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Want to monitor climate change? P-p-p-pick up a penguin!

We are used to hearing about the effects of climate change in terms of unusual animal behaviour, such as altering patterns of fish and bird migration. However, scientists at the University of Birmingham are trying out an alternative bio-indicator — the king penguin — to investigate whether they can be used to monitor the effects of climate change. “If penguins are travelling further or diving deeper for food, that tells us something about the availability of particular fish in regions of the Antarctic. We may be able to assess the pressure exerted by king penguins on this ecosystem, and look at the effects of both climate change and overfishing in this region of the world”, says Dr Lewis Halsey who will present his results on Wednesday 4th April at the Society for Experimental Biology’s Annual Meeting in Glasgow.

A new way of using animals as bio-indicators is to ascertain their energy requirements. Dr Halsey and co-workers measured the heart rate and energy expenditure of king penguins whilst walking on a treadmill and whilst swimming in a long water channel, and obtained relationships between these two variables. They then implanted heart rate loggers in penguins going to sea such that they could infer the energy expended by these birds from the recorded heart rate. Researchers were then able to find out if there was a correlation between the energetic costs of foraging at sea and the levels of fish available to the penguins i.e. did penguins have to work harder when food was scarce. King penguins are good candidates as bio-indicators for several reasons. Firstly, while at sea foraging, they cover hundreds of kilometres and are able to dive to depths of several hundred metres, so they explore a relatively large portion of the expansive Southern Oceans. Secondly, the diets of several populations of king penguins are well known. Thirdly, while foraging for food is done at sea the penguins also come ashore to breed and moult, making them accessible to researchers.

Science Daily
April 17, 2007

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In zebra finches males express higher levels of sex-chromosome genes than females do

Sexual inequality is alive and kicking in the bird world. A new study reveals that, unlike humans, birds do little to compensate when one gender gets more of a particular sex chromosome than another. As a result, male birds express sex-linked genes at up to 40% higher levels than females–an imbalance biologists had assumed would be lethal. Human males get short-changed when it comes to X chromosomes. Stuck with an X and a Y, they inherit half as much X DNA as their XX female counterparts. To even things out, Mother Nature shuts off one X chromosome in each female cell–a phenomenon known as dosage compensation. Other animals, such as flies and nematodes, adopt similar strategies. Previous studies have indicated that birds–where males double up on the “Z” sex chromosome and females are “ZW”–may not follow suit. But the results have been inconsistent.

Now a team of researchers at the University of California, Los Angeles, may have settled the debate–and quite by accident. Physiological scientist Arthur Arnold and colleagues were probing the genetic basis of brain differences between songbird genders when they came upon a puzzling finding: Z-linked genes seemed to be expressed at much higher levels in males than in females. So Arnold’s team dug deeper. The researchers compared the expression of sex chromosome genes in zebra finches, chickens, mice, and humans using gene chips called microarrays. As expected, mammals showed little gender differences in the expression of X-chromosome genes. In contrast, males of both bird species expressed Z-chromosome genes at levels that were up to 40% higher than those in females, the team reports today in the Journal of Biology. Still, some Z genes showed little difference between males and females, notes Arnold, indicating that birds do employ a mild form of dosage compensation. But it’s likely a selective process that only affects “the Z genes that would cause big problems,” he says.

Biologist James Birchler of the University of Missouri, Columbia, says that the findings are surprising because the Z chromosome comprises about 7% to 10% of the avian genome. “One might think that such a large number of uncompensated genes would be detrimental.” Clearly, in birds, it’s not. And because the ZW system of chromosomes evolved before the XY, he notes, the study may provide important clues to the evolution of dosage compensation.

ScienceNow
April 3, 2007

Original web page at ScienceNow

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The nuthatch picks up on subtle cues in the chickadee’s alarm call

When trying to stay safe from enemies, it helps to eavesdrop on your neighbors. Like many birds, the red-breasted nuthatch will mob a potential predator when birds of another species sound an alarm call–a tactic that benefits all avians on the scene. New research reveals that nuthatches are especially astute eavesdroppers: They can tell which type of predator is in the neighborhood by sussing out subtle cues in the chickadees’ warning calls. The findings suggest there’s a wealth of information that animals can glean about their environments from the calls of other species. Black-capped chickadees (Poecile atricapillus) have one of the most sophisticated avian alarm call systems known. When a predator approaches, the birds make their familiar “chick-a-dee-dee-dee” call. The number of “dees” corresponds to the size and relative threat of the predator. Fewer “dees” connotes a lesser threat, says Christopher Templeton, a biology doctoral student at the University of Washington, Seattle, who–with colleagues–cracked the chickadee code in a recent study.

To find out whether other birds could also decrypt the calls, Templeton and fellow biologist Erick Greene of the University of Montana in Missoula took a look at the red-breasted nuthatch (Sitta Canadensis), a common chickadee neighbor. The researchers placed a speaker at the base of trees within known territories of nuthatch pairs, but where no chickadees were present. They then observed nuthatch behavior as they played chickadee alarm calls for the small, agile pygmy owl (5 “dee” notes) and the larger, less-maneuverable great horned owls (2 “dee” notes). Trials with 20 nuthatch pairs showed the nuthatches were roughly twice as likely to exhibit vigorous mobbing behavior–flying close to the speaker, flicking their wings in apparent agitation, and making their own alarm calls–when they heard the alarm for the pygmy owl versus that for the great horned one. It doesn’t pay for the nuthatches to waste precious energy if the threat is relatively low, says Templeton, whose team reports its findings online this week in Proceedings of the National Academy of Sciences. The research is a “good demonstration of how birds living closely together get to know one another’s language,” says biologist David Winkler of Cornell University. Such inter-species comprehension of alarm calls is mutually beneficial, and there are likely “lots of social birds to which this result would apply,” he adds.

ScienceNow
April 3, 2007

Original web page at ScienceNow

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Scientists reconstruct migration of avian flu virus

UC Irvine researchers have combined genetic and geographic data of the H5N1 avian flu virus to reconstruct its history over the past decade. They found that multiple strains of the virus originated in the Chinese province of Guangdong, and they identified many of the migration routes through which the strains spread regionally and internationally. By knowing where H5N1 strains develop and migrate, health officials can better limit the spread of the virus by strategically intervening. Local vaccinations can be better administered by using strains from regions that have repeatedly contributed to infections. “If you can control the virus at its source, you can control it more efficiently,” said Walter Fitch, professor of ecology and evolutionary biology in the School of Biological Sciences at UCI and co-author of the study. “With a road map of where the strain has migrated, you’re more likely to isolate the strain that you should be using to make the vaccine.” The study appeared in the online early edition of the Proceedings of the National Academy of Sciences.

This research offers the first statistical analysis detailing the geographic distribution of influenza A H5N1, the bird flu strain. While previous work informally identified H5N1 strains by location, the UCI analysis is the first to systematically track the migration of H5N1 through its evolutionary history, adding new details that identify the relative importance of the geographic and evolutionary advances the virus makes. From 192 samples obtained across Eurasia, the UCI team reconstructed the virus’s geographic reach and evolution. The analysis shows that Guangdong — home to a large poultry industry — is the source of many H5N1 strains that have spread to other provinces and countries. To the south in nearby Indochina, the strains appear largely limited to dispersal among local areas.

Genetic sequences the scientists analyzed suggest that parallel evolution of different H5N1 strains lets the virus infect and cycle through different host species in a region, regardless of the host or vector species it infects first. This way, the virus can find the right host to spread the infection to the next location. This parallel evolution — the independent evolution of similar traits — enables H5N1 to spread quickly, the scientists believe. “The ability to develop the right mutation allows the virus to hop from one host type to the next,” said Robert Wallace, UCI postdoctoral researcher and lead author of the study. “By spreading across a large area, the virus in essence can run multiple experiments in multiple locations, increasing the likelihood that it will mutate into a form that can be transmitted from human to human.”

Avian flu has been isolated almost exclusively among bird populations. The H5N1 virus has only sporadically been passed on from a bird host to humans; there is little evidence that the virus can efficiently be passed on from human to human. Although fewer than 300 recorded human cases of this flu have been recorded worldwide, its high mortality rate raises concerns that if the virus mutates to where humans can pass it on, a flu pandemic may occur.

