ADVANCED

1. ADVANCED LEC 16 University of Rio Grande Donald P. Althoff, Ph.D. ORNITHOLOGY Reproduction Part I Reference Chapters 12 - 17

2. Reproductive Behavior • _________________ = gamete shedding • _________________ of all kinds of mating systems • __________ of mating systems • COMPLEX: a) _________________—involves courtship behavior b) _________________—all species of birds do this c) _________________ * pre & post highly variable among birds

3. Mating Systems • Considerable variety in pair bonds for birds—ranging from _______ sexual union to __________ mutual efforts: 1) monogamy – “mono” + “marriage” 2) polygamy – “many” + “marriage” 3) polygyny – “many” + “woman” 4) polyandry – “many” + “man” 5) polgynandry – “many” + “woman” + “man” 6) promiscuity – “pro” + “mix” Greek for…

4. Mating Systems Largely Driven by Coloration and Vocalizations • Typically, males ____________ than females • Combination of coloration and vocalizations result in breeding displays…much variety across the class Aves • “Experience” matters…as older males tend to be have better songs than young males • Color “_________________” ….and size influences rate of breeding opportunities • Note: songs – breeding/mating vocalizations vs. calls - feeding, begging, alarm, flock communication

5. F + M Monogamy –____________________ • “the” predominant avian mating system • ______ of bird species (but % probably continuing to ______ because of DNA evidence on paternal “contributions” to clutches…suggesting promiscuity) • Prolonged and essentially exclusive bond with a single member of the opposite sex for purposes of raising young. • Appears common among passerines, raptors (hawks and owls) • Common among geese and swans…all Procellariformes (remember: albatrosses) and Sphenisciformes…all ____________________________________________

6. F + M Monogamy – __________________ • Male remains around until fledging • Common among a) gulls b) grebes c) many passerines (woodpeckers, bluebirds—which have multiple clutches/broods d) mourning doves—which have multiple clutches

7. F + M Monogamy – Pair-Bond until _________________ • Together until all eggs laid…before ‘split’ before incubation starts • Many ducks (Anatidae) • Some phalaropes (where clutch is laid, then female leaves and male incubates)

8. David Lack – _______(one of the pre-eminent ornithologists) “Well-over nine-tenths (93%) of all passerine subfamilies are ___________ ____________….Polyandry (multiple male mates) is _____________.” Today, through DNA analysis…we know this above statement to be wholly false. This is known as “DNA fingerprinting”

9. Thus, only ~_____ truly monogamous “________” the pair bond paternity (i.e., extra-paternity) Thus, over ______ of pair-bonded species have “outside” the pair bond contributions Gill Fig 12-21 p361

10. F + M Pairing - Miscellaneous • Wood thrushes and ptarmigan: no obvious sexual dimorphism (although maybe UV-perceptible???)– mates take longer to work out acceptance • Geese and swans: pair in 2nd year of life with a very long “engagement period” • Swans: some waiting to have engagement and mate for 3 to 5 years

11. Variation within a Family: MEGAPODIDAE • Willow ptarmigan: monogamous, well-developed/ established territory • Ring-necked pheasant: polygamous, ill-defined territory, not necessarily where females will nest • Black grouse: small, well-defined territories with alpha/master cock. No help of males in rearing young

12. F + M.…M M + F...F Polygamy • Any mating system involving pair bonds with ________ mates of the opposite sex • These are all “subsets” of the polygamy category: Polygyny Polyandry Polygyandry

13. M + F…F Polygyny • ______of bird species (but % probably continuing to ________because of DNA evidence on paternal “contributions” to clutches that we originally thought had monogamous status) • Male pairs with 2 or more females (bigamy if M with 2 F). • Sustained association with the females (pre- and post-copulation) separates this from promiscuity • Example: red-winged blackbirds • _______________________ male controls access to critical resource like nesting habitat and/or food resources. More common where “patchy” distributions of these resources

14. Polygyny..con’t • _______________________—males are not defending females nor are they defending a resource. Instead, males compete for females by establishing “dominance” or by demonstrating their quality through displays. Aggregations of many males in a small area are called ______ex. prairie chickens sage grouse sharp-tailed grouse V

15. Leks…what favored evolution of this approach to breeding? A couple of hypotheses… • _________—_____gather at a location where they are most likely to encounter roaming females. Gives male(s) a chance to establish strategic position (usually center of lek) to convey dominance • _________—________can go to a group display which facilitates comparisons  which male is the “best”/most fit is more easily determined. Assessment can be made more rapidly (in a few minutes, even) than if she had to visit each males with territories scattered across a landscape

16. AFRICAN LONG-TAILED WIDOWBIRD

18. F + M…M Polyandry • _____of bird species • Female pairs with 2 or more males • Sustained association with the males (pre- and post-copulation to varying degrees) • Males tend to the clutch, stay with hatchlings • Females tend to be more brightly colored than males • Examples: phalaropes, spotted sandpipers • ________________________ female controls access to critical resource like nesting habitat and/or food resources. More common where “patchy” distributions of these resources. Clutch sizes usually small

