Part 5 – Avian Life Histories Bird Sex Chapter 14

Gonads genitalia typically internal Paired testes in males 1 ovary in females (left side) 2 ovaries typical of many raptors 500 to several thousand primary oocytes Testes & follicles dramatic size changes Affected by FSH & LH Follicle Stimulating Hormone & Luteinizing Hormone Produce testosterone & estrogen FSH – regulates gamete formation in tested & ovary LH – regulates hormone secretion in testes & maturation of ova

Sex Chromosomes Females = heterogametes (ZW) Males = ZZ Inactive W sex chromosome Active Z sex chromosome Males = ZZ Female’s ova determines sex of young Female’s seem to be able to adjust sex ratios in clutch!

Figure 1. The sex ratio in relation to hatching order in populations in (A) Montana (B) Alabama  

Sperm Production At night when cooler Stored at distal end of vas deferens; ~4° C cooler than body

Ova Maturation Oocytes present at hatching Ova by 2 months of age Add yolk in week prior to ovulation Time varies by spp. (4 to 16 days) Each structure labeled “F” is an egg (center) with yolk developing around it

This female House Sparrow (Passer domesticus or HOSP ) was caught on March 23, 2008, and dissected. (HOSP are not protected under the federal Migratory Bird Treaty Act, as they are a non-native, invasive species.) This female had already laid four eggs in a nestbox. You can see the fifth egg in the oviduct, forming a lining over the egg yolkd and egg white. A sixth and seventh egg are forming with a yolk in the center of the photo. To the left are another 15 or so smaller "seed" eggs. The female HOSP can cut off this string when she completes a full clutch (HOSP generally lay 1-8 eggs per clutch.)

Fertilization Occurs at infundibulum After cloacal kiss No phallus in most Sperm swim to top in <30 min Viable for 1-2 weeks Record = 72 d in chicken

Harlequin Duck  & (B) African Goose, 2 species with a short phallus and no forced copulations, in which females have simple vaginas. (C) Long-tailed Duck & (D) Mallard, 2 species with a long phallus and high levels of forced copulations, in which females have very elaborate vaginas (size bars = 2 cm). ] = Phallus, * = Testis, open star = Muscular base of the male phallus, > = upper and lower limits of the vagina

Development of Embryo Moves thru oviduct in ~24 hours: Albumen (3-4 hrs) Egg membranes (1 hr) Shell (20 hrs)

Albumen – Magnum Membranes – Isthmus Shell – Uterus Egg colors

Egg Composition Yolk = food supply Albumen = H20 supply Shell 21-36% lipids 16-22% proteins Albumen = H20 supply 90% H20 10% protein Shock absorber (T & jarring) Shell Protection (CaCO3) Thousands of pores = gas exchange

Egg Laying ~1 egg per day in most

Vary in: Shape Size Color Number (lots of interest)

Determinate Layers – lay a fixed # Indeterminate Layers – try for set # in nest Flicker laid 71 eggs in 73 days

Exams Song portion of lab final on this Thursday Lecture Exam #3 Monday - April 30 8 a.m. in this room