Science Daily
March 20, 2007

Original web page at Science Daily

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Birds found to plan for the future

Planning and worrying about the future has always been considered an exclusively human activity, but now at least one species of bird has also been found to plan for tomorrow. The finding also raises the intriguing possibility that, like humans, birds may get anxious about the future. Research published in the journal Nature shows that western scrub-jays are able to plan for future food shortages by caching food. The birds are shown to have learned from their previous experiences of food scarcity, storing food for future use in places where they anticipate future slim pickings. The researchers at the University of Cambridge believe this is the first known example of future planning in animals.

On alternate mornings eight jays were given breakfast in one compartment or refused breakfast in another, before being allowed free access to food the rest of the day. On the sixth day of the experiment they were suddenly given whole pine nuts suitable for caching in the evening. The researchers observed that the jays consistently cached most pine nuts in the tray in the ‘no breakfast’ compartment, anticipating that they would not be fed in the following morning in that compartment. Another experiment showed that the birds were able to plan ahead to provide themselves with a more varied diet. The jays were consistently given a breakfast of peanuts in one compartment and dog kibble in the other. When the birds in the evening were offered both foods, they preferred to cache peanuts in the kibble compartment and vice versa – to make sure they had an interesting breakfast the following morning.

“The jays spontaneously plan for tomorrow, without being motivated by their current needs”, said Nicola Clayton, Professor of Comparative Cognition at the University of Cambridge. “People have assumed that animals only have a concept of the present, but these findings show that jays also have some understanding of future events and can plan for future eventualities. The western scrub-jays demonstrate behaviour that shows they are concerned both about guarding against food shortages and maximising the variety of their diets. It suggests they have advanced and complex thought processes as they have a sophisticated concept of past, present and future and factor this into their planning.” Previous research by Clayton’s team has shown that scrub-jays have a concept of the past. They remember what they have cached where and how long ago, and they also keep track of which particular bird was watching when they cached so that they can protect their caches accordingly from being stolen by observant thieves.

Science Daily
March 20, 2007

Original web page at Science Daily

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Indian warbler ‘lost’ for 139 years makes spectacular return

Ornithologists across the world are celebrating with the news that a wetland bird that has eluded scientists ever since its discovery in India in 1867 has been refound. The Large-billed Reed-warbler is the world’s least known bird. A single bird was collected in the Sutlej Valley, Himachal Pradesh, India, in 1867, but many had questioned whether it was indeed represented a true species and wasn’t just an aberrant individual of a common species. But on 27 March 2006, ornithologist Philip Round, Assistant Professor in the Department of Biology, Mahidol University, was bird ringing (banding) at a wastewater treatment centre (the royally initiated Laem Phak Bia Environmental Research and Development Project) near Bangkok, Thailand.

“Although reed-warblers are generally drab and look very similar, one of the birds I caught that morning struck me as very odd, something about it didn’t quite add up; it had a long beak and short wings,” said Round. “Then, it dawned on me—I was probably holding a Large-billed Reed-warbler. I was dumbstruck, it felt as if I was holding a living dodo.” “I knew it was essential to get cast-iron proof of its identity. I took many photographs, and carefully collected two feathers for DNA analysis, so as not to harm the bird.” Round contacted Professor Staffan Bensch, from Lund University, Sweden, who had previously examined the Indian specimen and confirmed it did represent a valid species. He examined photographs and DNA of the Thai bird and confirmed the two were the same species. “A priority now is to find out where the Large-billed Reed-warbler’s main population lives, whether it is threatened, and if so, how these threats can be addressed.”

“This rediscovery of the Large-billed Reed-warbler on the shores of Inner Gulf of Thailand (a BirdLife Important Bird Area, IBA) illustrates the importance of wetland habitats and the remarkable biodiversity they are home to,” said Ms Kritsana Kaewplang, BCST Director. “It also demonstrates the contribution of routine monitoring and ringing of migratory birds at even well-known sites.” “This remarkable discovery gives Indian ornithologists an added incentive to continue our search for the Large-billed Reed-warbler in India,” said Dr Asad Rahmani, Director of the Bombay Natural History Society. “Like the discovery of Bugun Liocichla last year in Arunachal Pradesh, it shows us just how much we still have to learn about our remarkable avifauna.”

BirdLife International’s Dr Stuart Butchart, commented: “Almost nothing is known about this mysterious bird. The Indian specimen has short, round wings and we speculated it is resident or short-distance migrant, so its appearance in Thailand is very surprising. A priority now is to find out where the Large-billed Reed-warbler’s main population lives, whether it is threatened, and if so, how these threats can be addressed.” But, in a further twist to this remarkable tale, six months after the rediscovery, another Large-billed Reed-warbler specimen was discovered in the collection of the Natural History Museum at Tring, in a drawer of Blyth’s Reed-warblers (Acrocephalus dumetorum) collected in India during the 19th Century. Once again, Professor Staffan Bensch confirmed the identification using DNA.

“Finding one Large-billed Reed-warbler after 139 years was remarkable, finding a second—right under ornithologists’ noses for that length of time—is nothing short of a miracle,” said Butchart. The second specimen is from a different part of India and is bound to fuel debate as to the whereabouts of more Large-billed Reed-warblers. “Now people are aware Large-billed Reed-warblers are out there, we can expect someone to discover the breeding grounds before long. Myanmar or Bangladesh are strong possibilities, but this species has proved so elusive that it could produce yet another surprise,” said Butchart.

Science Daily
March 20, 2007

Original web page at Science Daily

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‘Mafia’ behavior in cowbirds?

Cowbirds have long been known to lay eggs in the nests of other birds, which then raise the cowbirds’ young as their own. Now, however, a University of Florida study finds that cowbirds actually ransack and destroy the nests of warblers that don’t buy into the ruse and raise their young. Jeff Hoover, an avian ecologist at the Florida Museum of Natural History, is the lead author on the first study to document experimental evidence of this peeper payback — retaliation to encourage acceptance of parasitic eggs. Findings are published online in the Proceedings of the National Academy of Sciences.

“It’s the female cowbirds who are running the mafia racket at our study site,” said Hoover, who has a joint appointment with the Illinois Natural History Survey. “Our study shows many of them returned and ransacked the nest when we removed the parasitic egg.”So-called “brood parasitic birds” lay eggs in the nests of host birds that raise the parasite’s offspring, usually at the expense of some of their own. The brown-headed cowbird parasitizes more than 100 host species, including many Neotropical migratory birds such as warblers, tanagers and vireos. Prothonotary warblers were used for this study because they almost always accept cowbird eggs, Hoover said. Hosts that use their beaks to grasp or puncture parasitic eggs and remove them from the nest are called “ejecters.” “Accepter” hosts raise parasitic eggs.

“Retaliatory mafia behavior in cowbirds makes hosts’ acceptance of cowbird eggs a better proposition than ejection,” Hoover said. “The accepting warblers in our study produced more of their own offspring, on average, than those where we ejected cowbird eggs.” Hosts may lose some, but not all, of their biological offspring by accepting parasitism. The retaliatory behavior of ransacking nests encourages warblers to raise the cowbirds’ offspring. “We wanted to determine if the cowbirds were responsible for nest predation after we removed cowbird eggs from parasitized warbler nests,” Hoover said. To test for this, Hoover collaborated with Scott Robinson, Florida Museum Ordway eminent scholar and natural history chair, to manipulate cowbird access to warbler nests in the Cache River watershed of southern Illinois. The researchers monitored 182 predator-proofed nests over four breeding seasons.

Hoover and Robinson found that warbler nests were ransacked 56 percent of the time when researchers experimentally removed the parasitic eggs and cowbirds were allowed nest access, versus only 6 percent when the cowbird eggs were accepted and cowbirds had nest access. No nests were ransacked when researchers removed cowbird eggs and cowbirds were denied nest access. Together, these results implicate cowbirds and provide evidence of mafia behavior. “We also found evidence for ‘farming’ behavior,” Hoover said. “Cowbirds ‘farm’ a non-parasitized nest by destroying its contents so that the host will build another. The cowbird then syncs its egg laying with the hosts’ ‘renest’ attempt.” Hoover found that warbler nests that were never parasitized but that cowbirds had access to, were ransacked 20 percent of the time. “Cowbirds parasitized 85 percent of the renests, which is strong supporting evidence for both farming and mafia behavior,” he said.

