1. Developing Ova inside Follicle
Bird Ovaries:
Developing Ova inside Follicle
Follicle is a fluid filled Sac

2. Ovum (Gamete) Production
Oogenesis
Ovum (Gamete) Production
(Meiosis Partially Completed at Birth)

3. Follicle Maturation Primary Oocytes: 500 - 2000 Follicle Containing
Egg (= Ovum)
Ovum is tremendous in size

4. Follicle Maturation Timeframe Enlargement Egg (Ovum)
Passerines: 4-5 Days
Ducks/Pigeons: 6-8 Days
Penguins: 6-8 Days
Enlargement
Up to 1000X Initial Size
Yolk contains most of nutrition needed by developing embryo (Proteins, Lipids)
Egg (Ovum)

5. Follicle Maturation: Materials Yolk Contents of Ovum
Nutrition (Proteins, Lipids)
Hormones (e.g., Testosterone)
Immune Factors (e.g., Carotenoids,
Immunoglobins)
Antioxidants (e.g., Carotenoids,
a Vitamin A precursor)

6. Follicle Maturation: Yolk Anatomy of Ovum Vitelline Membrane
Yellow Yolk (Day Deposition)
White Yolk (Night Deposition)
(Germ Spot)
Egg Yolk can be Aged like Tree Rings
Central Latebra (contains
clear Vitelline Fluid)

7. Yolk Content in Altricial versus Precocial Birds
Follicle Maturation:
Yolk Content in Altricial versus Precocial Birds
Altricial:
Precocial:
Fig in Gill 2007

8. Mature and Atretic Follicles
Follicle Maturation:
Mature and Atretic Follicles
Stigma of
Maturing Follicle
Atretic Follicles

9. Ovulation
Clutch

10. Fertilization

11. Sex Determination: Birds vs. Mammals

12. Gynandromorphs

13. Egg Development: Magnum (Albumin and Chalaza Deposition)

14. Egg Development: Magnum (Albumin and Chalazae Deposition)
Composition: Water (90%)
Protein (10%)
Function: Water Supply
Shock Absorption
Insulation
“Egg Whites”

15. Egg Development: Magnum
1) Chalazal Albumin
(Dense)
2) Inner Albumin
(Watery)
3) Fibrous Albumin
(Viscous)
4) Outer Albumin
(Watery)
Chalaza – Twisted, Ropy Albumin

16. Egg Development: Isthmus
(Additional Albumin, Shell
Membrane (2) Deposition)

17. Egg Development: Isthmus
(Additional Albumin, Outer and Inner Shell Membrane Deposition)
Outer Shell Membrane
Inner Shell Membrane
Inner Shell Membrane – Hold Contents of Egg Together
Outer Shell Membrane – Keeps Shell Intact
(Air Space)

18. Egg Development: Uterus
(with Shell Gland)

19. Egg Development: Uterus (with Shell Gland)
Function
Additional Albumin
Shell
Pigments
Papillae
Fig in Podulka et al. 2004

20. Egg Development: Uterus (with Shell Gland)
(Cuticle, Calcite Crystals, Pore, Shell Membranes, Chorioallantoic Membrane)
Fig in Podulka et al

21. Egg Development: Uterus (with Shell Gland)
(Consequences of Shell Porosity)
DDT

22. Egg Development: Consequences of Egg Shell Porosity

23. Embryo Development: Yolk Sac and 3 Extra-Embryonic Membranes
2) Allantoic Sac
3) Amnion
3) Chorion
Yolk Sac

24. Egg Development: Shell Gland (Uterus)
(Egg Color: Among Species Variation)
Birds are only vertebrates with colored eggs

25. Spotted Streaked Egg Development: Shell Gland (Uterus)
(Egg Markings: Among Species Variation)
Spotted
Streaked
Spots: Slow Turning
Streaks: Rapid Turnings 24 25

26. Egg Development: Shell Gland (Uterus)
(Egg Markings: Among Species Variation)
Fig in Podulka et al. 2003

27. Egg Development: Shell Gland (Uterus)
(Egg Color and Markings: Among Species Variation)
Markings – Camouflage
No Color – No Need

28. Egg Development: Shell Gland (Uterus)
(Egg Color: Within Species Variation)
Common Murre
Murres will only accept eggs colored like its own
Individual Egg Recognition in Colonies
(Common Murres only accepts eggs colored like its own)

29. Egg Development: Shell Gland (Uterus)
(Egg Markings and Shape – Within Clutch Variation)
(Adaptive Value?)
Adaptive Value: ?
American Crow Clutch

30. Egg Development: Shell Gland (Uterus)
(Egg Color: Within Species Variation in “Egg-Dumping” Birds)
Female 1
Female 2
Greater Among versus Within Female Variation in Egg Color
? Mechanism for recognizing foreign egg removal?
Female 3
Northern Masked-Weaver

31. Egg Expulsion: Vagina and Cloaca
Fig in Podulka et al. 2004

32. Egg Laying
Many Birds (e.g., Passerines, Woodpeckers) Lay Eggs about
24 Hours Apart
Some Birds Lay their Eggs Two Days Apart (Ostrich, Herons,
Doves, Owls, Hummingbirds, Swifts, Kingfishers,
Some Accipiters
Penguins Lay their Eggs Three to Six Days Apart
Kiwis lay their Eggs Days Apart

33. Egg Size

34. Egg Size: Among Species Variation
Bigger birds have larger eggs, though smaller proportion of entire body mass
Fig in Podulka et al. 2003

35. Egg Size: Among Species Variation (Precocious versus Altricial Birds)
Everything else being equal, precocious birds tend to lay larger eggs and incubate them for longer times than altricial birds.
Fig in Podulka et al. 2003

36. Egg Shape : Among Species Variation
Fig in Podulka et al. 2003

37. Egg Shape : Among Species Variation
Nomenclature
Fig in Podulka et al. 2003

38. Egg Shape – Adaptive Value of Shape
Common Murre
Pyriform Shape seems Adaptive, but NOT FOUND in other Cliff Nesters
Pyriform Shape Adaptive,
But NOT FOUND in other
Cliff Nesters
Fig in Podulka et al. 2004

39. Swift’s Mating 28