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Animals are smart, but not savants

Do animals think like autistic savants? Intriguing as that question is, it now seems as if they don’t, despite the “savant-like” behaviour many show. The question was raised in a book by animal scientist Temple Grandin, of Colorado State University, Fort Collins. Animals in Translation became a best-seller, and Grandin’s views gained widespread attention. Grandin herself is autistic, and it is her experience of processing memories using images rather than words that forms the basis of her theory. “If you want to understand animals, you have to get away from language,” she says. There is no doubt that some animals have amazing abilities. Birds such as Clark’s nutcrackers can remember the locations of thousands of caches of nuts; Australian magpies are able to mimic the entire song of a different species after just one listen. But is this savant-like, or an evolutionary adaptation? Giorgio Vallortigara, of the University of Trento, Italy, and colleagues think it is the latter. “Autism is a pathological condition,” he says. “The extraordinary feats of remembering thousands of caches or sounds shown by some animal species are exhibited by healthy animals.”

If Grandin is right, there should be similarities between the brains of autistic people and animals. Autism is often associated with a malfunction of the brain’s left hemisphere, which can lead to an over-emphasis on details at the expense of an understanding of the big picture. Vallortigara and colleagues give the example of an autistic boy who learned the concept of “giraffe” by concentrating on the pattern of the coat. This led him to misidentify a leopard as a giraffe.

To look at animal brain function, Vallortigara and Lesley Rogers, a colleague at the University of New England, Armidale, Australia, have independently carried out experiments using domestic chicks to see which hemisphere of the brain was involved in performing certain tasks. Birds were presented with a familiar and an unfamiliar stimulus, and were allowed to choose between them when either the left or the right eye was covered with a patch. When the left eye was covered, the bird was forced to use only the left hemisphere, and in these cases it could only attend to the detail of the stimulus. When a patch covered the right eye, and the bird could only use the right hemisphere, it was able to process only large, categorical differences. “These specialisations of the hemispheres are the same as in humans,” Rogers says. This shows that only when forced to use one hemisphere over another did animals exhibit “autistic-like” behaviour, indicating that animal brains are more like “neurotypical” humans than autistic humans. The team have reviewed a series of similar experiments by other researchers, which they say back up their findings.
Source: PLoS Biology

New Scientist
March 4, 2008

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Pioneering eagle eye surgery removes cataract, restores vision, after injury

Surgeons from the University of Glasgow’s Small Animal Hospital have restored the sight of a golden eagle. It is believed the shock caused a cataract to develop and the 14lb bird of prey was taken to the Small Animal Hospital where the tricky surgery was carried out. It is the first time a procedure to remove a cataract caused by trauma has been carried out on a golden eagle. The bird was found on the island of Mull by staff from the Wings Over Mull bird sanctuary, who brought it the University of Glasgow. Putting birds under general anaesthetic is considered very risky as the shock often kills them. But it was decided that without sight, the bird’s future was bleak. Ophthalmologist George Peplinski carried out the surgery on the bird’s right eye. However, a second cataract operation on the other eye was ruled out. He said: “With such a small chance of any improvement I don’t think it was justified. We worked on the eye that we know is the healthiest and we are best just leaving it there and not risking a prolonged anaesthetic and a prolonged recovery.” The bird, named Electra, is now a permanent resident at the Wings Over Mull sanctuary, as with its reduced eyesight, it could not survive in the wild.

Science Daily
March 4, 2008

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Cracking the code of bird flu time bomb

Researchers at Griffith University Institute for Glycomics, Queensland led by Professor Mark von Itzstein have developed a technique to ‘crack-the-code’ of the deadly H5N1 avian influenza virus. It will enable influenza virus specialists and drug researchers to interrogate one of the virus’ key surface proteins without risk of infection. This approach will enable the rapid identification of avian and other influenza viruses that have attained the capacity to recognize human receptors and therefore acquired the potential for easy human-to-human transmission. The Griffith team collaborated with an international project partner team at the Hong Kong University-Institut Pasteur led by Professor Malik Peiris who developed a method to insert the deadly bird flu’s H5 protein in a harmless vehicle called a ‘virus-like particle’.

