CLOCK-SHIFT EXPERIMENTS WITH MIGRATORY YELLOW- FACED HONEYEATERS, LICHENOSTOMUS CHRYSOPS (MELIPHAGIDAE), AN AUSTRALIAN DAY-MIGRATING BIRD

1993 ◽  
Vol 181 (1) ◽  
pp. 233-244 ◽  
Author(s):  
U. Munro ◽  
R. Wiltschko
Keyword(s):  
Initial Response ◽  
Internal Clock ◽  
The Sun ◽  
Sun Compass ◽  
Conflicting Information ◽  
Natural Photoperiod ◽  
In The Wild ◽  
Migrating Birds ◽  
Clock Shift

The behaviour of an Australian day migrant, the yellow-faced honeyeater Lichenostomus chrysops, was studied in order to assess the role of the sun in migratory orientation. During autumn migration, all tests took place under a sunny sky; birds were tested while living in the natural photoperiod (control) and with their internal clock shifted 4 h fast and 4 h slow. In spring, all birds were shifted 3 h fast; tests in overcast conditions, with the birds relying on their magnetic compass, served as controls. In control tests in both seasons, the birds preferred directions corresponding to those observed in the wild. When tested under sunny conditions with their internal clock shifted, the birds changed their directional tendencies. However, their preferred directions were different from those expected if a time-compensating sun compass was being used. After about 6 days, the shifted birds' directions were no longer different from the control direction. This behaviour argues against a major role of the sun compass in the orientation of day migrants. The dramatic changes of the sun's arc with geographic latitute might cause day-migrating birds to prefer a more constant orientation cue, such as the geomagnetic field. The initial response to the clock-shift might have occurred because the birds were confused by the conflicting information from solar and magnetic cues. This suggests that the sun is usually used as a secondary cue in combination with the magnetic field.

An analysis of clock-shift experiments: is scatter increased and deflection reduced in clock-shifted homing pigeons?

1997 ◽  
Vol 200 (16) ◽  
pp. 2269-2277 ◽  
Author(s):  
J Chappell
Keyword(s):  
Internal Clock ◽  
Magnetic Compass ◽  
Control Group ◽  
The Sun ◽  
Visual Landmarks ◽  
Sun Compass ◽  
Homing Pigeons ◽  
Vector Length ◽  
The Mean ◽  
Clock Shift

Clock-shifting (altering the phase of the internal clock) in homing pigeons leads to a deflection in the vanishing bearing of the clock-shifted group relative to controls. However, two unexplained phenomena are common in clock-shift experiments: the vanishing bearings of the clock-shifted group are often more scattered (with a shorter vector length) than those of the control group, and the deflection of the mean bearing of the clock-shifted group from that of the controls is often smaller than expected theoretically. Here, an analysis of 55 clock-shift experiments performed in four countries over 21 years is reported. The bearings of the clock-shifted groups were significantly more scattered than those of controls and less deflected than expected, but these effects were not significantly different at familiar and unfamiliar sites. The possible causes of the effects are discussed and evaluated with reference to this analysis and other experiments. The most likely causes appear to be conflict between the directions indicated by the sun compass and either unshifted familiar visual landmarks (at familiar sites only) or the unshifted magnetic compass (possible at both familiar and unfamiliar sites).

scholarly journals In Situ Clock Shift Reveals that the Sun Compass Contributes to Orientation in a Pelagic Seabird

2018 ◽  
Vol 28 (2) ◽  
pp. 275-279.e2 ◽  
Author(s):  
Oliver Padget ◽  
Sarah L. Bond ◽  
Marwa M. Kavelaars ◽  
Emiel van Loon ◽  
Mark Bolton ◽  
...  
Keyword(s):  
The Sun ◽  
Sun Compass ◽  
Pelagic Seabird ◽  
Clock Shift

Hippocampal lesion effects on learning strategies in homing pigeons

1996 ◽  
Vol 263 (1370) ◽  
pp. 529-534 ◽  
Keyword(s):  
Learning Strategies ◽  
Hippocampal Lesion ◽  
Food Reward ◽  
The Sun ◽  
Sun Compass ◽  
Homing Pigeons ◽  
Directional Information ◽  
Intact Control ◽  
Hippocampal Lesions ◽  
Clock Shift

Several studies have shown that birds have a directional view of space and tend to use the sun compass over landmark beacons when both are available. Intact homing pigeons can use either the sun compass or colour beacons to locate a food reward, whereas pigeons with hippocampal lesions are unable to use the sun compass, but quickly learn to use colour beacons. We trained hippocampal ablated and intact pigeons to find a reward in an outdoor octagonal arena when both sun compass information (directional cues) and intramaze landmark beacons (colour cues) were available. The intact control pigeons learned the task by preferentially relying on directional cues while effectively ignoring the colour beacons. The behaviour of the hippocampal ablated birds, based on a clock-shift manipulation and after the rotation of the colour beacons, showed that they learned to locate the food reward in the arena only on the basis of the landmark beacons, ignoring the sun compass directional information.

