Links for Keyword: Animal Migration

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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
Related chapters from MM:Chapter 10: Biological Rhythms and Sleep
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 Ċkesson 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

It has been known for some time that many species of birds use the Earth's magnetic field to select a direction of movement--for example, during migration. However, although such birds clearly have a sense of direction, until now it has not been possible to train birds to move in a certain direction in the laboratory, even if they are motivated by a food reward. The reasons for this failure have been perplexing, but researchers now report that they have been able to successfully accomplish this training task, providing new insight into the evolution of magnetic sensing and opening new opportunities for further study of magnetoreception. In the new work, researchers including Rafael Freire from the University of New England (Australia), Wolfgang Wiltschko and Roswitha Wiltschko from the University of Frankfurt, Germany, and Ursula Munro from the University of Technology in Sydney, demonstrated for the first time that birds could be trained to respond to a magnetic direction. The researchers trained domestic chicks to find an object that was associated with imprinting and was behind one of four screens placed in the corners of a square apparatus, and, crucially, showed that the chicks' direction of movement during searching for the hidden imprinting stimulus was influenced by shifting the magnetic field. One important difference between this work and earlier attempts to train birds is that the researchers used a social stimulus to train the birds, whereas most previous attempts have used food as the reward. The authors of the study hypothesize that in nature, birds do not use magnetic signals to find food, and tests involving such a response may be alien to them.

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: 7781 - Posted: 08.23.2005

Jerusalem -- While "navigation" systems in automobiles are a fairly new (and still costly) innovation, monarch butterflies have managed for millennia to navigate their way for a distance of some 3000 miles (4800 kilometers) each fall from Canada to Mexico (and vice-versa in the spring) without losing their way. The phenomenon of long-range bird migration is a well-known one, but not in the insect world. Also, among birds their migration route is a round-trip one, which they make more than once in their lifetimes, while for the monarch it is strictly a one-way trip for each butterfly. How do these creatures do it? The mystery of the mechanisms involved in this remarkable phenomenon has been resolved by a team of scientists who did this by exploring the infinitesimal butterfly brain and eye tissues to uncover new insights into the biological machinery that directs this delicate creature on its lengthy flight path. The research team, led by Prof. Steven Reppert of the University of Massachusetts Medical School, included Dr. Oren Froy, now of the Faculty of Agricultural, Food and Environmental Quality Sciences of the Hebrew University of Jerusalem. Others involved were from the Czech Academy of Sciences and the University of California, Irvine. Their latest findings were published in a recent issue of Neuron magazine, constituting a continuation of their earlier work, published in the journal Science.

Related chapters from BP7e: Chapter 10: Vision: From Eye to Brain; Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 7: Vision: From Eye to Brain; Chapter 10: Biological Rhythms and Sleep
Link ID: 7723 - Posted: 08.02.2005

How did University of Alberta researchers discover that animals zig when they were only supposed to zag? A little birdie told them. In studying the spatial memory of wild-caught mountain chickadees, University of Alberta researchers were surprised to discover the birds contradicting prior research that showed how animals navigate. This study is the first to reveal a different pattern. Previously, only animals that had been raised in human-made enclosures had been tested. The findings are published in the July issue of Biology Letters. To get their bearings, humans and other animals are often guided by the geometrical shape of their environment. For example, humans have an easy time distinguishing the door located at the ends of a hallway from those located in the middle, but may confuse doors at the two ends, such as when they re-enter a hallway in a hotel. "This has been observed in every species tested, even when landmarks alone could be used, suggesting that animals are predisposed to go by geometry," said co-author Dr. Chris Sturdy, a professor of psychology and member of the Centre for Neuroscience at the University of Alberta.

