Links for Keyword: Animal Migration

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Migratory birds not only get to see the world. A new study finds that these globetrotters also have better long-term memories than stay-at-home relatives. The extra brain power could help ensure that the birds don’t get lost on their travels. Birds flying long distances use celestial cues, their sense of smell, and Earth’s magnetic field as rough guides to navigation. As they near their final destination, however, they switch strategies. They look for landmarks such as bushes and trees they have memorized during previous trips. That's how the birds return to the same breeding, wintering, and stopover sites year after year. Anatomical studies suggested that migrants do a lot of learning en route. Garden warblers, for example, return to central Europe from their first trip to Africa with a bigger hippocampus, a region of the brain involved in learning spatial information. Nonmigrating Sardinian warblers, on the other hand, show no such change. But direct evidence that life on the move makes birds remember better was missing. Copyright © 2003 by the American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 3747 - Posted: 06.24.2010

TUNA dive fast and deep twice a day because they use an internal compass to navigate, a new study suggests. It has long been known that tuna dive around dawn and dusk but no one has been quite sure why. To find out, Jay Willis at the University of Tasmania in Hobart, Australia, and colleagues attached tags to 21 southern blue fin tuna (Thunnus maccoyii) and used them to monitor water temperature, time, depth and light levels for 135 days (Behavioral Ecology and Sociobiology, DOI: 10.1007/s00265-009-0818-2). The team found that the tuna initiated these "spike dives" when the sun was precisely 6 degrees below the horizon, 30 minutes before dawn and 30 minutes after sunset. At this time of day magnetic interference created by the solar wind is at its lowest. Since some fish can detect and navigate using magnetic fields, Willis thinks that diving at this time may help tuna to get a clearer magnetic signal. As surface wind and waves also cause interference, Willis suggests that they dive deep to "fine-tune their personal compass". Others are not so sure. "There may be other reasons besides geolocation at work here, namely keeping track of food," says Molly Lutcavage of the University of New Hampshire in Durham. She points out that tuna's prey migrate to depth at around the same time. © 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: 13196 - Posted: 06.24.2010

By Kelli Whitlock Burton Homing pigeons use landmarks to guide them safely home. But how do the birds track these familiar sites hundreds of meters below as they zip by at 65 kilometers per hour? Scientists are trying to answer that question with a new device that lets them record brain activity as pigeons fly. Exactly how pigeons find their way home is a mystery. While some studies suggest the birds rely on smells, the position of the sun, or Earth's magnetic field to navigate, scientists also know that pigeons use visual landmarks. To see how the pigeons' brains processed these sights, Alexei Vyssotski and colleagues at the University of Zurich in Switzerland developed the Neurologger2, a device that simultaneously tracks the birds' route while also recording brain activity as they fly over familiar sites. Neurologger2 weighs just 2 grams and uses an electroencephalogram to record brain activity. In a study published online this week in Current Biology, the scientists trained 26 pigeons to recognize a loft as their home base. Then, they implanted tiny electrodes on the birds' brains and connected them with Neurologger2. They outfitted the birds with global positioning system monitors and then released them from different points 10 to 30 kilometers away from the loft. Once the birds returned, the researchers removed the devices and compared the record of the birds' brain activity with their positions at the time. Vyssotski found that when the birds flew over landmarks, such as a familiar highway, high-frequency brain waves suddenly got more intense. © 2009 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 12993 - Posted: 06.24.2010

Daniel Cressey Despite thousands of years of coexistence, exploitation and cheese, humanity seems to have missed an intriguing fact about cows: they like to point north. Or possibly south. An analysis of more than 8,000 cows claims they have a statistically significant preference to align themselves in a north-south direction. The team behind this study has also found a similar preference in deer, and believes the animals must be sensing the Earth's magnetic field. While 'magnetoreception' has been documented in insects, birds and some mammals, the idea that such a prominent example of it could have gone unrecognised for years comes as a surprise. What evolutionary advantage, if any, the cattle might accrue is unclear. "It is amazing that this ubiquitous conspicuous phenomenon apparently has remained unnoticed by herdsmen and hunters for thousands of years," write Sabine Begall, of the University of Duisberg-Essen in Germany, and colleagues in Proceedings of the National Academy of Sciences. Begall's team used satellite photos from Google Earth to analyse the orientation of 8,510 cattle at 308 sites around the globe. The photos were chosen to ensure the animals were clearly visible, standing on flat ground, and not close to water or feeding areas that would influence their position. "The whole search was quite time-consuming," says Begall. "Sometimes you find several pastures within minutes, and at other times you search and search without finding anything useful." © 2008 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: 11972 - Posted: 06.24.2010