“To better interrogate a virus protein, researchers need to be able to observe and monitor the way it functions when associated with a virus particle,” Professor von Itzstein said. “It’s similar to the way it would be difficult to work out how a gun functions by only studying a bullet.” The use of these virus-like particles as a vehicle for the virus protein enables researchers to work without the need for high-containment laboratory procedures mandatory for handling live virus.

Science Daily
February 19, 2008

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Feed the birds: Winter feeding makes for better breeding

Keep feeding the birds over winter: that’s the message from research by the University of Exeter and Queen’s University Belfast. The study shows for the first time that the extra food we provide garden birds in winter makes for a more successful breeding season in the spring. By providing some birds with extra food, such as peanuts, and leaving others to fend for themselves, the team was able to compare productivity between the two groups. Those that were given extra food laid eggs earlier and, although they produced the same number of chicks, an average of one more per clutch successfully fledged. Although it was well known that garden feeding helps many birds survive the winter, this is the first time that the benefits to spring breeding and productivity have been shown.

Dr Stuart Bearhop of the University of Exeter, corresponding author on the paper, said: “Our study shows that birds that receive extra food over winter lay their eggs earlier and produce more fledglings. While this research shows how the extra food we provide in winter helps the birds that take it, it is still unclear whether this has a knock-on effect on other species. This is something we are keen to investigate, but in the meantime I will certainly be putting out food for garden birds for the rest of the winter.” US and UK households provide over 500,000 tonnes of food for garden birds each year. Despite this, there is a debate on whether we should continue feeding birds in the spring, when natural food sources become more readily available. This research shows, for the first time, that birds will continue to benefit from winter feeding well into the breeding season, which starts in April for most song birds in the UK.

Dr Dan Chamberlain of the British Trust for Ornithology, a collaborator on the project, adds “These results demonstrate that feeding birds in gardens over winter can be vital to their breeding success. It is highly likely that the benefits of extra food continue year-round, so don’t just stock your bird feeders in winter if you want to do the best for the birds in your garden”. Now that the research team has shown the long-lasting benefits of supplementary food for garden birds, they are keen to investigate exactly what is happening in terms of nutrition. Dr Stuart Bearhop of the University of Exeter continued: “The extra food we put out for birds contains fat, protein and carbohydrates, which may make the female bird stronger and more able to produce eggs. Foods like peanuts and bird seed also include vitamins and minerals, which can also produce healthier eggs and chicks, and we currently have a research project looking at the role of energy versus vitamins in explaining these effects.”

Science Daily
February 19, 2008

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Migrating birds detect latitude and longitude, but how remains a mystery

Eurasian reed warblers captured during their spring migrations and released after being flown 1,000 kilometers to the east can correct their travel routes and head for their original destinations, researchers report. The new evidence suggests that the birds have true navigation, meaning that they can identify at least two coordinates that roughly correspond to geographic latitude and longitude.The findings challenge the notion held by some that birds might be limited to navigation in the north-south direction. But scientists still don’t know how they do it. “We have experimentally shown beyond reasonable doubt that long-distance, intercontinental avian migrants can correct for east-west displacements during their return migration in spring,” said Nikita Chernetsov of the Biological Station Rybachy at the Zoological Institute in Russia. “This means that they can determine geographic longitude, even though we do not currently know how they do it.”

Latitude, which defines the location north or south, may be relatively easily defined from the position of the sun at midday or through the use of geomagnetic information, Chernetsov explained. Experimental studies by others have strongly suggested that geomagnetic cues are indeed used by avian migrants for this purpose, he said, although other cues might also be important. Longitude is trickier. Migrants could perhaps deduce their longitudinal location from the rotational phase of the starry sky, but experimental data do not support that idea, he said. Migrating birds might use a dual time-sense, relying on two internal clocks, one set to their “home time” and the other to their wintering grounds. They might also rely on geomagnetic information, but in some parts of the world that doesn’t vary with longitude, Chernetsov said.