Related chapters from BP7e: Chapter 1: Biological Psychology: Scope and Outlook
Related chapters from MM:Chapter 1: An Introduction to Brain and Behavior
Link ID: 7692 - Posted: 07.27.2005

By Dr David Whitehouse Increased solar activity causing disturbances in the Earth's magnetic field may cause whales to run aground in the North Sea, say researchers. Analysis of whales stranded between 1712 and 2003 shows that more are stranded when solar activity is high. Writing in the Journal of Sea Research, scientists propose that whales use the Earth's magnetic field to assist navigation like homing pigeons do. As the Sun disrupts the magnetic field whales can become confused, they say. The Sun goes through a cycle with an average length of about 11 years, though individual cycle lengths have ranged from 8 to 17 years. Some evidence exists that shorter cycles produce a higher flux of radiation from the Sun. Dr Klaus Vaneslow and colleagues from the University of Kiel have analysed the lengths of solar cycles and find that 87 of the 97 reported sperm whale strandings over the past 300 years in the North Sea region occurred when the length of the Sun's activity cycle was below average. They argue that whales may be like pigeons and dolphins in having a magnetic sense based on small crystals of magnetite found in certain cells. Pigeons use such cells to sense the Earth's magnetic field to help in their navigation. Pigeon enthusiasts are well aware that the birds can go astray during times of high solar activity, when disturbances in the magnetic field confuse them. (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: 7347 - Posted: 05.13.2005

In their extraordinary annual migration from North America to Mexico, monarch butterflies are known to use the angle of polarized sunlight as a celestial guide to help them keep to a straight and true path southward. But details of their navigational machinery have remained a mystery. Now, researchers, led by Steven Reppert of University of Massachusetts Medical School, Ivo Sauman of the Czech Academy of Sciences and Adriana Briscoe of the University of California at Irvine, have explored the infinitesimal butterfly brain to uncover new insights into that machinery. Their findings show that the same ultraviolet light that has become an anathema to cancer-wary humans is critical for butterfly navigation. Also, the researchers were surprised to discover a key wiring connection between the light-detecting navigation sensors in the butterfly's eye and the creature's circadian clock--a critical link if the butterflies are to compensate for the time of day in using their "sun compass." The researchers' techniques include molecular analysis of butterfly brain proteins, as well as flight tests in which the scientists manipulated the light reaching their insect subjects and measured the navigational response. In their studies, the researchers discovered that ultraviolet photoreceptors dominated in the region of the butterfly visual system known to specialize in polarized light detection.

Related chapters from BP7e: Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 7306 - Posted: 05.05.2005

Butterflies do not flutter aimlessly around the garden but instead follow precise flightpaths, scientists say. A UK team of researchers made the discovery by tracking the insects with radar, using tiny transponders attached to the backs of butterflies. This gave them information on the insects' flightpaths, speeds and foraging behaviour - some of which could guide conservation measures. Details of the research appear in Proceedings of the Royal Society B. "We've never been able to see their flight tracks up to 1km before and it's showing us that they do seem to be quite directive in the way they're flying," said co-author Lizzie Cant of Rothamsted Research in Harpenden, UK. The scientists tagged peacock (Inachis io) and small tortoiseshell (Aglais urticae) butterflies with transponders weighing just 12mg. After checking that the devices did not affect their behaviour, the researchers released 33 insects into a 500x400 sq m field being scanned by radar on the Rothamsted estate. This allowed them to track an individual butterfly at a range of up to about 1km. They successfully recorded the movements of 30 of the insects they released. (C)BBC

Related chapters from BP7e: Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 7167 - Posted: 04.10.2005

A study led by Princeton biologists has revealed a remarkably simple mechanism that allows flocking birds, schooling fish or running herds to travel in unison without any recognized leaders or signaling system. The finding, published in the Feb. 3 issue of Nature, helps settle age-old questions about how animals coordinate their actions. Previously, scientists had looked for subtle signals or other explicit systems that animals may use in disseminating information through groups. The new study showed that such complexity is not necessary: Large groups easily make accurate decisions about where to go even when no individuals are regarded as leaders and very few individuals have any pertinent information. In addition to shedding light on the graceful coordination of animal groups, the results may be useful in understanding how humans behave in crowds and in designing robots that explore remote locations such as the ocean or other planets. "When you see apparently complex behaviors, the mechanisms that coordinate these behaviors may be surprisingly simple and generic," said Iain Couzin, a postdoctoral researcher in Princeton's Department of Ecology and Evolutionary Biology and lead author of the study.

