Bird orientation: compensation for wind drift in migrating raptors is age dependent

Area of Science:

• Ornithology
• Animal Migration
• Behavioral Ecology

Background:

• Wind significantly influences bird migration, yet its precise effect on migratory bird orientation, known as wind drift, is not well understood.
• Understanding wind drift is critical for predicting migratory bird success, especially in the context of changing climate patterns and wind variability.

Purpose of the Study:

• To analyze how changing wind conditions affect the track direction variation in migrating birds.
• To compare the extent of wind drift between adult and juvenile raptors during autumn migration.
• To investigate age-related differences in orientation systems and wind drift compensation.

Main Methods:

• Utilized satellite-based radio telemetry data to track individual birds during migration.
• Analyzed the relationship between wind components (side-wind and following-wind) and bird movement.
• Compared wind drift effects on two raptor species: osprey (Pandion haliaetus) and honey buzzard (Pernis apivorus).

Main Results:

• Juvenile raptors exhibited full wind drift, with both side- and following-wind components significantly affecting their movement.
• Adult raptors demonstrated significantly reduced wind drift (29%), indicating a greater ability to compensate for wind effects.
• A notable difference in wind drift compensation was observed between adult and juvenile age classes in both studied species.

Conclusions:

• Adult birds possess a more sophisticated orientation system enabling them to detect and compensate for wind drift effectively compared to juveniles.
• The reduced wind drift compensation in juveniles may hinder their ability to reach specific wintering grounds, particularly under rapid climate-induced wind changes.
• Age-dependent differences in orientation capabilities are crucial for understanding migratory success and vulnerability to environmental shifts.