Ornithology exam 3 (final)

what are the 3 main benefits of territoriality?

• mate acquisition

  • potential mates want a bird with good territory

• primary food access

  • less competition for food

• reduced breeding interference

  • exclusive access to mates and nest material

what are the 3 major costs of territoriality?

• energy

  • defending territory takes energy

• time

  • mates may leave if they spend too much time away from them working

• Injury/death

  • fighting over territory

  • predation while in territory

What is the economic value in finding good territory?

Territorial defense of high quality prey is more economically viable than consuming poor quality, undefended prey

What is the optimal territory size?

Intermediate size

• maximizes costs and benefits

  • at a certain point, territory can get too big to provide benefits

What is Darwins theory of sexual selection?

reproductive success differs according to mating success

What is intrasexual competition?

Competition among individuals of the same sex

what is intersexual competition?

Choice of mate made by individuals of the oppsoite sex

In mating, who chooses and who competes?

Investment in reproduction determines who will choose

• sex that does the most is the limited resource

How are red-winged blackbirds an example of intrasexual selection?

Red shoulders colored in vs left normal

• colored group lost 64% of territory

• those who held territory had no difficulty finding mates

How are long-tailed widowbirds an example of intersexual selection?

Individuals with long vs. short tails

• individuals with longer tails mated more

• territory was held regardless of tail length

What 2 traits do female birds look for in male birds?

• good genes

• direct benefits

  • resources on territory

  • good parental care

What 3 things are females doing to choose mates?

• Assessment of territory quality

• observing secondary sex characteristics

  • quality characteristics = good health

• observing physical displays

  • good displays = good health

How is plumage a good indicator of mate quality?

plumage can change color according to diet

• ex. House finches may be a more vibrant color, as a result of eating lots of caterpillars. Not only does this indicate the male is adept at finding food, but it indicates they are a good forager (the time frame for caterpillars at the start of a season may be very short).

How are physical displays good indicators of mate quality?

flight and song displays, especially at the same time, demonstrate stamina.

heavier males have more energy and can display longer, indicating better physical condition.

What is the major male constraint on reproductive success?

Access to females

• mating with multiple females = more success

what is the major female constraint of reproductive success?

Access to high quality resources

• food

• nest sites

• paternal care

How has mating choice evolved over time?

Individuals in both sexes have evolved to maximize their OWN reproductive success

What is monogamy?

Exclusive bond with one individual for reproduction

• length varies by species

  • songbirds: 1 year

  • eagles, parrots: life

What percent of birds are socially monogamous?

90%

10% are purely monogamous due to not having contact with other mates

What are extra-pair copulations?

mating with neighboring birds, while already in a monogamous relationship

what 3 things impact males regarding extra-pair copulation?

• increases offspring production

• increases energy cost

• increased likelihood of a male raising a chick that is not related to them

what 3 things impact females regarding extra-pair copulation?

• ensures all eggs are fertilized

• improves gene quality and diversity

• improves access to and protection of resources

Describe EPCs in purple martins.

Purple martins nest colonially

• old males attract females

  • breed+lay eggs

• young males are called in

  • old males perform EPC with the females the young males call in

what is polygamy?

pair bonds with more than 1 individual

what is polygyny?

male has multiple females

what is polyandry?

female has multiple males

what is resource defense polygyny?

males defend resources needed to reproduce

where is resource defense polygyny most common?

• marshes

• grasslands

resources are in limited supply there

few males defend their highest quality territories b

What is Cuckoldry?

Males raising offspring that arent theirs

What is the polygyny threshold hypothesis?

females must choose mates with a net benefit of survival

• poly in a good territory is more worth it than mono on a poor territory

What is the sexy-son hypothesis?

good genes for her offspring offsets the cost of polygyny

• future offspring will have more success

When is polyandry beneficial for the female?

when the male takes care of the young

What is sex role reversal?

Male birds take on characteristics of traditionally female birds and vice versa

• appearance

• behavior

What is sequential polyandry?

female courts and defends male until he is protecting the clutch, then she leaves to find another mate

• guarantees the female has high reproductive success and that the male is only raising his own biological young

• seen in Red Phalaropes

What is resource defense polyandry?

female defends territory to attract mates

• paternity is assured for primary male

• other males fight to be the primary male

What happens to testosterone during mating?