19. 2♂ ♀ ____________________

20. Polyandry…con’t • ______________________ – female lays full clutches of eggs for successive mates…thus, incubation of eggs/nests are not essentially overlapping. Advantage: __________________________ vs. • _____________________ – female lays full clutches of eggs for two or more mates during the same time period…thus, incubation of eggs/nests are essentially overlapping. Advantage: ___________________________

21. F1 + M1, F1 + M3, F2 + M1 etc. Polygynandry • _____ of bird species • Female pairs with several males, each of which also pairs with several different females • Common among the tinamous, the flightless ratites (ostrich, rheas, emu), and some songbirds (Smith’s longspur and hedge accentors) • Among _______ and tinamous, males incubate mixed clutches of eggs from several different females, which deposit eggs successively with different males

22. Promiscuity • ______ of bird species • Indiscriminant sexual relationships—usually of ______duration • Examples: male hummingbirds and male manakins(…and technically, one could classify grouse species—lek or non-lek like the ruffed grouse found locally as promiscuous)

23. Promiscuity…con’t • Advantage for ______: 1) chance to “spread” genes around with multiple females (not all “genes” in one basket, so-to-speak ) 2) can sire more offspring in _________breeding season 3) __________________________…so if predator takes out one nest, he still may end up siring offspring that breeding season

24. Promiscuity…con’t • Apparent advantages for ________: 1) Some males are more fertile than others, so reduce risk of incubating infertile eggs 2) “________” hypothesis: female increases fitness of her male offspring by mating with a male who has especially attractive _______________characteristics

25. Copulation • Copulation—in and of itself—is usually not important in pair formation…but everything leading up to it is! • Some duck species: semen may be good for 14 days in female’s reproductive tract, which is good for fertilizing the entire clutch • Waterfowl: males usually have specialized copulatory structure…an “extension” of the cloaca) (see next slide) • Some species (coots and gallinules): the female mounts the male

26. Lack extension Penis-like structure GALLIFORMES Quail Chicken ANSERIFORMES Duck Goose

27. Egg laying & Nesting/Parental Care • Nest preparation variable, ranging from… a) _______ (just “lay” eggs) (ex. Nighthawks, fairy tern) b) _______(ex. gulls) c) _______________ (ex. piping plovers, killdeer) d) _______ a nest (most common) e) _______ a nest (ex. weaverbirds, orioles) f) _______(many years, in some cases… ex. eagles, hawks) • Value of nest with respect to incubation of eggs: a) _________provided for development b) _________to many predators

28. Oviparity • Considering the diversity of birds…including a wide variety of mating strategies….all are limited to laying eggs • All lay a single egg laid at a time (usually 24-36 hours between eggs). ______________________________ _________….multiple eggs are retained in the oviducts of the female for extended (>24-36 hr) periods of time. The strategy of viviparity suggest that for this group of vertebrates, the benefit of egg retention outweighs its cost (makes sense in “cold climates”—eggs can start to develop sooner). Vice versa with respect to birds…laying one egg per day, then incubating them all must outweigh the cost.

29. ovary infundibulum • Site of fertilization • Albumen and shell membranes (not shell) are secreted • Egg enclosed in calcareous shell • Deposited 1 2 1 2 2 3 4 2 shell gland 3 Fig. 17-29 p473, PJH cloaca 4

30. Different patterns of Laying Eggs • Some species are ________________layers: a) a fixed number of eggs are laid b) usually those species that have 1, 2, 3, 4, or 5 eggs for an average clutch size. c) remove and egg and they probably won’t lay a “replacement” egg d) example: piping plover • Some species are ________________layers: a) not usually a “fixed” number of eggs b) usually those species that have 10 or more eggs for a clutch c) remove an egg or eggs and they just keep laying (example: chicken)

31. Different patterns of Incubating Eggs • Some species start to incubate eggs after 1-2 are laid even if clutch ends up being 3-5 or more eggs ex. Most raptors (hawks and owls)….results in _________________hatching of young advantage? ______________________ • Some species do not start incubation until all eggs in the clutch are laid. Common among species with small clutches (i.e., 2-5) and large clutches Results in __________________hatching of young advantage? _______________________

32. The Egg • Inorganic part of the eggshell contains about 98% crystalline calcite (CaCO3)…and the ________ obtains about _____of its calcium from the egg shell. • Two shell membranes are secreted to enclose the yolk and albumen: a) “outer” shell membrane b) “inner” shell membrane….. …as these membranes are laid down, H2O and carbohydrates are added to the albumen via active transport of Na & osmotic flow of H20. • Mammillary bodies are sites of calcite crystal forming

33. Mammilary core Outer shell membrane inner shell membrane chorioallantoic membrane embryo Fig. 17-31 p474, PJH

34. The Egg…con’t • Changes in fluid concentrations surrounding the egg change as the shell is put down, with increased concentrations of Mg and P…and a pattern in the change of crystallization in the surfaced layers of the shell • In “end” product, pores are present that allow O2 and CO2 to diffuse in and out, respectively. Pores represent about 0.02% of the surface of the eggshell • ________________________ serves for gas exchange until 1-2 days before hatching. Air cell at the blunt end of the egg is punctured by about to hatch chick and ventilation of lungs takes over gas exchange • Egg tooth helps chick “saw” its way out!

35. Pores—not all are ‘straight’ chorioallantoic membrane Fig. 17-31 p474, PJH

36. Next time… More eggs and nests