Sun Compass Research Articles

ECR Spotlight – Haneal Pae

ECR Spotlight is a series of interviews with early-career authors from a selection of papers published in Journal of Experimental Biology and aims to promote not only the diversity of early-career researchers (ECRs) working in experimental biology but also the huge variety of animals and physiological systems that are essential for the ‘comparative’ approach. Haneal Pae is an author on ‘ Drosophila require both green and UV wavelengths for sun orientation but lack a time-compensated sun compass’, published in JEB. Haneal is a PhD student in the lab of Ysabel Giraldo at University of California, Riverside, USA, investigating how sensory information is integrated and processed in the nervous system and influences Drosophila orientation during flight.

Drosophila require both green and UV wavelengths for sun orientation but lack a time-compensated sun compass.

Celestial orientation and navigation are performed by many organisms in contexts as diverse as migration, nest finding and straight-line orientation. The vinegar fly, Drosophila melanogaster, performs menotaxis in response to celestial cues during tethered flight and can disperse more than 10 km under field conditions. However, we still do not understand how spectral components of celestial cues and pauses in flight impact heading direction in flies. To assess individual heading, we began by testing flies in a rotating tether arena using a single green LED as a stimulus. We found that flies robustly perform menotaxis and fly straight for at least 20 min. Flies maintain their preferred heading directions after experiencing a period of darkness or stopping flight, even up to 2 h, but reset their heading when the LED changes position, suggesting that flies do not treat this stimulus as the sun. Next, we assessed the flies' responses to a UV spot alone or a paired UV-green stimulus - two dots situated 180deg apart to simulate the solar and antisolar hemispheres. We found that flies respond to UV much as they do to green light; however, when the stimuli are paired, flies adjust for sudden 90deg movements, performing sun orientation. Lastly, we found no evidence of a time-compensated sun compass when we moved the paired stimuli at 15degh-1 for 6 h. This study demonstrates that wavelength influences how flies respond to visual cues during flight, shaping the interpretation of visual information to execute an appropriate behavioral response.

Initial orientation and homing performances in the lacertid lizard Podarcis siculus

Homing abilities of lizards after experimental dislocations have been found to be well developed in several species. Following our preliminary findings in Podarcis siculus, the present paper reports a new series of experiments on homing performances and initial orientation behaviour upon release. For this purpose, three series of releases were performed at increasing distances from the home areas in which the lizards were captured (range 85–245 m). In each series, two groups of lizards were released: the route-based visual cues during displacement were denied to one of them (NVIS), but allowed for the other (YVIS). The results of initial orientation showed that both are significantly homeward oriented at all three distances tested. Male and female YVIS and female NVIS are similarly homeward oriented, while the male NVIS are not. All 74 lizards successfully returned to their respective home areas. Eleven lizards homed on the same day they were released, while most of them homed during the 1st day after release (n = 51) and the rest on the 2nd day (n = 12). The different transport treatments did not influence homing success at the different distances tested. These results seem to support the use of a geocentric pilotage strategy to re-enter home from the release spot. Alternatively, the possibility that P. siculus use a sun compass and a mosaic map to find their way home is also discussed.

Time-compensated sun compass in juvenile sprat (Sprattus sprattus) reveals the onset of migratory readiness.

Sprat (Sprattus sprattus) is one of the most commercially exploited fish species in the Baltic Sea and expresses a pronounced seasonal migration pattern. Spawning takes place, among other places, in the Kiel Bight and Kiel Fjord in early summer. Juvenile sprat leave the nursery areas in late summer/early autumn to move to their feeding and overwintering grounds. What kind of orientation mechanisms sprat use for migration is not known yet. This study shows that juvenile sprat can use a time-compensated sun compass, heading towards the northeast, in the direction of their proposed overwintering grounds in Bornholm Basin. The sprats tested at the end of August oriented themselves in the predicted direction, whereas the sprats tested at the beginning of August only showed a random orientation. For the first time, this demonstrates the onset of migratory readiness in juvenile sprat, indicating the preparation for starting their migration.

The efficiency of varying methods and degrees of time compensation for the solar azimuth.