Testosterone levels drop after eggs are laid

• testosterone inhibits incubation behavior

What is promiscuity?

copulation with no pair bond

• male provides no parental care

• offspring are usually independent on hatching

• maximum male reproductive success

What is a lek?

A symbolic territory where promiscuity occurs

• dominant males stand in the center, and get most mates

• other males stick around

What is the hot-spot hypothesis?

males (in a lek) are more likely to dance where there are more females

What is the hot-shot hypothesis?

subordinate males (in a lek) hang around dominant males in an attempt to be chosen by females

• females benefit from lots of choice

Which sex is the homogametic sex?

Females (zw)

• females determine the sex of offspring

What are bilateral gynadromorphs?

egg cell is fertilized with two different nuclei, one male and one female

• one testi and one ovary

How do males compensate for the short lifespan of sperm?

Short lifespan is caused by high temps, so:

• sperm produced at night

  • colder

• seminal vesicles (sperm storage) protrude out around the cloaca

  • external air

What are male copulatory organs?

Few birds have a cloacal outgrowth copulatory organ

• common in ducks

males will attempt to rape females

• females have internal defense organs to prevent undesirable ducks from fertilizing

What is notable about semipalmated sandpiper mating?

semipalmated sandpipers are monogamous, with shared incubation

What is the yolk made From?

oocytes in the ovary → Ovum (mature egg cell)

how are yolk layers different?

• yellow layers added during the day

• white layers added during the night

color vibrance is determined by diet

color has no effect on egg quality or nutrition

Where are ova produced in the ovary?

in the stigma of folicles

• ruptures and releases ova, becoming a discharged folicle (DF)

What is the infindibulum?

top of oviduct

• where fertilization occurs

Why is speed important during copulation?

sperm must get to the ovum before the egg forms

• frequently occurs before the first egg is ovulated

  • 1-2 hours before ovulation

• males will continue to copulate to ensure this happens

What can females do with sperm?

store sperm in the lining of the oviduct in storage tubules

• storage lasts for ~1 month

• viability decreases over time

What is sperm competition?

2+ males compete to fertilize the egg of one female

• most recent mate has precedence

How can females get rid of unwanted sperm?

Defecation

What do males do to ensure paternity?

• increase teste size

• copulate more frequently

• defend mates

  • smiths longspur

What is polygandry?

communal breeding where males and females have multiple mates

• 400+ copulations a day!

is an egg an open or closed system?

closed, except for gas exchange

What are the 4 main parts of a fertilized egg, and what are they made of?

Blastodisc

• embryo

Yolk

• fat and protein

albumen

• 90% water, 10% protein

chalaza

• protein fibers

Where is the first layer of albumen and the chalaza added to the ovum?

Magnum

• takes 3 hours

Where is the egg membrane, shell membranes(x2), and a second layer of albumen added?

Isthmus

• 1 hour

Where is the third layer of albumen, the shell, and the pigments added?

uterus

• 20 hours

What is the cuticle?

Outer shell layer

• antimicrobial

• provides waterproofing

What is significant about the cuticle of processed eggs in the US?

Eggs in the US are bleached to remove visual imperfection, which results in removal of the cuticle

• without cuticle, eggs must be refrigerated

What is the chalky region?

layer between the cuticle and the shell membrane

• provides calcium for the embryos through calcium carbonate

• has pores to allow for gas exchange

Where is the calcium used to form egg shells sourced from (2 places)?

Mother’s Diet

• molluscs

• snails

Medullary bone

• 12% of bone mass is lost

• calcium decreases with age

How does DDT affect birds?

Interferes with the enzyme that controls calcium deposition in the ovaries

• less calcium = thinner, fragile shells

What are the two shell membranes, and what do they do?

inner and outer shell membrane

• stay together, mostly

  • separates on the blunt end of the egg, to form an air pocket for the chick before hatching

• retains moisture

• antimicrobial

How does bird size correlate with egg size?

larger birds lay larger eggs

• few exceptions

  • kiwis

How does bird size correlate with egg size?

bigger birds lay more eggs

How many eggs are laid per day?