Many previous experiments performed with young birds on their first autumn migration have suggested that the young birds rely on a very simple navigation strategy, yet few experiments had been performed on more experienced birds during the return migration in spring. “Consequently,” the researchers wrote, “our knowledge about the spatiotemporal navigation strategies of experienced migrants in spring is very sparse and rather speculative. Do birds on return migration in spring perform true navigation towards a specific goal area?” The answer, for the reed warblers at least, is yes. After the researchers dropped the migrants off many kilometers to the east, the birds corrected for their displacement by shifting their orientation from the northeast at the capture site to the northwest, the researchers reported. That new direction would lead the birds to their expected breeding areas. “Our results suggest that Eurasian reed warblers are able to determine longitude and perform bicoordinate navigation,” the researchers concluded. “This finding is surprising and presents a new intellectual challenge to bird migration researchers, namely which cues enable birds to determine their east-west position?”

Science Daily
February 19, 2008

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Quick feather test determines sex of chicks

Scientists in Germany are reporting development of test that can answer one of the most frustrating questions in the animal kingdom: Is that bird a boy or a girl? Their study is a potential boon to poultry farmers and bird breeders. Juergen Popp and colleagues point out that the boy-girl question can be difficult to answer in birds that lack distinctive, gender-related plumage. Since birds lack external genital organs, sexing a bird typically involves endoscopic examination of the animal’s gonads under general anesthesia or specific molecular biological methods. Since these methods are expensive, time-consuming, and stressful for the bird, scientists long have sought a quick, minimal-invasive sexing alternative. In the new study, researchers describe such a test, which involves analysis of tissue pulp from birds’ feathers using a highly sensitive lab instrument. The method, called ultraviolet-resonance Raman (UVRR) spectroscopy, took less than a minute, and identified the birds’ sex with 95 percent accuracy, the scientists say.

Science Daily
February 19, 2008

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Experimental infection of swans and geese with highly pathogenic avian influenza virus (H5N1) of Asian lineage

The role of wild birds in the epidemiology of the Asian lineage highly pathogenic avian influenza (HPAI) virus subtype H5N1 epizootic and their contribution to the spread of the responsible viruses in Eurasia and Africa are unclear. To better understand the potential role of swans and geese in the epidemiology of this virus, we infected 4 species of swans and 2 species of geese with an HPAI virus of Asian lineage recovered from a whooper swan in Mongolia in 2005, A/whooper swan/Mongolia/244/2005 (H5N1). The highest mortality rates were observed in swans, and species-related differences in clinical illness and viral shedding were evident. These results suggest that the potential for HPAI (H5N1) viral shedding and the movement of infected birds may be species-dependent and can help explain observed deaths associated with HPAI (H5N1) infection in anseriforms in Eurasia.