Daytime migrants are known to orientate using the position of the sun, compensating for its changing position throughout the day with a 'time-compensated sun compass'. This compass has been demonstrated in many migratory species, with various degrees of accuracy for the actual movement of the sun. Here, we present a model for differing levels of compensation for the solar ephemeris that shows that a high degree of efficiency, in terms of distance travelled, can be achieved without full time compensation. In our model, compensating for the sun's position had a diminishing return with an accuracy of 80% leading to only a 2% reduction in distance travelled. We compare various modes of time compensation-full, partial, time averaged and step-revealing their directional efficiency in terms of distance travelled under an autumn migration scenario. We find that the benefit of time compensation varies with latitude, with time averaging performing very well, especially at all high latitudes, but step compensation performing better at very low latitudes. Importantly, even rudimentary adjustment can dramatically increase the efficiency of migration, which suggests an easy pathway for the independent evolution of time compensation.

Use of the sun compass by monocularly occluded homing pigeons in a food localisation task in an outdoor arena

Functional asymmetries of the avian visual system can be studied in monocularly occluded birds, as their hemispheres are largely independent. Right and left monocularly occluded homing pigeons and control birds under binocular view have been trained in a food localisation task in an octagonal outdoor arena provided with one coloured beacon on each wall. The three groups were tested after the removal of the visual beacons, so to assess their sun compass learning abilities. Pigeons using the left eye/right hemisphere system exhibited slower learning compared to the other monocular group. During the test in the arena void of visual beacons, the three groups of birds, regardless of their visual condition, were generally able to identify the training sector by exclusively relying on sun compass information. However, the directional choices of the pigeons with the left eye/right hemisphere in use were significantly affected by the removal of the beacons, while both control pigeons and birds with the right eye/left hemisphere in use displayed unaltered performances during the test. A subsample of pigeons of each group were re-trained in the octagonal arena with visual beacons present and tested after the removal of visual beacons after a 6 h fast clock-shift treatment. All birds displayed the expected deflection consistent to the sun compass use. While birds using either the left or the right visual systems were equally able to learn a sun compass-mediated spatial task, the left eye/right hemisphere visual system displayed an advantage in relying on visual beacons.

THE EARLY HISTORY OF MAGNETIC EXPLORATION IN NORTH AMERICA

ABSTRACT Over the past nearly two centuries the magnetic method has been one of the most useful and broadly applied techniques for geologic mapping. Prior to the development of aeromagnetic surveying following World War II magnetic exploration was restricted to ground surveying using primarily mechanical instruments which measured the angular relationships or oscillation of a magnetic needle. This instrumentation was developed initially in western Europe for mapping the geomagnetic field and then iron ore deposits beginning in the seventeenth century. As the instrumentation evolved, sensitivity increased allowing the magnetic method to map additional geologic units of decreasing magnetization. The method was brought to North America where abnormal declination of the magnetic field as measured with the compass was used to map intensely magnetic ironrich rocks in the New Jersey highlands and adjacent New York in the early 1700s. Counterweighted magnetic needles (dip needles) oscillating vertically in the magnetic meridian were developed during the late eighteenth century in Scandinavia for measuring magnetic intensity anomalies that are more readily interpreted than the angular measurements of the compass. These instruments were brought to the eastern United States and were put into use in the mid-1800s in the search for banded iron formations and magnetite-bearing metamorphic and igneous rocks of interest to ore exploration. Similar instrumentation was developed in the British Isles in the first half of the 1800s for national surveys and later for geological exploration. The dip needle and a modification of the sun compass for geologic purposes, the dial compass, were commonly used together for mapping magnetic anomalies of iron ore deposits especially in the Lake Superior region from the U.S. Civil War to World War II. To increase the sensitivity and precision of the measurements numerous additional instruments were developed based on the principle of the dip needle. Particularly important among these were the Schmidt-type magnetometer and Hotchkiss superdip which were widely used in North America after the early 1920s and well into the 1950s. These and similar instruments opened the application of the magnetic method to a broad range of geologic problems important to mineral and petroleum exploration and engineering studies. Interpretation of the mapped magnetic anomalies was advanced with newly developed theoretical representations and model studies of the magnetic intensity of idealized geologic sources that were compared to observed magnetic anomalies.

