Links for Keyword: Animal Migration

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Daniel Cressey In 2008, the world’s media was captivated by a study apparently showing that cows like to align themselves with magnetic fields. But attempts to replicate this finding have left two groups of researchers at loggerheads, highlighting the problems faced by scientists working to replicate unusual findings based on new methods of data analysis. Magneto-reception has been detected in animals from turtles to birds. Three years ago, Hynek Burda, a zoologist at the University of Duisburg-Essen, Germany, and his colleagues added cattle to the magnetic family with a paper in Proceedings of the National Academy of Sciences. The team used data from Google Earth to show that domestic cattle seem to prefer to align their bodies along Earth’s magnetic field lines1, and showed a similar phenomenon in field observations of deer. A follow-up study by Burda and his colleagues showed no such alignment near electric power lines, which might be expected to disrupt magneto-sensing in cattle2. Cow conundrum Earlier this year, a group of Czech researchers reported their failed attempt to replicate the finding using different Google Earth images3. The Czech team wrote in the Journal of Comparative Physiology A: “Two independent groups participated in our study and came to the same conclusion that in contradiction to the recent findings of other researchers, no alignment of the animals and of their herds along geomagnetic field lines could be found.” © 2011 Nature Publishing Group,

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 16027 - Posted: 11.12.2011

by Caroline Williams The idea that animals can navigate using their own internal compass is so startling it was once dismissed as pure fantasy. Now there is good evidence that many species - including pigeons, sea turtles, chickens, naked mole rats and possibly cattle - can detect the Earth's geomagnetic field, sometimes with astonishing accuracy. Young loggerhead turtles, for example, read the Earth's magnetic field to adjust the direction in which they swim. They seem to hatch with a set of directions, which, with the help of their magnetic sense, ensures that they always stay in warm waters during their first migration around the rim of the North Atlantic. Over time they build a more detailed magnetic map by learning to recognise variations in the strength and direction of the field lines, which are angled more steeply towards the poles and flatter at the magnetic equator. What isn't known, however, is how they sense magnetism. Part of the problem is that magnetic fields can pass through biological tissues without being altered, so the sensors could, in theory, be located in any part of the body. What's more, the detection might not need specialised structures at all, but may instead be based on a series of chemical reactions. Even so, many researchers think that magnetic receptors probably exist in the head of turtles and perhaps other animals. These might be based on crystals of magnetite, which align with the Earth's magnetic field and could pull on some kind of stretch receptor or hair-like cell as it changes polarity. The mineral has already been found in some bacteria, and in the noses of fish like salmon and rainbow trout, which also seem to track the Earth's magnetic field as they migrate. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 15707 - Posted: 08.23.2011

By Katherine Harmon Wandering the neighborhood randomly is not usually the best strategy to find a great dinner—especially if you live in a place where such meals are few and far between. The resulting trajectory, known in mathematics as "a random walk," does not always make for the best use of time and energy, particularly in locations where resources can be scarce, such as the open ocean. But a more purposeful "directed walk" to a destination takes a pretty sophisticated memory and spatial sense (or a device with GPS) that many animals don't have. New research, however, shows that thresher and tiger sharks are actually quite adept at highly directed swimming, with tiger sharks finning it over to a familiar spot from six to eight kilometers away within a home territory that covers hundreds or even thousands of square kilometers. Demonstrating that an animal is traveling directly to a desired destination—rather than stumbling on it accidentally—is challenging, given communication barriers and the fact that even straight paths are not always part of a purposeful travel pattern. To find out whether sharks were always circling their home range randomly or were intentionally returning to a place they remembered to offer food, shelter or mates, a team of researchers used fractal analysis to assess old GPS tracking data from three shark species: tiger sharks (Galeocerdo cuvier), thresher sharks (Alopias vulpinus) and blacktip reef sharks (Carcharhinus melanopterus). Tracking for each individual shark lasted for at least seven hours. © 2011 Scientific American,

