Related Experiment Video
Updated: Jun 20, 2026
07:47
Assessing the Influence of Personality on Sensitivity to Magnetic Fields in Zebrafish
Published on: March 18, 2019
Magnetoreception in birds: no intensity window in "fixed direction" responses
Wolfgang Wiltschko1, Lars Dehe, Katrin Stapput
1FB Biowissenschaften, J.W. Goethe-Universität Frankfurt, Siesmayerstrasse 70, 60054, Frankfurt am Main, Germany.
Die Naturwissenschaften
|September 18, 2009
Summary
European robins exposed to specific light and dark conditions exhibit fixed directional responses, regardless of seasonal changes. This fixed directionality is observed across varying magnetic field intensities, suggesting a distinct magnetic sensing mechanism.
Area of Science:
- Animal behavior
- Magnetoreception
- Avian navigation
Background:
- European robins (Erithacus rubecula) use celestial cues and the Earth's magnetic field for seasonal migration.
- Normal compass orientation in birds is sensitive to specific magnetic field intensity ranges.
- The underlying mechanisms of avian magnetoreception are still under investigation, with proposed roles for both the radical pair mechanism and magnetite-based receptors.
Purpose of the Study:
- To investigate the directional responses of European robins under combined turquoise and yellow light, and in complete darkness, across different geomagnetic field intensities.
- To determine if "fixed direction" responses, observed under specific light conditions, are also independent of magnetic field intensity.
- To explore the potential role of a magnetite-based receptor in mediating these fixed direction responses.
Main Methods:
- European robins were exposed to a combination of 502 nm turquoise light and 590 nm yellow light, or complete darkness.
- Experiments were conducted under three different magnetic field intensities: 46 microT (local field), 92 microT, and 138 microT.
- Directional preferences were recorded and compared to control conditions with seasonally appropriate orientation.
Main Results:
- Under turquoise and yellow light, robins consistently oriented easterly, irrespective of magnetic field intensity.
- In complete darkness, robins consistently oriented northwesterly across all tested magnetic field intensities.
- These "fixed direction" responses differed from seasonally appropriate orientations observed under control conditions and were not limited by magnetic intensity.
Conclusions:
- "Fixed direction" responses in European robins under specific light/dark conditions are independent of magnetic field intensity.
- This suggests a different sensory mechanism, potentially a magnetite-based receptor in the upper beak, underlies these responses.
- Fixed direction responses may represent a relict function of a receptor mechanism primarily providing magnetic intensity information.
Related Concept Videos
01:05Atomic Nuclei: Magnetic Resonance
The number of nuclear spins aligned in the lower energy state is slightly greater than those in the higher energy state. In the presence of an external magnetic field, as the spins precess at the Larmor frequency, the excess population results in a net magnetization oriented along the z axis. When a pulse or a short burst of radio waves at the Larmor frequency is applied along the x axis, the coupling of frequencies causes resonance and flips the nuclear spins of the excess population from the...
01:13The Cochlea
The cochlea is a coiled structure in the inner ear that contains hair cells—the sensory receptors of the auditory system. Sound waves are transmitted to the cochlea by small bones attached to the eardrum called the ossicles, which vibrate the oval window that leads to the inner ear. This causes fluid in the chambers of the cochlea to move, vibrating the basilar membrane.
01:15Equilibrium and Balance
The inner ear assumes dual functionalities of auditory perception and equilibrium maintenance. The vestibule is the organ responsible for balance. This organ contains mechanoreceptors, specifically hair cells, endowed with stereocilia, which aid in deciphering information regarding the position and motion of our heads. Two intrinsic components, the utricle and saccule, help perceive head position, while the semicircular canals track head movement. Neurological messages initiated in the...
01:18Other Unique Bacteria
Magnetic bacteria exhibit a directed movement called magnetotaxis, driven by structures called magnetosomes. These magnetosomes consist of chains of magnetic particles made of either magnetite (Fe₃O₄) or greigite (Fe₃S₄) and are organized in a linear conformation by a protein scaffold within invaginations of the cell membrane. The bacteria align along the north–south magnetic field lines, much like a compass needle. They are typically microaerophilic or anaerobic and are commonly found near the...
01:23Atomic Nuclei: Nuclear Relaxation Processes
In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis, the precessing magnetic moments are randomly oriented around the z-axis. This...
01:27Magnetic Field Due To A Thin Straight Wire
Consider an infinitely long straight wire carrying a current I. The magnetic field at point P at a distance a from the origin can be calculated using the Biot-Savart law.