Hoover and Robinson’s results imply that cowbirds actively monitor nests they parasitize — which supports the idea that cowbirds continue to visit nests they have parasitized to see the results of their handiwork. Stephen Rothstein, a zoology professor at the University of California in Santa Barbara, said other studies have shown evidence contrary to mafia and farming behaviors. “Video surveillance would show the proportion of nest predation attributable to cowbirds,” Rothstein said. “The phenomenon may be perfectly true for these warblers, but that doesn’t mean it holds true for other species, especially those that aren’t nesting in special circumstances. Nevertheless, this new study may extend our knowledge of the extent to which parasitic cowbirds may have evolved tactics to facilitate their parasitism.”

Science Daily
March 20, 2007

Original web page at Science Daily

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New research finds people and pigeons see eye to eye

Pigeons and humans use similar visual cues to identify objects, a finding that could have promising implications in the development of novel technologies, according to new research conducted by a University of New Hampshire professor. Brett Gibson, an assistant professor of psychology who studies animal behavior, details his latest research in the journal article, “Non-accidental properties underlie shape recognition in mammalian and non-mammalian vision,” published in Current Biology. Gibson and his colleagues found that humans and pigeons, which have different visual systems, have evolved to use similar techniques and information to recognize objects. “Understanding how avian visual systems solve problems that require considerable computational prowess may lead to future technological advances, such as small visual prosthetics for the visually impaired, in the same way that understanding visual processing in honeybees has led to the development of flying robots and unmanned helicopters,” the researchers say.

So a software engineer who wants to design a program to help a robot recognize objects can get a leg up from evolution, which has been developing “programs” for object recognition in animals long before humans ever thought of doing such things, Gibson says. “To the extent that we can learn how different animals recognize objects and whether they are doing the same things or different things based on their environments may really help us in designing our own system of object recognition.” Gibson and his colleagues from the University of Iowa (Olga Lazareva and Edward Wasserman), the University of Montreal (Frédéric Gosselin), and the University of Glasgow (Philippe Schyns) found that pigeons, like humans, primarily rely on corners (coterminations) of an object in order to recognize it instead of relying on other features such as shading and color.

For example, a person could easily identify a AA battery from the side profile. But, let’s say the person could see the same battery only from the bottom with the negative terminal. From this perspective, the only visible outline would be a circle; from the bottom, the corners of the battery now are not visible and information about the corners cannot be seen. “The task of recognizing the object becomes much more difficult. For most people, it would take them a bit longer to recognize the image as a battery,” Gibson says. The researchers employed a new procedure, which Gosselin and Schyns developed, called Bubbles, to determine what features humans and pigeons were using to recognize objects. Three pigeons were trained to recognize four objects: an arch, a barrel, a brick, and a wedge. The researchers then partially revealed different parts of the object pictures. They then conducted the same experiment with six people.

Not only did both the pigeons and people recognize the four objects based mostly on corners, but they used these properties more than the shading information contained in the images. More notably, the pigeons and people used corner information more than a computer programmed to extract the most useful information for recognizing the object pictures, which suggests that the pigeons and people were using comparable information. “When members of different species respond similarly to the same visual information, we gain confidence in the prominence of this information, irrespective of cultural or genetic influences. Birds represent an important group to compare with mammals, the other major class of warm-blooded, highly mobile, visually oriented animals,” the researchers say. “Because of the unique demands of flight, for the last 200 million years birds have been under strong evolutionary pressures to keep their overall size to a minimum. Although a very large portion of the avian central nervous system is devoted to visual processing, the bird brain is still just a fraction of the size of our own. It is this extraordinary mixture of visual competence and small size that makes the study of birds critical to our understanding of the general mechanisms of visual cognition,” they say.

Science Daily Health & Medicine
March 6, 2007

Original web page at Science Daily Health & Medicine

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Hard-wired for home

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. The geomagnetic anomaly threw the pigeons for a loop. Of the 92 pigeons released around the anomaly, 59 clearly flew relative to the direction of the local field–not Earth’s field. As soon as they got beyond the anomaly, however, the pigeons corrected their direction and headed right home. Dennis concludes that the birds are keeping track of gradients in the field to navigate.

The study is “fantastic,” says Joe Kirschvink, a biophysicist at the California Institute of Technology in Pasadena. “Now we have the data to convert the speculation” about pigeon navigation “into reality.” The next key experiment, says Cordula Mora, a biologist at Duke University in Durham, North Carolina, who led the magnetic wind tunnel study, “will be to see whether this observation holds true at other sites in Europe and North America” and to find out how the pigeon’s magnetic organ–thought to reside in the beak–is wired to its brain.

ScienceNow
march 6, 2007

Original web page at ScienceNow

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Experts play down risk to humans

Experts have stressed the outbreak of bird flu at a farm in Suffolk poses no immediate risk to human health. The outbreak has been confirmed as the H5N1 strain of the virus which has infected 270 people, and killed 164 – most in south east Asia – since 2003. However, the virus cannot easily pass from human to human at present. So far, all those who have been infected have been poultry workers who have come into intimate contact with infected birds. Experts warn that if the virus acquires the ability to pass from human to human, then it will pose a potential threat to millions across the globe. Health chiefs in the UK have warned that if such a modified strain does emerge then tens of thousands of people could die in Britain alone. However, at present H5N1 remains overwhelmingly a disease of birds, and not humans. So at present the threat to human health from the outbreak in Suffolk is minimal – particularly as it appears to have been rapidly contained.

BBC News
February 20, 2007

Original web page at BBC News

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Europe must get to grips with bird flu

A year after deadly H5N1 bird flu first arrived in Europe, the UK is dealing with its first outbreak on a farm. Yet European efforts to track the virus, let alone defend its poultry, are still in disarray. Later this month, scientists will meet to hammer out a Europe-wide surveillance scheme that will try to work out exactly where the virus is lurking and prevent further outbreaks. The British outbreak, on a large turkey farm in eastern England, follows repeated insistence by British officials that the nation’s wild birds do not have the virus, even though an infected dead swan turned up in Scotland last April. But there is a chance that surveillance is missing the virus.

Thus year’s emergence of H5N1 in western Europe seems to be following a similar pattern to last year. The highly pathogenic virus evolved in poultry in East Asia and crossed Eurasia during 2005. It was then carried to western Europe that autumn by wild birds possibly dabbling ducks, which unlike many birds stay healthy while carrying H5N1. However, there were no visible outbreaks in western Europe until February 2006. Now the same thing is happening this year, with outbreaks of H5N1 in Hungary on 24 January and the UK on 3 February. This suggests H5N1 arrived in the ducks’ wintering grounds in autumn but didn’t immediately strike a visible target. Yet there was no warning of impending flu outbreaks, partly because Europe has no coordinated surveillance for flu in wild birds that would enable researchers to work more closely and share data.

For example, between August 2006 and January 2007 the UK Veterinary Laboratories Agency (VLA) tested 4054 wild British birds, nearly half of them dabbling ducks, but only 15 (0.8 per cent) of the ducks tested positive for any strain of bird flu. In contrast, last autumn Björn Olsen of the University of Kalmar in Sweden, who runs one of Europe’s largest flu surveillance programmes, found ordinary flu in 20 to 40 per cent of ducks using the same migration path as British ducks. Similar findings last year led researchers to query whether the VLA’s sampling technique had let virus degrade through samples drying out (New Scientist, 12 April 2006, p 12). “I would say 0.8 per cent is too low,” says Olsen. “But it is important to harmonise our sampling techniques, or we can’t compare data.”

Later this month, European scientists will meet in Rotterdam, the Netherlands, to launch the NEW-FLUBIRD programme to standardise sampling methodology and determine exactly which birds carry the virus. No sampling so far has detected a healthy bird carrying H5N1. “I’m most concerned that we may be sampling the wrong end of the bird,” says Osterhaus, who now believes H5N1 may be more likely to turn up on a throat swab than in a faecal sample.

New Scientist
February 20, 2007

Original web page at New Scientist

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Mild form of bird flu slows down migration of swans

Migratory swans carrying a mild form of avian influenza depart from The Netherlands more than a month after their healthy counterparts do. They also feed slower and fly shorter distances. These insights will be published on January 31, 2007 in PLoS ONE, the International, peer-reviewed, open-access, online publication from the Public Library of Science (PLoS) by scientists from the Netherlands Institute of Ecology (NIOO-KNAW) and the Department of Virology of the Erasmus MC. This contrasts previous ideas that mild forms of bird flu do not cause illness among wild birds. Moreover, these patterns can affect the rate of spread of avian influenza.