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 15065 - Posted: 03.03.2011

by Aria Pearson Newly hatched sea turtles can sense their longitudinal position – something that took sailors hundreds of years and many lost ships to figure out. Surprisingly, they do so using the Earth's magnetic field. Recently, it was discovered that a handful of species – including older sea turtles and migratory birds – seem able to perceive longitude. But it was unclear what cues they could be using. The Earth's magnetic field, which animals can use to gauge latitude, was considered an unlikely candidate because of how little it varies in the east-west direction around the globe. However, in certain parts of the world at the same latitude there are subtle differences in the intensity and angle of the magnetic field. Could these be used by animals to figure out longitude? One such area is in the Atlantic Ocean, where Puerto Rico in the western Atlantic and the Cape Verde Islands in the eastern Atlantic have the same latitude but different longitudes. In between these locations is the North Atlantic Gyre. Loggerhead sea turtles (Caretta caretta) in Florida navigate the North Atlantic Gyre during their five to 10 year migration around the Atlantic Ocean. During this trip the turtles manage to avoid areas where they would get swept up by other currents and ejected out of the gyre. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 15050 - Posted: 02.26.2011

by Elizabeth Pennisi Every year, some 50 billion birds take to the air for their seasonal migrations. They may go 500 kilometers in a day and a few even travel from pole to pole. But how do they know when, where, and how far to fly? Although some of the answer lies in their DNA, nobody knew which genes or how they worked. Now ornithologists have pinned down one of those genes, and strange as it may sound, the length of that gene influences the length of the flights. "If we understand the genetics underlying migratory behavior, we can understand more about how and why migration evolves," says Chris Guglielmo, who studies bird migration at the University of Western Ontario in Canada. "We may also be better able to understand how quickly migration can disappear in response to climate change." As the moment for migration approaches, birds bulk up, adding muscle and fat. They hop and flap restlessly at night, shifting their internal clocks in anticipation of nighttime flights. Breeding experiments have shown that these shifts have a genetic basis, as do the timing, amount, and intensity of flights. Since the 1970s, ornithologists at the Max Planck Institute for Ornithology in Starnberg, Germany, have studied European blackcaps (Sylvia atricapilla), a common warbler in Europe, which typically head to the Mediterranean for the winter. Some blackcaps had established a new wintering area in the past few decades. The researchers wanted to know the genetic basis for the change. © 2010 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 0: ; Chapter 14: Attention and Consciousness
Link ID: 15014 - Posted: 02.17.2011

by Sara Reardon Next time you have a cold, be glad you're not a messenger pigeon carrying important orders over a battlefield. Breathing through both nostrils, especially the right one, is essential to these birds' famed ability to fly away home, scientists report today in the Journal of Experimental Biology. The researchers saddled a group of homing pigeons with GPS tracking devices, placed a rubber plug in either their right or left nostrils, and released them 25 miles outside of their home in Pisa, Italy. Pigeons with their left nostrils blocked had a little more trouble navigating than clear-nosed pigeons, but eventually made it home. Birds with their right nostrils blocked made it back, too, but they stopped more often and took an even more circular route than the others. The researchers believe that the birds needed time to gather more smells and construct a map based on odors in the wind. And the finding that the right nostril is the better sniffer suggests that the right and left hemispheres of bird brains have different functions. © 2010 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 14927 - Posted: 01.29.2011

by Rachel Courtland "BIRD brain" is usually an insult, but that may have to change. A light-activated compass at the back of some birds' eyes may preserve electrons in delicate quantum states for longer than the best artificial systems. Migrating birds navigate by sensing Earth's magnetic field, but the exact mechanisms at work are unclear. Pigeons are thought to rely on bits of magnetite in their beaks. Others, like the European robin (pictured), may rely on light-triggered chemical changes that depend on the bird's orientation relative to Earth's magnetic field. A process called the radical pair (RP) mechanism is believed to be behind the latter method. In this mechanism, light excites two electrons on one molecule and shunts one of them onto a second molecule. Although the two electrons are separated, their spins are linked through quantum entanglement. The electrons eventually relax, destroying this quantum state. Before this happens, however, Earth's magnetic field can alter the relative alignment of the electrons' spins, which in turn alters the chemical properties of the molecules involved. A bird could then use the concentrations of chemicals at different points on its eye to deduce its orientation. Intrigued by the idea that, if the RP mechanism is correct, a delicate quantum state can survive a busy place like the back of an eye, Erik Gauger of the University of Oxford and colleagues set out to find out how long the electrons remain entangled. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 7: Vision: From Eye to Brain
Link ID: 14890 - Posted: 01.21.2011