Black swans were the most susceptible species examined in this study; 100% died within 2–3 dpe. Most black swans were found dead without having exhibited any clinical signs of disease. When disease was observed, it lasted for <24 hours, and clinical signs included severe listlessness and neurologic dysfunction consisting of seizures, tremors, and marked incoordination. Influenza viral antigen was detected primarily in endothelial cells lining the blood vessels throughout most visceral organs and the brain. Microscopic examination showed that all black swans that died had widespread multiorgan necrosis with mild acute inflammation, which was strongly correlated with the distribution of the virus. All of the black swans shed virus before death and, as with all birds in this study, titers were higher in respiratory secretions than in feces. All waterfowl that died shed virus in respiratory secretions and feces; shedding generally increased with time and reached a maximum within 24–48 hours of death. Susceptibility was similar in the remaining 3 species of swans. Disease and death occurred later in these species, and the duration of illness, with 1 exception, was longer. Clinical signs consisted of mild to moderate listlessness, which progressively worsened to severe listlessness with neurologic signs similar to those observed with the black swans. Viral antigen was detected in the neurons, astrocytes, and other parenchymal cells of the brain and most of the examined visceral organs, as opposed to the vasculotropic distribution in black swans. Microscopic lesions were strongly associated with the anatomic location of detectable viral antigen and consisted of multifocal to coalescing necrosis with mild to moderate heterophilic inflammation. Within this category, the Mongolia/2005 virus infection in mute swans was unique. Clinical signs occurred later (5–7 dpe) in mute swans than in any of the other species examined in this study. The duration of disease in mute swans was extremely short (<24 hours) and comparable to the duration of disease in black swans. The clinical signs observed in mute swans were similar to those in the whooper and trumpeter swans. Birds in all 3 of these species shed high concentrations of virus in respiratory secretions with maximum titers approximating those of the black swans. The 2 species of geese differed in their susceptibility to the Mongolia/2005 virus and both were less susceptible than the swan species. All of the cackling geese became sick after inoculation with the Mongolia/2005 virus, but only 3 of the 4 birds died and the remaining bird slowly recovered until clinical signs of disease were no longer apparent. The cackling geese that died exhibited severe listlessness and marked neurologic signs similar to those observed in the swans. The single goose that survived became moderately listless with ruffled feathers and cloudy eyes before clinical signs resolved but did not exhibit neurologic clinical signs during the study. This goose produced postexposure antibodies to AIV that were detected by the AGP and HI tests. Cackling geese that died had a short duration of illness (average duration 1.67 days) as opposed to the goose that survived, which exhibited detectable clinical signs for 9 days before resolution. Viral antigen in the 3 geese that died was restricted to the brain, pancreas, liver, and adrenal gland. Microscopic lesions primarily involved these organs and included multiple foci of necrosis with moderate heterophilic to lymphoplasmocytic inflammation. The single goose that survived had minimal amounts of viral antigen in the neurons of the brain and mild perivascular encephalitis. The surviving goose also shed lower concentrations of virus (maximum oropharyngeal titer 103.9 EID50/mL) than the 3 geese that died (average maximum oropharyngeal titer 105.7 EID50/mL), but the duration of shedding was approximately similar in both oropharyngeal and cloacal swabs. Bar-headed geese were the least susceptible of the 6 species examined in this study. All 5 of the geese infected with the Mongolia/2005 virus exhibited clinical signs of infection; 2 of these birds died, and the remaining 3 became ill, but the clinical signs slowly resolved until they were no longer apparent. The duration of clinical signs and onset of illness and death were similar to those of the cackling geese. The bar-headed geese that died exhibited severe depression and neurologic signs. The 3 geese that survived became mildly depressed with transiently cloudy eyes but did not exhibit neurologic signs. The duration of disease was longer for the geese that survived (average duration 5.33 days) than for the geese that died (average duration 2.50 days). All 3 of these surviving geese produced antibodies to AIV that were detected by the AGP and HI tests. Viral antigen and microscopic lesions in bar-headed geese were primarily present in the brain. Viral antigen staining was more widespread in the 2 geese that died than in the 3 that survived. Microscopic lesions consisted of moderate perivascular encephalitis and neuronal necrosis in geese that died and mild perivascular encephalitis in birds that survived. The concentration and duration of viral shedding were similar between bar-headed geese that died and those that survived. Cloacal shedding was detected in all of the bar-headed geese except one, which was one of the surviving birds. Emerging Infectious Diseases
February 5, 2008

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Barrier to bird flu transmission found in humans

An electron micrograph picture shows the H5N1 virus binding to human lung cells. Umbrella-shaped sugars that decorate proteins in the nose and throat could be preventing widespread human-to-human transmission of avian flu, new research suggests. Whereas normal winter flu viruses easily latch onto these sugars, the H5N1 virus that causes bird flu cannot. This helps to prevent it from colonizing the upper respiratory tract — a key step in triggering an epidemic. The results could someday lead to new therapeutic approaches to treat or prevent the disease. But more immediately, the findings could also provide health officials with a way to test whether a newly emerging strain is likely to spark a human-to-human epidemic. There have been rare cases of people catching bird flu from others living in close quarters. Instances of ‘clusters’ of bird flu in people periodically raise concerns that the virus may be mutating to become more transmittable in humans, potentially starting a pandemic.

