scholarly journals Weak Broadband Electromagnetic Fields are More Disruptive to Magnetic Compass Orientation in a Night-Migratory Songbird (Erithacus rubecula) than Strong Narrow-Band Fields

2016 ◽  
Vol 10 ◽  
Author(s):  
Susanne Schwarze ◽  
Nils-Lasse Schneider ◽  
Thomas Reichl ◽  
David Dreyer ◽  
Nele Lefeldt ◽  
...  
Keyword(s):  
Electromagnetic Fields ◽  
Narrow Band ◽  
Magnetic Compass ◽  
Erithacus Rubecula ◽  
Compass Orientation ◽  
Magnetic Compass Orientation ◽  
Migratory Songbird

scholarly journals A novel isoform of cryptochrome 4 (Cry4b) is expressed in the retina of a night-migratory songbird

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Angelika Einwich ◽  
Karin Dedek ◽  
Pranav Kumar Seth ◽  
Sascha Laubinger ◽  
Henrik Mouritsen
Keyword(s):  
Mrna Expression ◽  
Expression Pattern ◽  
Migratory Birds ◽  
Radical Pair ◽  
The Novel ◽  
Erithacus Rubecula ◽  
Compass Orientation ◽  
Additional Exon ◽  
Magnetic Compass Orientation ◽  
Migratory Songbird

Abstract The primary sensory molecule underlying light-dependent magnetic compass orientation in migratory birds has still not been identified. The cryptochromes are the only known class of vertebrate proteins which could mediate this mechanism in the avian retina. Cryptochrome 4 of the night-migratory songbird the European robin (Erithacus rubecula; erCry4) has several of the properties needed to be the primary magnetoreceptor in the avian eye. Here, we report on the identification of a novel isoform of erCry4, which we named erCry4b. Cry4b includes an additional exon of 29 amino acids compared to the previously described form of Cry4, now called Cry4a. When comparing the retinal circadian mRNA expression pattern of the already known isoform erCry4a and the novel erCry4b isoform, we find that erCry4a is stably expressed throughout day and night, whereas erCry4b shows a diurnal mRNA oscillation. The differential characteristics of the two erCry4 isoforms regarding their 24-h rhythmicity in mRNA expression leads us to suggest that they might have different functions. Based on the 24-h expression pattern, erCry4a remains the more likely cryptochrome to be involved in radical-pair-based magnetoreception, but at the present time, an involvement of erCry4b cannot be excluded.

scholarly journals Electromagnetic 0.1–100 kHz noise does not disrupt orientation in a night-migrating songbird implying a spin coherence lifetime of less than 10 µs

2019 ◽  
Vol 16 (161) ◽  
pp. 20190716 ◽  
Author(s):  
Dmitry Kobylkov ◽  
Joe Wynn ◽  
Michael Winklhofer ◽  
Raisa Chetverikova ◽  
Jingjing Xu ◽  
...  
Keyword(s):  
Electromagnetic Fields ◽  
Migratory Birds ◽  
Radical Pair ◽  
Coherence Time ◽  
Magnetic Compass ◽  
Radio Waves ◽  
Spin Coherence ◽  
Compass Orientation ◽  
Magnetic Compass Orientation ◽  
Migrating Birds

According to the currently prevailing theory, the magnetic compass sense in night-migrating birds relies on a light-dependent radical-pair-based mechanism. It has been shown that radio waves at megahertz frequencies disrupt magnetic orientation in migratory birds, providing evidence for a quantum-mechanical origin of the magnetic compass. Still, many crucial properties, e.g. the lifetime of the proposed magnetically sensitive radical pair, remain unknown. The current study aims to estimate the spin coherence time of the radical pair, based on the behavioural responses of migratory birds to broadband electromagnetic fields covering the frequency band 0.1–100 kHz. A finding that the birds were unable to use their magnetic compass under these conditions would imply surprisingly long-lived (greater than 10 µs) spin coherence. However, we observed no effect of 0.1–100 kHz radiofrequency (RF) fields on the orientation of night-migratory Eurasian blackcaps ( Sylvia atricapilla ). This suggests that the lifetime of the spin coherence involved in magnetoreception is shorter than the period of the highest frequency RF fields used in this experiment (i.e. approx. 10 µs). This result, in combination with an earlier study showing that 20–450 kHz electromagnetic fields disrupt magnetic compass orientation, suggests that the spin coherence lifetime of the magnetically sensitive radical pair is in the range 2–10 µs.

scholarly journals Night-migratory garden warblers can orient with their magnetic compass using the left, the right or both eyes