By Marissa Cevallos A quantum effect known as entanglement may be part of the compass that birds use to sense Earth’s magnetic field, researchers report in an upcoming Physical Review Letters. Critters from bacteria to mole rats use tiny variations in the Earth’s magnetic field to navigate, but exactly how they sense the magnetism is a mystery. One idea is that magnetic fields disrupt pairs of entangled electrons in a light-sensitive protein in the retina. In quantum entanglement, particles are linked to each other so that one always knows instantly what the other is doing, even if they get separated. In the new research, physicists at the University of Oxford and the National University of Singapore calculated that quantum entanglement in a bird’s eye could last more than 100 microseconds — longer than the 80 microseconds achieved in physicists’ experiments at temperatures just above absolute zero, says Elisabeth Rieper, a physicist at the National University of Singapore. That would be a surprising feat for a bird warbling at room temperature, which people thought was too hot to see quantum effects. “It may all be right, but I would personally like to be cautious about this,” says Thorsten Ritz, a biophysicist at University of California, Irvine, who is a proponent of the model but wasn’t involved in this research. © Society for Science & the Public 2000 - 2011

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 14847 - Posted: 01.10.2011

by Ed Yong IT WAS a bunch of robins that started it. The birds were locked in cages in Frankfurt, Germany, where they were being studied by biologist Hans Fromme. When the time came when they would normally migrate to sunny Spain, Fromme noticed they were becoming restless. What's more, they always tried to flee their cages in the same direction. This was in the late 1950s, and the thinking at the time was that migrating birds navigated using the sun, moon and stars. The cages were in a shuttered room, though, so the robins must have worked out which direction was which some other way. Magnetism was one possibility. The idea that migrating birds navigate across continents and oceans with the help of an internal compass had been suggested a century earlier by a Russian zoologist, but attempts to prove it had failed. That changed in 1966, when zoologist Wolfgang Wiltschko showed that the direction in which the robins attempted to escape could be changed by powerful magnets. His work suggested that most birds can sense the Earth's magnetic field, although many of his peers refused to believe it. "You don't want a stupid little bird doing something you don't do", says Roswitha Wiltschko of the University of Frankfurt, who together with her husband Wolfgang has been studying this ability for four decades. Their studies and others have proved the sceptics utterly wrong; we now know that a wide array of animals, from beetles to bats, rely on the Earth's magnetic field to help them navigate. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 14728 - Posted: 12.02.2010

Sönke Johnsen and Kenneth J. Lohmann Like the theory of plate tectonics, the idea that animals can detect Earth's magnetic field has traveled the path from ridicule to well-established fact in little more than one generation. Dozens of experiments have now shown that diverse animal species, ranging from bees to salamanders to sea turtles to birds, have internal compasses. Some species use their compasses to navigate entire oceans, others to find better mud just a few inches away. Certain migratory species even appear to use the geographic variations in the strength and inclination of Earth's field to determine their position. But how animals sense magnetic fields remains a hotly contested topic. Whereas the physical basis of nearly all other senses has been determined, and a magnetoreception mechanism has been identified in bacteria, no one knows with certainty how any animal perceives magnetic fields. Finding this mechanism is thus the current grand challenge of sensory biology. The problem is difficult for several reasons. First, humans do not appear to have the ability to sense magnetic fields. Whereas most nonhuman senses, such as polarization detection and UV vision, are relatively straightforward extensions of human abilities, magnetoreception is not. As a result, neither intuitive understanding nor the medical literature on human senses provides much guidance. Another complicating factor is that biological tissue is essentially transparent to magnetic fields, which means that magnetoreceptors, unlike most other sensory receptors, need not be located on an animal's surface and might instead be anywhere in the body. That consideration transforms a routine two-dimensional visual inspection into a three-dimensional search requiring advanced imaging techniques. Another impediment is that large accessory structures for focusing and otherwise manipulating the field—the analogs of eardrums and lenses—are unlikely to exist because few materials of biological origin affect magnetic fields. Indeed, magnetoreception might be accomplished by a small number of microscopic, possibly intracellular structures scattered throughout the body, with no obvious structure devoted to magnetoreception. Finally, the weakness of the interaction between Earth's field and the magnetic moments of electrons and atoms, roughly one five-millionth of the thermal energy kT at body temperature, makes it difficult to even suggest a feasible mechanism. © 2007 by the American Institute of Physics

