Ornithology exam 3
Nests & Incubation
What are the challenges to nesting we discussed in lecture?
Predation, Starvation, Adverse weather
What causes the most nest failures?
Predation
What are nests constructed of?
Natural and inorganic materials.
What are the three basic categories of passerine nests?
Cavities, Open-Cup, Domed
How do young birds know how to construct a nest? Are they good at building their first nests?
Genetics and no, it comes with practice.
Do monogamous male passerines in NA assist in nest building? Why?
Yes, for sexual selection and protection.
What is a secondary cavity nester?
Tree cavity nesters that do not make their own holes.
How do bird parents reduce potential predation of their eggs or nestlings?
Many attack trespassers.
Where can birds nest to try and ensure nest safety?
Cryptic sites (invisibility), Difficult locations (inaccessibility),
Which types of nests / nesters are most vulnerable to predators?
Ground nests/nesters, like waterfowl and tooth-billed pigeons.
Why is nest microclimate so important and how does it influence the eggs, young, and adults?
Influences the energy of adults, rates of water loss and warmth which are all crucial to the survival of young.
What hormone mediates incubation behavior?
Prolactin
Why is nest success higher in northern latitudes and in cavity-nesters?
Cavity nests are safer and have better microclimates. Northern latitudes do not get too hot in the summer.
What happens to males that incubate in terms of hormonal changes?
Testosterone drops
How do incubation shifts influence predation rates?
Predation decreases with reduced parental activity
What is the incubation period?
Interval between laying and hatching last egg
How do incubation periods relate to adult lifespan?
Longer incubation period = longer adult lifespans
How do parents endure all eggs hatch around the same time?
Wait to incubate until all eggs are laid.
What is a brood patch and how does it differ from apteria?
Bare skin on breast. Only appears during the incubation period.
Do all birds have brood patches? Give an example of a bird that doesn’t and how it incubates its eggs.
No, gannets and boobies incubate eggs with feet.
Describe the process of a chick hatching. What structures / muscles does the chick use to emerge?
Hatching muscle, egg tooth.
Why will an adult bird remove the eggshells from the nest?
To camouflage and protect nest.
Parents & Their Offspring
Know the morphological differences between precocial and altricial young.
Precocial: feathered, open eyes, mobile
Altricial: naked, blind, immobile
Was precocial or altricial young the original mode of development among birds?
Precocial
What is bird “milk”? Specifically ,what does it contain and where does it come from in birds?
Protein and fat from the lining of the crop.
What is the tissue allocation hypothesis and how / what does it influence regarding the growth of young birds?
Channeling resources efficiently into growth.
Influences: delays wing and flight muscle development, smaller brains to body size at hatching, postpones tissue maturation
Why is eating insects better than fruits in developing birds?
Insects are high in protein
What influences the growth rates of young birds?
Quality/quantity of food, pattern of feeding, temperature.
Define the practice of siblicide and why is it exhibited in some birds?
Chicks killing siblings for competition of resources.
How does parenting make an adult bird more susceptible to disease and parasites?
Energetically expensive, stress affects the immune system.
Do bird parents always prefer the largest and loudest nestling? If no, provide an example.
No, such as the American coot which favors smaller and more colorful chicks.
Why/how can asynchronous hatching be advantageous?
Protects parents from losing entire brood, lower peak food demands, predictable siblicide.
Define nestling period.
Interval between hatching and departure from nest
Define fledgling period.
Interval between hatching and flight
Is the ability to identify danger innate, learned, or both in young birds? Provide an example.
Both, such as in domestic chickens and turquoise browed motmots.
Define the process of sexual imprinting and provide an example.
Choosing mates that are the same color as parents
Life Histories
Define annual fecundity.
Number of young successfully fledged in a year
Do short-lived species have high or low annual fecundity and why?
High fecundity – species has higher mortality
Do long-lived species have high or low annual fecundity and why?
Low fecundity – species has lower mortality
How does annual survival and reproduction (i.e., number of young produced) change with age in adult birds?
Survival and reproduction start low then increase with age before decreasing.
Define fecundity.
Number of young raised successfully
Understand what influences lifetime reproductive success.
Age at first breeding, lifespan, annual reproductive performance
Understand what influences annual fecundity.
#of nesting attempts, rate of success, # of eggs laid, age/experience
What is a double brooded female? Why is this advantageous?
Lay second clutch after successful first clutch. Increased fecundity
What limits clutch sizes in precocial and altricial birds?
Precocial: egg nutrition requirements limit clutch size
Altricial: Parents ability to feed young limit clutch size
Why is it advantageous to delay breeding?
Maximizes reproductive success, more successful when competition is high
How does investment in a clutch influence physical condition and reproductive potential in the next breeding season?
What is the food limitation hypothesis?
Clutch size is determined by the availability of food
What is the benefit of raising smaller clutches even when resources are plentiful?
Higher rates of chick survival.
What is actuarial senescence
Death rates that increase with age
What is senescence
Age-related declines in immunie function
Populations
Changes in population size are a result of changes in...?
Survivorship and fecundity
Define annual growth potential?
Maximum rate a population can increase in size within 1 year
How does recruitment drive local population growth?
Recruits include young from other places.
What are the four major attributes that specify performance of the average bird in a population?
Age at 1st reproduction
Fecundity
Survival of Young
Longevity
How do white-tailed deer pose a threat to bird populations in eastern North America?
