scholarly journals Feasibility of sun and magnetic compass mechanisms in avian long-distance migration

2018 ◽  
Vol 6 (1) ◽  
Author(s):  
Rachel Muheim ◽  
Heiko Schmaljohann ◽  
Thomas Alerstam
Keyword(s):  
Magnetic Compass ◽  
Long Distance ◽  
Compass Mechanisms

scholarly journals Orientation cues and mechanisms used during avian navigation: A review

2021 ◽  
Vol 13 (2) ◽  
pp. 627-640
Author(s):  
Tushar Tyagi ◽  
Sanjay Kumar Bhardwaj
Keyword(s):  
Migratory Birds ◽  
Field Studies ◽  
Magnetic Compass ◽  
Spatial Cues ◽  
Sun Compass ◽  
Long Time ◽  
Celestial Rotation ◽  
Compass Mechanisms ◽  
And Migration ◽  
Navigational Systems

The navigational systems of different animal species are by a wide margin less notable as compared to birds. Humans have been interested in how migratory birds discover their way more than thousands of miles for quite a long time. This review summarizes the cues and compass mechanisms applied in orientation and navigation by non-migrants, diurnal and nocturnal migrants. The magnetic compass, landmarks, olfactory, and memory of spatial cues en route were utilized in homing and migration. The equivalent is valid for the sun compass despite the fact that its job during migration might be undeniably less significant than commonly presumed. Stellar compass and celestial rotation, as a result of their nighttime accessibility, appear to influence the direction of nighttime migrants during the course of migration. The celestial cues go through notable changes because of the latitude shift during bird migration. Sunset cues alter their location with seasons and latitudes. The recognizable stars lose height and lastly vanish underneath the horizon, whereas new stars show up. These new ones must be calibrated. As celestial rotation not imparting a reference, it is not unexpected that the magnetic compass turns into the main cue that controls the directional importance of stars and sunset cues. Field studies have revealed that, in certain species, a considerable extent of individuals get back to similar breeding, overwintering, and stopover areas in progressive years. This review proposes that migratory birds have advanced uncommon cognitive capacities that empower them to achieve these accomplishments.      

scholarly journals The magnetic compass mechanisms of birds and rodents are based on different physical principles

2006 ◽  
Vol 3 (9) ◽  
pp. 583-587 ◽  
Author(s):  
Peter Thalau ◽  
Thorsten Ritz ◽  
Hynek Burda ◽  
Regina E Wegner ◽  
Roswitha Wiltschko
Keyword(s):  
Geomagnetic Field ◽  
Migratory Birds ◽  
Radical Pair ◽  
Broad Band ◽  
Static Field ◽  
Magnetic Compass ◽  
Radical Pair Mechanism ◽  
Zeeman Frequency ◽  
Compass Mechanisms ◽  
Physical Principles

Recently, oscillating magnetic fields in the MHz-range were introduced as a useful diagnostic tool to identify the mechanism underlying magnetoreception. The effect of very weak high-frequency fields on the orientation of migratory birds indicates that the avian magnetic compass is based on a radical pair mechanism. To analyse the nature of the magnetic compass of mammals, we tested rodents, Ansell's mole-rats, using their tendency to build their nests in the southern part of the arena as a criterion whether or not they could orient. In contrast to birds, their orientation was not disrupted when a broad-band field of 0.1–10 MHz of 85 nT or a 1.315 MHz field of 480 nT was added to the static geomagnetic field of 46 000 nT. Even increasing the intensity of the 1.315 MHz field (Zeeman frequency in the local geomagnetic field) to 4800 nT, more than a tenth of the static field, the mole-rats remained unaffected and continued to build their nests in the south. These results indicate that in contrast to that of birds, their magnetic compass does not involve radical pair processes; it seems to be based on a fundamentally different principle, which probably involves magnetite.

scholarly journals Straight as an arrow: humpback whales swim constant course tracks during long-distance migration

2011 ◽  
Vol 7 (5) ◽  
pp. 674-679 ◽  
Author(s):  
Travis W. Horton ◽  
Richard N. Holdaway ◽  
Alexandre N. Zerbini ◽  
Nan Hauser ◽  
Claire Garrigue ◽  
...  
Keyword(s):  
Humpback Whale ◽  
Open Ocean ◽  
Sea Surface ◽  
Humpback Whales ◽  
Surface Currents ◽  
Migration Routes ◽  
Long Distance ◽  
Seasonal Migrations ◽  
Compass Mechanisms ◽  
Better Than

