L19 Habitat Selection
Animal Habitat Selection
Animals choose habitats based on survival and resource needs, not randomly
Habitat Selection Factors
Animal habitat choice driven by predation, resources, competition, and seasonality
Habitat Selection Explained
Habitat selection is non-random, maximizing fitness and distinguishing use from selection
Ideal Free Distribution
Individuals distribute across habitats so that resource availability matches population density
Ideal Free Distribution Experiment
Fish distribute themselves by feeder ratio, following the ideal free distribution (IFD) model
Resource Matching and Intake
Animals congregate according to resource availability, but stronger individuals gain more with unequal resources
Habitat Use and Risk
Animals balance resource gain and predation risk in habitat selection under landscape of fear
Competition and Population Dynamics
Competition influences habitat access and fitness, causing density-dependent growth rates
Ideal Despotic Distribution
Dominant individuals monopolize best habitat; subdominants use suboptimal or edge habitats. Habitat quality→Fitness\text{Habitat quality} \rightarrow \text{Fitness}Habitat quality→Fitness
Optimal Foraging Decisions
Animals balance food quality, risk, and time to maximize foraging efficiency
Optimal Foraging and Density
As resource density increases, grater selectivity for larger prey pieces increases
Animal Foraging Strategies
Animals trade off risk and safety in habitat choice and use memory and compasses for efficient foraging
Hierarchical Habitat Selection
Animals use nested, multi-scale decision making for habitat selection
GPS Telemetry Analysis
GPS data enables studying animal locations, behaviors, and habitat preferences over time
Wolf Extinction Impact
Wolf removal caused elk overpopulation, degrading vegetation and ecosystem health
Trophic Cascades and Wolves
Wolves induce trophic cascades, altering elk behavior and restoring ecosystem diversity
Wolf Trophic Cascades Debate
Wolf impact is significant but not solely responsible for river ecosystem changes
Context Dependent Habitat Selection
Animals balance energy, risk, competition; habitat selection affects fitness and distributions
Here’s a detailed bullet-point summary of Habitat Selection with 30 MCQs and answer key.
✅ Detailed Bullet-Point Summary: Habitat Selection
Why Habitat Selection Matters
Animals distribute themselves in space and time relative to key resources:
Food
Mates
Shelter or refuge from predators
Habitat selection is active: animals make choices on where to live and forage.
Evolutionary question: How did these behaviors evolve to maximize fitness?
Definition
Habitat selection = non-random use of environments to maximize survival and reproduction.
Use: where an animal is found.
Selection: behavioral process behind distribution.
Ideal Free Distribution (IFD) Model (Fretwell 1972)
Explains how animals distribute across habitats:
Assumes animals can move freely and have perfect knowledge.
Predicts equilibrium distribution:
Moving from one patch reduces payoff (fitness).
Resource matching rule:
Distribution of individuals matches resource availability.
Individual food intake:
At equilibrium, all individuals receive roughly equal resources.
Limitations:
Ignores predators, disease, humans, and intra/inter-specific competition.
Real-world distributions may deviate due to these factors.
Experimental Evidence
Milinski (1979): Stickleback fish distributed themselves in proportion to water flea availability (5:1, 2:1 ratios).
Harper (1982): Mallards distributed themselves to maintain equal food intake, but aggressive interactions caused deviations → IFD needs recalibration.
Ideal Despotic Distribution
Competition limits access to preferred habitats.
Dominant individuals occupy high-quality patches.
Subordinate individuals forced into suboptimal areas, reducing fitness.
Landscape of Fear
Habitat selection involves trade-offs between food and safety:
Open sites → high food, high predation risk.
Covered sites → low food, low predation risk.
Dynamic Habitat Selection
Habitat use is context-dependent:
Daily cycles: forage at night, rest by day.
Seasonal changes: summer foraging vs. winter shelter.
Long-term: disturbance, climate shifts.
Animals constantly balance energy gain, safety, and competition.
Link with Foraging
Food is patchy in space and time:
Decisions: what to eat, where, when, and when to stop.
Optimal foraging strategies maximize energy gain and minimize costs:
Energy expenditure
Risk
Spatial memory improves foraging success, especially in sparse high-value patches.
Stress hormones (corticosterone) can impair spatial memory.
Navigation in Habitat Selection
Animals use multiple navigational tools:
Sun compass
Star compass
Odour maps
Magnetic maps
Landmarks
Nested decisions (Johnson 1980):
Geographic area selection
Habitat selection within area
Microhabitat or behavioral use
Conservation Example: Yellowstone
Wolves extirpated → elk population rose → over-browsing of willows/aspen → ecosystem degradation.
Wolves reintroduced → elk altered habitat use → vegetation recovery → improved ecosystem diversity.
Demonstrates behavioral cascades: predator presence shapes prey distribution, affecting community dynamics.
Key Takeaways
Habitat selection is non-random, hierarchical, and context-dependent.
Driven by resource acquisition, predation risk, competition, and reproductive needs.