A few genetic changes have been identified that are thought to help bird viruses latch onto human — rather than avian — cell receptors more effectively, to survive in the cool nasal regions of the respiratory tract, and to target receptors in the nose and throat rather than the lungs. Despite these changes, widespread human-to-human transmission hasn’t yet kicked in; work in animal models has shown that these mutant H5N1 viruses still are not transmitted efficiently. When looking for parts of the virus that make it more dangerous to humans, researchers have mainly focused on H5N1’s ability to bind characteristic sugar chains found on proteins of the human upper respiratory tract. The composition of those sugars differs between birds and humans, and among different regions of the body. A virus that can’t bind to human throat sugars is unlikely to establish an infection there. But the focus has traditionally been on how the virus interacts with the types of chemical linkages in these sugars, rather than with the sugar’s shape, says Carole Bewley, a virologist at the National Institutes of Health in Bethesda, Maryland, who was not involved with this work. “We tend to draw carbohydrate structures as chemical structures on two-dimensional pieces of paper,” says Bewley. “But that doesn’t really give us an idea of what they look like three-dimensionally. And that’s really a neglected area.”

Now Ram Sasisekharan of the Massachusetts Institute of Technology in Cambridge and his colleagues have found that those three-dimensional structures matter. In a survey of human and avian flu viruses, they observed that avian viruses bind shorter sugar chains that form cone-shaped structures. Successful human flu viruses, on the other hand, were able to bind larger, umbrella-shaped sugars that are particularly common in the human nose and throat. The results are published online today by Nature Biotechnology. The H5N1 strains that were tested all lacked the ability to bind to these umbrella-shaped sugars. But they could develop this ability. Sasisekharan estimates that it may take only two or three amino-acid changes in a single viral protein to allow the virus to latch on to the umbrella-shaped sugars. “It does not take a lot to switch that specificity,” says Sasisekharan. “The key question is to find out what combination of amino acids it takes to allow that.” Sasisekharan and his colleagues have thus far only tested nine flu virus strains, including four human flu varieties, two non-H5 avian flu varieties, and three reference avian flu strains provided by the US Centers for Disease Control and Prevention. They have not yet tested recent H5N1 isolates, such as the culprits behind a cluster in Pakistan in late 2007, or a similar cluster found in Turkey in 2006. If their finding holds true as more viruses are examined, it will be “incredibly valuable” information, says Bewley. Emerging H5N1 strains could be tested for their ability to bind umbrella-shaped sugars, allowing researchers to quickly pinpoint strains likely to fuel an epidemic.

Nature
January 22, 2008

Original web page at Nature

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UK bird flu outbreak confirmed as H5N1

The H5N1 bird flu virus has been confirmed in three dead swans on a nature reserve in Dorset, on the south coast of England. The outbreak, coming barely two months after H5N1 killed domestic turkeys on a farm 500 kilometres away, raises the possibility that the virus could be lurking in the UK’s wild bird population. “While this is obviously unwelcome news, we have always said that Britain is at a constant low level of risk of introduction of avian influenza,” said acting chief veterinary officer Fred Landeg on announcing the finding on Thursday. This is the fourth time H5N1 has been found in Britain. The first time was in a dead wild whooper swan in Scotland. It was not clear whether that bird became infected in Britain or migrated in while carrying the virus. The subsequent two outbreaks were on turkey farms in the county of Suffolk in February and November 2007. Both were located near nature reserves with migrant ducks, which are known to carry H5N1.

The site of the current outbreak, picked up by routine surveillance, is a swannery originally established by 11th century monks, and now a tourist attraction. It hosts hundreds of swans and other aquatic birds, including migrants. Dead swans have been found across Europe where there have been local outbreaks of H5N1, and are considered a sensitive indicator of the presence of the virus in wild bird populations. The birds found in Dorset were mute swans, which do not generally migrate long distances. “The outbreak of H5N1 virus…in November was thought to have been spread to turkeys from wild fowl that may have migrated from Europe,” said John McCauley of Britain’s National Institute For Medical Research in London. “The swans infected in Dorset are not of a species that undergoes significant migration, but it is likely that the mute swans mix with waterfowl from regions in which H5N1 infection is more common.”