Wild birds were thought not to suffer from mild forms of avian influenza. But new data suggest that so-called ‘low-pathogenic’ avian influenza viruses do affect the lives of birds. The Bewick’s swan (Cygnus columbianus bewickii) is a migratory bird that breeds in NW-Russia and overwinters in NW-Europe, especially in The Netherlands. In this species, a team of ecologists and virologists showed that infected individuals initiate their migration by the end of January or early February, while uninfected individuals already do so by the end of December. Also, their next ‘fuelling station’ is only 35 km away instead of the usual 250 km. Sick birds fuel at a lower rate: they take fewer bites per day and their digestion seems to be impaired. Presumably, this is due to their need to channel more energy towards their immune system.

Being ill is no fun for us, but for a migratory bird being ill could potentially mess up its whole calendar for the rest of the year. According to scientist Jan van Gils from NIOO, “Infected swans clearly suffer from their ‘mild’ disease. The late departure from the wintering grounds could lead to late arrival in the breeding grounds, and thus to a lost breeding season. All in all, these low-pathogenic viruses have a much greater impact than previously thought. Because of their slower migration, ill birds get in touch with many more healthy birds passing by them on migration. In this way the virus can spread itself more rapidly than previously thought.” Acquiring more knowledge about mild but illness-causing avian influenza viruses is very important. Van Gils adds, “These mild virus-types always formed the origin of massive pandemics such as the Spanish Flu. Only such viruses that are non-lethal to birds can be spread easily by (wild or captive) birds, simply because the birds stay alive.” Only after mixing with human flu can such a low-pathogenic avian flu cause the nightmare of a deadly pandemic among humans. “High-pathogenic avian flu that causes death among birds seems to originate from intensive poultry farms.”

In the Dutch study 25 swans were investigated. The birds were caught in polder Wieringermeer (NW-Netherlands) last winter and were measured, weighed and screened for the prevalence of avian influenza viruses. Twelve birds were equipped with a GPS attached to their neck collar (80 g in total). This enabled the researchers to follow the birds’ movements in great detail. When within 300 m of the bird, all “travel data” were downloadable by wireless modern technology. Birds were found back by volunteer bird watchers reading and reporting the code on each bird’s neck collar. Among the twelve neck-collared birds, two were infected with bird flu: type H6N2 and H6N8. These mild virus types are common among free-living waterfowl. From antibodies found back in blood samples it could be concluded that a few more individuals had been infected before but were fully recovered and behaved as the other healthy birds. Both birds that were infected last winter have returned this winter and seem fully recovered too.

Science Daily
February 20, 2007

Original web page at Science Daily

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A pair of rooks may twine beaks for comfort after a neighborhood squabble

The close quarters of a rookery can be a lot like a crowded row-house neighborhood: Every now and then, there’s bound to be a fight. And after a nasty squabble with a neighbor, what better way to smooth those ruffled feathers than with a kiss at home? Bill-twining, which looks remarkably like kissing, is rooks’ chosen way to ease their tempers, reports experimental psychologist Amanda Seed from the University of Cambridge, United Kingdom. Such behavior has long been known among primate species, such as chimpanzees, but this is the first time it’s been documented in birds. Animal behaviorists have studied squabbling among numerous mammalian species, particularly primates, which after a fight often seek comfort through mutual grooming with an animal not involved in the row. This tactic is believed to reduce stress. Chimps, bonobos, and a few other mammals go a step further: They even engage in grooming or other forms of affiliative behavior with their opponent, which is seen as a form of reconciliation.

In the wild, rooks nest in treetops with thousands of rook neighbors. Pairs typically mate for life and return to the same nesting site each year, giving the group a degree of social permanence. A big social group has its advantages–more eyes to watch for predators and to find food–but there are also drawbacks: Every rook wants the best sticks to build their nests, and the best morsels of food. “It’s like walking a tightrope, trying to find a balance between those group benefits and your own,” says Seed, “and of course that leads to arguments.” Seed videotaped and studied post-conflict behavior in a captive group of 10 rooks, which includes four monogamous pairs, watching to see if the birds sought solace from other birds after a fight. Although paired rooks did not fight with each other, individuals often quarreled with neighbors, squawking and flapping over a contested stick or bit of food. After such fights, the antagonists flew to their mates. The pairs preened, shared bits of food, and twined their bills, Seed reports in the January 23 issue of Current Biology. They did not make up with their opponents, however.

The rooks’ kiss-and-calm-down behavior with their socially valuable mates has “remarkable similarities to behaviors among the great apes,” says animal behaviorist Filippo Aureli at Liverpool John Moores University, U.K. But Emory University’s Frans de Waal (who discovered reconciliation and consolation in chimpanzees) notes that the birds may not actually be consoling their mates, an act requiring that they initiate the calming kisses. Nevertheless, he’s pleased to see birds added to “the long list of animals that try to manage stress caused by conflicts in their societies.”

ScienceNow
February 6, 2007

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European Union to ban imports of wild birds

The trade in wild birds is to be permanently banned across the European Union starting in July, EU animal health officials have decided. The move will replace a temporary ban imposed by Brussels in 2005 as part of measures to prevent outbreaks of the deadly H5N1 strain of bird flu. Animal welfare campaigners say the permanent ban will save millions of birds, including many rare species. Only captive-bred birds from approved countries will be allowed into the EU. Tighter controls on the health and quarantine of imported birds are also to be imposed.

Campaigners have blamed Europe’s trade in wild birds as a significant factor in the decline of many threatened species such as the African grey parrot. Before the temporary ban was imposed, about 1.7 million wild birds were imported annually into the EU. About 60% of the birds caught for import died before they reached Europe from poor handling or disease, Britain’s Royal Society for the Protection of Birds said. The temporary ban was imposed in October 2005 after wild birds at a quarantine station in Britain were found to have avian flu.

BBC News
January 23, 2007

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Testosterone gives male birds their color

New research suggests that as testosterone in male birds increases, so does the level of carotenoids, the chemicals that create the bright coloring on birds’ feathers, beaks, and legs. The brilliant reds, yellows, and oranges serve as indicators of sexual competitiveness, signaling to females that the bearer is healthy and a potentially good mate. Scientists already knew that testosterone in male birds brings out their macho best, making them sing more sweetly and court with added vigor—other key indicators of males’ health and sexual appeal. But until now the relationship between bird coloring and testosterone had eluded biologists. Researcher Julio Blas, a biologist at the University of Saskatchewan in Saskatoon, Canada, and colleagues decided to tackle the issue through experiments in Spain with native red-legged partridges.

Blas’s team increased the testosterone of male partridges during the mating season and saw a 20 percent rise in carotenoids—which birds get from food such as berries and insects—in their blood and livers. “A bird in good shape should be colorful and also should sing more,” said Blas, whose research appears this week in the journal Proceedings of the National Academy of Sciences. “Until now these lines of evidence have been researched independently of each other. What we did is connect these two lines of research.” The finding could solve another outstanding puzzle. High levels of testosterone come with a price, as the hormone usually depresses the immune system, increasing birds’ susceptibility to disease. But recent studies have shown that birds manipulated in the lab to have high testosterone could still have robust immune systems. The link between testosterone and carotenoids may be the answer, Blas says. Carotenoids help build vitamins and are strong antioxidants—chemicals that help animals detoxify harmful molecules called free radicals. In short, carotenoids appear to compensate for the effect of testosterone by keeping the immune system strong.

Sick male birds have dull coloring. This is probably because the carotenoids are being used by the struggling bird’s immune system in an effort to fight off disease, Blas says. “When a chicken becomes sick, its yellow legs become paler,” he said. “Why? Because it is using its carotenoids to fight illness.” But birds that are in good shape can have it all—elevated testosterone, a healthy immune system, and large deposits of color-carrying carotenoids in their legs, beaks, and feathers. “It may be that only the really high-quality individuals can withstand the immunosuppressive effect of testosterone,” said Lynn Siefferman, a biologist at Indiana University in Bloomington who studies bluebirds, feather color, and testosterone. “The idea is that they will put health before reproduction” and not mate, she said.

National Geographic
December 19, 2006

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Can flu viruses survive winter in frozen lakes?

Evidence of flu viruses frozen in Siberian lakes has prompted researchers to examine the possibility that global warming may release microbes locked in glaciers for decades or even centuries. “Our hypothesis is that influenza can survive in ice over the winter and re-infect birds as they come back in spring,” says Scott Rogers of Bowling Green State University, Ohio, US. He believes the frozen lakes act as “melting pots” for flu viruses, allowing viruses from one year to mix with those from previous years. Rogers has spent decades searching ice for micro-organisms. He teamed up with Dany Shoham at Bar-Ilan University, Israel, and David Gilichinsky, at the Russian Academy of Sciences, to obtain samples of ice from Siberian lakes where migratory birds stop.

