separated from one another by relatively long pauses

42. Bird Songs & Calls • Songs often serve as substitute for physical combat (territory defense) • Maintaining pair bond • Stimulate, synchronize reproduction • More commonly modified by learning than are calls

43. Bird Songs & Calls • Overall functions: • Reproductive • Social • Individual

44. Many different birds have different calls Enable members of a species to “talk” to one another Different calls have different meanings: Assembly Alarm Distress Feeding Individual “name” calls Calls as Vocabularies

45. Chicken has at least 10 different calls for communicating with others Species generally have calls numbering in the teens or twenties Songbirds average ~15 ¿Como estan ustedes? Some calls also may be interspecific Species that often flock together have relatively common calls that all species can understand Cluck-Cluck-Cluck

46. Chink-Chink-Chink • Used by many species to indicate stationary threat • Low frequency • Repeated • Easy to locate caller

47. Seeet • Used to indicate moving threat • High frequency • Singular • Difficult to locate caller

48. Source of Sound • Syrinx - found only in birds • Sounds produced by vibrations of vocal membranes in syrinx, or vibration of air columns

49. Source of Sound • Air in trachea or air sacs may also resonate and either dampen or enhance vibrations caused by vocal membranes

50. Source of Sound • Some birds capable of producing two unrelated (harmonically) sounds simultaneously • Duplicate membranes controlled by separate muscles in each bronchus