By Rachel Zelkowitz Who needs a GPS when you have, well, whatever migratory birds and sea turtles have? For centuries, humans have marveled at the ability of these and other animals to navigate the globe, in some cases returning to the same breeding spot year after year from as far as 15,000 kilometers away. How they find their way remains a mystery, but new research suggests their prowess may depend on the ability to "see" Earth's magnetic field. Researchers agree that however animals navigate, they use Earth's magnetic field as a guide. Theories about how animals detect these fields, a property called magnetosensitivity, generally fall into two camps. One group argues that tiny crystals of a magnetic mineral known as magnetite, which is found in the brains of some birds and in bacteria, are key. Other scientists say that animals carry photoreceptor molecules that enable them to actually "see" magnetic fields. How these molecules work is not clear, but some researchers think light might destabilize electrons in the photoreceptors, making them susceptible to Earth's magnetic pull. Previous work has shown that animals must be able to respond to blue light to detect magnetic fields, so researchers have eyed cryptochrome, a protein that allows plants and animals to sense blue light, as a likely candidate for the magnetosensitivity photoreceptor. But it's hard to isolate the effects of a single protein in a complex organism. So a team of researchers from the University of Massachusetts Medical School in Worcester swapped small, forgoing migratory birds and other large animals for the humble fruit fly. © 2008 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 10: Vision: From Eye to Brain; Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain; Chapter 5: The Sensorimotor System
Link ID: 11852 - Posted: 06.24.2010

By Rick Weiss Four decades after scientists showed that migratory birds use Earth's magnetic field to orient themselves during their seasonal journeys, researchers have at last found a molecular mechanism that may explain how they do it. The work, described online yesterday in the journal Nature, was conducted in a test tube and does not prove that birds actually use the mechanism. And researchers aligned with a competing model say they are not convinced. But by identifying for the first time a molecule that reacts to very weak magnetic fields, the experiments prove the plausibility of a long-hypothesized method of avian navigation that has had a credibility problem because no one had ever found a molecule with the required sensitivity. "This is a proof of principle that a chemical reaction can act as a magnetic compass," said Peter Hore of the University of Oxford, who with fellow chemist Christiane Timmel led the research. Hore is testing similar molecules, called cryptochromes, isolated from the eyes of migratory birds. Devens Gust, a chemist at Arizona State University who worked with Hore and Timmel, said the molecules "seem to have the right structural and chemical features to allow them to show this effect." © 2008 The Washington Post 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: 11608 - Posted: 06.24.2010

Catherine Brahic Far from being lethargic and lazy creatures, crocodiles will travel hundreds of miles to return home, the first satellite-tracking experiment of the reptile has confirmed. Australian scientists tracked three saltwater crocodiles after moving them between 56 and 126 kilometres away from their home territory. The study confirms that the world's largest reptile has a remarkable homing instinct and will cover great distances in order to get home. It also suggests that airlifting problematic crocs to new areas may be ineffective at keeping them away. Aided by crocodile expert and TV presenter Steve Irwin, who died in September 2006, Craig Franklin of the University of Queensland and colleagues captured the three large male saltwater crocodiles (Crocodylus porosus) from coastal areas between August and September 2004. After fitting each with a satellite tracking device, the researchers airlifted each of the animals by helicopter to a new stretch of coastline either 56 km, 99 km or 126 km away. All three animals behaved in roughly the same way. After a few weeks of exploring their new habitats, each set off home, travelling around the coast back to their point of departure, taking between 5 and 20 days to get home. © 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: 10780 - Posted: 06.24.2010