The group looked for pieces of genetic material from flu viruses in ice taken from three lakes that freeze and thaw each year. In the lake that is most visited by migratory birds, Lake Park, they found fragments of RNA coding for haemagglutinin, the surface protein that allows flu viruses to bind to the cells they infect. Genetic analysis revealed the haemagglutinin was most closely related to an H1-strain flu virus that was around in the 1930s and later resurfaced in the 1960s. Rogers’ team is now looking at ice cores from glaciers in Alaska and Wyoming in the US, and from Canada. They intend to study cores from Siberia and the Himalayas as well. Many of these glaciers are on the flight paths of migratory birds, which will deposit virus onto the ice in their droppings, where it freezes. Rogers believes there is a possibility that, as global warming melts glaciers, they will release the viruses, and perhaps other microbes such as bacteria and fungi that have otherwise disappeared from our environment.

The idea is plausible, says Jonathan Stoye, head of virology at the UK National Institute for Medical Research in London. But he adds: “The important issue is whether or not there’s infectious virus” in the ice, rather than just fragments of RNA. Rogers is collaborating with researchers at sufficiently biosecure labs to try and answer this question. Stoye says that whether or not the viruses are infectious depends largely on how the virus was frozen. Viruses frozen in water are likely to be inactivated by the water’s relatively low pH. “But if the virus was in droppings, which presumably is how it was deposited, there seems to be no reason why it should not freeze and survive at low temperatures.” He adds that viruses are more likely to survive in a frozen state if they freeze and thaw only once, as the freeze-thaw process kills at least 90% of virus each time.
Source: Journal of Virology

New Scientist
December 19, 2006

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Floating lovers count too — in the health of eagle populations

Floaters are dispersed individuals who enter the reproductive population when breeding territory or a potential mate become available. The researchers’ work has shown that factors affecting the survival of floaters within their settlement areas may directly influence the dynamics of the whole population. Vincenzo Penteriani, Fermín Otalora, and Miguel Ferrer looked at population data for the Spanish imperial eagle Aquila adalberti over the last century. With less than 150 pairs in the whole Iberian Peninsula, this eagle is one of the most threatened raptors in the world. They found that extremely high mortalities of floaters in settlement areas cause a decrease in the number of breeders, due to the increasing difficulty of breeding pair formation and, consequently, a positive density-fecundity relationship in the breeding portion of the population.

The results support the novel idea that taking floater dynamics within settlement areas into consideration can illuminate inexplicable positive density-dependent patterns in breeding populations. “Population studies that ignore floater dynamics may fail to understand all the different factors influencing density-dependent population patterns,” Penteriani says. He continues, “Clearly defining the portion of the population that shapes density-dependent patterns may help to solve some of the ambiguities that, after some seventy years of debate, still surround density-dependence and population dynamics in general.”

Science Daily
December 5, 2006

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Group decisions: From compromise to leadership in pigeon homing

By studying how homing pigeons decide between two attractive options–following a habitual route home and flying in the company of another homing pigeon–researchers have deepened our understanding of the forces that underlie decision-making by social animals. The findings are reported by a research group led by Dora Biro of the University of Oxford and appear in Current Biology. Social animals have to make decisions that affect not just themselves, but everyone in the group. For example, when embarking on a journey together, individuals must agree on the route–a difficult task if group members cannot assess who are the best navigators or who is best informed about possible routes. Is a “democratic” average of everyone’s opinion best? Or is it better to trust a leader? And what circumstances influence how animals decide which of these strategies to follow?

In the new study, the researchers used miniature GPS tracking devices to follow the homing flights of pairs of pigeons, where both individuals had their own, previously established preferred routes leading back to the loft. When the birds were released as a pair, and when the two preferred routes were not very different, the conflict between birds’ preferences was resolved by a mutual compromise in which both birds flew by an intermediate route. When preferred routes of the two birds differed greatly, however, the compromise position was replaced by a scenario in which the preferred route of one bird–who would emerge as the “leader”–was followed by both birds for the rest of the journey. Using a mathematical model to better understand the basis of the paired birds’ navigation choices, the researchers found that both forms of decision-making could emerge from just two simple forces acting simultaneously on the pigeons’ behavior: “move toward your familiar route” and “move toward your partner.” In cases of small disagreements about the route, these two forces, or rules, lead to mutual compromise. However, when preferred routes are sufficiently different, behavior resembling compromise turns to behavior characterized by leadership as one bird abandons its own route to instead follow that of its partner. The outcome of the mathematical modeling therefore indicated that compromise and leadership are two outcomes of the same decision-making process.

In another aspect of the study, the analysis of pigeon behavior showed that birds flying in pairs seem to take more efficient routes home than those flying alone, suggesting that in addition to safety in numbers, traveling in the company of others brings navigational benefits to individual group members.

Science Daily
December 5, 2006

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Satellites to track bird flu virus spread

The international team, led by Professor Xiangming Xiao of the University of New Hampshire, was recently awarded $1.55 million for a 4-year project by the U.S. National Institutes for Health to develop quantitative analysis and modeling capacity for better understanding the relationship between man-made environmental change and transmission of infectious agents. The project will use environmental remote sensing data from Earth observing satellites in combination with research in epidemiology, ornithology and agriculture to provide a better picture of how the bird flu virus survives and is transmitted among poultry and wild birds. The study will focus on China, where outbreaks of the virus have been prominent.

Science Daily
December 5, 2006

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Scientists regenerate wing in chick embryo

Chop off a salamander’s leg and a brand new one will sprout in no time. But most animals have lost the ability to replace missing limbs. Now, a research team at the Salk Institute for Biological Studies has been able to regenerate a wing in a chick embryo — a species not known to be able to regrow limbs – suggesting that the potential for such regeneration exists innately in all vertebrates, including humans. Their study, published in the advance online edition of Genes and Development demonstrates that vertebrate regeneration is under the control of the powerful Wnt signaling system: Activating it overcomes the mysterious barrier to regeneration in animals like chicks that can’t normally replace missing limbs while inactivating it in animals known to be able to regenerate their limbs (frogs, zebrafish, and salamanders) shuts down their ability to replace missing legs and tails.

“In this simple experiment, we removed part of the chick embryo’s wing, activated Wnt signaling, and got the whole limb back – a beautiful and perfect wing,” said the lead author, Juan Carlos Izpisúa Belmonte, Ph.D., a professor in the Gene Expression Laboratory. “By changing the expression of a few genes, you can change the ability of a vertebrate to regenerate their limbs, rebuilding blood vessels, bone, muscles, and skin – everything that is needed.” This new discovery “opens up an entirely new area of research,” Belmonte says. “Even though certain animals have lost their ability to regenerate limbs during evolution, conserved genetic machinery may still be present, and can be put to work again,” he said. Previously, scientists believed that once stem cells turned into muscles, bone or any other type of cells, that was their fate for life — and if those cells were injured, they didn’t regenerate, but grew scar tissue.

Manipulating Wnt signaling in humans is, of course, not possible at this point, Belmonte says, but hopes that these findings may eventually offer insights into current research examining the ability of stem cells to build new human body tissues and parts. For example, he said Wnt signaling may push mature cells go back in time and “dedifferentiate” into stem-like cells, in order to be able to then differentiate once more, producing all of the different tissues needed to build a limb. “This is the reverse of how we currently are thinking of using stem cells therapeutically, so understanding this process could be very illuminating,” he says. “It could be that we could use the Wnt signaling pathway to dedifferentiate cells inside a body at the site of a limb injury, and have them carry out the job of building a new structure.”

Members of the Wnt gene family (for “wingless,” originally discovered in fruit flies) are known to play a role in cell proliferative processes, like fetal growth and cancer development, and Belmonte’s lab has characterized the crucial role of Wnt signaling in limb growth. In 1995, the Salk researchers were first to demonstrate that they could induce the growth of extra limbs in embryonic chicks, and in 2001, they found that the Wnt signaling system played a critical role in triggering both normal and abnormal limb growth. The current study was designed to see if Wnt signaling also was involved in the regeneration of limbs and included three groups of vertebrates: zebrafish and salamanders, which can regenerate limbs throughout their lives; frogs, which can only regenerate new limbs during a limited period during their fetal development; and chicks, which cannot regenerate limbs. To manipulate animals’ regeneration ability, the Salk researchers used inhibitory and excitatory factors for Wnt signaling, which they delivered directly to the remaining bulge after they cut a limb from the experimental embryos.