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 11502 - Posted: 06.24.2010

Creation of signposts detected in the first non-human species Humans are not alone in creating ‘signposts’ to help them find their way, according to new research published in the open access journal BMC Ecology. Wood mice, say scientists, move objects from their environment around using them as portable signposts whilst they explore. The finding is significant as this is the first time such sophisticated behaviour has been identified in any mammal except humans. According to the authors, “This is precisely how a human might tackle the problem of searching efficiently in a homogeneous environment – for example by placing a cane in the ground as a reference point from which to search for a set of keys dropped on a lawn.” Quick, effective navigation is vital for the wood mouse. Home-ranges are vast in comparison to the mammal’s size and consist of uniform areas, like ploughed fields, without obvious landmarks. These environments are not the same all year round, and harvest time drastically changes the availability of any ‘fixed’ landmarks, food supplies and hiding places.

Related chapters from BP7e: Chapter 1: Biological Psychology: Scope and Outlook; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 1: An Introduction to Brain and Behavior; Chapter 8: Hormones and Sex
Link ID: 3744 - Posted: 06.24.2010

Migrating birds stay on track because of chemical reactions in their bodies that are influenced by the Earth’s magnetic field, a UC Irvine-led team of researchers has found. The birds are sensitive even to rapidly fluctuating artificial magnetic fields. These fields had no effect on magnetic materials such as magnetite, indicating that the birds do not rely on simple chunks of magnetic material in their beaks or brains to determine direction, as experts had previously suggested. The results are reported in the May 13 issue of Nature. The study is the first to reveal the mechanism underlying magnetoreception – the ability to detect fluctuations in magnetic fields – in migratory birds. In the study, Thorsten Ritz, assistant professor of physics and astronomy, and colleagues exposed 12 European robins to artificial, oscillating magnetic fields and monitored the orientation chosen by these birds. The stimuli were specially designed to allow for responses that could differ depending on whether birds used small magnetic particles on their bodies or a magnetically sensitive photochemical reaction to detect the magnetic field. © Copyright 2002-2004 UC Regents

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 5461 - Posted: 06.24.2010

Alison Abbott Tiny trackers help to reveal a bird's thoughts in flight.H-P. LippNeuroscientists have fitted pigeons with recorders that pick up brain activity as the birds fly. The devices confirm that the birds really do use features from a landscape to find their way home. And researchers hope that they will be able to use the caps to unpick how birds use other types of navigational signals at different points in a journey. Scientists are pretty sure from tracking experiments that pigeons use the Sun, Earth’s magnetic field and possibly smells as guiding cues when navigating. In 2004, Hans-Peter Lipp, a behavioural neuroscientist from the University of Zrich in Switzerland, showed that pigeons probably also use visual information. He noted that the birds tend to turn when they hit obvious landmarks like a highway exit1. These tracking experiments collected good information about the birds' location, by fitting modern global positioning system (GPS) loggers to the pigeons’ backs. But no-one has been able to measure directly what information the pigeon are using to navigate — no one has accessed the pigeons' thoughts in flight. "If we see a bird continuing along its path after crossing a bump in the magnetic field that would normally cause it to change direction — is this because it failed to sense the information or had a good reason to ignore it?" asks Lipp. "What’s going on in their minds?" © 2007 Nature Publishing Group

