Lecture 14 Predation

1
Lecture 14 Predation

• I. Introduction
• A. Definition of predation
• B. Three types of predators
• C. Why is predation important? (Lecture 13)

2
Lecture 14 Predation

• I. Introduction
• A. Definition of predation - Individual of one
  species eats all or part of a living
  individual of another species, often killing it
  and nearly always reducing growth and
  reproduction.
• B. Three types of predators
• C. Why is predation important? (Lecture 13)

3
Lecture 14 Predation

• I. Introduction
• A. Definition of predation - Individual of one
  species eats all or part of a living
  individual of another species, often killing it
  and nearly always reducing growth and
  reproduction.
• B. Three types of predators
• 1. True predators
• 2. Grazers
• 3. Parasites and parasitoids (Lecture 13)
• C. Why is predation important?

4
Lecture 14 Predation

• I. Introduction
• A. Definition of predation - Individual of one
  species eats all or part of a living
  individual of another species, often killing it
  and nearly always reducing growth and
  reproduction.
• B. Three types of predators
• 1. True predators - almost always kill their
  prey and consume many prey throughout their
  life.
• 2. Grazers
• 3. Parasites and parasitoids (Lecture 13)
• C. Why is predation important?

5
Lecture 14 Predation

• I. Introduction
• A. Definition of predation - Individual of one
  species eats all or part of a living
  individual of another species, often killing it
  and nearly always reducing growth and
  reproduction.
• B. Three types of predators
• 1. True predators - almost always kill their
  prey and consume many prey throughout their
  life. Examples - lions, spiders, insectivorous
  birds, cutworms, granivorous rodents, baleen
  whales.
• 2. Grazers
• 3. Parasites and parasitoids (Lecture 13)
• C. Why is predation important?

6
Lecture 14 Predation

• I. Introduction
• A. Definition of predation - Individual of one
  species eats all or part of a living
  individual of another species, often killing it
  and nearly always reducing growth and
  reproduction.
• B. Three types of predators
• 1. True predators - almost always kill their
  prey and consume many prey throughout their
  life. Examples - lions, spiders, insectivorous
  birds, cutworms, granivorous rodents, baleen
  whales.
• 2. Grazers - consume only part of many prey
  and dont kill the prey.
• 3. Parasites and parasitoids (Lecture 13)
• C. Why is predation important?

7
Lecture 14 Predation

• I. Introduction
• A. Definition of predation - Individual of one
  species eats all or part of a living
  individual of another species, often killing it
  and nearly always reducing growth and
  reproduction.
• B. Three types of predators
• 1. True predators - almost always kill their
  prey and consume many prey throughout their
  life. Examples - lions, spiders, insectivorous
  birds, cutworms, granivorous rodents, baleen
  whales.
• 2. Grazers - consume only part of many prey
  and dont kill the prey. Examples - cattle,
  sheep, locusts, leeches, mosquitos.
• 3. Parasites and parasitoids (Lecture 13)
• C. Why is predation important?

8
Lecture 14 Predation

• I. Introduction
• B. Three types of predators
• 1. True predators - almost always kill their
  prey and consume many prey throughout their
  life. Examples - lions, spiders, insectivorous
  birds, cutworms, granivorous rodents, baleen
  whales.
• 2. Grazers - consume only part of many prey
  and dont kill the prey. Examples - cattle,
  sheep, locusts, leeches, mosquitos.
• 3. Parasites and parasitoids (Lecture 13) -
  consume part of host but generally dont kill
  their prey (parasites). Usually confined to one
  or a few hosts. Almost always in symbiotic
  relationship with host.
• C. Why is predation important?

9
Lecture 14 Predation

• I. Introduction
• B. Three types of predators
• 1. True predators - almost always kill their
  prey and consume many prey throughout their
  life. Examples - lions, spiders, insectivorous
  birds, cutworms, granivorous rodents, baleen
  whales.
• 2. Grazers - consume only part of many prey
  and dont kill the prey. Examples - cattle,
  sheep, locusts, leeches, mosquitos.
• 3. Parasites and parasitoids (Lecture 13) -
  consume part of host but generally dont kill
  their prey (parasites). Usually confined to one
  or a few hosts. Almost always in symbiotic
  relationship with host. Examples -
  Plasmodium, spirochetes that cause Lyme disease.
  
