Exam 3 Flashcards
What needs determine how and where birds live?
Food and protection
These needs also determine whether a bird is:
Social or Asocial
Cooperative or Competitive
Self interests can foster hostility or corporation when two birds interact
Why do individual birds typically maintain small distances between themselves and other birds?
their individual spaces reduce hostile interactions
What is allopreening
Individuals of highly social species overcome the individual distances to preen each other
What is territorial behavior typically over? How do birds defend a territory with invisible boundaries?
Territorial behavior is a form of aggressive spacing.
This may be over a single resources territory (food) or an all-purpose territory (food, courtship, nesting)
Males and females will defend territories, sometimes a small group will defend a territory
Birds broadcast their presence and intended control of a territory with loud vocalizations or with nonvocal communication sounds, such as the familiar tree drumming or rapping by woodpeckers. Both males and females may display and defend, sometimes together. Territory residents chase trespassers until they leave, resorting to physical contact as needed. Sometimes these contests for the control of a territory last for hours. Beneath the conspicuous surface of territorial control and ownership exists an inconspicuous underground of subordinate individual birds that will surface and take charge when the owner is absent or dies.
Why would a predator need a larger territory than herbivores?
Territories or home ranges of birds increase directly in relation to body size, energy requirements, and selection of food types. The correlation suggests that territory size is geared to the food and energy requirements of the bird. Predators have higher daily energy requirements than do herbivores , which have correspondingly smaller territories.
What are some of the costs and benefits of territoriality?
Mid-sized territories have benefits that out way the cost
How do birds assert their dominance? What factors might affect dominance?
Individual birds that prevail in aggressive encounters become dominant; losers become subordinate. As social ranks are established in new groups of birds, losers cease challenging dominant birds with the result that stable dominance relations lower the frequency and intensity of overt hostility.
Dominant birds use threat displays to assert their status and reserve their access to mates, space, and food. They move without hesitation to a feeder or desirable perch, supplanting subordinates and pecking those that do not yield at their approach. Subordinates are tentative in their actions and frequently adopt submissive display postures. Age, sex, physiology, genetics, and possibly parasite load all affect dominance.
How do birds identify dominance in members of their own species?
Plumage patterns
Size
Voice
Behavior
Some species wear badges
What is mimicry?
an evolutionary convergence in appearance
Mimicry improves the competitive ability of a subordinate species to access resources controlled by dominant species (including protection and avoidance of aggression)
What are the costs/benefits of flock formation?
On the positive side of the ledger, flocking behavior enables cooperative foraging and reduces the risk of predation. Members of a flock are attentive and sensitive to what their flock mates are doing and adjust their own behavior accordingly. A wealth of information is available from one’s neighbors. Which ones find food and where?
High on the list of costs are increased competition for limited food supplies, increased risk of disease, and increased aggression to maintain individual distances.
What is the beater effect?
Feeding in flocks can flush prey
Information sharing - example pelicans
Producer-scrounger - exploitation of actively searching bird that waits for another bird to find something and then eats/takes that food
What are nuclear species?
Mixed-species flocks
Nuclear species tend to be highly sensitive to predators and followers are subordinates that join opportunistically
What are the advantages/disadvantages of colonies?
Advantage: Decreased predation and increased foraging/food
Disadvantages: Increase competition for nest sites and mates and increase disease also large number can attract predators
Give an example of disadvantages in swallow colonies
The globular mud nests in large colonies of the American Cliff Swallow, for example, are more likely to be infested by fleas or other bloodsucking parasites than are nests in small colonies (Brown and Brown 1986). Experiments in which some burrows were fumigated showed that these parasites lowered survivorship by as much as 50 percent in large colonies but not significantly in small ones. The swallows inspect and then select parasite-free nests. In large colonies, they tend to build new nests rather than use old, infested ones. On balance, the advantages of colonial nesting clearly outweigh the disadvantages given the many times at which colonial nesting has evolved independently among different groups of birds
Interspecific vs Intraspecific
The globular mud nests in large colonies of the American Cliff Swallow, for example, are more likely to be infested by fleas or other bloodsucking parasites than are nests in small colonies (Brown and Brown 1986). Experiments in which some burrows were fumigated showed that these parasites lowered survivorship by as much as 50 percent in large colonies but not significantly in small ones. The swallows inspect and then select parasite-free nests. In large colonies, they tend to build new nests rather than use old, infested ones. On balance, the advantages of colonial nesting clearly outweigh the disadvantages given the many times at which colonial nesting has evolved independently among different groups of birds
What are the gonads in males and females? What do they do?
