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Individuality in bird migration: routes and timing
Yannis Vardanis1, Raymond H G Klaassen, Roine Strandberg
1Department of Animal Ecology, Lund University, Ecology Building, 22362 Lund, Sweden. yannis.vardanis@gmail.com
Biology Letters
|February 11, 2011
Summary
Individual marsh harriers show consistent migration timing but flexible routes each year. This suggests internal biological clocks guide timing, while environmental factors influence route choice for migrating birds.
Area of Science:
- Ornithology
- Animal Ecology
- Movement Ecology
Background:
- Individual-based tracking is revolutionizing animal migration studies.
- Understanding variation in migratory behavior is crucial for conservation.
Purpose of the Study:
- To analyze individual variation in migratory routes and timing of the marsh harrier (Circus aeruginosus).
- To investigate repeatability of migratory journeys over multiple years.
Main Methods:
- Long-term, individual-based tracking of marsh harriers.
- Analysis of migratory routes and timing data from repeated journeys.
Main Results:
- Individual migration timing was highly repeatable across years.
- Migratory routes showed considerable variation even for the same individual on repeated journeys.
- Timing repeatability was stronger than spatial repeatability.
Conclusions:
- Marsh harrier migration timing appears strongly endogenously controlled.
- Route flexibility may result from adaptation to short-term environmental conditions.
- Navigation likely relies on mechanisms beyond landmark-based route memorization.
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