ANALISIS KOMPUTASIONAL APLIKASI SUN COMPASS DALAM PENENTUAN ARAH KIBLAT MUSLIM

Sun Compass is a smartphone app that was developed to determine the Muslim qibla direction around the world. The invention of the Sun Compass is said to be a solution to the inaccuracy problem in Qibla app due to its susceptibility to magnetic interference. Based on the calibration technique of the sun’s shadow and true north reference, the Sun Compass showed a high accuracy of the Qibla direction angle. Therefore, this study was conducted to check the Sun Compass’s accuracy by comparing the Qibla direction display with the Qibla shadow. Data collection was carried out through field observation and the collected data were analysed computationally and comparatively. The results of the study found that the Sun Compass application has a deviation value of less than 0.5° with a 99%-confidence level of 0.1015 and it is still below the limit of deviation from the direction of the qibla (had al-tahawwul ‘ani al-qiblah) which, in Malaysia, is allowed for not more than 3°. This study concludes that the application of Sun Compass in assisting Muslims to determine the direction of Qibla is more accurate empirically than other Qibla apps.

Coral reef fish larvae show no evidence for map-based navigation after physical displacement

Millions of minute, newly hatched coral reef fish larvae get carried into the open ocean by highly complex and variable currents. To survive, they must return to a suitable reef habitat within a species-specific time. Strikingly, previous studies have demonstrated that return to home reefs is much more frequent than would be expected by chance. It has been shown that magnetic and sun compass orientation can help cardinalfish maintain their innate swimming direction but do they also have a navigational map to cope with unexpected displacements? If displaced settling-stage cardinalfish Ostorhinchus doederleini use positional information during their pelagic dispersal, we would expect them to re-orient toward their home reef. However, after physical displacement by 180km, the fish showed a swimming direction indistinguishable from original directions near the capture site. This suggests that the tested fish rely on innate or learned compass directions and show no evidence for map-based navigation.

Juvenile Atlantic herring (Clupea harengus) use a time-compensated sun compass for orientation.

Atlantic herring (Clupea harengus), an ecologically and economically important species in the northern hemisphere, shows pronounced seasonal migratory behaviour. To follow distinctive migration patterns over hundreds of kilometers between feeding, overwintering and spawning grounds, they are probably guided by orientation mechanisms. We tested whether juvenile spring-spawning Atlantic herring, caught in the western Baltic, use a sun compass for orientation just before they start leaving their hatching area. Fish were randomly divided into two groups, one of them clock-shifted 6 h backwards, to investigate whether they shift their orientation direction accordingly. Individual fish were placed in a circular bowl and their orientation was tested multiple times with the sun as a sole visual orientational cue. Our results show for the first time that juvenile Atlantic herring use a time-compensated sun compass during their migration. Their swimming direction was impaired, but still present, even when the sky was very cloudy, indicating additional orientation capabilities.

Oriented migratory flight at night: Consequences of nighttime light pollution for monarch butterflies

SummaryWe show that light trespass—a form of nighttime light pollution (NLP)—elicits normal daytime clock-mediated migratory behavior in fall monarch butterflies during their night-cycle. In controlled indoor flight simulator studies isolating the role of NLP on the expression of oriented migratory flight using a time-compensated sun compass,a full-spectrum light source consistent with lights used outdoors at night by the public,triggered proper fall directional flight at night in monarchs. Monarchs remained quiescent when initially placed in the flight simulator in the dark, but flight was immediately triggered when our light source was turned on. This nighttime behavior was identical to that seen in outdoor free-flying fall conspecifics during the day. The light source provided directional cues equivalent to those provided by the sun and could either phase-advance or phase-delay monarchs. Our study highlights the negative consequences of NLP on diurnal animals, especially those that rely on clock-mediated behavior.

Stimulus-dependent orientation strategies in monarch butterflies.

ABSTRACTInsects are well known for their ability to keep track of their heading direction based on a combination of skylight cues and visual landmarks. This allows them to navigate back to their nest, disperse throughout unfamiliar environments, as well as migrate over large distances between their breeding and non-breeding habitats. The monarch butterfly (Danaus plexippus), for instance, is known for its annual southward migration from North America to certain trees in Central Mexico. To maintain a constant flight route, these butterflies use a time-compensated sun compass, which is processed in a region in the brain, termed the central complex. However, to successfully complete their journey, the butterflies’ brain must generate a multitude of orientation strategies, allowing them to dynamically switch from sun-compass orientation to a tactic behavior toward a certain target. To study whether monarch butterflies exhibit different orientation modes and if they can switch between them, we observed the orientation behavior of tethered flying butterflies in a flight simulator while presenting different visual cues to them. We found that the butterflies' behavior depended on the presented visual stimulus. Thus, while a dark stripe was used for flight stabilization, a bright stripe was fixated by the butterflies in their frontal visual field. If we replaced a bright stripe with a simulated sun stimulus, the butterflies switched their behavior and exhibited compass orientation. Taken together, our data show that monarch butterflies rely on and switch between different orientation modes, allowing the animal to adjust orientation to its actual behavioral demands.