They eat the understory in deciduous forests that many birds need.
Why are slow-maturing species easily endangered?
Slow to replace reproductive adults
Understand population sources and sinks.
Sources: produce excess young
Sinks: cannot sustain themselves except through immigration
What are population limitations? Provide some examples.
Ceilings on population growth, habitat, food, climate, predation, disease
What are population regulations? Provide an example.
Effects of population density on population size, like changing birth and mortality rates
How does habitat and food supplies influence population size? Provide examples.
Species requiring special habitats yield smaller population sizes (RCWP). Seabird populations mirror food supplies, decline during overfishing.
What is NAWMP and what does it do?
North American Waterfowl Management Plan. Seeks to conserve and protect habitats of waterfowl.
Speciation Pt. I
How does assortative mating influence the speciation process?
Isolates populations from other similar populations
Define and understand the biological species concept.
A species is a broad and dynamic population of organisms that can interbreed and produce fertile offspring
Define and understand the phylogenetic species concept.
Defines a species as the smallest group of organisms that unique evolutionary history
What is allopatric speciation?
Biological populations become isolated due to geographical changes
How is sexual selection important to speciation?
Traits and adaptations shared among a species develop from sexual selection
What is secondary contact and what does it provide to birds and what can it lead to?
Interactions of divergent sister taxa coming back into contact.
Hybridization, or reproductive isolation
Define ring species.
Two reproductively isolated forms connected through interbreeding populations
How did the Pleistocene climate (i.e., glaciers) define many modern birds of northern continents?
Populations fragmented around glaciers and birds followed when glaciers retreated.
How does natal dispersal influence gene flow?
Movement of young birds from hatching to breeding sites==large distances equals more gene diversity, small distances enhance genetic isolation
Understand the differences in natural selection and gene flow.
Natural selection: different propagation of genotypes
Gene flow: movement of alleles among local populations due to dispersal
Speciation Pt. II
Define hybridization.
Individual breeding w/another individual outside its species
Hybridization is most common in what group of birds?
Waterfowl
How / why are different genera able to hybridize?
Retained genomic compatibility
Define Haldane’s Rule.
The sex with two different sex chromosomes tend to be sterile (females, in birds)
Are male or female bird hybrids more likely to be sterile? Why?
Females, because they are ZW
Define F2 Breakdown.
Incompatible gene combinations disrupting embryo development in 2nd generation offspring.
When is biological species status warranted?
No hybrids present, and clear reproductive isolation
What is a hybrid zone?
Location where two or more species ranges come into contact and interbreed
Define the bounded superiority model.
Hybrid zones occur w/intermediate ecological or climatic conditions
Define the dynamic equilibrium model.
A stable hybrid zone is a population sink of inferior hybrids
How can cultural transmission of behavior & traits can drive speciation?
Influences sexual selection and reproductive isolation.
Communities Pt. I
Understand the differences in open vs. closed communities.
Open communities: coincidental dynamic assemblages of species
Closed communities: stable combinations of species drawn from a larger pool of possible colonists
What is environmental filtering?
Adaptation to specific temperature regimes along elevation gradients
What habitat type has higher species and community diversity?
Tropical habitats
Define species richness.
Total number of different species in a specific area or habitat
Define community diversity.
Variety of species that interact within a specific area, considers species richness and abundance.
Define alpha diversity.
Species diversity on a local scale
Define beta diversity.
Ration between regional and local diversity
Define gamma diversity.
Total species diversity in a landscape
Why does alpha diversity increase with forest complexity?
More foraging opportunities with different habitats
How is species diversity influenced by food availability?
More food = greater diversity in tropics
If tropical and temperate forests don’t differ in overall heterogeneity / complexity, why are there more species in the tropics?
More specialized forest floor behaviors in tropic species, less overlap in foraging stations
What are some benefits and costs of being a resident and non-resident?
Residents: accommodate monthly changes in weather and food availability
Non residents: take advantage of predictable periods of food abundance
How does climate influence adaptations and community structure?
Physiological adaptations are needed for extreme climates, community structures can change as habitat specialists develop, migrant behaviors change etc.
Communities Pt. II
Define interspecific competition.
Birds of coexisting species want the same resources
Define intraspecific competition.
Birds of same species want the same resources
Define foraging guild.
Group of species that eat the same resources in same time and place
Define Hutchinson’s ratio.
Each co-existing species has 2x the body mass of the next smallest
Define Gause's competitive exclusion principle.
Resource partitioning might reflect competition limiting which species can occur un a community
Define inference competition and provide an example.
Overt aggressive displacement of individual birds. Feeder competition, hummingbirds.
Define exploitative competition and provide an example.
Reduction of fecundity and survival of one species by another. Great tits and Blue tits coexist and directly affect each others populations
Define ecological release and provide an example.
The population of one species increases due to a reduction in limiting environmental factors. Anna’s hummingbird increase due to more widespread food availability
How do community interactions affect geographical distributions of bird species?
One species may abruptly replace another
What is the issue in determining the influence of predation on bird populations?
No true baseline.
How do parasites and pathogens affect community composition? Think of mainland vs island populations.
Reduce community diversity on islands. Continental populations will only have temporary community changes
How can mutualistic interactions increase community diversity?
Promotes evolution of specialization
What is the equilibrium theory of island biogeography?
Population losses and gains are a predictable balance