• C. Why is predation important?

10
Lecture 14 Predation

• I. Introduction
• B. Three types of predators
• 1. True predators - almost always kill their
  prey and consume many prey throughout their
  life. Examples - lions, spiders, insectivorous
  birds, cutworms, granivorous rodents, baleen
  whales.
• 2. Grazers - consume only part of many prey
  and dont kill the prey. Examples - cattle,
  sheep, locusts, leeches, mosquitos.
• 3. Parasites and parasitoids (Lecture 13) -
  consume part of host but generally dont kill
  their prey (parasites). Usually confined to one
  or a few hosts. Almost always in symbiotic
  relationship with host. Examples -
  Plasmodium, spirochetes that cause Lyme disease.
  
• C. Why is predation important?
• 1. Most obvious interaction (true predators)
• 2. Basis of food webs and trophic structure
• 3. Effects on population dynamics

11
Lecture 14 Predation

• I. Introduction
• C. Why is predation important?
• 1. Most obvious interaction (true predators).
  True predators can be seen capturing and
  eating their prey. Much more obvious than
  competition, amensalism, or most mutualisms or
  commensalisms.
• 2. Basis of food webs and trophic structure
• 3. Effects on population dynamics

12
Lecture 14 Predation

• I. Introduction
• C. Why is predation important?
• 1. Most obvious interaction (true predators).
  True predators can be seen capturing and
  eating their prey. Much more obvious than
  competition, amensalism, or most mutualisms or
  commensalisms.
• 2. Basis of food webs and trophic structure.
  All links in a food web are (,)
  interactions. All predation interactions are
  part of trophic structure of a community
  (Lecture 17).
• 3. Effects on population dynamics

13
Lecture 14 Predation

• I. Introduction
• C. Why is predation important?
• 1. Most obvious interaction (true predators).
  True predators can be seen capturing and
  eating their prey. Much more obvious than
  competition, amensalism, or most mutualisms or
  commensalisms.
• 2. Basis of food webs and trophic structure.
  All links in a food web are (,)
  interactions. All predation interactions are
  part of trophic structure of a community
  (Lecture 17).
• 3. Effects on population dynamics. Predators
  can have dramatic effects on size of prey
  populations and can create population cycles
  (see Section II below).

14
Lecture 14 Predation

• II. Models and Examples of Predation
• A. Lotka-Volterra models (FIG. 1)
• B. Modification of Lotka-Volterra models
• C. Examples of predator-prey cycles in nature
  (FIG. 3)

15
Lecture 14 Predation

• II. Models and Examples of Predation
• A. Lotka-Volterra models (FIG. 1)
• 1. Prey population
• a. Basic Lotka-Volterra prey model
• b. Zero isocline for prey
• 2. Predator population
• a. Basic Lotka-Volterra predator model
• b. Zero isocline for predators
• 3. Predictions of Lotka-Volterra models
• 4. Assumptions of Lotka-Volterra models

16
Lecture 14 Predation

• II. Models and Examples of Predation
• A. Lotka-Volterra models (FIG. 1)
• 1. Prey population
• a. Basic Lotka-Volterra prey model
• where a searching attacking
  efficiencies
• aPN no. of prey (N) killed by
  predators (P)
• b. Zero isocline for prey

17
Lecture 14 Predation

• II. Models and Examples of Predation
• A. Lotka-Volterra models (FIG. 1)
• 1. Prey population
• a. Basic Lotka-Volterra prey model
• where a searching attacking
  efficiencies
• aPN no. of prey (N) killed by
  predators (P)
• b. Zero isocline for prey

18
Lecture 14 Predation

• II. Models and Examples of Predation
• A. Lotka-Volterra models (FIG. 1)
• 1. Prey population
• a. Basic Lotka-Volterra prey model
• where a searching attacking
  efficiencies
• aPN no. of prey (N) killed by
  predators (P)
• b. Zero isocline for prey
• In other words, there is a constant number of
  predators that will stabilize the population of
  prey.