The role of the biological clock in the sun compass orientation of free-running individuals of Talitrus saltator

2005 ◽  
Vol 69 (4) ◽  
pp. 835-843 ◽  
Author(s):  
Felicita Scapini ◽  
Claudia Rossano ◽  
Giovanni M. Marchetti ◽  
Elfed Morgan
Keyword(s):  
Biological Clock ◽  
The Sun ◽  
Compass Orientation ◽  
Sun Compass ◽  
Talitrus Saltator ◽  
Free Running

The sun compass of the sandhopperTalitrus saltator: the speed of the chronometric mechanism depends on the hours of light

2002 ◽  
Vol 205 (20) ◽  
pp. 3225-3230 ◽  
Author(s):  
Alberto Ugolini ◽  
Bruno Tiribilli ◽  
Vieri Boddi
Keyword(s):  
The Sun ◽  
Sun Compass ◽  
Solar Motion ◽  
Subjective Night ◽  
Proposed Model ◽  
Natural Photoperiod ◽  
The Hours ◽  
Confined Environment ◽  
H 20 ◽  
Differential Speed

SUMMARYExperiments on solar orientation were conducted with adult amphipods(Talitrus saltator) subjected to a reduction and/or phase shift of the hours of light (L) or dark (D) with respect to the natural photoperiod: 15 h:9 h L:D (controls), 15 h:9 h inverted (i.e. phase-shifted by 12 h and tested with the sun during the subjective night), 4 h:20 h, 20 h:4 h inverted. The sandhoppers were released in a confined environment, and individual orientation angles were recorded. The results confirm the continuous operation, through the entire 24-h period, of a chronometric mechanism of compensation for apparent solar motion. They show excellent agreement with a recently proposed model of compensation for the sun at constant (not differential) speed and they demonstrate a dependence of the speed of the chronometric mechanism on the L:D ratio in the 24-h period.

Pigeon homing: observations, experiments and confusions

1996 ◽  
Vol 199 (1) ◽  
pp. 21-27 ◽  
Author(s):  
C Walcott
Keyword(s):  
Release Site ◽  
Internal Clock ◽  
The Sun ◽  
Sun Compass ◽  
Homing Pigeons ◽  
Multiple Cues ◽  
Pigeon Homing ◽  
Flight Direction ◽  
Do So

Homing pigeons can return from distant, unfamiliar release points. Experienced pigeons can do so even if they are transported anesthetized and deprived of outward journey information. Airplane tracking has shown that they make relatively straight tracks on their homeward journey; therefore, pigeons must have some way of determining the home direction at the release site. Manipulating the pigeon's internal clock causes predictable deviations in their flight direction relative to home. When the sun is not visible, such clock shifts have no effect. This result implies a two-step system: the determination of the home direction and the use of a sun compass to fly in that direction. When pigeons cannot see the sun they use a magnetic compass. The use of compass cues to select and maintain a direction of flight is well understood compared with the uncertainty surrounding the nature of the cues used to determine the home direction when pigeons are released at an unfamiliar site. Because they generally home successfully from any direction and distance from the loft, without requiring information gathered on the outward journey, it seems likely that they use some form of coordinate system. Presumably, a displaced pigeon compares the values of some factor at the release site with its remembered value at the home loft. This factor might be olfactory, it might be some feature of the earth's magnetic field or it might be something else. There is some evidence that pigeons may use several cues and that pigeons raised in different lofts under different environmental conditions may prefer to use one cue over another. I believe that it is this flexible use of multiple cues that has led to so much confusion in experiments on pigeon homing.

