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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
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


What are the costs of migration?

Greater metabolic demands
Pathogen transmission
Greater predation risk
Flying over large bodies of water


What did Baker et al 2004 find?

Weight ~110g
Add ~70g
Eat fat rich eggs to fuel long trip to Arctic breeding grounds
Overharvesting 90%
Population here 75%
Remaining left with lower weight – less likely to be recaptured following year