2009 ◽  
Vol 7 (suppl_2) ◽  
Author(s):  
Christine Maira Hein ◽  
Manuela Zapka ◽  
Dominik Heyers ◽  
Sandra Kutzschbauch ◽  
Nils-Lasse Schneider ◽  
...  
Keyword(s):  
Magnetic Compass ◽  
Compass Orientation ◽  
Orientation Behaviour ◽  
Eyes Open ◽  
Magnetic Compass Orientation ◽  
Migratory Songbird ◽  
Sylvia Borin ◽  
The Right

Several studies have suggested that the magnetic compass of birds is located only in the right eye. However, here we show that night-migrating garden warblers ( Sylvia borin ) are able to perform magnetic compass orientation with both eyes open, with only the left eye open and with only the right eye open. We did not observe any clear lateralization of magnetic compass orientation behaviour in this migratory songbird, and, therefore, it seems that the suggested all-or-none lateralization of magnetic compass orientation towards the right eye only cannot be generalized to all birds, and that the answer to the question of whether magnetic compass orientation in birds is lateralized is probably not as simple as suggested previously.

scholarly journals A magnet attached to the forehead disrupts magnetic compass orientation in a migratory songbird

2021 ◽  
Author(s):  
Florian Packmor ◽  
Dmitry Kishkinev ◽  
Flora Bittermann ◽  
Barbara Kofler ◽  
Clara Machowetz ◽  
...  
Keyword(s):  
Bird Species ◽  
Magnetic Compass ◽  
Disruptive Effect ◽  
Free Flight ◽  
Compass Orientation ◽  
Experimental Conditions ◽  
Magnetic Compass Orientation ◽  
Orientation Cues ◽  
Migratory Songbird ◽  
Small Bird

For studies on magnetic compass orientation and navigation performance in small bird species, controlled experiments with orientation cages inside an electromagnetic coil system are the most prominent methodological paradigm. These are, however, not applicable when studying larger bird species and/or orientation behaviour during free flight. For this, researchers have followed a very different approach. By attaching small magnets to birds, they intended to deprive them of access to meaningful magnetic information. Unfortunately, results from studies using this approach appear rather inconsistent. As these are based on experiments with birds under free flight conditions, which usually do not allow exclusion of other potential orientation cues, an assessment of the overall efficacy of this approach is difficult to conduct. Here, we directly test the efficacy of small magnets for temporarily disrupting magnetic compass orientation in small migratory songbirds using orientation cages under controlled experimental conditions. We found that birds which have access to the Earth's magnetic field as their sole orientation cue show a general orientation towards their seasonally appropriate migratory direction. When carrying magnets on their forehead under these conditions, the same birds become disoriented. However, under changed conditions that allow birds access to other (i.e. celestial) orientation cues, any disruptive effect of the magnets they carry appears obscured. Our results provide clear evidence for the efficacy of the magnet approach for temporarily disrupting magnetic compass orientation in birds, but also reveal its limitations for application in experiments under free flight conditions.

Auditory and Magnetic Compass Orientation in C57BL/6 mice

2006 ◽  
Author(s):  
John B. Phillips ◽  
R. Muheim ◽  
N. M. Edgar ◽  
K. S. Sloan
Keyword(s):  
Magnetic Compass ◽  
Compass Orientation ◽  
Magnetic Compass Orientation

Lateralisation of magnetic compass orientation in silvereyes, Zosterops lateralis

2003 ◽  
Vol 51 (6) ◽  
pp. 597 ◽  
Author(s):  
Wolfgang Wiltschko ◽  
Ursula Munro ◽  
Hugh Ford ◽  
Roswitha Wiltschko
Keyword(s):  
Geomagnetic Field ◽  
Magnetic Compass ◽  
Compass Orientation ◽  
Directional Information ◽  
Zosterops Lateralis ◽  
Magnetic Compass Orientation ◽  
Directional Preference ◽  
The Right ◽  
The Brain ◽  
The Magnetic Field

The ability of migratory silvereyes to orient was tested in the geomagnetic field with one eye covered. Silvereyes using only their right eye were able to orient in migratory direction just as well as birds using both eyes. Using only their left eye, however, the birds did not show a significant directional preference. These data indicate that directional information from the magnetic field is mediated almost exclusively by the right eye and processed by the left hemisphere of the brain. Together with corresponding findings from European robins and indications for a similar phenomenon in homing pigeons, they suggest that a strong lateralisation of the magnetic compass is widespread among birds.

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