Birds are strictly bi-sexual (Female and male)
Gonads (sex organs) located inside the body cavity on surface of kidney which secretes sex hormones and produce gametes
Paired testes in males - secrete testosterone
Single ovary in female - secretes estrogen
Describe the sex chromosomes of birds.
Birds have ZW sex chromosomes
Females are heterogametic ZW while males are homogametic ZZ
What is bilateral gynandromorphism?
Aberration in the 1st cell division of a fertilized egg will cause half of a bird embryo to become female (ZW) and the other half to become male (ZZ)
These birds will have testes on one side of body and an ovary on the other and will also display distinct male and female plumages on corresponding sides of the body
What does ovulation do?
Releases an egg (ovum) from the ovary.
An ovum in the oviduct (specifically in the open upper infundibulum) is ready for fertilization
What is parthenogenesis?
The development of unfertilized eggs into offspring
How is avian sperm different from mammalian sperm?
Avian sperm have evolved to survive higher body temperatures than mammal sperm, so they can be stored in testes housed inside the body.
What bird orders have penises in males?
Paleognathae, Galliformes and Anseriformes
Why do ostriches have a large penis? Why do ducks evolve a large, anatomically complex penis?
positively correlated with the frequency of forced extra-pair copulations
The coevolution of male and female genitalia is an antagonistic sexual arms race that proceeds through sexual conflict over paternity.
Where is sperm stored during fertilization?
It can be stored in sperm-storage tubules above the cloaca at the junction of the uterus and vagina but also at the infundibulum itself (open upper-end of oviduct)
What is a cleodoic egg?
A closed, self-contained egg containing all the nutrients and water required for development
What factors are necessary for proper development?
Warmth and nutrition
What is the function of egg shells?
Structural support
Protection from soil invertebrates and microbial infection
Conservation of food and water
Facilitation of respiratory exchange of gases
Vary in thickness from paper thin to 2.7mm thick in ostriches
Why might a nightjar (Caprimulgiformes) lay a bright white egg, even though it is a ground nester?
Nocturnal
What 3 components does a freshly laid egg consist of?
- Ovum (if unfertilized) or embryo
- Full supply of food to nourish embryo
- Protective layers safeguard internal environment
What is a clutch? What determines clutch size?
The number of eggs that a bird lay in one set
Availability of energy and other resources
What is sexual selection?
The differences in mating or fertilization success that arise from
1. Contests amongst males for mates
And/or
2, Female preferences for particular males (also known as female mate choice)
What is sexual dimorphism?
The difference in plumage, size or behavior of males and females
List and briefly describe the three hypotheses for why females choose “fancier” males
- The “Good Genes” hypothesis - Exaggerated male plumage and/or courtship displays are an honest signal of genetic or physiological superiority which requires greater energy expenditure
- The “Direct Benefits” hypothesis - it is communicating a mate’s ability to provide resources or protections - material benefit instead of genetic
- The “Arbitrary Choice and Runaway Selection” hypothesis - these traits are merely attractive and there is no additional benefit conferred to the female. Mating with an attractive male will simply result in attractive male offspring that are more popular and will attract more mates themselves.
How does parasitism affect the quality of male ornaments?
It can reduce sheen of ultraviolet color of feathers in Bowerbirds
Reduced fleshy comb size of Red Junglefowl
Reduced size of tail streamers in Barn Swallows
What is a lek? What 3 models support how they might have evolved?
Lek is an aggregation of male display territories that include no extra resources other than opportunities to mate. (Only promiscuous males)
- Hotspot Model - males gather at sites where they are most likely to encounter roaming females
- Hotshot Model - males gather around experienced, attractive, or dominant males to increase their chances of being noticed within large aggregations
- Female Preference Model - females prefer to visit large clusters of males over small clusters or solitary males.