Models like IFD and Ideal Despotic Distribution help explain patterns but must be modified in real-world conditions.
Selection is dynamic: shifts with hunger, breeding stage, season, and environmental changes.
📝 30 MCQs: Habitat Selection
1. Habitat selection is primarily aimed at:
A. Random movement
B. Maximizing fitness
C. Avoiding all predators
D. Social dominance
2. “Use” in habitat selection refers to:
A. Behavioral process of choosing habitat
B. Physical location of an animal
C. Competition intensity
D. Predator density
3. “Selection” in habitat selection refers to:
A. Actual location of the animal
B. Behavioral process behind habitat use
C. Random choice
D. Migration pattern
4. The Ideal Free Distribution (IFD) assumes:
A. Animals cannot move between patches
B. Animals have perfect knowledge of resources
C. Only predators determine distribution
D. Resources are irrelevant
5. IFD predicts equilibrium when:
A. Moving patches increases fitness
B. Moving patches decreases fitness
C. Resources are infinite
D. Predators are absent
6. Resource matching rule states:
A. Individuals cluster in a single patch
B. Distribution matches resource availability
C. Dominant individuals monopolize resources
D. Food intake is unequal
7. IFD prediction: individual food intake at equilibrium is:
A. Equal
B. Maximized for dominants only
C. Random
D. Minimal
8. Milinski’s stickleback experiment demonstrated:
A. Random distribution of fish
B. Fish matched patch abundance of food
C. Fish avoided high-density patches
D. Fish ignored resource availability
9. Harper’s mallard experiment showed deviations from IFD due to:
A. Predator presence
B. Aggression and competition
C. Water temperature
D. Disease
10. Ideal Despotic Distribution describes:
A. Free movement without competition
B. Dominants monopolize high-quality habitat
C. Equitable resource distribution
D. Random dispersal
11. “Landscape of fear” refers to:
A. Habitat selection based only on food
B. Predation risk influencing habitat use
C. Competition among conspecifics
D. Seasonal changes
12. Open sites typically provide:
A. Low food, low danger
B. High food, high danger
C. Low food, high safety
D. High food, low danger
13. Covered sites typically provide:
A. Low food, low danger
B. High food, high danger
C. High food, low danger
D. Random resources
14. Daily habitat selection example:
A. Summer vs winter
B. Day vs night activity
C. Long-term climate shifts
D. Predation risk only
15. Seasonal habitat selection example:
A. Resting by day
B. Summer vs winter foraging
C. Daily movement in home range
D. Predator presence
16. Long-term habitat selection can be influenced by:
A. Disturbance
B. Climate change
C. Both A and B
D. Neither
17. Food is distributed:
A. Evenly in space and time
B. Patchily
C. Randomly
D. Only seasonally
18. Optimal foraging theory predicts animals:
A. Maximize energy gain, minimize cost
B. Minimize energy intake
C. Avoid high-density patches always
D. Forage randomly
19. Spatial memory improves:
A. Predator detection only
B. Foraging success
C. Social interactions
D. Territory defense
20. Stress hormones like corticosterone typically:
A. Improve memory
B. Impair spatial memory
C. Have no effect
D. Increase energy intake
21. Navigational devices in animals include:
A. Sun compass
B. Star compass
C. Odour and magnetic maps
D. All of the above
22. Johnson (1980) proposed nested decisions:
A. Food selection → predator avoidance → migration
B. Geographic area → habitat → behavioral use
C. Random movement
D. Competition avoidance only
23. Habitat selection links:
A. Behavior, ecology, fitness
B. Only feeding behavior
C. Only predator avoidance
D. Migration only
24. Wolves extirpation in Yellowstone led to:
A. Reduced elk numbers
B. Increased elk numbers → overbrowsing
C. Recovery of vegetation
D. Stable ecosystem
25. Wolves reintroduction caused:
A. No effect on elk
B. Altered elk habitat use
C. Elk occupied open valleys freely
D. Decrease in predation risk
26. Behavioral cascades refer to:
A. Predator presence changing prey space use → affecting community
B. Random habitat use
C. Only competition-driven distribution
D. Daily activity cycles
27. Habitat selection is:
A. Random
B. Context-dependent
C. Static
D. Determined only by food
28. IFD assumes:
A. Predators are present
B. Perfect movement freedom
C. Only competition shapes distribution
D. Environmental variation irrelevant
29. Habitat selection is hierarchical:
A. True
B. False
30. Animals make trade-offs in habitat choice between:
A. Food and safety
B. Competition and reproduction
C. Both A and B
D. Neither
✅ Answer Key: Habitat Selection MCQs
1—B
2—B
3—B
4—B
5—B
6—B
7—A
8—B
9—B
10—B
11—B
12—B
13—A
14—B
15—B
16—C
17—B
18—A
19—B
20—B
21—D
22—B
23—A
24—B
25—B
26—A
27—B
28—B
29—A
30—C
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