Related chapters from BP7e: Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 15: Language and Our Divided Brain
Link ID: 6808 - Posted: 02.04.2005

By HENRY FOUNTAIN Homing pigeons are renowned for their ability to navigate over long distances, and after decades of study scientists are pretty sure they know how the birds do it. They use their sense of smell to figure out where they are and the position of the sun to determine the direction they must fly. But less is known about how pigeons navigate when they are close to home, in more familiar surroundings. Many researchers have thought that in such situations the birds must rely, at least partly, on visual cues. "There's been controversy about whether familiar landmarks have been used," said Jessica Meade, a doctoral student in the Animal Behavior Research Group at the University of Oxford in England. "Because there was no tracking of the birds along the homeward route, the hypotheses aren't very clear." Ms. Meade and two colleagues, Dr. Dora Biro and Dr. Tim Guilford, set out to rectify that situation, using small Global Positioning System loggers attached to the backs of 15 homing pigeons. These devices, which weigh about an ounce, use satellite signals to record precise location fixes every second. The researchers released the birds about three miles from home, and each bird had about 20 flights from the same point. The results are published in Proceedings B, a journal of the Royal Society. Copyright 2005 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: 6713 - Posted: 01.18.2005

Using satellite tracking to study the paths pigeons take on homeward-bound journeys, researchers have obtained strong new evidence to support a long-held theory: in some environments, pigeons instinctively learn to follow major roadways in navigating their flight. The new findings are reported by a research group headed by Dr. Hans-Peter Lipp of the University of Zürich. Anecdotal evidence from breeders of racing pigeons as well as initial aerial tracking studies together suggested that pigeons may follow roadways and use highway landmarks as turning points in their flight. However, the challenge of accurately tracking the birds stood in the way of solid quantitative analysis. In the new work, miniaturized GPS "flight-loggers," which pigeons carried on their backs, allowed researchers a clear and reliable picture of the birds' flight paths. Over three years, the researchers analyzed more than 200 flight paths of 20-80 km in length made by pigeons travelling toward their home loft from numerous release sites located in the general vicinity of Rome, Italy. They found that, when released from familiar sites, pigeons with homing experience were significantly attracted to highways and a railway track running in the approximate directions home. When these structures began to veer significantly from the beeline to the loft, some birds tended to break away and head in a more homeward direction, but others took a detour by following the highway until a main junction, at which point they followed a valley road in the direction of the loft.

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 13: Memory, Learning, and Development
Link ID: 5888 - Posted: 07.27.2004

As dusk settles across the Belfast skyline, Joe Neeson whistles and calls down his racing pigeons. Joe doesn't count - he doesn't need to. After years looking after his tiny loft in the yard behind his west Belfast home, he knows every bird by name. So when Joe scanned the roof above the loft on the day of Linda's first race, he knew there was a bird missing. The young pigeon had been released more than 300 miles away in Penzance. And as darkness fell, Joe knew that Linda was not coming home. Seven hundred miles away across the North Sea, Linda was beginning what would be a year-long adventure. No-one knows for sure how Linda arrived at the petrol refinery at Mongstad - one of Europe's biggest ports. It seems likely though that the exhausted pigeon "jumped ship" in the fading light as she flew across the North Sea. Refinery workers found her cowering under clothes lockers and took pity on the bird which seemed close to death. A Norwegian television crew was at the refinery to record a wildlife film, and journalist Hans Gunnar Skarstein realised that the band on the pigeon's leg held the key to her identity. (C)BBC

Related chapters from BP7e: Chapter 1: Biological Psychology: Scope and Outlook
Related chapters from MM:Chapter 1: An Introduction to Brain and Behavior
Link ID: 5856 - Posted: 07.21.2004

Nature article reports photoreceptors involved in sensing the earth's magnetic field Migratory birds, as well as many other animals, are able to sense the magnetic field of the earth, but how do they do it? "A fascinating possibility is that they may actually see the earth's magnetic lines as patterns of color or light intensity superimposed on their visual surroundings," said John B. Phillips of Blacksburg, associate professor of biology at Virginia Tech. The results of more than two decades of research allow him to let such an image cross his mind. A paper in the May 13 issue of Nature, "Resonance effects indicate a radical-pair mechanism for avian magnetic compass," reports evidence that the earth's magnetic field is sensed by light-absorbing molecules in the retina of a bird's' eye. Any effect of the earth's magnetic field on a photoreceptor's response to light is expected to be extraordinarily weak -- so weak in fact that the possibility of such effects have been largely ignored. But animals have developed specialized visual systems. "Some animals can see ultraviolet light. Some animals can see polarized light," Phillips said.