By John Bohannon Take a pigeon hundreds of kilometers from its home, and it has no problem finding its way back. For years, scientists have suspected that the bird's stellar navigation has to do with its ability to read Earth's magnetic fields. Now, thanks to a geomagnetic anomaly in New Zealand, researchers have the strongest evidence yet that this is indeed the case. Until now, support for a pigeon's internal compass has been mostly anecdotal. The birds tend to fly in erratic patterns during electrical storms, for example. The first hard evidence for the geomagnetic theory came from a study showing that pigeons could detect a magnetic field in a wind tunnel (ScienceNOW, 24 November 2004), but that field was many times more intense than Earth's. Also, because the field was either completely on or off, it left the question open of how exactly pigeons might use subtle magnetic differences in the wild to correct their trajectories. Taking a more natural approach, a team led by Todd Dennis, a behavioral ecologist at the University of Auckland in New Zealand, released pigeons close to a place called the Auckland Junction Magnetic Anomaly. Here, a cluster of massive rock slabs deep below the surface causes a detectable spike in the geomagnetic field. Dennis reasoned that if the pigeons were released here, they would reveal how they were using geomagnetic information as they struggled to get clear of the anomaly. To keep track of their trajectories, the researchers strapped global positioning system (GPS) devices to the birds' backs. © 2007 American Association for the Advancement of Science

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: 9974 - Posted: 06.24.2010

Michael Hopkin It's official: homing pigeons really can sense Earth's magnetic field. An investigation of their ability to detect different magnetic fields shows that their impressive navigation skills almost certainly relies on tiny magnetic particles in their beaks. The discovery seems to settle the question of how pigeons (Columba livia) have such an impressive 'nose for north'. Some experts had previously suggested that the birds rely on different odour cues in the atmosphere to work out where they are. But the latest findings suggest that they are using magnetic cues. The idea that pigeons' beaks contain tiny particles of an iron oxide called magnetite is not a new one, says Cordula Mora, who led the latest study at the University of Auckland, New Zealand. But the particles themselves are likely to be only a few micrometres across, and no one has ever seen them under the microscope. Mora's behavioural experiments therefore give the best indication yet that pigeons are aware of Earth's magnetic field. She and her colleagues taught the pigeons to discriminate between magnetic fields by placing them in a wooden tunnel with a feeder platform at either end and coils of wire around the outside. ©2004 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: 6482 - Posted: 06.24.2010

Most animals sniff, listen, and look to learn about the world around them. But weakly electric fish probe their environment using pulses or waves of electricity. Now, scientists have shown that the fish's electric sense is sharper than they'd realized: The fish can judge the shape and orientation of objects using electricity alone. Electric fish get their picture by generating an electric field and checking to see how it gets distorted. Objects that conduct electricity, such as other fish, warp the field differently than, say, rocks do. Scientists think the extra sense aids these stream-dwelling natives of Africa and South America in their nocturnal foraging. Previous work suggested that the fish can use touch and their electric sense to identify shapes. Now, a team of biologists and neuroscientists has shown that electricity alone is enough to size things up. In the 4 May issue of Current Biology, the researchers, led by Christian Graff of the Laboratoire de Biologie du Comportement in Grenoble, France, describe how they put the fish's electric sense to the test. The team trained six fish--three each of two species--to recognize virtual objects created by the interaction of the fish's electric field with electrodes in an aquarium maze. Depending on the pattern of connected electrodes, the fish would detect different arrangements of bars or planes oriented horizontally or vertically. Copyright © 2004 by the American Association for the Advancement of Science.

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: 5419 - Posted: 06.24.2010

Tim Radford, science editor, The Guardian Migrating songbirds check their direction each night before take-off - by taking a bearing on the setting sun. Many migrating creatures - honeybees, certain fish, many birds, and even monarch butterflies - possess built-in compasses to follow the lines of the Earth's magnetic field, and today in the journal Science ornithologists report on how they tried to mislead thrushes by exposing them to magnetic fields distorted towards the east. It seemed to work. Released after dark, the birds flew west instead of north to their summer breeding grounds. They were fitted with radio transmitters, and the German and American ornithologists followed them by car for up to 1,100km (680 miles). However, once free to decide where they were, the birds noted the direction of twilight and corrected their flight northward. The conclusion: thrushes steer by compasses at night, and update them from the setting sun every 24 hours. Guardian Unlimited © Guardian Newspapers Limited 2004