What is the unique display of bowerbirds? How did they evolve?
Bowers - elaborately constructed out of sticks and grasses for the sole purpose of courting and mating. Display male social status and health
2 types - Maypole - more elaborate and Avenue
How did song and mate choice evolve in birds?
Song repertoires also enhance male attractiveness to females and ability to compete with other males.
Evolve by BOTH mate choice and male-to-male competition.
Females use the songs of males to assess quality of potential mates, typically choosing older, more experienced mates.
But, evidence on whether this honestly indicates superior male genes is weak and mixed.
What are extra-pair copulations? Why is this advantageous?
Broods of many bird species exhibit mixed-paternity due to copulations by females with additional males, called extra-pair copulations.
Males can produce more offspring by engaging in extra-pair copulations, thus increasing their overall reproductive success.
Females can increase the diversity and quality of their broods by deliberate outbreeding and the selection of superior neighbors.
What is social monogamy?
This breeding system, when birds form a social bond for reproduction and parental care, but are not necessarily sexually exclusive, is called social monogamy.
List and briefly describe the different types of mating systems
Monogamy - refers to a prolonged pair bond with a single member of the opposite sex for purposes of raising young
Polygamy - multiple mates
Polygyny - one male mates with multiple females
Polyandry - female birds attract and pair overtly with several males - Charadriiformes
What is brood parasitism? What are the two types?
Laying eggs in another female or pair’s nest
- Intraspecific Brood parasitism - occasional laying of eggs in nest of females of the same species (as a supplement to own nest)
- Obligate Brood parasitism- never build their own nest or raise their women young. They depend entirely on other species or parental care.
What are adaptations of parasitic chicks? What are adaptations of host parents?
Parasitic Chicks
•Eggs may mimic host egg and require less incubation time (2 - 4 days less)
• Faster growth than host nestlings
•Larger bodies than host nestlings
•Imitates begging calls of entire brood of host nestlings
• Some hatchlings even purposely dispose of host eggs or kill host nestlings with bill hooks
Host
• Nest defense (mob chase, or distract brood parasite female
•Sitting on the nest longer in the morning
•Removal of parasitic egg
•Abandoning entire nest
•Rebuild fresh nest on top of parasitized nest
What are the effects of brood parasitism on host populations?
Brood parasites reduce reproductive success of host.
For species that have evolved host-parasite specialization, effects on host species has become less virulent over time and number of nests parasitized overall is low (less than 5%).
Cowbirds are generalist parasites (not host specific), and can pose severe threat to host already suffering population declines.
Brown-headed cowbirds are more numerous than most host species, and can parasitize ¾ of nests of neotropical migrants in fragmented forests.
What is cooperative breeding? What are the direct and indirect benefits?
“helpers” care for young that are not their own
Helpers receive both direct benefits:
-Enhance their later reproduction by gaining experience helping parents at nest.
And indirect benefits such as:
-Kin selection: enhancing inclusive fitness through production of genetic relatives.
-Reciprocal altruism: Obtaining help in return
What are helpers? Why are they important?
and contribute to defense of territory and protection and feeding of younger siblings.
In Florida Scrub Jays, as many as six helpers (male and female) stay with parents for 1-7 years!
Studies show that helpers actually help, and are not just interfering or competing for resources.
-Per season, fledglings in each nest increase when helpers are present.
-Helpers also improved survival of breeding parents compared to those without helpers.
Why don’t helpers disperse and breed sooner?
Ecological Constraints:
-Unpredictable or difficult breeding conditions
-Long-term territoriality of adult pairs
-Habitat saturation (shortage of high-quality territories)
Gained Social Benefits:
-Improved survivorship and learning skills
What are family structures?
are social groups in which offspring continue to interact beneficially with their parents into adulthood and demonstrate social complexity.
These birds exhibit excellent individual recognition and long-term memory.
What are the causes of nest failure? What is the #1 cause?
1 cause is - Predation
Predation
Starvation
Desertion
Hatching failure
Adverse weather
What is the purpose of a nest?
Protection of self and of eggs/young from weather and predators.
Subtler functional features of nests include regulation of temperature and humidity, and choosing plant matter that combats disease and parasites.
