Ornithology - TRUE Exam 3

hatching synchrony

varies depending on incubation behaviors

immediate incubation

asynchronous hatching, can facilitate brood reduction

open nesters

tend to have a shorter parenting cycling due to predators

seabirds

tend to have a longer parental cycle due to lack of predators on islands

brood reduction

bet hedging strategy, smallest might not survive if not enough resources

infanticide

parents killing offspring

siblicide

offspring killing siblings

facultative siblicide

siblicide through competition, occurs through specific circumstances (stress, resource scarcity)

obligate siblicide

siblings unconditionally kill siblings, parents always produce more than they can raise

delayed incubation

synchronous hatching, facilitates group dispersal from vulnerable nests

hatching synchrony mallard example

all young hatch in two hour span, young ready to hatch vocalize slowly, young not ready to hatch vocalize quickly

young ready to hatch vocalize slowly

tends to accelerate hatching behaviors of others

young not ready to hatch vocalize quickly

tends to decelerate hatching behaviors in others

Super precocial

young are wholly independent as quickly as possible,

Precocial

leave nest immediately but stay with parents, parents help chicks find food but young feed themselves

Sub precocial

chicks leave nest immediately but stay with parents, chicks are fed by parents

Semi precocial

stay in the nest but can regulate body temperature and are mobile, chicks are fed by parents

semi altricial

stay in nest, eyes are open, have down, fed and brooded (incubated) by parents

altricial

naked, blind, helpless, fed and brooded by parents

super precocial birds

leave nest early, slow growth rate

altricial birds

leave nest later, fast growth rate

precocial birds have

open eyes, down, mobility, minimal parental care, self-feeding, large egg/yolk/brain sizes, slow growth rates

altricial birds have

closed eyes, no down, immobile, required parental care, nourished by parents, small egg/yolk/brain size, fast growth rate

tissue allocation hypothesis

reaching adult size fast or slow, growth rates reflect channeling energy into two competing demands, growth vs mobility

altricial allocation

favors growth over mobility

precocial allocation

favors mobility over growth

precocial and altricial are two different

strategies to maximize fitness

Nutrition

many chicks fed teeth and eggshell fragments, water typically not provided

foods must provide

amino acids, fats, minerals (calcium), vitamins, trace elements

insects

common early food even for seed eaters

fruits

poor in some essential nutrients and for species that feed fruits, growth is 50% slower

“milk”

produced by crop in pigeons, flamingos, emperor penguin, high in protein and fat

early nutrition shapes

life history, peak in spider provision in early passerines

fine-scale prey selection is a mechanism by which

parents can manipulate behavioral phenotype of offspring

methods of feeding

mostly directly from parents beak, some regurgitated, some open mouth and let young retrieve

specific mouth patterns

inhibit parasitism

hawks

rip food into small pieces and put into young mouths

most altricial

gape and flutter and adults simulated to feed

begging

can be hazardous in ground nesting birds

fledging

critical period in terms of offspring mortality, can drive parent-offspring conflict

just fledged birds

are easy prey, mortality is highest within first few days out of nest

mortality

grown nestlings and fledglings 50%, newly independent young 50%, 11% banded nestlings return following year

parent-offspring conflict: parents

natural selection favors genotypes that result in parental behavior that maximizes lifetime reproductive success

parent-offspring conflict: offspring

natural selection favors genotypes that result in offspring behavior that maximizes that offspring’s lifetime reproductive success

long-term studies importance

to understand bird ecology, evolution, and behavior

critical components of lifetime reproductive success

annual survival and longevity, age at first breeding attempt, annual reproductive success

why is it hard to conduct long-term demographic studies

funding, security of study area, longevity of study species, hard to measure reproductive success, even harder to measure survivorship

dispersal creates bias

potential risk of missing birds that return following year travel to new location

on average, females move

2x as far next year if unsuccessful nesting

offspring survival

hard to estimate survival for fledglings, most birds in spring unbanded, rarely any return

return rate can be of little value

unless study area is very large relative to dispersal distance

annual survival

mortality highest in 1st year, high predation, high post-fledging predation, starvation in transition to independent feeding

Sx

survival rate at year x

Lx

probability of surviving to age x

Mx

annual fecundity (#female offspring)

LxMx

expected reproduction in year x

lifetime reproduction values R0>1

indicate growing populations

negative correlation between

longevity and fecundity

fecundity is directly proportional to

mortality

high longevity

low fecundity and low mortality

low longevity

high fecundity and high mortality

reproductive effort may increase with

age

reproductive success tends to peak

at mid-life

antagonistic pleiotropy

mutations that increase fitness early in life may have negative effects later in life

replacement clutches

females lay new clutches if first is lost

most second clutches are smaller

in egg number or egg size

As date advances in breeding season

young might be less valuable because of insufficient time to reach independence, not enough food, too much competition

strategic allocation

put less energy into second clutch due to lower value due to higher costs, low probability of success

environmental constraint

too little food available

methods of strategic allocation

take first clutch of pairs to make them produce second clutch, only provide food to some pairs

results of strategic allocation experiment

both food supplemented and non supplemented produced smaller eggs for second clutch

multiple broods

more common in tropics where breeding season is longer and there is more predation, less likely in species with extended parental care

6 clutches per year is

not uncommon in tropics, more time between attempts

general patterns in survivorship

large birds live longer than small birds, seabirds live longer than land birds, fledgling survival is half that of adults

tropical birds are assumed to live longer

than temperate zone birds

males live longer than

females

it is not clear what proportion of birds

die to old age

age at maturity decreases

as annual adult mortality increases

why do some birds delay breeding

cost of early breeding is too high

population demography: life tables

useful way of predicting population stability based on female numbers

life tables need

number of female young fledged/reproductive female as a function of reproductive female’s age, survivorship as function of age

Paternal aging reduces

both the likelihood that eggs hatch and the rate at which chicks grow

cost of paternal aging on offspring development is of a similar scale to that associated with

maternal aging

sperm of immature males produce the

fastest growing offspring

Any good genes benefit that might be offered by older ‘proven’ males will be

eroded by aging of their germline DNA

Adult females were

smaller with increasing experimental brood size in which their mother had been raised

Reproductive success at hatching and fledging covaried

negatively with the experimental brood size in which their mothers were raised

Early developmental stress can have long-lasting effects affecting

reproductive success of future generations

introduced species offer

opportunity for study

difficult to predict

population growth

density dependent population regulation

competition, parasites, diseases, processes whose impact is positively correlated with population size

density independent population regulation

changes which occur regardless of population size but affect population sizes

density independent population examples

weather/climate events, habitat abundance, food abundance, predation

predation can also be

density dependent regulation

metapopulation

network of interconnected populations that may vayr in demography

carrying capacity

theoretical maximum number of individuals that can be supported taking into account availability of resources that limit population sizes

carrying capacity factors

habitat, food, nest sites, roost sites