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 10951 - Posted: 06.24.2010

Katharine Sanderson How do migrating birds perceive which way is north? Research now points to the idea that they actually 'see' the Earth's magnetic fields, rather than feeling or sensing them in some other way. Previous work has suggested that the Earth's magnetic field might act on the sensitivity of a migratory bird's eye, so that sight might be involved in finding magnetic north. Now researchers have firmed that up with evidence that molecules in the eyes of migratory birds are connected to the part of the brain that guides their direction of flight. Dominik Heyers, at the University of Oldenburg, Germany, and colleagues injected migratory garden warblers (Sylvia borin) with a tracer capable of travelling along neuronal fibres along with nerve signals. They injected one tracer into the part of the forebrain known to be the only active area when birds orient themselves (known as Cluster N), and a different tracer into the retina. After a bird experienced a desire to migrate, both tracers ended up in the same place, the researchers report in the Public Library of Science One1 — a part of the thalamus responsible for vision. This anatomical link strongly supports the notion that the birds probably experience magnetic fields as a visual sensation, say the researchers. ©2007 Nature Publishing Group

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 10777 - Posted: 06.24.2010

Narelle Towie Bats have a novel device for guiding them home on starless nights. In addition to their well-known sensory talents, it seems that big brown bats can tune into the Earth's magnetic field, using it as a compass to guide them to roost. This ability comes in handy on long-distance flights, where their usual mode of navigation — bouncing sounds waves off objects using ultrasound — doesn't do much good. Richard Holland from Princeton University, New Jersey, and colleagues looked at 15 North American big brown bats (Eptesicus fuscus), which travel up to 100 kilometres to find hibernation sites for the winter. To first test the animals' natural navigational abilities, they attached small radio transmitters to the bats and transported them 20 kilometres from their roost. One by one they let them go, and tracked them from a small aircraft. All of them headed directly back to their roost. How did they do this? Researchers have previously suggested that bats might use the direction of the sunset to set their compass. Others have found traces of magnetic materials within bats, suggesting that they might use the planet's magnetic fields to find north. ©2006 Nature Publishing Group

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 9707 - Posted: 06.24.2010

By DONALD G. McNEIL Jr. LAWRENCE, Kan. — Pinching a bright orange butterfly in one hand and an adhesive tag the size of a baby’s thumbnail in the other, the entomologist bent down so his audience could watch the big moment. “You want to lay it right on this cell here, the one shaped like a mitten,” the scientist, Orley R. Taylor, told the group, a dozen small-game hunters, average age about 7 and each armed with a net. “If you pinch it for about three seconds, the tag will stay on for the life of the butterfly, which could be as long as nine months.” Dr. Taylor, who runs the Monarch Watch project at the University of Kansas, is using the tags to follow one of the great wonders of the natural world: the annual migration of monarch butterflies between Mexico and the United States and Canada. The northward migration this spring was the biggest in many years, raising hopes of butterfly enthusiasts throughout North America. But a drought in the Dakotas and Minnesota meant that not nearly as many butterflies started the return trip. And without the late-summer hurricanes that normally soak the Texas prairies and sprout the nectar-heavy wildflowers where the monarchs refuel, many are presumably finding that leg of the journey a death march. Dr. Taylor has already halved his prediction for the size of the winter roosts in central Mexico, to 14 acres from 30. Nevertheless, the 4,000-mile round trip made by millions of monarchs holds a central mystery that Dr. Taylor and a network of entomologists are trying to solve. Copyright 2006 The New York Times Company

