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Questions and Answers
Hypothalamus and pituitary glands play a role in initiating migration by regulating the secretion of feeding hormones.
Hypothalamus and pituitary glands play a role in initiating migration by regulating the secretion of feeding hormones.
True
Birds migrate solely for the purpose of finding mates during the breeding season.
Birds migrate solely for the purpose of finding mates during the breeding season.
False
The first theory of migratory behavior suggests that certain bird species evolved in northern latitudes.
The first theory of migratory behavior suggests that certain bird species evolved in northern latitudes.
False
Meteorological cues can assist migrating birds by helping them fly downwind.
Meteorological cues can assist migrating birds by helping them fly downwind.
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Migration in marine mammals, such as gray whales, only occurs in the summer months.
Migration in marine mammals, such as gray whales, only occurs in the summer months.
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Cells in certain migratory birds can detect geomagnetic fields for navigation during migration.
Cells in certain migratory birds can detect geomagnetic fields for navigation during migration.
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Birds that migrate do so only when food supplies are insufficient in their original habitats.
Birds that migrate do so only when food supplies are insufficient in their original habitats.
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The accumulation of fat deposits is monitored by neural and hormonal systems before migration begins.
The accumulation of fat deposits is monitored by neural and hormonal systems before migration begins.
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Migration involves a periodic movement from one location and climate to another.
Migration involves a periodic movement from one location and climate to another.
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Homing refers to an animal's inability to return to its home site after being displaced.
Homing refers to an animal's inability to return to its home site after being displaced.
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All migratory bird species completely deplete their fat reserves during migration.
All migratory bird species completely deplete their fat reserves during migration.
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The average weight loss for migratory birds can be as high as 40%.
The average weight loss for migratory birds can be as high as 40%.
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Birds show migratory restlessness (Zugunruhe) when migration time approaches, which is influenced by day-length.
Birds show migratory restlessness (Zugunruhe) when migration time approaches, which is influenced by day-length.
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Researchers primarily use color-coded bands on birds to trace their migratory patterns.
Researchers primarily use color-coded bands on birds to trace their migratory patterns.
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Radar technology helps researchers determine the specific species of birds in a migratory flock.
Radar technology helps researchers determine the specific species of birds in a migratory flock.
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The timing of migration in birds is entirely independent of external stimuli.
The timing of migration in birds is entirely independent of external stimuli.
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Study Notes
Migration and Homing
- Migration: A periodic movement of an animal between two locations with different climates.
- Homing: The ability of an animal to return to its home site or locate it after being displaced.
- Bird Migration: The most common example of migratory behavior.
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Migration Trigger Questions:
- What species migrate, where they go, and when?
- What external cues and internal physiology initiate migration?
- What is the evolutionary history of migration?
- How do birds navigate long distances?
Studying Migratory Behavior
- Banding: Researchers attach colored or numbered bands to bird legs to track their movements.
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Radar: Provides information on:
- Number of birds in flight
- Speed of movement
- Altitude of the flock
- Flight path of the flock
Triggers of Migration
- Endogenous Biological Clocks: Internal mechanisms that control migration timing adjusted by external stimuli.
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Preparation Phase:
- Increased fat deposition: Birds build fat reserves for energy during flight, losing 30-40% of their weight.
- Migratory restlessness (Zugunruhe): Increased activity levels leading up to migration, linked to day length and weather conditions.
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Initiation Triggers:
- Neuro-endocrine Mechanisms: Hypothalamus and pituitary glands secrete hormones increasing feeding behavior.
- Fat Deposits: Sufficient fat reserves likely signal migration initiation.
- Favorable Weather: Optimal weather conditions trigger the start of migration.
Advantages of Migration
- Adequate Food Supply: Migration allows birds to access optimal food and climate conditions year-round.
- Reproduction: Migration reduces risks of death or unsuccessful breeding, enhancing reproductive synchrony.
Evolution of Migratory Behavior
- Theory 1: Birds evolved in Southern latitudes and expanded northward, returning to their ancestral homelands for the winter.
- Theory 2: Migration evolved in northern latitudes due to glaciations, forcing birds to seek better conditions south and later returning to ancestral breeding grounds.
Bird Orientation During Migration
- Celestial Cues: Using the sun and stars for navigation.
- Meteorological Cues: Flying downwind.
- Topographic Landmarks: Following coastlines or river valleys.
- Geomagnetism: Using the Earth's magnetic field for orientation.
Migration in Marine Mammals
- Gray Whales (Eschrichtius gibosus): Migrate between the Arctic Ocean and North Pacific Ocean, spending summers in the Arctic and winters in warmer waters.
- Harbor Seals (Phoca vitulina): Also exhibit seasonal migration patterns.
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Description
Explore the fascinating concepts of migration and homing in animals, particularly in birds. Learn about the periodic movements, triggers for migration, and the techniques used by researchers to study these behaviors. Discover how animals navigate and the evolutionary significance of these phenomena.
