Migration introduction
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Animal migration involves regular movement between locations and ensures animals have adequate food and can reproduce. There are different types of migration including round trips and return migrations corresponding with seasons. Animals use internal signals like hormones and external cues like temperature and daylight changes to know when to migrate. They navigate using specialized abilities, landmarks, the sun, and some use the Earth's magnetic field. Migration is mostly instinctive but many animals must learn routes from older members of their group. Animals primarily migrate to find food and water and to find a safe place to reproduce. Hazards of migration include natural threats and man-made barriers.
Migration introduction
- 2. 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.
- 3. 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
- 4. 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
- 5. 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
- 6. 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
- 7. 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.
- 8. 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.
- 9. 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
- 10. 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