In adult zebrafish and salamanders, they found that blocking Wnt signaling with the inhibitory factors, prevented normal regeneration. And, conversely, when they treated mutant adult zebrafish that cannot regenerate with the excitatory agent, the ability to regenerate their fins was rescued, Belmonte says. Using an inhibitory agent on frogs before the regeneration-enabled developmental window closed resulted in loss of that ability, but treating them with the excitatory agent after they had lost their regenerative capacity induced new limb growth. They then performed the key experiment, successfully testing the ability of an excitatory factor to produce limb regeneration in chick embryos. “The signal restarted the process, and genes that were involved in the initial development of the limb were turned back on,” Belmonte says. “It is simply amazing.”

Science Daily
December 5, 2006

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Call me bird-brained

A new study has shown that pigeons can memorise 800 to 1,200 pictures before reaching their limit. So calling someone “bird-brained” isn’t quite the insult it used to be. In the experiment, researchers tested the capacity of two Silver King pigeons to recall various images by progressively showing the birds more and more pictures. The birds had to peck a cross or circle to indicate if they had seen the picture before. Researchers say that it is one of the first studies to test animals’ long-term memory capacity. The study also assessed the long-term memory skills of two baboons that learned 3,500-5,000 images over the course of about four years. But the authors of the new paper, which appears in the Proceedings of the National Academy of Sciences, stress that the baboons had not yet reached their maximum memory capacity when the trial ended.

The findings don’t surprise me one bit. There is an obvious evolutionary advantage to having better long-term memory. Even a bird-brained person knows that! So it makes sense that the baboons outperformed the pigeons. But the results of the experiment also explain something less obvious: For years I wondered why the pigeons in my neighbourhood always seemed to drop their – ehem – mess on my car while leaving the surrounding area spotless. Now I realise that the birds held an image of my car in their minds. To them it was a picture-perfect target.

New Scientist
November 21, 2006

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Evolutionary oddity : Erectile tissue helps flamingos eat

Flamingos are known for their peculiar feeding behavior. While standing in shallow water, they bend their necks, tilt their bills upside down in the water and swish their heads from side-to-side. Their large tongue acts like a piston, sucking water into the front of the bill and then pushing it out the sides. Fringed plates on the tongue trap algae and crustaceans in the circulating water. “The flamingos’ feeding habits have captured people’s curiosity for ages, but that wasn’t the original focus of our research,” said Casey Holliday, who recently earned a doctorate in biological sciences from Ohio University and served as lead author on the study. “We were investigating the evolution of jaw muscles in lizards, birds and dinosaurs. By sheer luck we discovered something new about flamingos.”

To get a detailed look at the flamingo’s jaw muscle structure, the researchers injected a colored barium/latex mixture into the blood vessels of a bird that had died and was donated by the Brevard Zoo in Florida. A 3-D view of the bird’s head was created using a new computed tomography (CT) scanning technique developed by the Ohio University team that highlights blood vessel anatomy. The researchers noticed large oval masses of erectile tissue located on the floor of the mouth on either side of the tongue. “No one ever anticipated finding something like this, and now we’re scratching our heads trying to understand the role these tissues play,” said Lawrence Witmer, a professor of anatomy in Ohio University’s College of Osteopathic Medicine who directed the study.

The researchers know that when the erectile tissues fill with blood, they stiffen, strengthening and supporting the floor of the mouth. “We suspect this stabilizes the mouth and tongue and helps with the peculiar way that flamingos eat,” he said. “It’s an important new piece of the puzzle of flamingo feeding—frankly, a piece we hadn’t known was missing!”
Source: The Anatomical Record

Science Daily
November 21, 2006

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Zoo celebrating rare dove birth

A rare Mexican bird that died out in the wild in the 70s has been successfully bred at London Zoo. The Socorro dove is native to Socorro Island in the Revillagigedo Islands, 600 miles off the west coast of Mexico. The species was last sighted in Socorro in 1972 and there are now thought to be fewer than 100 in captivity. Zoo keepers have named the new dove, Arnie – after Arnold Schwarzenegger. They hope successful captive breeding will increase their numbers. John Ellis, The Zoological Society of London’s Curator of Birds, said: “This is an enormous success for London Zoo and a real tribute to the hard work and expertise of our keepers. “I would like to think that this captive breeding success marks a change in the fortunes of the Socorro dove, and we are delighted to be playing our part in the reintroduction programme.”

The species died out after falling prey to a rising number of feral cats. They were hunted by humans for food and overgrazing by sheep also destroyed much of their forest floor habitat. As part of the European Association of Zoos and Aquaria breeding programme, it is hoped Arnie’s descendants will eventually be reintroduced into the forests of Socorro.

BBC News
November 6, 2006

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Study identifies North American wild bird species that could transmit bird flu

University of Georgia researchers have found that the common wood duck and laughing gull are very susceptible to highly pathogenic H5N1 avian influenza viruses and have the potential to transmit them. Their finding, published in the November issue of the journal Emerging Infectious Diseases, demonstrates that different species of North American birds would respond very differently if infected with these viruses. David Stallknecht, associate professor in the department of population health at the UGA College of Veterinary Medicine and co-author of the study, said knowing which species are likely to be affected by highly pathogenic H5N1 viruses is a vital component of efforts to quickly detect the disease should it arrive in North America. “If you’re looking for highly pathogenic H5N1 in wild birds, it would really pay to investigate any wood duck deaths because they seem to be highly susceptible, as are laughing gulls,” said Stallknecht, a member of the UGA Biomedical and Health Sciences Institute. “It was also very interesting that in some species that you normally think of as influenza reservoirs — the mallard, for instance — the duration and extent of viral shedding is relatively low. This may be good news since it suggests that highly pathogenic H5N1 may have a difficult time surviving in North American wild birds even if it did arrive here.”

Working under controlled conditions in an airtight biosecurity lab at the USDA Agricultural Research Service’s Southeast Poultry Research Laboratory, the researchers determined how much of the virus was shed in the feces and through the respiratory system of several species of wild birds. The work was jointly funded by the United States Poultry and Egg Association, the Morris Animal Foundation and the USDA. “We chose birds that, because of their behavior or habitat utilization, are most likely to transmit the virus or bring the virus here to North America,” said lead author and doctoral student Dr. Justin Brown.

The species studied were: Mallards, which are often infected with commonly circulating, low-pathogenic avian influenza viruses in North America and Eurasia; Northern pintails and blue-winged teal, which migrate long distances between continents; redheads, a diving species; and wood ducks, which breed in Northern and Southern areas of the United States. The laughing gull is a common coastal species ranging from the Southern Atlantic to the Gulf Coast. Stallknecht explained that in low-pathogenic avian influenza, most of the virus is shed in the feces of birds. The virus then spreads as other birds drink from contaminated water. The study found that in highly pathogenic H5N1 avian influenza, however, the birds shed most of the virus through their respiratory tract. Stallknecht said that with this knowledge, scientists can more effectively detect the virus in live birds by swabbing the birds’ mouths and throats. “Doing avian influenza surveillance is pretty tricky because there are a lot of species differences and there are also seasonal differences,” he said. “So you’ve got to pick the right species at the right time and you’ve got to collect the right samples.” In a related study scheduled to be published in December issue of the journal Avian Diseases, the researchers have quantified how long the virus persists in water samples. They found that highly pathogenic H5N1 avian influenza viruses don’t persist as long as common low-pathogenicity strains. In some cases, persistence times were reduced by more than 70%. This could affect transmission and supports the idea that these viruses may not have much of chance of becoming established in North America. Stallknecht said the finding is encouraging, but cautions that it’s difficult to put it into context without results from a study his team is currently working on that will assess the minimum amount of virus it takes to infect a bird.

In the first phase of the project, the researchers will examine the prevalence, persistence and distribution of the viruses in various environments. In the next phase, they’ll work with state public health departments to determine the groups of people who — by virtue of their occupation or recreational activities — are likely to come into contact with the viruses. The researchers will then assess the ability of low-pathogenic avian influenza viruses to infect mammals so that the risk of human contact can be put into perspective. “With this information, public health officials will be able to better understand the human health risks associated with both low-pathogenic and highly pathogenic avian influenza viruses in both domestic and wild bird populations,” Stallknecht said. “Many of these potential risks are not very well understood or even defined, and it is possible that they could be very effectively controlled with simple preventive measures.”