~1

How many eggs per clutch?

variable (1-18)

What are the extra-embryonic membranes?

4 membranes that surround embryo and support its development

what is the yolk sac?

sac that stores fat

• energy and nutrient storage

What is the Amnion?

fluid filled sac

• absorbs shock

• helps retain moisture

What is the allantoic sac?

sac that stores metabolic waste

• nitrogenous waste (uric acid)

What is the chorion?

embryonic outermost layer

• shock absorber

• retains moisture

How do the chorion and allantoic sac interact during development?

They fuse together

• becomes vascularized

• used for gas exchange

What is metabolic incubation?

metabolic heat is applied to the egg for incubation

• begins when whole clutch is laid

• 37-38 degrees c is optimum

what are the two major non-metabolic incubation methods?

• heat from decomposing vegetation/sun

• buried in a mound of dirt

  • done by megapodes

What are the suspected origins of incubation?

Some reptilian dinosaurs are suspected of incubating eggs, although they would need to be endothermic to do so; there is no current evidence of endothermy in dinosaurs

• this is still seen today, with how snakes and lizards dont incubate

• this topic is highly debated

Who incubates the eggs?

Both parents (most common)

female only (second most common)

What is the brood patch?

bare skin patch on the chest with a fluid filled sac under it, used for brood patch incubation

• heats up and swells to create a warm patch to heat eggs

• typically more developed in females

What two chemicals spur brood patch activation?

• prolactin

• estrogen

What 2 methods are used for incubation (excluding the brood patch)?

Feathers are plucked to insulate nest

• ducks

Patch to insulate egg near legs

• Penguins

How does environmental temperature influence incubation?

Higher temps = less incubation needed from parent

• less need for artificial heat

• eggs can get too hot, and need to be cooled

What 2 main methods are used to keep eggs cool?

Shading

• standing over eggs to block them from the sun

Burying

• burying eggs in ground (usually sand)

Why are eggs moved/turned?

ensures proper heat distribution

• eggs rotated inside to out

ensures proper development

• too little movement = early fusing and poor development

What is the incubation period?

Period of time between laying of last egg and hatching that egg

• fixed period of time

  • species-specific

• bigger the egg, the longer the incubation period

• longer incubation = less post hatch development

What is the hatching position?

• Head is between body and right wing, with the beak pointing toward the air cell at the blunt end

• egg tooth allows for breaking the shell

• hatching muscle allows for pecking motion

  • both features are re-absorbed as a chick

What is the hatching sequence?

begins a few days before cracking

• shell gets cut in half

How are egg shells removed (for the 2 bird types)?

Precocial

• shells are left behind

  • precocial birds leave immediately

Altricial

• shells are removed by parent

  • altricial birds remain and keep developing

Why would a bird remove eggshells from its nest (2 main reasons)?

Shells reduce camouflage

• attract predators

egg capping may occur

• egg gets laid inside an old eggshell and the bird cannot hatch

What are the 8 key features of precocial birds (at birth)?

• mobile

• eyes open

• downy feathers

• parents lead chicks to food

• large eggs

• large yolks

• slow growth rate

• ancestral

What are the 8 key features of altricial birds (at birth)?

• immobile

• eyes closed

• little/no downy feathers

• parents must feed chicks

• small eggs

• small yolks

• fast growth rate

• newly evolved

What are the 2 major benefits of having altricial chicks?

• delays brain development until high quality food can be acquired

• faster development at hatch = easier to escape from predators

What are superprecocial birds?

Birds that are completely independent and require no parental care upon hatching

• megapodes

  • black-headed duckl

What is brood parasitism?

Bird lays its eggs in a host bird’s nest

• host bird does all the parental care

What is obligate parasitism?

Bird will always be a parasite and never make a nest

• 1% of parasites

  • cuckoos

What is faculitative parasitism?

Bird will sometimes be a parasite and always builds a nest

• parasitizes nests of the same soecies

What is a host specialist?

Parasite that only targets a specific species of bird

What is a host generalist?

Parasite with no specific target species