Territory and Migration Flashcards
What is Ideal free distribution theory?
As the density of consumers increases in a location there will be increased competition for food, space & other resources
There will come a point where an individual can gain higher fitness by settling in a lower ranked habitat that has fewer conspecifics
Describe territory.
High quality territories are often limited
Use of resources e.g. food or nesting material, without the interference of others
Attract potential mate(s)
More offspring
Defending a territory has significant costs
Energy expenditure
Risk of injury / death
What is Economic defensibility?
Cost vs benefit
Individual predicted to defend territory when benefits outweigh the costs
What is Resource holding potential?
The ability of an animal to win a fight
Describe Resource holding potential in American redstarts.
Breeds in NA
Competes for territory during non-breeding winter in Caribbean & Central AmericaIn Jamaica, older, heavier males tend of occupy black mangrove forests along the coast.
Females and younger males forced towards second rate habitats
Redstarts living in mangroves retain weight over winter
Those in the inferior scrub generally lose weight
Body mass and condition not the only thing influenced
Structure of the genome
Telomere length greater in those birds that wintered in the favored location
Link between survival, telomere length & winter habitat quality
Carry over effects from non-breeding season to breeding season
Influences reproductive success
Which male red-shouldered widowers are more likely to hold territories?
Males with larger and redder shoulder patches more likely to hold territories
Territory holders are often what?
Territory holders are often relatively large and aggressive individuals
What is Resource value and payoff asymmetries?
Two individuals may value the same resource differently
Typically the resident will gain more from maintaining a territory than a newcomer would gain by taking it
Describe Tobias 1997 first experiment on Resource value and payoff asymmetries.
Experiment 1:
Remove territory holder to captivity for 10 days
On day 9 new bird takes up residency
Day 10: original territory holder released
Qn: Who holds the territory?
Describe Tobias 1997 second experiment on Resource value and payoff asymmetries.
Experiment 2:
Remove territory holder to captivity for 10 days
On day 1 new bird takes up residency
Day 10: original territory holder released
Qn: Who holds the territory?
Describe Shier & Swaisgood (2011) findings on kangaroo rats.
Move endangered kangaroo rats to a nature reserve in California
Initial attempts to establish a new breeding population were unsuccessful
A further attempt made but changed methods
1. Half were moved and left able to retain familiar neighbours
2. Half unfamiliar pairs
Group 1 fought less & produced more offspring
What is Dispersal?
The permeant movement from place of birth to another location
What is costly about dispersal?
Energy for the move Falling prey in unfamiliar location Time Reduced fitness if don’t select best location Aggressive conspecifics
What is Migration?
The movement away from and subsequent return to the same location on an annual basis
What are the benefits of migration?
Access to resources e.g. food, water
Escaping deteriorating conditions e.g. driven by seasonal cycles