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 9445 - Posted: 06.24.2010

One of Nature's great phenomena is how tiny songbirds can make their way over thousands of miles each fall to their winter feeding grounds and back again the following spring. Scientists have known for years that they travel by night to avoid predators, navigating by the stars and the Earth's invisible magnetic field. Yet how these birds "see" the Earth's magnetic field — a protective field that shields Earth from radiation, and is the basis for the magnetic north and south poles, but which people can't sense at all — has remained a mystery. Now researchers based in the United States and Europe have found a brain region in night-migrating songbirds that they think can "process" information from the Earth's magnetic field and turn it into an internal compass they can see. The brain region is called "Cluster N" — "N" for night-vision because the researchers believe the birds' ability to sense the Earth's magnetic field and transform it into a navigation tool is dependent on their ability to see at night. "What we discovered was that this brain area wasn't exclusively used for sensing magnetic fields, but instead it's being used to perhaps see at night," says Duke University neurobiologist Erich Jarvis. Jarvis collaborated with animal navigation researcher Henrik Mouritsen from the University of Oldenburg, in Germany, to compare the brains of two distantly related types of migrating songbirds, the Garden Warbler and the European Robin, to two types of non-migrating song birds, Canaries and Zebra Finches. © ScienCentral, 2000-2006.

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 7: Vision: From Eye to Brain
Link ID: 8745 - Posted: 06.24.2010

One of Nature's great phenomena is how tiny songbirds can make their way over thousands of miles each fall to their winter feeding grounds. Scientists have known for years that they travel by night to avoid predators, navigating by the stars and the Earth's invisible magnetic field. Yet how these birds "see" the Earth's magnetic field — a protective field that shields Earth from radiation, and is the basis for the magnetic north and south poles, but which people can't sense at all — has remained a mystery. Now researchers based in the United States and Europe have found a brain region in night-migrating songbirds that they think can "process" information from the Earth's magnetic field and turn it into an internal compass they can see. The brain region is called "Cluster N" — "N" for night-vision because the researchers believe the birds' ability to sense the Earth's magnetic field and transform it into a navigation tool is dependent on their ability to see at night. Jarvis collaborated with animal navigation researcher Henrik Mouritsen from the University of Oldenburg, in Germany, to compare the brains of two distantly related types of migrating songbirds, the Garden Warbler and the European Robin, to two types of non-migrating song birds, Canaries and Zebra Finches. "This area is only active in the night-migratory birds at night and it's never active in the non-migratory birds, not during the day, nor during the night," says Mouritsen who published the finding with Jarvis in the journal Proceeding of the National Academy of Sciences. © ScienCentral, 2000-2005.

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 7: Vision: From Eye to Brain
Link ID: 7916 - Posted: 06.24.2010

— Surges of solar activity may cause whales to run aground, possibly by disrupting their internal compasses, German scientists suggest. University of Kiel researchers Klaus Vaneslow and Klaus Ricklefs looked at sightings of sperm whales found beached in the North Sea between 1712 and 2003. They then compared this record with another set of historical data — astronomers' observations of sunspots, which is an indicator of solar radiation. More whale strandings occurred when the sun's activity is high, they found. The sun experiences cycles of activity which range from eight to 17 years, with 11 years being the average. Short cycles are linked with periods of high energy output, while long cycles are believed to be low energy. Changes in levels of solar radiation have a big effect on Earth's magnetic field. The most notable events are bouts of highly-charged particles, called solar flares, that cause the shimmering Northern Lights, also called aurorae, in the magnetic fields in polar regions. Big solar flares can also disrupt telecommunications and power lines and knock out delicate electronic circuitry on satellites. Copyright © 2005 Discovery Communications Inc.

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 7360 - Posted: 06.24.2010

— Migrating birds may get their internal compass through a chemical reaction induced by the Earth's magnetic compass, rather than through magnetic material in their beaks as the conventional theory holds. University of California physicist Thorsten Ritz and colleague exposed European robins to weak but rapidly oscillating magnetic fields in a lab. When the artificial field was aligned with the Earth's own magnetic field, the birds faced in the right direction. But when the artificial field was shifted to a different direction, they were instantly confused. Copyright © 2004 Discovery Communications Inc.

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 5469 - Posted: 06.24.2010