Foraging

Cards (24)

  • Foraging: the search for food, which can include grazing, browsing, hunting, and scavenging.
    • provides energy
    • individuals must search for and capture food
    • know when to move on to another resource
  • Optimal Foraging Theory: a behavioral ecology modeling approach that predicts how an animal behaves when searching for food.
  • Optimal Diet Model: predicts that animals will select a diet that maximizes energy intake rate.
    • foragers maximize fitness by max. energy
    • food items are encountered one at a time
    • food items can be ranked by profitability
  • Handling Time: time to manipulate items before consumption.
  • Profitability: energy/ handling time.
  • Seagulls at the beach will take clams, fly with them, and then drop them to break them open.
  • Optimal Patch Use: predicts how long a forager should exploit a food patch.
    • foragers attempt to max. energy intake
    • all patches are identical
    • travel time is constant
  • Optimal Patch Time is Affected by Travel Time:
    • for shorter travel times, the optimal patch time is small.
    • for longer travel times, the optimal patch time is longer.
  • Animals can combine sample info. from a patch with prior knowledge about the distribution of patch types in the environment, using Bayesian statistics.
  • Antipredator Behavior: Behavior that reduces the likelihood of being preyed upon.
    • animals can do this alone or in a group, actively or passively
  • Active Social Defense Example:
    • meerkats come together (mobbing) to protect their colony against a snake. There is a guard to alert them of any dangers.
  • Passive Defense Example:
    • Harvest ants aggregating so they are less likely to be eaten by a dragonfly
  • Dilution Effect Hypothesis: proposes that associating in groups makes it less likely that any one individual will be preyed upon.
  • Selfish Herd Hypothesis: suggests that individuals in a group attempt to reduce predation risk by putting other individuals between themselves and the predator.
    • "Using other animals as a shield between yourself and the predator"
  • Other Ways to Avoid Predation:
    • Blend In: camouflage yourself to the environment. Ex. moths
    • Stand Out: aposematic coloration to avoid being eaten. Ex. monarch butterflies.
    • Batesian Mimicry: palatable species mimics a dangerous species to deter predators. Ex. coral snakes
  • Stotting in Thomson's Gazelles
    There are many hypotheses for stotting behavior. Stotting is when they jump and show their rear ends.
    • Alarm Signals
    • Social Cohesion
    • Confusion Effect
    • Attack Deterrence
  • The primary prediction of the selfish herd hypothesis is that individuals should do which of the following?
    Attempt to move to the center of the group
  • Dispersal: a relatively short distance, one-way movement away from a site.
  • Competition Hypothesis: If two sites have the same density of individuals but differ in the quantity of food, we can expect higher levels of dispersal behavior in the site with less food.
  • Inbreeding Avoidance Hypothesis: one factor driving the evolution of dispersal is a minimization of inbreeding.
  • Breeding habitats differ in quality and therefore individuals differ in reproductive success.
    • individuals with low reproductive success may exhibit breeding dispersal
    • individuals with high reproductive success should exhibit site fidelity
  • Win Stay Lose Shift: many species exhibit site fidelity after reproductive success and exhibit breeding dispersal after a reproductive failure.
  • Migration: relatively long distance and a two-way movement.
    • Evolves when fitness benefit of migration > fitness cost of migration
  • In the Serengeti, mammals appear to track biomass and quality of grass during their migration.