Predation

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Predation

• Next Time Disease

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Predation

• Management of predators - emotionally charged
  topic
• Poor experiments
• Topic of long-term debate

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Terminology

• Predators Animals killing and eating other live
  animals
• Scavengers Animals that eat animals that are
  already dead
• 5 types of predators
• Carnivore kills and eats animal prey
• Insectivore
• Herbivore consumes living green plants and
  seeds
• Cannibalism eats and kills animals of same
  species
• Compensatory predation - prey without access to
  habitat (cover) are more vulnerable to predation
• Non-compensatory predation related to prey
  density not habitat
• Additive and Compensatory Mortality

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Predator-Prey Relationships

• Response of Predators to Prey Density
• Functional Response how behavior of predator
  changes with prey densities
• Search patterns, appetite, and handling time
• Numerical Response how population processes of
  predators changes with prey densities
• Survival, Reproduction, and Movement
• Total Response Combined Functional and
  Numerical
• Number of prey eaten per predator x predator
  density prey mortality rate

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Features of Total Response

• Number of prey eaten per predator x predator
  density prey mortality rate
• Predation can regulate prey density only with a
  type III functional response because
• Only type of response that allows prey mortality
  rate to increase with prey density
• Regulation limited to interval where mortality
  rate increases (line below the linear line in
  Type I response) predator pit
• If prey exceeds limit of this interval, mortality
  due to predation declines, and prey growth will
  be regulated by other factors escape from
  natural enemies

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• Prey mortality rate initially increases with
  increase in prey density
• Can prey reach densities to escape predator
  pit?

Prey Mortality Rate
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Effects of Predation on Prey

• Limiting Factor Density-dependent and
  independent factors that limit change (l)of prey
• Regulating Factor Density-dependent factor
• All factors can be limiting, only those that are
  density-dependent can be regulating

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Predator-Prey Models

• Lotka-Volterra
• Constant food supply for prey
• Constant effects of disease and other predation
  on prey
• Decline in predator populations in absence of
  prey
• Recurrent Fluctuation Model
• Used for Moose and Predators
• Predators as regulator factor
• Tanana Flats, Kenai

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Can you recognize the pit and the escape from
predation.
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Low Density Equilibrium Model

• Prey never escapes predator pit fully
• Denali, Isle Royale

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Multiple Equilibrium Model
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Predator Control
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