The roles of the sun and the landscape in pigeon homing

1999 ◽  
Vol 202 (16) ◽  
pp. 2121-2126 ◽  
Author(s):  
H.G. Wallraff ◽  
J. Chappell ◽  
T. Guilford
Keyword(s):  
Experimental Evidence ◽  
Great Variability ◽  
Initial Orientation ◽  
Visual Features ◽  
Visual Environment ◽  
The Sun ◽  
Visual Landmarks ◽  
Sun Compass ◽  
Pigeon Homing ◽  
Clock Shift

It seems reasonable to assume that pigeons use visual features in the landscape for orientation when they are homing over familiar terrain. Experimental evidence to prove or disprove this possibility is, however, difficult to obtain. Here, we link the problem with the observation that deflections of initial orientation caused by clock-shift are often smaller than predicted on a pure sun compass basis. We substantiate the hypothesis that consistently reduced deflections and increased angular scatter occur only when pigeons are released in familiar areas where a remembered pattern of landscape features can conflict with the position of the sun. Repeated releases of the same individuals under clock-shift, or elimination of non-visual navigational clues (odours), appear to strengthen the conflicting influence of familiar visual landmarks. Accelerated returns of birds allowed to preview the surrounding familiar scenery before release also support the conclusion that the visual environment is included in the homing system of pigeons. The landscape, however, not only helps home-finding, if it is familiar, but may also have a distracting influence that contributes to the great variability of initial orientation patterns.

Sun-compass orientation in homing pigeons: compensation for different rates of change in azimuth?

2000 ◽  
Vol 203 (5) ◽  
pp. 889-894 ◽  
Author(s):  
R. Wiltschko ◽  
M. Walker ◽  
W. Wiltschko
Keyword(s):  
Internal Representation ◽  
Apparent Movement ◽  
Internal Clock ◽  
Time Of Day ◽  
The Sun ◽  
Compass Orientation ◽  
Sun Compass ◽  
Homing Pigeons ◽  
Rates Of Change ◽  
Compensation Mechanisms

Birds using their sun compass must compensate for the apparent movement of the sun with the help of their internal clock. The movement of the sun is not uniform, being much faster around noon than near sunrise and sunset. If the sun-compass mechanisms are not adjusted to these variations, considerable errors might arise. To learn whether birds are able to take the different rates of sun azimuth change into account, we subjected homing pigeons to a 4 h fast clock-shift. The experiments were performed near Auckland, New Zealand, at a latitude of 37 degrees S, where the expected deflections for a 4 h shift in summer vary from less than 40 degrees to more than 120 degrees, depending on time of day. One group of birds was released just after sunrise or during the corresponding period in the afternoon when the expected deflections were minimal, the other group during late morning when they were maximal. The different sizes of the observed deflections - between 26 degrees and 51 degrees in the first group, and between 107 degrees and 153 degrees in the second group - clearly show that the birds' compensation mechanisms are closely tuned to the varying rates of change in sun azimuth. The results suggest that pigeons have a rather precise internal representation of the sun curve, which makes the avian sun compass a highly accurate mechanism of direction finding.

The Safe Aircraft Competition, The Sun Compass, and more

1930 ◽  
Vol 142 (3) ◽  
pp. 232-234
Author(s):  
Alexander Klemin
Keyword(s):  
The Sun ◽  
Sun Compass

The role of science in the study of and response to space threats

2019 ◽  
Vol 89 (8) ◽  
pp. 777-799
Author(s):  
B. M. Shustov
Keyword(s):  
Comparative Analysis ◽  
20Th Century ◽  
21St Century ◽  
Space Debris ◽  
The Sun ◽  
National Program ◽  
Biological Hazard ◽  
Academy Of Sciences ◽  
Space Activities

During the second half of the 20th century and the beginning of the 21st century, space hazards multiplied, the most urgent of which is space debris. Professionals working in space are exposed to this hazard daily and are aware of it as a problem. Furthermore, increasing attention is being paid to the unpredictable behavior of the Sun, which produces the so-called space weather. The asteroid-comet hazard is considered as potentially having the most catastrophic consequences. No manifestations of biological hazard have yet been observed, although as space activities develop, it is becoming increasingly important. The appropriate time scale for astrophysical hazards is many millions of years, so from a practical perspective, they have no importance. This article briefly describes the main types of space hazards. The author analyzes the results of research and practical work in the field, both worldwide and specifically in Russia. Comparative analysis leads to the clear conclusion that a national program must be developed for the study of space hazards and to respond to space threats. This article is based on a report made by the author at the meeting of the Presidium of the Russian Academy of Sciences (RAS) on January 15, 2019.

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