19
Lecture 14 Predation

• II. Models and Examples of Predation
• A. Lotka-Volterra models (FIG. 1)
• 1. Prey population
• a. Basic Lotka-Volterra prey model
• where a searching attacking
  efficiencies
• aPN no. of prey (N) killed by
  predators (P)
• b. Zero isocline for prey
• In other words, there is a constant number of
  predators that will stabilize the population of
  prey. Below that number of predators the prey
  population always increases and above that number
  of predators the prey population always
  decreases.

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Lecture 14 Predation

• II. Models and Examples of Predation
• A. Lotka-Volterra models (FIG. 1)
• 2. Predator population
• a. Basic Lotka-Volterra predator model
• b. Zero isocline for predators

22
Lecture 14 Predation

• II. Models and Examples of Predation
• A. Lotka-Volterra models (FIG. 1)
• 2. Predator population
• a. Basic Lotka-Volterra predator model
• where f efficiency of turning prey
  into offspring
• q mortality rate of predators
• faPN no. of predator offspring
  produced
• b. Zero isocline for predators

23
Lecture 14 Predation

• II. Models and Examples of Predation
• A. Lotka-Volterra models (FIG. 1)
• 2. Predator population
• a. Basic Lotka-Volterra predator model
• where f efficiency of turning prey
  into offspring
• q mortality rate of predators
• faPN no. of predator offspring
  produced
• b. Zero isocline for predators

24
Lecture 14 Predation

• II. Models and Examples of Predation
• A. Lotka-Volterra models (FIG. 1)
• 2. Predator population
• a. Basic Lotka-Volterra predator model
• where f efficiency of turning prey
  into offspring
• q mortality rate of predators
• faPN number of predator offspring
  produced
• b. Zero isocline for predators
• If then so
• In other words, the predator population remains
  stable for some given number of prey.

25
Lecture 14 Predation

• II. Models and Examples of Predation
• A. Lotka-Volterra models (FIG. 1)
• 2. Predator population
• a. Basic Lotka-Volterra predator model
• where f efficiency of turning prey
  into offspring
• q mortality rate of predators
• faPN number of predator offspring
  produced
• b. Zero isocline for predators
• If then so
• In other words, the predator population remains
  stable for some given number of prey. Below that
  number of prey the predator population always
  decreases and above that number of prey the
  predator population always increases.

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Lecture 14 Predation

• II. Models and Examples of Predation
• A. Lotka-Volterra models (FIG. 1)
• 3. Predictions of Lotka-Volterra models
• Coupled oscillations with a time lag
  between prey abundance and predator
  abundance.
• 4. Assumptions of Lotka-Volterra models

28
Lecture 14 Predation

• II. Models and Examples of Predation
• A. Lotka-Volterra models (FIG. 1)
• 3. Predictions of Lotka-Volterra models
• Coupled oscillations with a time lag
  between prey abundance and predator
  abundance. These continuing oscillations with a
  time lag in response of prey to predators
  vice versa is called neutral stability.
• 4. Assumptions of Lotka-Volterra models

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Lecture 14 Predation

• II. Models and Examples of Predation
• A. Lotka-Volterra models (FIG. 1)
• 3. Predictions of Lotka-Volterra models
• Coupled oscillations with a time lag
  between prey abundance and predator
  abundance. These continuing oscillations with a
  time lag in response of prey to predators
  vice versa is called neutral stability.
• 4. Assumptions of Lotka-Volterra models
• We can see the assumptions by looking at
  the equations.

31
Lecture 14 Predation

• II. Models and Examples of Predation
• A. Lotka-Volterra models (FIG. 1)
• 3. Predictions of Lotka-Volterra models
• Coupled oscillations with a time lag
  between prey abundance and predator
  abundance. These continuing oscillations with a
  time lag in response of prey to predators
  vice versa is called neutral stability.
• 4. Assumptions of Lotka-Volterra models
• We can see the assumptions by looking at
  the equations.
• First, growth of N is limited only by P
  (predation by this predator).

