Ornithology Lecture Exam 3

Behaviors used to define a mating system

display, intersexual competition, sexual division of investment in gametes and parental care, copulations, social pair bonds, and whether 1st year juveniles help parents

What percent of birds are socially monogamous?

90%

What are the 3 types of polygamy?

polyandry, polygyny, and promiscuity

What characterizes promiscuity?

No male care of offspring

What percent of mammals are monogamous?

3%

Why can birds do social monogamy?

males can contribute by feeding female, incubating eggs, and provisioning chicks

What factors contribute to a monogamous system

lack of opportunity for polygamy: synchronous breeding, high competition, or resources spread out

Give an example of a species that lacks the opportunity for polygamy due to synchronous mating

Longspurs, they mate over 1-2 days

Why is polygyny more common than polyandry?

Females invest heavily in eggs, males can desert after copulation, and lack of paternity certainty

Explain the extrapair copulation system in Pied Flycatcher males

Males form a primary pair bond, then set up a distant secondary territory to mate with another female. The secondary female has lower male help and a lower success rate

Explain the extrapair copulation system in Pied Flycatcher females

Females that lose eggs during incubation solicit copulations from neighboring males to trick them into helping raise the clutch

Explain the breeding system of the Saltmarsh Sparrow

No territorial defense, no parental care, and no pair bonds. Most nests have multiple fathers, with an average of 2 eggs per male in the nest

Name species that pair bond for life

swans, albatross, and owls

What are the 2 polygyny systems

Resource defense and female defense

Give an example of resource defense polygyny

Redwing Blackbirds with the polygyny threshold model. Past the threshold, secondary female fitness in a better territory equals her fitness as a primary female in a worse territory

Explain female defense polygyny

Males defend females rather than resources. Precondition for the natural clumping of females

Give an example of female defense polygyny

Oropendolas, where females like nesting together so a male can monopolize a nest group

How can you identify a polygynous species by appearance?

Males are larger

What are the 2 types of polyandry?

Cooperative and sequential

What are the preconditions for cooperative polyandry, and give an example

Saturated environment, stable groups, and skewed sex ratio. Galapagos hawks where females hold maternally inherited territory

Explain and give an example of sequential polyandry

Females mate and lay eggs for a sequence of males, males care for the nests. Jacanas, the females are larger and territorially aggressive, will kill a males eggs to lay in his nest

What are the 2 types of promiscuity?

resource defense and display site defense

Explain and give an example of resource defense promiscuity

Males defend a resource females need and may receive copulations in return. Orange-rumped Honeyguide males defend beehives

Give an example of display-site defense promiscuity and what conditions support this system

Manakins, females and resources not monopolizable, precocial young makes parental care less valuable, and lekking systems

2 theories for how leks form

hotspots - females gather in an area for a different reason, so males set up there too

hotshots - younger males gather around more experienced males

Give an example of a species with a highly variable mating system

Dunnock, the sexes establish independent overlapping territories based on resources, mating occurs with any overlapping territories.

Explain extrapair copulation system in Purple Martins

Older males establish a nest and then attract younger males to nest nearby. The older male then mates with all the females, leaving only 30% of eggs belonging to younger males

What is the cost of sexual reproduction

The cost of males, reducing reproductive potential for females

What are the benefits of sexual reproduction?

purge deleterious alleles and greater adaptation to changing environments

Explain Muller’s Ratchet

The buildup of deleterious alleles from mutations in asexual reproduction can be “reset” through sexual reproduction

In what environments are asexual organisms found?

stable environments like caves or thermal vents

Explain host-pathogen evolution

The Red Queen Hypothesis, pathogen and host competitively evolve, running forward to remain in place

What is the advantage of extrapair copulations?

increase genetic diversity of offspring to better respond to changing environments

What are 2 examples of species where females have more elaborate traits than males?