Akurasi Arah Kiblat Masjid Menggunakan Qibla Tracker Di Kecamatan Tamalanrea Kota Makassar

This study examines how the accuracy of the Qibla direction of the mosque is determined using one of the modern tools, namely the Taracker Qibla, combined with qualitative descriptive methods through field research (Field Research), with the object of research matching the Qibla direction of several mosques in Tamalanrea District, Makassar City. The approach in this study uses a sociological synthesis approach. Researchers conducted deductive and inductive analyses of the collected data. Then the main tool used in this research is the Qiblat Tracker tool. Qibla direction determination activities using the sophistication of modern tools such as Sun Compass, GPS, Qiblat Tracker, and Google Earth, nowadays, are no longer new. The results of the study found that there were 2 mosques with significant deviations, namely the Baitul Afiah Mosque at 009° and the Nurul Yaqin Mosque at 018°. The biggest deviation is 018°, so the direction of the destination country is towards an African country, not Mecca.Qibla Direction, Qibla Tracker, Mosque

Hoverflies use a time-compensated sun compass to orientate during autumn migration.

The sun is the most reliable celestial cue for orientation available to daytime migrants. It is widely assumed that diurnal migratory insects use a ‘time-compensated sun compass’ to adjust for the changing position of the sun throughout the day, as demonstrated in some butterfly species. The mechanisms used by other groups of diurnal insect migrants remain to be elucidated. Migratory species of hoverflies (Diptera: Syrphidae) are one of the most abundant and beneficial groups of diurnal migrants, providing multiple ecosystem services and undergoing directed seasonal movements throughout much of the temperate zone. To identify the hoverfly navigational strategy, a flight simulator was used to measure orientation responses of the hoverflies Scaeva pyrastri and Scaeva selenitica to celestial cues during their autumn migration. Hoverflies oriented southwards when they could see the sun and shifted this orientation westward following a 6 h advance of their circadian clocks. Our results demonstrate the use of a time-compensated sun compass as the primary navigational mechanism, consistent with field observations that hoverfly migration occurs predominately under clear and sunny conditions.

Orientation cues and mechanisms used during avian navigation: A review

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.

Migratory birds’ physiology: A review

Migration has come from the latin word “migrare” may be defined as the seasonal movement of animals from one place to another. Bird migration was described by L. Thomson as “changes of habitat periodically recurring and alternating in direction, which tend to secure optimum environment conditions at all times”. Temperature, food supply, or the amount of daylight animals migrate, breeding is one of the purposes. Migratory birds undergo two migrations per year: a fall migration and a spring migration. Pre-migratory fattening is the behavior shown by the migratory birds in which they eat food in excess (hyperphagia) and gain weight quickly just to deal with the high energy demands for long migratory flight. This fueling is done before the migratory take off as well as at stopover sites of their routes. Fuel reserves reach maximum levels when birds start long non-stop flight. Feathers’ aerodynamic and insulatory functions are affected by long flight and its exposure to light therefore, the plumage is replaced periodically through a process known as molt. The corticosterone plays a major role in metabolic and behavioral functions to manage fuel utilization on a daily and seasonal basis. Migratory birds usually fly in a V formation and they follow a definite order during migration. Generally adults or old birds start first and the young follow them. Variety of senses helps in the navigation during migratory flight. It’s one of the peculiar system followed by the birds to know their route of migration and is followed by them each and every yearly of their flight. The most commonly used navigation tool is the use of sun compass. Using the sun for direction involves the need for making compensation based on the time. Other abilities include detecting the magnetic fields, visual landmarks and olfactory cues. Anatomical, physiological and molecular analyses have revealed that in birds independent clocks are present at a minimum of three levels: retina of the eyes, pineal gland and hypothalamus. Each of these has input, pacemaker and output components. It is becoming clearer that environmental input to the clock, such as seasonal changes in temperature, rainfall and food abundance, can regulate temporal relationships between physiology and behavior, linked with migration and reproduction.