Humpback whale seasonal migrations, spanning greater than 6500 km of open ocean, demonstrate remarkable navigational precision despite following spatially and temporally distinct migration routes. Satellite-monitored radio tag-derived humpback whale migration tracks in both the South Atlantic and South Pacific include constant course segments of greater than 200 km, each spanning several days of continuous movement. The whales studied here maintain these directed movements, often with better than 1° precision, despite the effects of variable sea-surface currents. Such remarkable directional precision is difficult to explain by established models of directional orientation, suggesting that alternative compass mechanisms should be explored.

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.

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 Sailors and Astronomy

1988 ◽  
Vol 98 ◽  
pp. 51-53
Author(s):  
Antoine Demerliac
Keyword(s):  
Magnetic Compass ◽  
The Sun ◽  
Long Distance ◽  
Ursa Minor ◽  
Faint Band ◽  
Insight Into

Sailors are neither professional nor amateur astronomers, but people who have to observe the sky in the course of following their professional calling. As soon as sailors ventured far from the coast they required some guide and even in antiquity (as shown by mentions in Homer’s Odyssey and, considerably later, by Aratus) they used Ursa Minor and Ursa Major. With journeys farther afield, they gained some insight into latitude from the changes of the altitude of the circumpolar constellations above the horizon. Although the very last Viking voyagers knew of the magnetic compass, earlier ones still relied on the Sun and the stars. Describing the methods used, Harald Akerlund says “One saga mentions a man, Oddi Heldagon, who was known as “Oddi the Star” and who served as long-distance pilot for an Icelandic magnate towards the end of the 900s. He left notes that included a complete table of the changes in declination of the Sun throughout the year, expressed as the height of the Sun on the meridian in semi-diameters. There is also a small table of azimuths giving the direction at different times of the year, of dawn twilight, defined as being a faint band of light on the horizon, visible before sunrise. We know nothing of the instrument used to measure the altitude of the Sun.”

The Fine Structure of Phloem Cells

1985 ◽  
Vol 43 ◽  
pp. 632-635
Author(s):  
James Cronshaw
Keyword(s):  
Structural Studies ◽  
High Concentration ◽  
Long Distance ◽  
Phloem Tissue ◽  
Sieve Elements ◽  
Long Distance Transport ◽  
P Protein ◽  
Companion Cells ◽  
Electron Microscopical ◽  
Distance Transport

Long distance transport in plants takes place in phloem tissue which has characteristic cells, the sieve elements. At maturity these cells have sieve areas in their end walls with specialized perforations. They are associated with companion cells, parenchyma cells, and in some species, with transfer cells. The protoplast of the functioning sieve element contains a high concentration of sugar, and consequently a high hydrostatic pressure, which makes it extremely difficult to fix mature sieve elements for electron microscopical observation without the formation of surge artifacts. Despite many structural studies which have attempted to prevent surge artifacts, several features of mature sieve elements, such as the distribution of P-protein and the nature of the contents of the sieve area pores, remain controversial.

Popliteal entrapment syndrome and age

VASA ◽  
2012 ◽  
Vol 41 (4) ◽  
pp. 262-268 ◽  
Author(s):  
Schweizer ◽  
Hügli ◽  
Koella ◽  
Jeanneret
Keyword(s):  
Risk Factors ◽  
Leg Pain ◽  
Walking Distance ◽  
Therapeutic Approaches ◽  
Long Distance ◽  
Entrapment Syndrome ◽  
Long Distance Running ◽  
Popliteal Entrapment ◽  
Popliteal Entrapment Syndrome ◽  
Atherosclerotic Risk Factors

On the occasion of diagnosing a popliteal entrapment syndrome in a 59-year old man with no cardiovascular risk factors, who developed acute ischemic leg pain during long distance running, we give an overview on this entity with emphasis on patients’age. The different types of the popliteal artery compression syndrome are summarized. The diagnostic and therapeutic approaches are discussed. The most important clinical sign of a popliteal entrapment syndrome is the lack of atherosclerotic risk factors in patients with limited walking distance. Not only in young athletes but also in patients more than 50 years old the popliteal entrapment syndrome has to be taken into account.

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