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: 5470 - Posted: 05.14.2004

Homing pigeons are finding their way around Britain by following roads and railways, zoologists claim. They say the birds' natural magnetic and solar compasses are often less important than their knowledge of human transport routes. A 10-year Oxford University study discovered some pigeons turn off at certain motorway junctions and use landmarks to remember where they are. The scientists behind the study were "knocked sideways" by their findings. The pigeons' routes were mapped to within four yards by tiny tracking devices and global positioning system technology. Research team member Dr Tim Guilford said the results were "plain to see". "They don't follow linear lines all the time and sometimes when they're flying at 200 or 300ft above built-up areas it's difficult to see exactly what they are following. (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: 4935 - Posted: 02.08.2004

Fears are growing for the safety of a rare bird of prey which got lost at sea while making a record migration from Scotland to Africa. The young honey buzzard, which only learned to fly a month ago, went off course after it was caught in difficult weather conditions over the Atlantic. A satellite tracking system estimates that it has made the longest flight ever recorded by a bird of prey and was in the air for more than 100 hours during a journey in excess of 5,000 kilometres. However, concern about the fate of the bird is growing among conservationists and enthusiasts who have been following its progress over the internet. Two honey buzzards were being tracked as part of an attempt to learn the mysteries of their migration south. The Forestry Commission and the Highland Foundation for Wildlife teamed up to follow their journey. (C) BBC

Related chapters from BP7e: Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 2745 - Posted: 10.01.2002

Philippine researchers want to restore a sea snake that has been wiped out on Gato Island by translocating the species from other islands. But new research suggests that this may not work because these snakes have such a strong drive to return to their own islands. "The fidelity of snakes to their home island was absolute," say Sohan Shetty, then at the University of Sydney, Australia, and now at Nanyang Technological University in Singapore, and Richard Shine of the University of Sydney, Australia, in the October issue of Conservation Biology. Widely distributed in the Pacific Ocean, the snakes (yellow-lipped sea kraits) forage for moray and conger eels in the ocean, and typically return to land to digest their prey, mate, lay eggs. The up to 5-foot long snakes are prized for their meat and skins, which are used to make high-quality leather goods, and are easy to catch in huge numbers because they are concentrated on small islands and, although venomous, are so docile that they rarely bite or even try to escape.

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: 2704 - Posted: 09.25.2002

By NATALIE ANGIER Midway through a honeybee's fleeting, bittersweet, and, yes, busy little life, a momentous transformation occurs: the 2-week-old worker must abandon her cloistered career as a hive-keeping nurse, and venture out into the world to forage. She must learn to navigate over great distances at 12 miles per hour, select the finest flowers, assemble bits of pollen and droplets of nectar into a load nearly as heavy as she is, and then find her way back home. Once there, she must convey the coordinates of her discovery to her sisters in the classic cartographic waggle, the bee dance. And all this behavioral complexity is packaged in a brain no bigger than the loop of a letter b printed on this page. Copyright 2002 The New York Times Company

Related chapters from BP7e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 2020 - Posted: 05.07.2002

Emma Young Migrating birds use changing magnetic fields to tell them when to stop and eat, say Swedish researchers. The team exposed eight caged thrush nightingales to a magnetic field simulating a six-day journey from Sweden to northern Egypt, where wild birds stock up on food prior to crossing the Sahara desert. For a further five days, the birds were kept in "magnetic Egypt". Eight control birds were caged in a lab free from artificial magnetic fields. Both sets of birds had free access to food. Thord Fransson of Stockholm University and his colleagues found the experimental birds increased their eating between days six and 11. Journal reference: Nature (vol 414, p 35) © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 906 - Posted: 11.02.2001