Phalarope and Jacana

What are the 2 hypotheses for secondary sex characteristics

good genes or arbitrary choice with runaway selection

Explain the “good genes” hypothesis for ornamentation

Exaggerated traits are truthful signals of mate quality, such as bright colors signaling lower parasite load. Traits can only get so big before pushback by natural selection

Explain the “arbitrary choice with runaway selection” hypothesis for ornamentation

Females choose traits arbitrarily, and they get rapidly selected for. “sexy sons” hypothesis. There must be some genetic link

Explain the intrasexual selection model

Males compete with each other for access to females, males with superior display monopolize many females

Explain the intersexual selection model

Male advertise to females who prefer elaborate displays

Explain the sperm competition type of intrasexual selection

fertilization chance enhanced by producing more sperm, polygynous species have larger testes for body size

Explain the Møller experiment on barn swallows

Color banded territorial males into 4 groups, one with shortened tail feathers, one mock altered, one only banded, and one lengthened. Lengthened-tailed males mated sooner and had more second clutches. Shortened-tailed males had mates who sought extrapair copulations

Explain the Blue Tit mating system

Females prefer males with brighter UV crown patches, increasing the proportion of males in the clutch. They mate assortatively. UV reflectance indicates increased heterozygosity

What birds don’t have a syrinx?

vultures, storks, and ratites

What percent of air passing through the syrinx can be used by mammals and birds, respectively?

2%, 100%

How many syrinx muscles do non-passerines and passerines have, respectively?

2 pairs, 6-8 pairs

The syrinx is 2 sided. Why, and how many birds do this? What example was shown in class?

to self-duet, 20% of birds, wood thrush

What is the average size of a bird vocabulary?

5-14 distinct calls

What are the functions of calls and songs?

territorial display, mate attraction, warning, social contact, and to broadcast self

What are 2 example species that select for larger vocabularies?

Song sparrows and Common Canary, males with variable songs receive more copulations, and females build nests faster and lay larger clutches in the territory of a verbose male

What is the intrasexual impact of a large vocal repertoire?

Older males tend to have larger vocab, younger males are slower to reoccupy territories of those males in subsequent years

Give an example of vocal dueling, a form of intrasexual competition

Marsh wrens

Give an example of intersexual competition in terms of vocalizations

advertise to unmated females who select for polished songs and larger vocabularies

What is the loudest bird?

White Bellbird at 125 decibels because they have large rainforest territories

Give examples of the variety of repertoire between species? (Least songs learned and most songs learned)

White-throated sparrows only learn 1 while Wrens and Mockingbirds learn 100s

What do unmated Black-throated Blue Warblers do to improve their songs?

eavesdrop on more experienced males

Explain and give an example of how songs can indicate the position of a bird within their territory?

Male Chestnut-sided Warblers sing more assertive songs in the center of their territory and less aggressive songs on the edges of their territory

Explain “floaters”

Birds that lack a territory. If territorial presence is not regularly advertised, floaters will take territory

What is the danger of using playback too often in a territory and what is the example species?

Playback can convince floaters that a territory is occupied or remove existing territory holders. Great Tits

Give an example of the uses of individual recognition by call

Colonial nesters, like Emperor Penguins, recognize and find their mates and offspring by call

What types of species duet? Give a local example

Species that practice long-term monogamy and defend year-round territories, like Cardinals

How do Bush-Shrikes use their calls?

To maintain territories, keep track of mate, and synchronize reproductive cycles as they are year-round breeders

Explain the “audience effect” and give an example

Birds sing louder and more rapidly with increased nesting density, Zebra Finches who sing more complex songs with an audience

What are 3 ways birds can learn songs?

inherited, learned, or invented

Give an example of a bird with an inherited song

Cowbirds who are nest parasites but still sing cowbird songs

Explain the 3 stages of song learning

1. Sensory acquisition, which is a critical learning period where hatchings store their dads and conspecifics songs without practice
2. Sensorimotor learning, the period of subsong “babbling”
3. Song crystallization, song stabilizes

Explain the experiment that demonstrated the importance of the silent stage to song learning

White-crowned Sparrows deafened in this stage never learn to sing

What are the 2 types of song learning ability?

open-ended learners like Corvids and age-limited learners like the White-crowned Sparrow

How do dialects form in birds like Song Sparrows? (3 causes : main takeaway)

Can arise in colonizing new areas, social forces like young birds imitating the most successful one, or influenced by regional genetics : because learning is not perfect

Why do female birds sing in the tropics but not temperate climes?