Finding Nemo\u2019s clock reveals switch from nocturnal to diurnal activity

Timing mechanisms play a key role in the biology of coral reef fish. Typically, fish larvae leave their reef after hatching, stay for a period in the open ocean before returning to the reef for settlement. During this dispersal, larvae use a time-compensated sun compass for orientation. However, the timing of settlement and how coral reef fish keep track of time via endogenous timing mechanisms is poorly understood. Here, we have studied the behavioural and genetic basis of diel rhythms in the clown anemonefish Amphiprion ocellaris. We document a behavioural shift from nocturnal larvae to diurnal adults, while juveniles show an intermediate pattern of activity which potentially indicates flexibility in the timing of settlement on a host anemone. qRTPCR analysis of six core circadian clock genes (bmal1, clocka, cry1b, per1b, per2, per3) reveals rhythmic gene expression patterns that are comparable in larvae and juveniles, and so do not reflect the corresponding activity changes. By establishing an embryonic cell line, we demonstrate that clown anemonefish possess an endogenous clock with similar properties to that of the zebrafish circadian clock. Furthermore, our study provides a first basis to study the multi-layered interaction of clocks from fish, anemones and their zooxanthellae endosymbionts.

Solar-tracking methodology based on refraction-polarization in Snell's window for underwater navigation

Underwater navigation system is an indispensable part for autonomous underwater vehicles. Due to the indiscernibility of satellite signal, however, the underwater navigation problem is quite challenging, and a satellite-free navigation scheme should be looked for. Polarization navigation, inspired by insects’ capability of autonomous homing and foraging, is an alternative solution to satellite navigation with great application potential. Underwater polarization provides an indirect sun compass to animals for orientation determination. However, it is difficult to apply terrestrial solar-tracking methodologies in underwater situations due to the refraction of polarized skylight at the air–water interface. To resolve this issue, an underwater solar-tracking algorithm is developed based on the underwater refraction-polarization pattern inside the Snell's window. By employing Snell's law and Fresnel refraction formula to decouple the refractive ray bending and polarization deflection, the celestial polarization pattern is obtained based on underwater measurement. To further improve the accuracy, the degree of polarization is employed as a weight factor for E-vector. A long-lasting underwater experiment was conducted to validate the effectiveness of the proposed approach, and the results showed the root-mean-square errors of solar zenith and azimuth employing this algorithm were 0.3° and 1.3°, respectively. Our experimental results show that the refraction-polarization pattern inside the Snell's window exhibits immense potential to improve the solar-tracking accuracy for underwater navigation.

Sun compass neurons are tuned to migratory orientation in monarch butterflies.

Every autumn, monarch butterflies migrate from North America to their overwintering sites in Central Mexico. To maintain their southward direction, these butterflies rely on celestial cues as orientation references. The position of the sun combined with additional skylight cues are integrated in the central complex, a region in the butterfly's brain that acts as an internal compass. However, the central complex does not solely guide the butterflies on their migration but also helps monarchs in their non-migratory form manoeuvre on foraging trips through their habitat. By comparing the activity of input neurons of the central complex between migratory and non-migratory butterflies, we investigated how a different lifestyle affects the coding of orientation information in the brain. During recording, we presented the animals with different simulated celestial cues and found that the encoding of the sun was narrower in migratory compared to non-migratory butterflies. This feature might reflect the need of the migratory monarchs to rely on a precise sun compass to keep their direction during their journey. Taken together, our study sheds light on the neural coding of celestial cues and provides insights into how a compass is adapted in migratory animals to successfully steer them to their destination.

Ontogeny of the star compass in birds: pied flycatchers (Ficedula hypoleuca) can establish the star compass in spring

The star compass of birds, as well as the sun compass, is not innate. To possess either of them, the birds have to observe the rotating sky and determine its' center of rotation (in the star compass case) or the sun's movement (in the sun compass). Young birds are believed to learn how to use the star compass before their first migration, even though the evidence of this is lacking. Here, we test whether hand-raised Pied flycatchers (Ficedula hypoleuca) which had not established the star compass prior to their first autumn migration can gain it later in their ontogeny, in spring. We also attempted to examine if the observation of diurnal celestial cues (the sun and the polarized light) prior to autumn migration would affect the process of the star compass learning in spring. When tested in the vertical magnetic field under the natural starry sky, the group of birds which observed the stars in spring as the first celestial cues could choose the migratory direction. In contrast, the birds, which had never seen the stars, were not able to use the nightly celestial cues in the vertical magnetic field. However, the group of birds which had seen the daytime celestial cues till autumn and the stars at spring was disoriented, although this might be due to the small sample size. Our data suggest the possibility that the star compass may be learned in spring and emphasize the necessity for the further research in the interaction of celestial compasses.