scholarly journals Very weak oscillating magnetic field disrupts the magnetic compass of songbird migrants

2017 ◽  
Vol 14 (133) ◽  
pp. 20170364 ◽  
Author(s):  
Alexander Pakhomov ◽  
Julia Bojarinova ◽  
Roman Cherbunin ◽  
Raisa Chetverikova ◽  
Philipp S. Grigoryev ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Narrow Band ◽  
Radical Pair ◽  
Magnetic Compass ◽  
Sensitivity Threshold ◽  
Erithacus Rubecula ◽  
Long Distance ◽  
Pair Model ◽  
Oscillating Magnetic Field ◽  
Sylvia Borin

Previously, it has been shown that long-distance migrants, garden warblers ( Sylvia borin ), were disoriented in the presence of narrow-band oscillating magnetic field (1.403 MHz OMF, 190 nT) during autumn migration. This agrees with the data of previous experiments with European robins ( Erithacus rubecula ). In this study, we report the results of experiments with garden warblers tested under a 1.403 MHz OMF with various amplitudes (∼0.4, 1, ∼2.4, 7 and 20 nT). We found that the ability of garden warblers to orient in round arenas using the magnetic compass could be disrupted by a very weak oscillating field, such as an approximate 2.4, 7 and 20 nT OMF, but not by an OMF with an approximate 0.4 nT amplitude. The results of the present study indicate that the sensitivity threshold of the magnetic compass to the OMF lies around 2–3 nT, while in experiments with European robins the birds were disoriented in a 15 nT OMF but could choose the appropriate migratory direction when a 5 nT OMF was added to the stationary magnetic field. The radical-pair model, one of the mainstream theories of avian magnetoreception, cannot explain the sensitivity to such a low-intensity OMF, and therefore, it needs further refinement.

scholarly journals Magnetic orientation of garden warblers ( Sylvia borin ) under 1.4 MHz radiofrequency magnetic field

2014 ◽  
Vol 11 (97) ◽  
pp. 20140451 ◽  
Author(s):  
Kirill Kavokin ◽  
Nikita Chernetsov ◽  
Alexander Pakhomov ◽  
Julia Bojarinova ◽  
Dmitry Kobylkov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Visual Information ◽  
Magnetic Compass ◽  
Erithacus Rubecula ◽  
Garden Warbler ◽  
Independent Replication ◽  
Migratory Songbird ◽  
Sylvia Borin ◽  
Magnetic Meridian ◽  
Rf Magnetic Field

We report on the experiments on orientation of a migratory songbird, the garden warbler ( Sylvia borin ) , during the autumn migration period on the Courish Spit, Eastern Baltics. Birds in experimental cages, deprived of visual information, showed the seasonally appropriate direction of intended flight with respect to the magnetic meridian. Weak radiofrequency (RF) magnetic field (190 nT at 1.4 MHz) disrupted this orientation ability. These results may be considered as an independent replication of earlier experiments, performed by the group of R. and W. Wiltschko with European robins ( Erithacus rubecula ). Confirmed outstanding sensitivity of the birds' magnetic compass to RF fields in the lower megahertz range demands for a revision of one of the mainstream theories of magnetoreception, the radical-pair model of birds' magnetic compass.

scholarly journals Light-dependent magnetoreception in birds: the crucial step occurs in the dark

2016 ◽  
Vol 13 (118) ◽  
pp. 20151010 ◽  
Author(s):  
Roswitha Wiltschko ◽  
Margaret Ahmad ◽  
Christine Nießner ◽  
Dennis Gehring ◽  
Wolfgang Wiltschko
Keyword(s):  
Magnetic Field ◽  
Flavin Adenine Dinucleotide ◽  
Radical Pair ◽  
Magnetic Compass ◽  
Radical Pairs ◽  
Intermittent Light ◽  
Pair Model ◽  
Dark Interval ◽  
Behavioural Experiments ◽  
The Magnetic Field

The Radical Pair Model proposes that the avian magnetic compass is based on spin-chemical processes: since the ratio between the two spin states singlet and triplet of radical pairs depends on their alignment in the magnetic field, it can provide information on magnetic directions. Cryptochromes, blue light-absorbing flavoproteins, with flavin adenine dinucleotide as chromophore, are suggested as molecules forming the radical pairs underlying magnetoreception. When activated by light, cryptochromes undergo a redox cycle, in the course of which radical pairs are generated during photo-reduction as well as during light-independent re-oxidation. This raised the question as to which radical pair is crucial for mediating magnetic directions. Here, we present the results from behavioural experiments with intermittent light and magnetic field pulses that clearly show that magnetoreception is possible in the dark interval, pointing to the radical pair formed during flavin re-oxidation. This differs from the mechanism considered for cryptochrome signalling the presence of light and rules out most current models of an avian magnetic compass based on the radical pair generated during photo-reduction. Using the radical pair formed during re-oxidation may represent a specific adaptation of the avian magnetic compass.

scholarly journals Can disordered radical pair systems provide a basis for a magnetic compass in animals?