Loss to predation drives evolution of nest architecture, placement, clutch size and protective behaviors.
What are the three basic categories of nests?
1)Cavity or hole nests
2)Open-cup nests outside of holes
3)Domed nests (constructed with roof)
What is an extended phenotype? Why is a nest considered part of this for birds?
A nest is an artifact of a pair of birds or an individual bird, and considered a component of a bird’s extended phenotype.
An extended phenotype is the total of the individual’s effect on its environment.
Nests are a product of a bird’s genes, morphology, behavior, and previous experience interacting with its environment (including social density, competition, and social relations).
Natural selection acting on these factors is responsible for evolution of the nest over time.
What is some of the evidence for nest evolution?
Non-avian theropod dinosaurs laid eggs in open ground nests, partially buried in sediment.
Many reptiles create nests, such as simple burrows or vegetation mounds.
These eggs are incubated by _________?
Evolution of sediment-free nesting and incubation likely occurred in the Mesozoic birds (think archeopteryx).
Existence of elaborate nests in neoavian birds thought to be a result of adaptive radiation and evolutionary success of songbirds.
Songbirds small body size and flexible nesting behaviors allowed them to compete with hole nesters.
Molecular phylogenies confirm that hole nesters evolved about 8 million years prior to songbirds (Passerines)
What are the different methods of nest construction?
Birds inherit behavioral preferences to seek out certain sites and material in the environment, and manipulate them in specific ways (innate behaviors).
Methods of Nest Construction Include:
Scraping
Digging
Drilling
Piling
Jamming
Interlacing
Felting
Sewing
Weaving
Tying
Accumulating mouthfuls of mud
What are secondary cavity nesters?
Cavity nesting birds that are unable to make their own holes are called secondary cavity nesters
How do birds transport nesting material to a site? How do birds use bills and feet for nest building?
Use of bills, feet, or wing tucking (mostly lovebirds)
How do birds use bills and feet for nest building?
-Bills serve as wood chisels, drills, picks, trowels, needles, and forceps
-Feet stamp, scrape, knead, scratch, and kick
Entire body is also used to help mold nests
Why is microclimate important for nesting?
Microclimates are crucial for successful incubation of eggs and health of baby birds.
Important factors include:
Warmth and Insulation
Proper Heat Absorption
Nest Placement
Proper Ventilation
Many birds will remove fecal sacs of young (as well as other debris) to prevent disease, insect infestations, or parasites.
Some birds will instinctively eject feces away from nest or through an opening.
What are the different types of incubation shifts? Which one applies to cavity nesting, open-cup nesting, pelagic birds, or tropic birds?
In mating systems with shared incubation, parents take regularly alternating shifts and achieve nearly continuous coverage of eggs
1-2 hours alternating - song birds (cavity)
12-hours alternating - open cup
24-hours alternating - sea birds
What are brood patches?
incubation patches, allow the transfer of body heat from adult to eggs.
Skin is bare, soft, and slightly swollen, with proliferation of blood vessels.
Birds typically lose feathers in a specific area on the abdomen or breast prior to incubation rather than using a normally bare aperterium.
Both incubating parents will develop a brood patch under control of hormones estrogen and prolactin, which will regress after hatching.
Why won’t most birds begin incubating until the clutch of eggs is complete?
is the time required by the embryos to develop within the freshly laid eggs (assuming normal attention by incubating parents).
Defined as the interval between laying the last egg in the clutch and the hatching of that egg.
Most birds won’t begin incubating until the clutch of eggs is complete-Why?
Why do some birds turn their eggs during incubation?
An incubating bird will rise periodically to turn its eggs, rearranging them so outermost eggs are moved to center and all eggs receive roughly the same amount of time in the warmest spot.
Turning of eggs also:
→Prevents chorioallantois from adhering prematurely to inner shell membranes
→Optimizes growth of extra-embryonic membranes and fluid dynamics (again preventing premature adhesion that would obstruct development and position of chick in egg).
Briefly describe the hatching process.
Hatching refers to a bird breaking from the eggshell and emerging from it.
In its final stages of development, a chick fills the space of the egg once occupied by the yolk and albumen.
At this stage, a chick can vocalize from its shell to communicate with parents and siblings in other eggs.