Science Daily
November 6, 2006

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Groups and grumps: Study identifies ‘sociality’ neurons

Led by James Goodson, associate professor of psychology and neuroscience, and detailed in this week’s early online edition of the Proceedings of the National Academy of Sciences, the research demonstrates that vasotocin neurons in the medial extended amygdala respond differently to social cues in birds that live in colonies compared to their more solitary cousins. Vasotocin neurons appear, according to the study, to selectively promote positive affiliation. The gregarious species also have greater numbers of the neurons and their baseline activity is about twice as high, putting the birds in a kind of perpetual “social mood.” “These findings,” Goodson said, “address the fundamental question of sociality: Why are some animal species highly social while others seem to have little or no tolerance for others?

“And while the observations were made in birds, they should apply to many other animals, including humans, since the cells are present in almost all vertebrates and the brain circuits that regulate the basic forms of social behavior are strikingly similar,” he said. Goodson worked with birds because, with more than 9,200 species and “a dazzling array of social structures,” they offer opportunities to study groups of species that differ only in one aspect of social behavior, making it possible to attribute that dimension — in this case, sociality — to differences in a particular brain function. Traveling as far as South Africa to collect the appropriate birds, Goodson focused on five species of closely related waxbills and finches: the melba finch, the violet-eared waxbill, the Angolan blue waxbill, the spice finch and the zebra finch. All the birds live in similar habitats, are monogamous pair bonders, exhibit biparental care and breed depending on rainfall, but where the melba finch and the violet-eared waxbill are territorial and live in male-female pairs, the spice and zebra finch establish colonies of about 100. The Angolan blue waxbill is an intermediate species, whose groups range from 8 to 40.

Goodson and lab assistant Yiwei Wang stained and examined the birds’ brain tissue for a protein known as “Fos” (a cellular marker of brain activity commonly used in neuroscience) specifically within neurons that produce vasotocin. Vasotocin and its equivalent in mammals, vasopressin, are neurochemicals that are known to be involved in a variety of social behaviors, from social recognition to monogamous pair-bonding. After the birds had viewed a same-sex member of their own species through a wire barrier, the researchers found that activity within one group of vasotocin neurons, in the medial extended amygdala, had increased significantly in the gregarious species. In the asocial species, however, it had decreased.

Goodson and Wang wondered if the results of the same-sex exposure pointed to a specialization of the vasotocin neurons — such that their activity increases in response to positive social situations that normally promote affiliation in a given species rather than those that provoke avoidance or attack. To test the idea, they conducted two additional experiments. In the first, territorial violet-eared waxbills were exposed to their pair bond partner. As predicted, and in contrast to the response seen after exposure to a bird of the same sex (a negative situation for a territorial, asocial species), the activity of vasotocin neurons increased dramatically in response to this positive scenario.

In the second experiment, highly social zebra finches were placed in a mate-competition situation. Subjects were either allowed to court or were prevented from doing so by a bully. Activity in the vasotocin neurons went up after the positive experience but not after the negative experience of being bullied, supporting the idea that the cells are selectively sensitive. “In sum,” Goodson said, “these vasotocin neurons increase their activity in response to positive social stimuli, and the neurons appear to have evolved in relation to sociality, so that the gregarious species have more vasotocin neurons with higher baseline levels of activity than do the asocial species.”

Vasotocin neurons may account for “personality” differences between individuals as well. In related work that has yet to be published, Goodson said, he has observed differences in the number and activity of the neurons in zebra finches that are either duds or studs when it comes to courtship behavior. Goodson also suspects that the neurons play an analogous role in human social behavior — though we are long way from being able to apply the findings and turn a misanthrope into a party animal.

Science Daily
November 6, 2006

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Whooping cranes, ultralight planes take flight on annual migration

Early this morning a unique flock of 18 birds joined the millions heading south for the winter. But this group of whooping cranes had surprising-looking “birds” at the helm: four ultralight aircraft. Researchers from Operation Migration, a Port Perry, Ontario-based nonprofit, are flying the whooping cranes from central Wisconsin to Florida with the ultimate goal of reintroducing a new migrating population of the endangered species. Seventeen cranes successfully flew the initial leg—4 miles (6 kilometers)—of the 1,228-mile (1,976-kilometer) journey on their first try. One crane, however, was reluctant. A female bird “decided she was quite comfortable on the runway,” said Liz Condie, Operation Migration’s communications director. One of the ultralights headed back for her. “It took some encouragement,” Condie said, “Eventually, she decided [to do it.]”

The group is part of the Whooping Crane Eastern Partnership, a team of government agencies and nonprofits in the United States and Canada working to establish a migratory population of whooping cranes in the eastern U.S. This year is a major milestone for the project: A pair of cranes that the group first led along the route in 2002 has hatched two chicks, the first migrating whooping cranes in eastern North America born in the wild in the last century. “We hope that they will lead the chicks along the same route,” said Joe Duff, chief executive officer and co-founder of Operation Migration. “That will really validate our work.” More than 10,000 whooping cranes once flew North American skies. But by the 1940s, habitat loss, hunting, and egg poaching had shrunk the population of the iconic birds to just 21.

U.S. and Canadian wildlife managers have since been working hard to boost whooping crane populations in what is often seen as a symbol of conservation efforts. The sole wild population of cranes, which migrates each year between Wood Buffalo National Park in northern Alberta, Canada, and Aransas National Wildlife Refuge in Texas, now has 214 birds. A smaller, reintroduced group lives in Florida year round. In the 1980s and 1990s efforts to create a new migratory population between Montana and New Mexico by introducing whooping cranes into migrating sandhill crane groups ran into trouble when whooping cranes tried to mate with the sandhills. “We had no way of reestablishing a migratory population until Operation Migration came along,” said Tom Stehn, coordinator of the U.S. Fish and Wildlife Service Whooping Crane Recovery Team. “It’s really a breakthrough.” If more than 125 birds can learn the route and start migrating on their own, the population could be self-sustaining, he says. The Operation Migration team started with 7 birds in 2001 and has now taught more than 60 birds the way to their wintering grounds.

National Geographic
October 24, 2006

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Researcher uncovering mysteries of memory by studying clever bird

Keeping track of one set of keys is difficult enough, but imagine having to remember the locations of thousands of sets of keys. Do you use landmarks to remember where you put them? Do you have a mental map of their locations? Scientists at the University of New Hampshire hope to learn more about memory and its evolution by studying the Clark’s nutcracker, a bird with a particularly challenging task: remembering where it buried its supply of food for winter in a 15-mile area. Like many animals preparing for the winter, every fall the Clark’s nutcracker spends several weeks gathering food stores. What makes it unique is that it harvests more than 30,000 pine nuts, buries them in up to 5,000 caches, and then relies almost solely on its memory of where those caches are located to survive through winter.

Brett Gibson, a scientist studying animal behavior, began studying Clark’s nutcrackers in graduate school and is continuing his research into memory and the behavior of nutcrackers as an assistant professor in UNH’s psychology department. “Nutcrackers are almost exclusively dependent upon cache recovery for their survival so if they don’t remember where they’ve made those caches, then they are in trouble,” Gibson says. “During winter, their cache locations are covered with snow so many of the small local features in the landscape during fall are no longer available to them. What’s clear is that they are using spatial memory to recover these caches. They are remembering these caches based on landmarks and other features of the terrain.”

The study of memory is important for several reasons. It helps us understand how memory develops and evolves. It teaches us about how we and other species successfully navigate using memory. It provides insights across species about brain function and the hippocampus, a part of the brain important for memory and one of the first regions of the brain to suffer damage in Alzheimer’s patients. “For us it would probably be very difficult to remember where we put 33,000 items, but these guys do it really well because of the environment they live in,” Gibson says. “It’s a problem evolution has solved by developing this very good memory for spatial information.” Clark’s nutcrackers are native to the upper elevations of western North America, such as the Colorado Rocky Mountains. They are a member of the corvid family, which also includes blue jays and crows that are native to New England.

Gibson was part of an initial program of research focused on studying the Clark’s nutcracker’s spatial memory and how it compared to other members of the corvid family. That research has found that nutcrackers have a better spatial memory compared to related birds that are not as dependent upon the recovery of food caches during the winter for their survival. His most recent research with the Clark’s nutcracker looks at the nature of the spatial cues specified by memory — how the bird uses these cues to find its food caches. “How do they use landmarks? What information do they remember about these landmarks? Are they using just one landmark as a beacon? Do they remember multiple landmarks and the geometrical relationship between those landmarks and the goal location?” Gibson says.