Females defend territories in the tropics, it’s the ancestral trait, and tropical species have less visible dimorphism and ID with song

What are 3 reasons birds might sing in the morning?

The air is drier and carries sound better, less light keeps them camouflaged, and early birds are more fit

What are reasons birds might sing at night?

Nocturnal foraging birds sing when conspecifics are active, others are adapting to light and sound pollution

In what species do females have more testosterone than males?

Phalaropes, because females are the larger and more colorful sex

The response of feather follicles to what hormone causes colorful male plumage, and why doesn’t it activate in females?

Luteinizing hormones, estrogen inhibits them

What is the downside of internal scrota and how do birds adapt?

Internal temperature not ideal for sperm, spermatogenesis happens at night

where is sperm stored to keep it cool?

seminal vesicles around the cloaca, forming a cloacal protuberance

Most birds have 1 ovary. Which groups have 2?

kiwis, owls, and falcons

Name the general parts of the egg

ovum/embryo, food supply, and protective layers

What are the main determinants of offspring viability?

egg mass and laying/hatching order

In what species does large last-laid eggs indicate a female chick and why?

Yellow-legged Gulls, mothers allocate extra resources to daughters to make up for the decreased viability of last-laid eggs

Due to trade-offs for female wellbeing, how does the second clutch in a season compare to the first?

Less eggs but larger in the second clutch to increase the survival of late-season offspring

Explain the example of Dutch Tit reproductive success based on timing

Tits time clutches for peak caterpillar abundance. As global warming makes caterpillars hatch earlier, tits timing using photoperiod hatch too late. Selection differential around how well parents are able to adjust to new timing

What determines paternity?

mating order and interval between copulations. Last sperm wins if copulations are separated by more than 4 hours

Explain how faster sperm relate to sperm competition

Sperm speed and length is positively correlated with frequency of extrapair copulations, sperm velocity and length are a heritable trait

What is the medullary bone and what is it used for?

hollow spaces in bones where extra calcium can be stored. Used because egg formation takes 10% of normal body calcium stores

What birds would deposit porphyrins in egg shells?

Open-cup nesters who need to camouflage their eggs

What types of birds are determinant layers and what does this mean?

Shorebirds, they tend to lay 4 eggs per clutch rather than variable numbers

How many developmental stages do embryos undergo before hatching and how many are specialized to the species?

42, 9

Name 2 transient hatching features

calcified egg tooth and a hatching muscle on the back of the neck

What happens to the egg tooth after hatching? (2 possibilities)

Songbirds reabsorb it for calcium and woodpeckers use it as a reflector to stimulate parental feeding

Most species hatch beak-first without parental assistance. What are 2 exceptions to this?

Megapodidae hatch feet-first and Ostriches yank chicks out of eggs

Why are shells eaten or removed from the nest after hatching?

To protect nest camouflage. Herring Gulls that removed shells reduced Crow predation from 65→22%

How do chickens do synchronous hatching?

older chicks click at 60 clicks/second, causing younger chicks to speed up hatching. Youngest chicks can click at 100 clicks/second to slow down older chicks if they’re not ready

How do later-laid eggs compare to older eggs in synchronous hatchers?

Later eggs have a higher metabolic rates and less yolk remaining when hatching

Explain imprinting

A special learning in the “critical learning period” that can’t be forgotten. Can determine adult mating/territory preferences, Shrike impaling, or determination of parents. Controlled by thyroid hormones

Is the pecking of the red spot on the bill of parent Herring Gulls innate or learned?

The behavior is innate, accuracy is learned

How do Coot chicks recognize their parent?

The adult that doesn’t attack them

When does imprinting occur?

First 13-16 hours in ducks, in the egg in Common Murre

What are the stages of precocial → altricial?

superprecocial, precocial, subprecocial, semiprecocial, semialtricial 1, semialtricial 2, and altricial

What is the difference between semialtricial 1 and semialtricial 2? Give an example of each.

Whether they are born with sight. Hawks are 1, Owls are 2

What characterizes precocial young?

larger eggs, yolks, and brains at birth, as smart as they will get