Bird Reproduction
Animal Breeding
Pensacola Jr College
Female Repro Tract
w Usually left side only
(raptors and kiwis have both sides)
w Ovary = site of oocyte
development / vitellogenesis
Yolk layed down in day and
night layers, with larger globules during daytime
w Magnum = site of albumen
deposition (with ropes)
Female Repro Tract
w Isthmus = site of deposition
of egg membranes
w Uterus / shell gland = site
of deposition of calcareous shell
w Vagina = route of passage of
egg to cloaca, sperm entry, opening to sperm storage tubules (in some)
Male Repro Tract
w Paired testes
retained internally high on
dorsal wall of body cavity
May increase by 500 times
size between nonbreeding and breeding season
Sperm production at night
Sperm have more elongated
heads (spiral in passerines)
Male Repro Tract
w Epididymides (2)
w Vas deferens (2)
w Accessory sex glands:
Seminal vesicles sperm
storage areas at base of vas deferens
w Mating by cloaca kiss
Copulatory organ in
waterfowl, tinamous, currasows, ostrich
Sex Determination
w Genetic sex determination
w Heterogametic sex (2 kinds
of gametes, determines offspring sex)
Female birds, have ZW
chromosomes
w Homogametic sex (1 kind of
gamete)
Male birds, have ZZ chroms
Sex Identification
w Dimorphic = males usually
more colorful, eyestripes, etc
w Size differences
Eg. Male raptors smaller
w Copulatory organs that can
be everted in a few
w Surgical sexing
w DNA testing
Bilateral
Gynandromorph
w Bird with chromosomal defect
First mitosis of embryo
causes half of chick to become ZZ and half ZW
Bird develops completely
with body (internal and external) half male and half female
Causes skeletal problems in
birds with size differences
BGM - Eastern
Towhee
BGM - Eastern
Towhee
Egg Structure
w Yolk = protein layers
w Blastodisc = early stage
embryo, sits on top of yolk
w Vitelline membrane =
surrounds yolk
Egg Structure
w Albumen = watery protein
layers
Provides water, cushioning,
insulation from temperature
Chalaza = rope formed from
inner layers of albumen, keeps blastodisc upright
Egg Structure
w Shell membranes
Amnion = watery cushioning
Allantois = uric acid waste
storage
Chorion = gas exchange
w Shell = hard coating
Made of calcium carbonate,
magnesium, phosphate
Pores allow gass exchange
Egg Structure
Membrane Structure
Egg Pores
Eggshell problems
w If magnesium or phosphate
ratios get too high ΰ inhibits calcium carbonate
deposition
w Too little calcium causes
eggshell thinning
w Example: pesticide DDT
slightly increases magnesium and phosphate