32
Lecture 14 Predation

• II. Models and Examples of Predation
• A. Lotka-Volterra models (FIG. 1)
• 1. Prey population
• a. Basic Lotka-Volterra prey model
• where a searching attacking
  efficiencies
• aPN no. of prey (N) killed by
  predators (P)
• b. Zero isocline for prey

33
Lecture 14 Predation

• II. Models and Examples of Predation
• A. Lotka-Volterra models (FIG. 1)
• 3. Predictions of Lotka-Volterra models
• Coupled oscillations with a time lag
  between prey abundance and predator
  abundance. These continuing oscillations with a
  time lag in response of prey to predators
  vice versa is called neutral stability.
• 4. Assumptions of Lotka-Volterra models
• We can see the assumptions by looking at
  the equations.
• First, growth of N is limited only by P
  (predation by this predator)
• Second, the predator is a specialist.

34
Lecture 14 Predation

• II. Models and Examples of Predation
• A. Lotka-Volterra models (FIG. 1)
• 2. Predator population
• a. Basic Lotka-Volterra predator model
• where f efficiency of turning prey
  into offspring
• q mortality rate of predators
• faPN number of predator offspring
  produced

35
Lecture 14 Predation

• II. Models and Examples of Predation
• A. Lotka-Volterra models (FIG. 1)
• 3. Predictions of Lotka-Volterra models
• Coupled oscillations with a time lag
  between prey abundance and predator
  abundance. These continuing oscillations with a
  time lag in response of prey to predators
  vice versa is called neutral stability.
• 4. Assumptions of Lotka-Volterra models
• We can see the assumptions by looking at
  the equations.
• First, growth of N is limited only by P
  (predation by this predator).
• Second, the predator is a specialist.
  faPN must be positive for P to
  increase.

36
Lecture 14 Predation

• II. Models and Examples of Predation
• A. Lotka-Volterra models (FIG. 1)
• 3. Predictions of Lotka-Volterra models
• Coupled oscillations with a time lag
  between prey abundance and predator
  abundance. These continuing oscillations with a
  time lag in response of prey to predators
  vice versa is called neutral stability.
• 4. Assumptions of Lotka-Volterra models
• We can see the assumptions by looking at
  the equations.
• First, growth of N is limited only by P
  (predation by this predator).
• Second, the predator is a specialist.
  faPN must be positive for P to
  increase.

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Lecture 14 Predation

• II. Models and Examples of Predation
• B. Modifications of Lotka-Volterra models
• 1. Prey population carrying capacity (FIG. 2)
• 2. Rosenzweig-MacArthur models

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Lecture 14 Predation

• II. Models and Examples of Predation
• B. Modifications of Lotka-Volterra models
• 1. Prey population carrying capacity (FIG. 2)
• Prey zero isocline slopes down to intersect
  X axis at K. This introduces resource
  limitation on the prey.
• 2. Rosenzweig-MacArthur models

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Lecture 14 Predation

• II. Models and Examples of Predation
• B. Modifications of Lotka-Volterra models
• 1. Prey population carrying capacity (FIG. 2)
• Prey zero isocline slopes down to intersect
  X axis at K. This introduces resource
  limitation on the prey.
• 2. Rosenzweig-MacArthur models

42
Lecture 14 Predation

• II. Models and Examples of Predation
• B. Modifications of Lotka-Volterra models
• 1. Prey population carrying capacity (FIG. 2)
• Prey zero isocline slopes down to intersect
  X axis at K. This introduces resource
  limitation on the prey.
• 2. Rosenzweig-MacArthur models
• Includes a reduction in prey isocline at
  low prey numbers because it shouldnt take
  many predators to control small prey populations.