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: 5300 - Posted: 06.24.2010

NewScientist.com news service The blind mole rat continually monitors its direction using the Earth's magnetic field when it makes long underground journeys, new research has revealed. It is first animal discovered to have this talent. Blind mole rats have no eyes and spend most of their time burrowing in subterranean tunnels. They often have to make long journeys from their nests to find food and yet are able to find their way efficiently through complex mazes of tunnels. They use signals such as smell and balance to check their direction and progress over short distances. But scientists have now discovered that on longer routes they combine this information with constant reference checks of the Earth's magnetic field. © 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: 4830 - Posted: 06.24.2010

Insect uses moon as nocturnal compass Keay Davidson, Chronicle Science Writer The moon is a quarter of a million miles away, and it may seem irrelevant to the evolution of life on Earth. It isn't totally irrelevant, though: Many a dung beetle owes its survival to the baleful rays of the moon. Without those rays, new research shows, the dung beetle couldn't find its way through nocturnal, predator-haunted terrain. True, you may not care what happens to dung beetles. They are among the more embarrassing members of the insect world, given their taste for, well, excrement; it's a prime source of nutrition for them. Upon finding fecal matter, they roll it into nutritious clumps, which they laboriously push to a safe place. ©2003 San Francisco Chronicle

Related chapters from BP7e: Chapter 1: Biological Psychology: Scope and Outlook
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Link ID: 4003 - Posted: 06.24.2010

First evidence of animal creating markers to navigate. HANNAH HOAG Wood mice fashion portable signposts from bright leaves and shells when they explore fields for food, a new study suggests1. This is the first time that animals other than humans have been found to use moveable landmarks. "No one thought that mice would be clever enough to use tools for navigation," says biologist Pavel Stopka of Charles University in Prague, the Czech Republic. Wood mice live in large fields that often lack features that they might use to locate nests, food sources or danger zones. So the animals build bundles of leaves and twigs as they explore, report Stopka and his colleague, David Macdonald of the University of Oxford, UK. © Nature News Service / Macmillan Magazines Ltd 2003

Related chapters from BP7e: Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 15: Language and Our Divided Brain
Link ID: 3764 - Posted: 06.24.2010

NewScientist.com news service Seafaring turtles may use smell to navigate during the epic ocean voyages they undertake to reach their breeding grounds, suggests a new satellite-tracking study. Green turtles swim over 2200 kilometres from foraging grounds in Brazil to nest on Ascension Island, which sits in the middle of the Atlantic Ocean. How they find their way has puzzled scientists since Darwin. Now Graeme Hays, at the University of Wales Swansea, and colleagues have shown that sniffing the air is at least part of the answer. The researchers abandoned turtles in the sea 50 kilometres from the island and found that those left downwind returned much more quickly. © Copyright Reed Business Information Ltd.

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: 3723 - Posted: 06.24.2010

By CATHERINE CLABBY, Staff Writer What do you get when you kidnap lobsters from their home waters, blindfold them and test whether they find their way back? Big news. Animals with brains the size of peas can navigate in places they've never been. Science long assumed that only a handful of creatures, mostly migrating birds, had smarts enough to pull that off. © Copyright 2003, The News & Observer Publishing 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: 3248 - Posted: 06.24.2010

Blacksburg, Va. -- Songbirds use multiple sources of directional cues to guide their seasonal migrations, including the Sun, star patterns, the earth's magnetic field, and sky polarized light patterns. To avoid navigational errors as cue availability changes with time of day and weather conditions, these "compass" systems must be calibrated to a common reference. Experiments over the last 30 years have failed to resolve the fundamental question of how migratory birds integrate multiple sources of directional information into a coherent navigational system. Last autumn, Rachel Muheim, a postdoctoral associate in biology professor John Phillips' lab at Virginia Tech, captured Savannah sparrows in the Yukon before they headed south. She was able to demonstrate that the birds calibrate their magnetic compass based on polarized light patterns at sunset and sunrise. The research appears in the Aug. 11, 2006, issue of Science, in the article, "Polarized Light Cues Underlie Compass Calibration in Migratory Songbirds," by Muheim, Phillips, and Suzanne Akesson. Muheim did her Ph.D. work at Lund University in Sweden with Akesson, who made the Alaska trip possible. Polarized light is light that oscillates in one plane relative to the direction of propagation. At sunrise and sunset, there is a band of intense polarized light 90 degrees from the sun that passes directly overhead through the zenith and intersects the horizon 90 degrees to the right and left of the sun. Just as the sun location changes with latitude and the time of year, so does the alignment of the band of polarized light.

