Chapter 18: Population Dynamics Flashcards
What can cause dramatic fluctuations in bird populations?
Hunter
Unpredictable climate change
Major storms
What is so legendary about the Short-Tailed Albatross?
Hunters and volcanos reduced it’s population to the point of near extinction.
Six pairs actually remained and restored the species.
Texas quail populations are declining or increasing?
Declining due to widespread habitat degradation.
what happened when Common Starling was introduced to Central Park?
multiplied from 120 birds to 200 million
benefits of short generation times?
- Accelerates rates of population growth
- promotes colonization, speciation, diversity
what is the reproductive rate of large bodies species?
10-30%
what is the reproductive rate of small-bodied species?
50-100%
define and explain the S-Shaped growth pattern
- sigmoid
- growth begins slow then accelerates then tapers off
Why does S shapes growth taper off?
- Negative feedback that lowers reproduction and survival
- carrying capacity
Define environmental carrying capacity
a population’s growth rate slows as availability of resources falls below the need for resources
values for per capital replacement, R that are greater than 1 indicates…?
lesser than 1…?
greater than 1: growing population
lesser than 1: declining population
what does Local Recruitment of a local population include?
1) number if young produced in the breeding season that survive
2) young that have immigrated from elsewhere
in reference to population size, define “limitation”
any ceiling on population growth
habitat, food, climate, resources, predation, availability of nest holes
in reference to population growth, define “regulation”
refers to effects of population density on the population size
as population density increases what decreases ?
- mean clutch size
- number of fledglings
- parental success due to increased predation
- quality & availability of resources
what type of trees do great tits prefer over pine?
oak and beech
deforestation favors which species?
It favors open country species over those that rely on large timber
where do Eurasian Blackcaps and Dunnocks tend to live?
undergrowth of forests
how do white-tailed deer harm certain bird populations?
they destroy the forest undergrowth that many bird populations usually dwell in.
why are tropical natural habitats important to preserve?
many migratory species converge into dense populations to winter in these lands
what is the main food of many seabirds?
anchovies
define “irruption”
mass evacuation of bird populations
ex: snowy owl in 1945
on what types of birds do predators serve as a limitation on population growth?
- island birds
- ducks
- game birds (since we have removed many of the top predators that preyed on mid-sized predators which are now free to kill birds)
exposure to parasites has caused birds to…
- invest more into immunity
- lose energy required for reproduction
- become more mate biased
- —-favor plumage quality and display endurance
what currently is parasitizing Darwin’s Galapagos finches?
blowflies which feed on the nestlings blood and burrow deep into their bodies and brains.
average finch had 23 maggots
how do abundant species overcome declines in local populations?
by recruiting young birds from other populations.
the best documented example of a decline in population due to bacterial disease is with what?
North American house finches with conjunctivitis from Mycoplasma gallisepticum
epizootic refers to what?
a new disease that exceeds expectations in an animal population
Explain the three stages of available habitats.
1) primary habitats fill up.
2) surplus birds move to suboptimal habitats and wait for vacancies in primaries.
3) floaters live singly on home ranges that overlap breeding pairs
what does the presence of floater birds in a population indicate?
that the breeding population is limited by the habitat
Recall the procedure when a vacancy arises in a suboptimal habitat.
the most dominant and sexually appropriate floater bird quickly seeks to replace the vacant bird by trying to mate with the remaining bird on the suboptimal or primary territory.
if the old bird returns, the floater is demoted again. ex: Rufous-collared Sparrow.
how is dispersal related to population density?
the greater the population density, the greater the dispersal length of the population. (they travel further for territories)