43
Lecture 14 Predation

• II. Models and Examples of Predation
• B. Modifications of Lotka-Volterra models
• 1. Prey population carrying capacity (FIG. 2)
• Prey zero isocline slopes down to intersect
  X axis at K. This introduces resource
  limitation on the prey.
• 2. Rosenzweig-MacArthur models
• Includes a reduction in prey isocline at
  low prey numbers because it shouldnt take
  many predators to control small prey populations.
• C. Examples of predator-prey cycles in nature
  (FIG. 3)
• 1. Wood mice, voles, and owls
• 2. Plants and moths
• 3. Hare and lynx

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Lecture 14 Predation

• II. Models and Examples of Predation
• C. Examples of predator-prey cycles in nature
  (FIG. 3)
• 1. Wood mice, voles, and owls - owl population
  not closely linked to populations of the
  owls prey.
• 2. Plants and moths
• 3. Hare and lynx

46
Lecture 14 Predation

• II. Models and Examples of Predation
• C. Examples of predator-prey cycles in nature
  (FIG. 3)
• 1. Wood mice, voles, and owls - owl population
  not closely coupled to populations of the
  owls prey. Owls may have alternative prey or
  be limited by some other factor.
• 2. Plants and moths
• 3. Hare and lynx

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Lecture 14 Predation

• II. Models and Examples of Predation
• C. Examples of predator-prey cycles in nature
  (FIG. 3)
• 1. Wood mice, voles, and owls - owl population
  not closely coupled to populations of the
  owls prey. Owls may have alternative prey or
  be limited by some other factor.
• 2. Plants and moths - moths are limited by
  plants but plants limited more by resources
  (light, water, nutrients) than by predation.
• 3. Hare and lynx

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50
Lecture 14 Predation

• II. Models and Examples of Predation
• C. Examples of predator-prey cycles in nature
  (FIG. 3)
• 1. Wood mice, voles, and owls - owl population
  not closely coupled to populations of the
  owls prey. Owls may have alternative prey or
  be limited by some other factor.
• 2. Plants and moths - moths are limited by
  plants but plants limited more by resources
  (light, water, nutrients) than by predation.
• 3. Hare and lynx - lynx population depends
  primarily on the hare population but hare
  population is determined by both predator
  abundance and food availability.

51
Lecture 14 Predation

• II. Models and Examples of Predation
• C. Examples of predator-prey cycles in nature
  (FIG. 3)
• 1. Wood mice, voles, and owls - owl population
  not closely coupled to populations of the
  owls prey. Owls may have alternative prey or
  be limited by some other factor.
• 2. Plants and moths - moths are limited by
  plants but plants limited more by resources
  (light, water, nutrients) than by predation.
• 3. Hare and lynx - lynx population depends
  primarily on the hare population but hare
  population is determined by both predator
  abundance and food availability.
• The models can imitate these actual cycles
  fairly well.

52
Lecture 14 Predation

• III. Foraging Behavior
• A. Questions that we might ask about animal
  foraging behavior.
• B. Concept of optimal foraging.
• C. Diet width
• D. Food preferences and switching (FIG. 4)
• E. Functional response models (C.S.
  Holling)(FIG. 5)

53
Lecture 14 Predation

• III. Foraging Behavior
• A. Questions that we might ask about animal
  foraging behavior.
• 1. Why are certain patterns of foraging
  behavior favored by natural selection?
• 2. What are the consequences for foraging
  behaviors on population dynamics?

54
Lecture 14 Predation

• III. Foraging Behavior
• A. Questions that we might ask about animal
  foraging behavior.
• 1. Why are certain patterns of foraging
  behavior favored by natural selection?
• 2. What are the consequences for foraging
  behaviors on population dynamics?
• B. Concept of optimal foraging. The optimal
  foraging strategy should give the highest net
  rate of energy intake.

55
Lecture 14 Predation

• III. Foraging Behavior
• A. Questions that we might ask about animal
  foraging behavior.
• 1. Why are certain patterns of foraging
  behavior favored by natural selection?
• 2. What are the consequences for foraging
  behaviors on population dynamics?
• B. Concept of optimal foraging. The optimal
  foraging strategy should give the highest net
  rate of energy intake. Accounts for energy used
  to obtain food but doesnt account for need to
  have certain nutrients or for preferences that
  animal might have.

