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

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

Follicle Maturation Primary Oocytes: 500 - 2000 Follicle Containing Egg (= Ovum) Ovum is tremendous in size http://www.hiltonpond.org/images/VultureBlackOvum01.jpg

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) http://www.hiltonpond.org/images/VultureBlackOvum01.jpg

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)

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)

Yolk Content in Altricial versus Precocial Birds Follicle Maturation: Yolk Content in Altricial versus Precocial Birds Altricial: Precocial: Fig. 14-14 in Gill 2007

Mature and Atretic Follicles Follicle Maturation: Mature and Atretic Follicles Stigma of Maturing Follicle Atretic Follicles http://partnersah.vet.cornell.edu/avian-atlas/sites/agilestaging.library.cornell.edu.avian-atlas/files/avian_atlas_assets/3.4.08.2DSC00050%20x750.jpg

Ovulation Clutch

Fertilization

Sex Determination: Birds vs. Mammals

Gynandromorphs

Egg Development: Magnum (Albumin and Chalaza Deposition)

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

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

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

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)

Egg Development: Uterus (with Shell Gland)

Egg Development: Uterus (with Shell Gland) Function Additional Albumin Shell Pigments Papillae Fig. 8-76 in Podulka et al. 2004

Egg Development: Uterus (with Shell Gland) (Cuticle, Calcite Crystals, Pore, Shell Membranes, Chorioallantoic Membrane) Fig. 8-66 in Podulka et al. 2004

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

Egg Development: Consequences of Egg Shell Porosity

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

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

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

Egg Development: Shell Gland (Uterus) (Egg Markings: Among Species Variation) Fig. 8-76 in Podulka et al. 2003

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

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)

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

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

Egg Expulsion: Vagina and Cloaca Fig. 4-111 in Podulka et al. 2004

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 14-30 Days Apart

Egg Size

Egg Size: Among Species Variation Bigger birds have larger eggs, though smaller proportion of entire body mass Fig. 8-69 in Podulka et al. 2003

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. 8-71 in Podulka et al. 2003

Egg Shape : Among Species Variation Fig. 8-72 in Podulka et al. 2003

Egg Shape : Among Species Variation Nomenclature Fig. 8-72 in Podulka et al. 2003

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. 8-73 in Podulka et al. 2004

Swift’s Mating 28