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Directional compass preference for landing in water birds
Vlastimil Hart1, Erich Pascal Malkemper, Tomáš Kušta
1Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, 16521 Praha 6, Czech Republic. hynek.burda@uni-due.de.
Frontiers in Zoology
|July 10, 2013
Summary
Birds exhibit a consistent landing preference along the north-south axis, regardless of arrival direction. This directional landing behavior is likely guided by Earth
Area of Science:
- Ornithology
- Animal Behavior
- Biophysics
Background:
- Bird landing requires precise visual control of velocity, distance, and descent slope.
- Flocking birds must coordinate landing to prevent collisions.
- While wind direction aids landing, the cue for direction under windless conditions was unknown.
Purpose of the Study:
- To investigate the directional cues birds use for landing under windless conditions.
- To determine if birds exhibit a preferred landing direction.
- To identify potential environmental factors influencing landing direction.
Main Methods:
- Analysis of landing directions from 3,338 flocks across 14 water bird species in eight countries.
- Detailed analysis of 2,431 mallard flocks, examining factors like time of year, sun position, weather, and magnetic declination.
- Comparison of geographic North vs. magnetic North as predictors of landing direction.
Main Results:
- Birds consistently preferred landing along the north-south axis, irrespective of their approach direction.
- No systematic influence was found from time of year, time of day, weather, light breeze, locality, latitude, or magnetic declination on landing direction.
- Magnetic North proved a more accurate predictor of landing direction than geographic North.
Conclusions:
- The magnetic field appears to serve as a landing direction indicator for birds.
- Alignment with magnetic field lines is the most plausible explanation for directional landing preferences.
- This finding is particularly relevant under windless and overcast conditions.
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