56
Lecture 14 Predation

• III. Foraging Behavior
• A. Questions that we might ask about animal
  foraging behavior.
• 1. Why are certain patterns of foraging
  behavior favored by natural selection?
• 2. What are the consequences for foraging
  behaviors on population dynamics?
• B. Concept of optimal foraging. The optimal
  foraging strategy should give the highest net
  rate of energy intake. Accounts for energy used
  to obtain food but doesnt account for need to
  have certain nutrients or for preferences that
  animals might have. Animals face many choices
  when foraging (see textbook pp. 269-270).

57
Lecture 14 Predation

• III. Foraging Behavior
• B. Concept of optimal foraging. The optimal
  foraging strategy should give the highest net
  rate of energy intake. Accounts for energy used
  to obtain food but doesnt account for need to
  have certain nutrients or for preferences that
  animals might have. Animals face many choices
  when foraging (see textbook pp. 269-270).
• C. Diet width
• 1. Monophagous
• 2. Oligophagous
• 3. Polyphagous

58
Lecture 14 Predation

• III. Foraging Behavior
• B. Concept of optimal foraging. The optimal
  foraging strategy should give the highest net
  rate of energy intake. Accounts for energy used
  to obtain food but doesnt account for need to
  have certain nutrients or for preferences that
  animals might have. Animals face many choices
  when foraging (see textbook pp. 269-270).
• C. Diet width
• 1. Monophagous - feed on one prey type. These
  are specialists such as parasites and
  parasitoids.
• 2. Oligophagous
• 3. Polyphagous

59
Lecture 14 Predation

• III. Foraging Behavior
• B. Concept of optimal foraging. The optimal
  foraging strategy should give the highest net
  rate of energy intake. Accounts for energy used
  to obtain food but doesnt account for need to
  have certain nutrients or for preferences that
  animals might have. Animals face many choices
  when foraging (see textbook pp. 269-270).
• C. Diet width
• 1. Monophagous - feed on one prey type. These
  are specialists such as parasites and
  parasitoids. Most true predators (lions, etc.)
  are not monophagous but Everglades kites feed
  only on Pomacea snails.
• 2. Oligophagous
• 3. Polyphagous

60
Lecture 14 Predation

• III. Foraging Behavior
• B. Concept of optimal foraging. The optimal
  foraging strategy should give the highest net
  rate of energy intake. Accounts for energy used
  to obtain food but doesnt account for need to
  have certain nutrients or for preferences that
  animals might have. Animals face many choices
  when foraging (see textbook pp. 269-270).
• C. Diet width
• 1. Monophagous - feed on one prey type. These
  are specialists such as parasites and
  parasitoids. Most true predators (lions, etc.)
  are not monophagous but Everglades kites feed
  only on Pomacea snails.
• 2. Oligophagous - feed on a few prey types.
• 3. Polyphagous

61
Lecture 14 Predation

• III. Foraging Behavior
• B. Concept of optimal foraging. The optimal
  foraging strategy should give the highest net
  rate of energy intake. Accounts for energy used
  to obtain food but doesnt account for need to
  have certain nutrients or for preferences that
  animals might have. Animals face many choices
  when foraging (see textbook pp. 269-270).
• C. Diet width
• 1. Monophagous - feed on one prey type. These
  are specialists such as parasites and
  parasitoids. Most true predators (lions, etc.)
  are not monophagous but Everglades kites feed
  only on Pomacea snails.
• 2. Oligophagous - feed on a few prey types.
  Many insect larvae and herbivores in general
  are oligophagous.
• 3. Polyphagous

62
Lecture 14 Predation

• III. Foraging Behavior
• C. Diet width
• 1. Monophagous - feed on one prey type. These
  are specialists such as parasites and
  parasitoids. Most true predators (lions, etc.)
  are not monophagous but Everglades kites feed
  only on Pomacea snails.
• 2. Oligophagous - feed on a few prey types.
  Many insect larvae and herbivores in general
  are oligophagous.
• 3. Polyphagous - feed on many prey types.