“These pine seeds are very small and these caches are very small so they have to be very accurate about how they use these landmarks to remember those cache locations,” he says. One way that nutcrackers might solve the problem of returning to their caches is by developing a mental map of landmarks in their environment and recalling the location of the caches relative to the landmarks in the map. If they do have a map then they might be able to plan efficient routes to get from one cache site to the next — a problem called the Traveling Salesman Problem. “Some mathematicians love this problem. We were interested in seeing how efficiently a non-human animal could solve it so we looked at pigeons. They were actually pretty very good at it so we’re going to start looking at the same problem with nutcrackers,” Gibson says. “We think they may be even better because nutcrackers have all of these places they have to travel in their environment; you might expect them to be very efficient in terms of where they travel.”

Gibson, in collaboration with his graduate student Tyler Wilks, also is looking at whether the birds use another navigational strategy in finding their food — dead reckoning, part of an internal sense of direction. Dead reckoning integrates awareness of direction and distance traveled in order to return to a previous location; no landmarks are used. “As humans we rely on landmarks a lot so we don’t think a lot about dead reckoning. But when you get lost in a forest and there aren’t a lot of familiar landmarks, your dead reckoning system kicks in and you try to determine the direction from which you came,” he says. Investigations of dead reckoning in Clark’s nutcrackers have been limited, although it has been explored in other animals, from ants to primates. “We suspect it might play an important role because they have this great demand for remembering locations in the environment,” Gibson says. Gibson also is interested in how animals create tools such as hooks and barbs out of items like twigs and branches, and use them to find food. “The Clark’s nutcracker being a member of the corvid family might be quite good at understanding some of the physical relationships involved in solving problems that require using tools,” he says.

Science Daily
October 24, 2006

Original web page at Science Daily

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Only winter bugs get a bird down

When breeding is in full swing in summer, the birds will ignore bacterial infections and continue to fend off territorial invaders as well as keeping up a constant weight. In winter, however, sick sparrows eat less and burn fat reserves to fight off the disease, while paying less attention to defending their territory. It’s the first time that animals have shown seasonal “sickness behaviour” in the wild.

Noah Owen-Ashley and John Wingfield of the University of Washington, Seattle, injected the song sparrows (Melospiza melodia morphna) in summer and winter with a lipopolysaccharide (LPS) that mimics a minor bacterial infection. Control birds received a saline injection. Birds treated with LPS became less aggressive in winter but not in summer (Journal of Experimental Biology, vol 209, p 3062). The researchers suspect that a number of hormonal factors, including high testosterone, may help suppress sickness behaviour, allowing the birds to keep up their weight and aggression.

New Scientist
September 12, 2006

Original web page at New Scientist

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Bird brains shrink from exposure to contaminants

The regions in robins’ brains responsible for singing and mating are shrinking when exposed to high levels of DDT, says new University of Alberta research–the first proof that natural exposure to a contaminant damages the brain of a wild animal. “These residues have been persisting since the late 1960s–that’s what is really disturbing,” said Dr. Andrew Iwaniuk, a post-doctoral research fellow in the U of A’s Department of Psychology. “It has been years since it has been used and still has this effect.” The new research, published in Behavioural Brain Research, strongly suggests that exposure to environmental levels of DDT causes significant changes in the brains of songbirds.

Previous studies have suggested that exposure to DDT residues affect the brain, but none have actually demonstrated it. The research team, including Iwaniuk’s supervisor, psychology professor and Tier II Canada Research Chair Douglas Wong-Wylie, used American Robins to test the idea. Birds are more susceptible to the effects of pesticide residues and other contaminants in the environment than other animals. As well, American robins are often exposed to high levels of DDT and other chemicals because they rely heavily on earthworms as part of their diet. They specifically chose these birds in the Okanagan Valley because at that location they are exposed to high levels of DDT, but relatively low levels of other chemicals.

The researchers captured 18 nestlings and then hand-reared and observed them for two years. They then sectioned the brains and examined the size of several brain regions. “We found that the regions sensitive to reproductive hormones–song production and courtship behaviour–were most affected by DDT,” said Iwaniuk. “Song production is extremely important in attracting a mate or to mark out a territory. “The issue is not that DDT is killing these robins but if they are growing up in this one area and then move to another, they won’t be able to attract any females.” These effects were most prominent in the males, some of which experienced up to a 30 per cent reduction in brain region size compared to males at lower DDT exposure levels.

Whether this also applies to other animals and humans is unclear because there is not yet a strong understanding of how these chemicals in the environment affect the brain, but it is possible that humans exposed to similar levels of DDT will also be at risk of neurological damage. “The take-home message is that people need to be more cognizant of their use of pesticides and herbicides,” said Iwaniuk. “People need to be careful about using chemicals in their homes or farms. Who knows the effects these will have down the road.”

Science Daily
August 1, 2006

Original web page at Science Daily

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Migratory passerine birds as reservoirs of Lyme borreliosis in Europe

To define the role of birds as reservoirs and disseminators of Borrelia spirochetes, we characterized tick infestation and reservoir competence of migratory passerine birds in Sweden. A total of 1,120 immature Ixodes ricinus ticks were removed from 13,260 birds and assayed by quantitative polymerase chain reaction (PCR) for Borrelia, followed by DNA sequencing for species and genotype identification. Distributions of ticks on birds were aggregated, presumably because of varying encounters with ticks along migratory routes. Lyme borreliosis spirochetes were detected in 160 (1.4%) ticks. Borrelia garinii was the most common species in PCR-positive samples and included genotypes associated with human infections. Infestation prevalence with infected ticks was 5 times greater among ground-foraging birds than other bird species, but the 2 groups were equally competent in transmitting Borrelia. Migratory passerine birds host epidemiologically important vector ticks and Borrelia species and vary in effectiveness as reservoirs on the basis of their feeding behavior.

Recent outbreaks of West Nile virus infection or avian influenza indicate that birds participate in the ecology of zoonotic infections, an important cause of illness and death in humans and animals. The emergence of these threats underscores the need for understanding the maintenance of bird-associated infections in nature, which is prerequisite for disease prevention.

Migratory birds are known to carry several microbial agents of human disease, including viruses, chlamydiae, and enterobacteria. Evidence of the last 2 decades indicates that birds in North America and Eurasia host vectorborne pathogens, such as Anaplasma species and Lyme borreliosis (LB) spirochetes. LB is the most common vectorborne zoonosis in temperate regions of the Northern Hemisphere and is transmitted to humans by Ixodes ticks. Borrelia spirochetes infect naive Ixodes larvae when they feed on a reservoir host and are transmitted back to the reservoir population by infected nymphs. Rodent species, such as the white-footed mouse (Peromyscus leucopus) in the northeastern United States and Apodemus and Clethrionomys species in continental Europe, are common hosts of both immature ticks and LB spirochetes. However, recent field vaccination and biodiversity studies suggest that alternative hosts play a greater role than expected in the natural cycle of LB.

In comparison with studies of mammals as LB reservoirs, few studies have been conducted on the role of birds as hosts of Borrelia. The natural cycle of LB spirochetes, in particular Borrelia garinii, involves seabirds in northern Europe and game birds in the United Kingdom, which are the most studied models. However, the relationship between migratory passerine birds and Borrelia is less understood. Although experimental studies on avian infection have been conducted, less is known about reservoir competence of natural bird populations, especially those that could transmit ticks that frequently bite humans.

Information that would allow comparison of the reservoir importance of bird and other vertebrate populations is not available or is controversial. Although 1 modeling study found that the frequency of LB cases was positively correlated with species diversity of ground-dwelling birds, other studies have found the contribution of birds in hosting and infecting ticks to be low. Another uncertainty is epidemiologic implications of LB group spirochetes associated with birds. For example, birds in Europe are reservoirs of B. valaisiana, which has not been associated with disease.

In the present study, we characterized tick infestation and Borrelia transmission from migratory passerine birds captured in southern Sweden to further define their importance as reservoirs and disseminators of these spirochetes. We found that these birds are hosts of epidemiologically important vector ticks and Borrelia species. However, exposure of birds to ticks, which depends on feeding habits, determines their effectiveness as Borrelia reservoirs.

Emerging Infectious Diseases
July 18, 2006

Original web page at Emerging Infectious Diseases