Migration introduction
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Migration introduction






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Migration introduction Migration introduction Presentation Transcript

  • Animal Migration
  • What is Migration?
    • Prerequisites for migration:
      • Sustained movement
      • Physical endurance
      • Mechanisms for storing energy
      • Designated food sources on the migration route
    • Migration ensures animals will have adequate food supplies & will be able to reproduce.
    Migration is the regular movement of animals from one location to another.
  • Types of Migration
    • Migration may occur:
      • As a round trip
      • As a return migration
        • Corresponds with the seasons
    • Some require a lifetime to complete:
      • Ex: Pacific salmon
        • Born in freshwater streams
        • Travel to the ocean
        • Return to the stream where they were born
          • Spawn and then die
  • Knowing When to Migrate
    • How do animals know when it is time to migrate?
      • Internal signals
        • Hormones trigger an overwhelming urge to…
          • eat, mate & reproduce
      • External signals (clues)
        • Temperature change
        • Daylight hours
        • Scarce food supply
  • Migration Destinations
    • How do animals know where to go?
      • Specialized abilities to navigate
      • External forces
        • Ex.: wind & water currents
      • Landmarks:
        • Ex.: coastlines, mountain ranges, river valleys & distinctive odors
      • Sun:
        • Track the passage of days and months
        • Track their position in relationship to the sun
  • Migration Destinations (cont.)
    • Internal Clues
      • Are sensitive to a mineral known as magnetite
        • Found in many animals, including humans
        • Allows animals to use the earth’s magnetic field as a guide.
        • Ex.: Gray whales
          • Large amount of magnetite in their retinas
            • Helps them navigate their 10,000 mile journey
  • Migration: Behavior or Instinct?
    • Monarch butterfly
      • Migration is instinctive
      • Fly without guidance or previous experience
      • Use little or no directional clues
    • Learning migration behaviors for most animals is critical to their survival.
  • Migration Behaviors
    • Older members of the group teach the younger animals:
      • The route traveled
      • Valuable strategies and/or behaviors
    • Humans teach younger animals, too.
      • Ultra-light aircraft
        • Taught various species of cranes their migration routes
    • Most animals must learn their migratory routes.
    • Animals who are not taught these behaviors will not likely survive.
  • Why Migrate?
    • Most animals migrate for two reasons:
      • Food & water:
        • Will migrate to find these resources
      • Reproduction:
        • Safe environment for bearing & nursing offspring.
        • Abundant food sources
  • Hazards of Migration
    • Two categories:
      • Natural hazards:
        • Climate changes
        • Drought
        • Food Supply
        • Predators
        • Physical demands of migration
      • Man-made hazards:
        • Barriers (fences, dams, & skyscrapers)
        • Water, aircraft, & fishing practices