New Scientist
January 22, 2007

Original web page at New Scientist

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Eating chocolate and the risk of dying

It was a sorry end. Cut down in his prime, the cunning thief lay on the slab, his cold body offering pathologist Brett Gartrell no outward sign of how he had met his maker. Once Gartrell had wielded his scalpel, however, the cause became clear: a belly stuffed with sticky brown gunk. Diagnosis? Death by chocolate. Divine – yes. Delicious – absolutely. But deadly? For some it certainly is. The corpse on Gartrell’s slab belonged not to a human but to a kea, an endangered New Zealand parrot. Like many animals, keas are acutely sensitive to chemicals in chocolate that are harmless to humans in all but huge doses. Scientists are now studying these chemicals, along with other substances in cocoa, hoping to exploit their toxic effects to control pests or microbes. If you’re reading this after scoffing your fifteenth chocolate Santa, don’t panic: we humans have been safely enjoying the beans of the cacao plant, Theobroma cacao, for millennia. Theobroma is Greek for “food of the gods”, reflecting the Mayan belief that cocoa had divine origins. Every April, they sacrificed a dog with cacao-coloured markings in honour of Ek Chuah, the god of cacao.

Knife-wielding priests aside, chocolate is still bad news for many animals. Cocoa beans are naturally rich in caffeine and its chemical relatives theobromine and theophylline, collectively called methylxanthines. To humans these are little more than benign stimulants, but to a number of animals they are highly toxic. Just 240 grams of unsweetened dark chocolate contains enough methylxanthines to kill a 40-kilogram dog, about the size of a German shepherd. It was methylxanthines that did for the kea too. Gartrell, a wildlife pathologist at Massey University in Palmerston North, New Zealand, is wearily familiar with keas’ propensity to poison themselves. Besides being arguably the world’s smartest birds, keas are extraordinarily inquisitive foragers, using their beaks to rip open tents and backpacks, open garbage bins and even pry pieces off cars in their quest for food. “They’ll try anything that is vaguely edible, which is part of the reason they get into trouble,” says Gartrell.

The dead kea was found outside a hotel kitchen in the holiday resort of Mount Cook Village in the Southern Alps. It had eaten more than 20 grams of dark chocolate, presumably pilfered from the kitchen garbage (New Zealand Veterinary Journal, vol 55, p 149). “He’d really pigged out,” says Gartrell. The ill-fated kea was by no means alone in its folly. Veterinary journals are peppered with stories of dogs, cats, parrots, foxes, badgers and other animals dropping dead after finding chocolate or being fed it by well-meaning humans. “The dead kea had eaten more than 20 grams of dark chocolate, pilfered from the kitchen garbage” The reason humans don’t turn up their toes after bingeing on chocolate is largely down to the speed at which our bodies metabolise theobromine, the most abundant methylxanthine in chocolate. Rats metabolise it much more slowly than humans, and dogs are slower still. There are no reliable figures for theobromine toxicity in humans, but based on caffeine toxicity an average adult would have to gorge on around 50 kilograms of milk chocolate in a single sitting to get anywhere near a lethal dose.

The observation that methylxanthines are highly toxic to animals, with dogs being especially vulnerable, prompted John Johnston, a chemist at the US Department of Agriculture in Fort Collins, Colorado, to investigate chocolate as a more selective way of controlling coyotes (Journal of Agricultural and Food Chemistry, vol 53, p 4069). Coyotes are a serious pest in the US, killing $44 million worth of livestock each year, damaging property and attacking people and pets. Measures such as fences are often ineffective. Sometimes culling them is the only option but unfortunately the poisons now used, such as sodium cyanide, are toxic to humans and most other animals too. “If we can come up with something that is more selective, it offers an advantage,” says Johnston. “It’s a more responsible approach.” Methylxanthines looked as though they might fit the bill. After testing the toxicity of several different types of chocolate, Johnson came up with a mixture of theobromine and caffeine that killed coyotes quickly and with minimal distress. The mixture can be hidden in bait and is currently undergoing field tests.