Related chapters from BP7e: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 9232 - Posted: 08.12.2006

By TINA KELLEY Who knew there was a noise for this? And not just one noise, but a billionfold chirping, all night long, all spring, all fall, barely audible but as elemental as the grinding of the Earth on its axis. Jeff Wells, an avian ecologist, shared the tiny calls, slightly amplified, at a Nocturnal Bird Migration Concert Friday night at the Prospect Park Audubon Center. A simple high-powered microphone was set up on the center's roof, connected to Dr. Wells' computer, which displayed pictures of birds that migrate through the city at this time of year. He also showed spectrograms, or pictures of their calls as ascending or descending black zigzag ribbons, the audible thumbprint of each species. "I want to let you in on this great secret, a great mystery only a tiny, tiny number of people in the world ever know about," he told a group of about 25 people, his voice hypnotic in its wonderment. "They're all up there in the air, migrating while we sleep, on high highways of wind," said Dr. Wells, the senior scientist at the Boreal Songbird Initiative, a conservation group that tries to protect the endangered boreal, or northern, forest that stretches from Alaska to Newfoundland and is the summer home of three to five billion birds. Copyright 2006 The New York Times Company

Related chapters from BP7e: Chapter 14: Biological Rhythms, Sleep, and Dreaming
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Link ID: 8945 - Posted: 05.22.2006

The epic journeys taken by dragonflies searching for warmer climates have been revealed by scientists in the US. The team, led by researchers from Princeton University, found that the insects are capable of flying up to 85 miles (137 km) in a day. Writing in the journal Biology Letters, the group describes how it tracked the movements by attaching tiny radio transmitters to the insects. A scientific posse followed the signals from a receiving aeroplane. Other researchers monitored the insects' progress from the ground. The dragonflies' route took them along the east coast of America towards the warmer south. The data revealed that the dragonflies' migration patterns are strikingly similar to those of songbirds, suggesting there is a strong evolutionary link to their behaviours. "Insects have been around far longer than birds, therefore we suspect that they have been migrating far longer than birds," said Professor David Wilcove of Princeton University and one of the authors of the paper. "It is just possible what we are seeing here are the basic primitive rules of migration and that birds converged on the tricks of the trade," he told Science In Action on the BBC World Service. Billions of common green darner dragonflies (Anax junius) migrate every year but until now hardly anything was known about their routes or strategy. (C)BBC

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: 8908 - Posted: 05.11.2006

By experimentally relocating migratory white-crowned sparrows (Zonotrichia leucophrys gambelii) from their breeding area in the Canadian Northwest Territories to regions at and around the magnetic North Pole, researchers have gained new insight into how birds navigate in the high Arctic. In particular, the findings aid our understanding of how birds might determine longitudinal information--a challenging task, especially at the earth's poles. The work is reported in Current Biology by Susanne Åkesson and colleagues at Lund University in Sweden. Migratory birds navigating over long distances can determine their latitude on the basis of geomagnetic and celestial information, but longitudinal position is much more difficult to determine. In the new work, researchers investigated whether birds can define their longitude after physical displacements in the high Arctic, where the geomagnetic field lines are steep and the midnight sun makes star navigation impossible for much of the summer. White-crowned sparrows are nocturnally migrating birds that breed in northern Canada and perform long migrations covering a few thousand kilometers to winter in the southern United States. In the study, young and adult white-crowned sparrows were captured with mistnets near Inuvik, NW Territories, Canada, during mid-July to mid-August--the end of the breeding period and shortly before migration--and transported by a Canadian icebreaker along a northeasterly route to nine sites on the tundra, among them the magnetic North Pole (located on Ellef Ringnes Island). The researchers then recorded the birds' directional orientation in cage experiments.

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: 7857 - Posted: 09.07.2005