Chicks get into a tucking position that allows pipping (or breaking of eggshell) with its egg tooth.
An egg tooth is a special, calcification that forms on the tip of the bill (not a real tooth–it will drop off or be absorbed).
Once in the tucking position, it will break into the air chamber with its beak (and egg tooth), and inflate lungs for first time.
Chick will peck feebly but regularly at the shell, while rotating in a counterclockwise direction (using its legs to pivot itself).
After one to two days of “bumping”, chick has left a circular series of fractures on the egg shell and finally breaks open the entire shell.
A hatching muscle on the back of the neck also gives chick power for the first pecks and withers once fully hatched.
Hatching may be synchronous (within a couple of hours all hatch) or asynchronous (more than a few hours apart to more than a week apart).
Asynchronous hatching occurs if a bird incubates prior to clutch being complete.
In some instances, first hatched will have advantage over younger sibling, which may succumb to shortage of food and sometimes physical abuse by older sibling.
Differentiate between precocial and altricial, and nidifugous and nidiculous.
-Precocial Development
→Nidifugous (leave the nest)
-Altricial Development
→Nidicolous (stay in the nest)
How did altricial development evolve? How is rapid growth advantageous?
Rapid growth may be an evolutionary advantage.
Altricial nestlings grow 3-4 times faster than precocial chicks.
Altricial young exhibit emphasis on forelimb development and locomotion (flight proficiency), since these species predominantly use their wings in adulthood (esp. songbirds, hummingbirds, swifts, etc.).
Why do nestlings beg? How do they beg?
Nestlings exhibit begging behavior, to communicate hunger to parents.
This includes both exaggerated movements as well as loud vocalizations.
Begging calls stimulate parents to deliver food to the nest, and parents will deliver more food as intensity of begging increases.
Begging behavior puts both parents and young at risk for discovery and death by predators.
Growth rates of altricial chicks begin to _______ as brood size increases
Decrease
What is siblicide? Why is this rare in some species and common in others?
When a sibling kills off another sibling.
Siblicide is rare in Great Blue Herons, but common in Great Egrets. Why? Because Great Blue Herons provide bigger fish and this decrease competition
What are a parent’s options for adjusting its investments?
-Choosing among rival nestlings (Favoritism)
-Weighing risk to self vs. risk to nestlings from a predator (longer-lived birds take less risk to self).
-Favoring one sex over the other (larger of the two sexes often makes more demands on parent)
-Sacrificing young (could be laying fewer eggs, starvation of weaker sibling, or overt siblicide)
How often do some parents feed their young?
Albatrosses: every 2-3 days.
Other seabirds, swifts, and large raptors: 1-2x daily.
Small and medium-sized landbirds: 4-12x per hour.
Bald Eagles: 4-5x daily.
Barn Owls: 10x per night.
Documented cases of extreme food delivery:
990 combined trips per day by Great Tit parents
491 combined trips per day by House Wren parents
What is the nestling period? Fledgling period? Post-fledgling period?
Nestling Period is defined as the interval between hatching and departure from nest.
Fledging Period is defined as the period between hatching and flight.
Post-fledging period is a final period of parent-offspring conflict.
Fledging is departure from the nest, and then eventually from parental care.
Mortality rate of fledglings is high (especially first few days), but then becomes safer than sitting in a vulnerable nest.
Fledglings respond to warning calls of parents by hiding or staying still.
Mobility allows them to follow parents to food and reduces strain on parents.
Is avoiding danger innate, learned, or both? Why?
Avoiding danger is both innate and learned.
Chickens innately avoid eating black and yellow prey (warning color of many caterpillars), but then refine choices with experience.
Turquoise-browed motmots are frightened by sticks painted with bands resembling coral snakes.
Many birds will learn to recognize predators by watching other birds, and improve on their own recognition skills.
What is imprinting? Why is it important?
Imprinting is a special kind of learning that takes place during a well-defined time period called the critical learning period.
Birds filter their learned experiences through a template of genetically predispositioned behaviors.
Imprinting is irreversible.
What is sexual imprinting? Assortative mating?
starts with specific signals of parents (visual or vocal), then extends more broadly, and finally will adjust to exclude the signals of other species.