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Lecture 14 Predation

• III. Foraging Behavior
• C. Diet width
• 1. Monophagous - feed on one prey type. These
  are specialists such as parasites and
  parasitoids. Most true predators (lions, etc.)
  are not monophagous but Everglades kites feed
  only on Pomacea snails.
• 2. Oligophagous - feed on a few prey types.
  Many insect larvae and herbivores in general
  are oligophagous.
• 3. Polyphagous - feed on many prey types.
  These generalists include many (but not all)
  true predators.

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Lecture 14 Predation

• III. Foraging Behavior
• C. Diet width
• 1. Monophagous - feed on one prey type. These
  are specialists such as parasites and
  parasitoids. Most true predators (lions, etc.)
  are not monophagous but Everglades kites feed
  only on Pomacea snails.
• 2. Oligophagous - feed on a few prey types.
  Many insect larvae and herbivores in general
  are oligophagous.
• 3. Polyphagous - feed on many prey types.
  These generalists include many (but not all)
  true predators.
• D. Food preferences and switching (FIG. 4)
• Reasons to switch when prey species becomes
  rare (FIG. 4b)
• Reasons not to switch when prey species
  becomes rare (FIG. 4a)

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67
Lecture 14 Predation

• III. Foraging Behavior
• D. Food preferences and switching (FIG. 4)
• Reasons to switch when prey species becomes
  rare (FIG. 4b)
• More prey of other species available and
  therefore easier to capture.
• Reasons not to switch when prey species
  becomes rare (FIG. 4a)

68
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69
Lecture 14 Predation

• III. Foraging Behavior
• D. Food preferences and switching (FIG. 4)
• Reasons to switch when prey species becomes
  rare (FIG. 4b)
• More prey of other species available and
  therefore easier to capture.
• Reasons not to switch when prey species
  becomes rare (FIG. 4a)
• Predator may have specific search image that
  makes it easier to capture a particular prey
  species. Predator may be more physically able
  to capture a specific prey species.

70
Lecture 14 Predation

• III. Foraging Behavior
• D. Food preferences and switching (FIG. 4)
• Reasons to switch when prey species becomes
  rare (FIG. 4b)
• More prey of other species available and
  therefore easier to capture.
• Reasons not to switch when prey species
  becomes rare (FIG. 4a)
• Predator may have specific search image that
  makes it easier to capture a particular prey
  species. Predator may be more physically able
  to capture a specific prey species. Predator may
  remain in a particular habitat where other prey
  are not available.

71
Lecture 14 Predation

• III. Foraging Behavior
• D. Food preferences and switching (FIG. 4)
• Reasons to switch when prey species becomes
  rare (FIG. 4b)
• More prey of other species available and
  therefore easier to capture.
• Reasons not to switch when prey species
  becomes rare (FIG. 4a)
• Predator may have specific search image that
  makes it easier to capture a particular prey
  species. Predator may be more physically able
  to capture a specific prey species. Predator may
  remain in a particular habitat where other prey
  are not available. Predator may prefer
  particular prey for some other reason (nutrition,
  flavor, etc.).

72
Lecture 14 Predation

• III. Foraging Behavior
• D. Food preferences and switching (FIG. 4)
• Reasons to switch when prey species becomes
  rare (FIG. 4b)
• More prey of other species available and
  therefore easier to capture.
• Reasons not to switch when prey species
  becomes rare (FIG. 4a)
• Predator may have specific search image that
  makes it easier to capture a particular prey
  species. Predator may be more physically able
  to capture a specific prey species. Predator may
  remain in a particular habitat where other prey
  are not available. Predator may prefer
  particular prey for some other reason (nutrition,
  flavor, etc.).
• E. Functional response models (C.S.
  Holling)(FIG. 5)
• 1. Type I functional response
• 2. Type II functional response
• 3. Type III functional response

73
Lecture 14 Predation

• III. Foraging Behavior
• E. Functional response models (C.S.
  Holling)(FIG. 5)
• 1. Type I functional response
• 2. Type II functional response
• 3. Type III functional response

74
Lecture 14 Predation

• III. Foraging Behavior
• E. Functional response models (C.S.
  Holling)(FIG. 5)
• 1. Type I functional response - each predator
  kills a constant proportion of prey
  regardless of prey population (FIG. 5b).
• 2. Type II functional response
• 3. Type III functional response

