L9 animal dispersion and competition

Why do animals occur at variable densities

Differences in resources and behaviour

What is biogeography

Study of population spacing

What is behavioural ecology

Study of individual spacing

What is ideal free distribution

Individuals distribute based on payoffs

What does ideal free model assume

Individuals can move freely

What determines distribution in ideal free model

Payoffs not patch quality

Who studied ideal free distribution in fish

Milinski

What organism was used in this study

Sticklebacks

What can individuals do between patches

Move and spend more time in better patch

What triggers movement between patches

Decline in food availability

Why might animals not be free to move

Competition

How can individuals differ in distribution

Ability to win contests

What is resource defence

Protecting resources from others

What is habitat saturation

Preferred habitats become full

What happens when habitat is full

Extra individuals excluded

What are floaters

Individuals without territory

What do floaters do

Occupy poor habitats

What is an example species for habitat saturation

Great tits

Which habitat do great tits prefer

Woodland

Why is woodland preferred

More food and nest sites

What limits woodland occupancy

Territorial behaviour

What happens when males are removed

Floaters move in quickly

What is an example species with floaters

Red grouse

What habitat do red grouse occupy

Heather moor

What do male red grouse defend

Territories

What happens to floaters in winter

Often die

What happens when territory holders are removed

Floaters take over

What are costs of territorial defence

Energy loss injury risk predation risk

What are benefits of territorial defence

Food mates predictable resources

When is territorial defence uneconomical

Costs exceed benefits

What options exist if defence is uneconomical

Defend smaller area move or float

What bird demonstrates territorial economics

Golden winged sunbird

What resource do sunbirds defend

Nectar

Why is nectar valuable

Renewable energy source

How does nectar availability differ

Higher in defended territories

What determines foraging time

Nectar amount and access time

When is defence worthwhile

Energy gain exceeds cost

Why do sunbirds defend territories

Marginal benefit

When would defence not be worthwhile

Faster nectar replenishment

How do high invader numbers affect defence

Increase costs

What happens when costs increase

Defence becomes uneconomical