Many birds exhibit assortative mating, where imprinting on a family color morph will lead to mating preferences for that morph.
Young Snow Geese raised by parents of a different color morph will prefer a mate with the color morph of the parents.
What is life history?
are sets of evolved traits or attributes that interact with environmental variables to determine an individual bird’s lifetime reproductive success.
What is age-specific survivorship? What is annual fecundity? What do life tables do?
Age-specific survivorship is the probability of living to a certain age.
Annual fecundity: the number of young successfully fledged in a year.
Life tables: statistical tables that integrate age-specific survivorship and age-specific fecundity.
How are lifespan and behavioral traits tied to cognition and intelligence?
Longer-lived birds tend to have larger brains in relation to their body mass (crows, parrots, and woodpeckers exhibit intelligence and advanced social behaviors including play behaviors).
No long-lived bird produces large numbers of young each year (longer incubations enable development of more advanced behavior).
Why does migration impose substantial mortality?
What is actuarial senescence? What can cause this?
a death rate that increases with age.
Declines in immune or physical functioning
What does total lifetime reproductive success depend on?
Compare single and multiple broods
Comparing Single and Multiple Broods
Factors:
-Length of breeding season (tropical birds generally attempt more broods than temperate birds due to prolonged breeding season. Two-six is typical).
-Long nesting cycles or restricted breeding seasons preclude extra broods (Snowy owls and pileated woodpeckers only attempt one brood).
-High-quality territories with more food will increase likelihood of second brood in many species.
What would be more beneficial? Increasing the size of a single clutch OR having more than 1 small clutch?
Multiple small clutches
How does clutch size vary? Why?
The number of eggs that a female lays in each nest (clutch size) is a heritable component of fecundity.
Waterfowl, pheasants, rails, and many other precocial birds have clutch sizes with up to 20 eggs.
Passerines and other small land birds that feed their young (altricial development) lay clutches of 2-6 eggs.
This can vary among species and with latitude, climate, age, and quality of territory.
What are common parenting mistakes?
Birds that breed for the first time typically produce fewer eggs and raise fewer offspring than do older birds. Delayed maturity or cooperative breeding can alleviate some of these concerns.
Common parenting mistakes:
-Accidentally being too aggressive (injuring/killing young)
-Laying egg(s) in wrong place
-Being inattentive or haphazard in incubation
-Leaving nest unattended too long
-Not feeding frequently enough
-Not spending enough time looking for food
Why can delayed maturity be beneficial?
Delayed maturity can be beneficial in providing more time for experience/skills to develop or put the younger bird at less of a disadvantage in competition for mates, territories, or resources.
What is the food-limitation hypothesis?
The avian clutch size is adjusted by natural selection to the maximum number of nestlings that parents can feed and nourish.
Or, food availability limits clutch size.
Hypothesis assumes individual birds will be disadvantaged by natural selection if they lay fewer eggs each year than they can raise.
Great Tit clutches experimentally increased to 10-12 (from typical 8.5 eggs) did produce the most surviving young.
How have clutch size and seasonality evolved? Clutch size and predation?
Variation in the seasonality of resources is the ultimate cause of geographical variations in clutch size.
Adult mortality in the cold or dry season of lowest food availability determines future population density and food consumption in a habitat.
Thus, survivors and seasonal visitors benefit from increased per capita food availability in the spring.
What is pyriform egg (egg station identify)
prevent rolling of cliff
What are the 3 hypotheses for the evolution of clutch size
The food-limitation hypothesis: The avian clutch size is adjusted by natural selection to the maximum number of nestlings that parents can feed and nourish.
Variation in the seasonality of resources is the ultimate cause of geographical variations in clutch size.
Nest predation favors smaller clutch sizes in songbirds in several ways:
-Small clutches take fewer days to complete
-Smaller numbers of young in a nest make less noise
-Reduced visitation by parents to feed smaller broods reduces risks that predators will find parents and/or nest
Egg colors/shape
Nightjar - white eggs nocturnal
Spherical eggs Owls, kingfisher,
Strength
Robin - blue egg - maybe uv protection
Cavity nesters vs open cup
types of nest/ build …