75
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76
Lecture 14 Predation

• III. Foraging Behavior
• E. Functional response models (C.S.
  Holling)(FIG. 5)
• 1. Type I functional response - each predator
  kills a constant proportion of prey
  regardless of prey population (FIG. 5b). This
  means each predator eats more and more prey as
  the prey population increases (FIG. 5a).
• 2. Type II functional response
• 3. Type III functional response

77
Lecture 14 Predation

• III. Foraging Behavior
• E. Functional response models (C.S.
  Holling)(FIG. 5)
• 1. Type I functional response - each predator
  kills a constant proportion of prey
  regardless of prey population (FIG. 5b). This
  means each predator eats more and more prey as
  the prey population increases (FIG. 5a).
• 2. Type II functional response - as the prey
  population increases, each predator becomes
  satiated and takes a constant number of prey
  (FIG. 5a).
• 3. Type III functional response

78
(No Transcript)
79
Lecture 14 Predation

• III. Foraging Behavior
• E. Functional response models (C.S.
  Holling)(FIG. 5)
• 1. Type I functional response - each predator
  kills a constant proportion of prey
  regardless of prey population (FIG. 5b). This
  means each predator eats more and more prey as
  the prey population increases (FIG. 5a).
• 2. Type II functional response - as the prey
  population increases, each predator becomes
  satiated and takes a constant number of prey
  (FIG. 5a). This means each predator takes a
  smaller proportion of the prey population as
  it increases (FIG. 5b). More realistic model!
• 3. Type III functional response

80
(No Transcript)
81
Lecture 14 Predation

• III. Foraging Behavior
• E. Functional response models (C.S.
  Holling)(FIG. 5)
• 2. Type II functional response - as the prey
  population increases, each predator becomes
  satiated and takes a constant number of prey
  (FIG. 5a). This means each predator takes a
  smaller proportion of the prey population as
  it increases (FIG. 5b). More realistic model!
• 3. Type III functional response - predators
  take smaller proportion of prey at high prey
  densities and at low prey densities (FIG. 5b).
  

82
Lecture 14 Predation

• III. Foraging Behavior
• E. Functional response models (C.S.
  Holling)(FIG. 5)
• 2. Type II functional response - as the prey
  population increases, each predator becomes
  satiated and takes a constant number of prey
  (FIG. 5a). This means each predator takes a
  smaller proportion of the prey population as
  it increases. More realistic model!
• 3. Type III functional response - predators
  take smaller proportion of prey at high prey
  densities and at low prey densities (FIG. 5b).
  At low prey densities, predators may have
  poor search image and low hunting efficiency
  (expend much energy without capturing many
  prey).

83
Lecture 14 Predation

• III. Foraging Behavior
• E. Functional response models (C.S.
  Holling)(FIG. 5)
• 2. Type II functional response - as the prey
  population increases, each predator becomes
  satiated and takes a constant number of prey
  (FIG. 5a). This means each predator takes a
  smaller proportion of the prey population as
  it increases. More realistic model!
• 3. Type III functional response - predators
  take smaller proportion of prey at high prey
  densities and at low prey densities (FIG. 5b).
  At low prey densities, predators may have
  poor search image and low hunting efficiency
  (expend much energy without capturing many
  prey). When this happens, they may switch to a
  different prey species.

84
Lecture 14 Predation

• III. Foraging Behavior
• E. Functional response models (C.S.
  Holling)(FIG. 5)
• 2. Type II functional response - as the prey
  population increases, each predator becomes
  satiated and takes a constant number of prey
  (FIG. 5a). This means each predator takes a
  smaller proportion of the prey population as
  it increases. More realistic model!
• 3. Type III functional response - predators
  take smaller proportion of prey at high prey
  densities and at low prey densities (FIG. 5b).
  At low prey densities, predators may have
  poor search image and low hunting efficiency
  (expend much energy without capturing many
  prey). When this happens, they may switch to a
  different prey species.