2009 ◽  
Vol 7 (suppl_2) ◽  
Author(s):  
Erin Hill ◽  
Thorsten Ritz
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Radical Pair ◽  
Magnetic Compass ◽  
Magnetic Field Direction ◽  
Chemical Signal ◽  
Radical Pairs ◽  
Directional Information ◽  
Minimum Number ◽  
Signal Production

A proposed mechanism for magnetic compasses in animals is that systems of radical pairs transduce magnetic field information to the nervous system. One can show that perfectly ordered arrays of radical pairs are sensitive to the direction of the external magnetic field and can thus operate, in principle, as a magnetic compass. Here, we investigate how disorder, inherent in biological cells, affects the ability of radical pair systems to provide directional information. We consider biologically inspired geometrical arrangements of ensembles of radical pairs with increasing amounts of disorder and calculate the effect of changing the direction of the external magnetic field on the rate of chemical signal production by radical pair systems. Using a previously established signal transduction model, we estimate the minimum number of receptors necessary to allow for detection of the change in chemical signal owing to changes in magnetic field direction. We quantify the required increase in the number of receptors to compensate for the signal attenuation through increased disorder. We find radical-pair-based compass systems to be relatively robust against disorder, suggesting several scenarios as to how a compass structure can be realized in a biological cell.

scholarly journals Magnetic Compass Orientation in a Palaearctic–Indian Night Migrant, the Red-Headed Bunting

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1541
Author(s):  
Tushar Tyagi ◽  
Sanjay Kumar Bhardwaj
Keyword(s):  
Magnetic Field ◽  
Northern Hemisphere ◽  
Spring Migration ◽  
Magnetic Compass ◽  
Day Length ◽  
Compass Orientation ◽  
Long Distance ◽  
Specific Direction ◽  
Magnetic Compass Orientation ◽  
Overcast Sky

Red-headed buntings (Emberiza bruniceps) perform long-distance migrations within their southerly overwintering grounds and breeding areas in the northern hemisphere. Long-distance migration demands essential orientation mechanisms. The earth’s magnetic field, celestial cues, and memorization of geographical cues en route provide birds with compass knowledge during migration. Birds were tested during spring migration for orientation under natural clear skies, simulated overcast skies at natural day length and temperature, simulated overcast at 22 °C and 38 °C temperatures, and in the deflected (−120°) magnetic field. Under clear skies, the red-headed buntings were oriented NNW (north–northwest); simulated overcast testing resulted in a northerly mean direction at local temperatures as well as at 22 °C and 38 °C. The buntings reacted strongly in favor of the rotated magnetic field under the simulated overcast sky, demonstrating the use of a magnetic compass for migrating in a specific direction.

Magnetic orientation in birds

1996 ◽  
Vol 199 (1) ◽  
pp. 29-38 ◽  
Author(s):  
W Wiltschko ◽  
R Wiltschko
Keyword(s):  
Magnetic Field ◽  
Magnetic Compass ◽  
Long Distance ◽  
Directional Information ◽  
Magnetic Parameters ◽  
Reliable Source ◽  
Field Lines ◽  
Navigational System ◽  
Migrating Birds ◽  
The Magnetic Field

The magnetic field of the earth is an omnipresent, reliable source of orientational information. A magnetic compass has been demonstrated in 18 species of migrating birds. In all species studied with regard to its functional properties, it was found to be an 'inclination compass', i.e. the birds derive directional information from the inclination of the field lines, and thus distinguish between 'poleward' and 'equatorward' rather than 'north' and 'south'. Such a mechanism means that birds from the northern and southern hemisphere may rely on the same migratory programme. Long-distance migrants, however, face the problem that their magnetic compass gives bimodal information at the magnetic equator. Transfers of information between the magnetic field and celestial sources of directional information have been demonstrated; the two systems interact in a complex way. The data on the use of magnetic parameters for position finding are less clear. The experiments involve releases of homing pigeons; correlations of their orientation with natural variations in the magnetic field and the effects of magnetic manipulation reveal an enormous variability. The role of magnetic parameters in the multifactorial navigational system is poorly understood.

Sign in / Sign up

Export Citation Format

Share Document