Methylxanthines are also shaping up as a way to dispatch other pests. Earl Campbell of the US Pacific Basin Agricultural Research Center in Hilo, Hawaii, discovered that caffeine sprays could kill two species of noisy and ecologically damaging Caribbean tree frogs that have plagued the island since they were accidentally introduced in the 1980s. Campbell noticed that the spray also killed slugs. His colleague Robert Hollingsworth then found that caffeine spray made snails kick the bucket too (Nature, vol 417, p 915). Hollingsworth is now developing caffeine as an alternative to conventional pesticides, such as those used in slug pellets. “There’s a huge amount of interest in using botanical extracts,” he says. “People are more comfortable with things that are natural.” The methylxanthines are just a start. “Cocoa is a real gold mine of different components,” says Herwig Bernaert, research manager at Barry Callebaut, a chocolate manufacturer in Zurich, Switzerland. Cocoa contains more than 700 compounds and there is a great deal of research on which of these can affect people or other creatures. Some of these compounds, such as the flavonoids, have commanded a lot of attention for their apparent health benefits, but researchers are also keen to exploit chocolate’s more sinister side.

Some studies suggest cocoa extracts can prevent Helicobacter pylori, the bacterium that causes stomach ulcers, from setting up shop in the lining of the gut. Others suggest that the extracts block the growth of disease-causing strains of the gut bacterium E. coli. Compounds isolated from chocolate could even be used to prevent tooth decay. Phil Marsh, a microbiologist at the Leeds Dental Institute in the UK, reported last year that a cocoa extract rich in polyphenols discouraged mouth bacteria from sticking to teeth and forming plaque. It also reduced the tooth-rotting powers of the bacterium Streptococcus mutans by reducing its ability to produce acid (European Journal of Oral Sciences, vol 114, p 343). But if you think that means it’s time to ditch the toothpaste and reach for that jumbo jar of chocolate spread instead, forget it. There’s far too little of these polyphenols in chocolate to outweigh the damage that will be done by all the sugar it contains. “There are many other compounds in a chocolate bar that would overwhelm any benefit of the polyphenol,” Marsh warns. As manufacturers fall over themselves to advertise chocolate’s health-boosting potential, there’s a wry satisfaction to be had in knowing that its sinister side is being put to good use too. While this may be good news for us, just make sure your furry or feathered friends can’t get their sticky paws or claws on it.

New Scientist
January 8, 2008

Original web page at New Scientist

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Protection and virus shedding of falcons vaccinated against influenza A virus (H5N1)

Because fatal infections with highly pathogenic avian influenza A (HPAI) virus subtype H5N1 have been reported in birds of prey, we sought to determine detailed information about the birds’ susceptibility and protection after vaccination. Ten falcons vaccinated with an inactivated influenza virus (H5N2) vaccine seroconverted. We then challenged 5 vaccinated and 5 nonvaccinated falcons with HPAI (H5N1). All vaccinated birds survived; all unvaccinated birds died within 5 days. For the nonvaccinated birds, histopathologic examination showed tissue degeneration and necrosis, immunohistochemical techniques showed influenza virus antigen in affected tissues, and these birds shed high levels of infectious virus from the oropharynx and cloaca. Vaccinated birds showed no influenza virus antigen in tissues and shed virus at lower titers from the oropharynx only. Vaccination could protect these valuable birds and, through reduced virus shedding, reduce risk for transmission to other avian species and humans.

Emerging Infectious Diseases
December 11, 2007

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Avian influenza, poultry vs. migratory birds: Europe

The avian influenza virus H5N1 could become entrenched in chickens and domestic ducks and geese in parts of Europe, FAO warned. The agency stressed that healthy domestic ducks and geese may transmit the virus to chickens and play a more important role in the persistence of the virus in the region than previously thought. H5N1 surveillance in countries with significant domestic duck and geese populations should be urgently increased. FAO’s warning followed the detection of H5N1 in diseased young domestic ducks by German scientists. “It seems that a new chapter in the evolution of avian influenza may be unfolding silently in the heart of Europe,” said FAO’s Chief Veterinary Officer, Joseph Domenech. “If it turns out to be true that the H5N1 virus can persist in apparently healthy domestic duck and geese populations, then countries need to urgently reinforce their monitoring and surveillance schemes in all regions with significant duck and geese production for the presence of H5N1. Europe should prepare for further waves of avian influenza outbreaks, most probably in an east-west direction, if the virus succeeds in persisting throughout the year in domestic waterfowl. This heightens the need for increased surveillance and monitoring of possible virus circulation in domestic ducks and geese.”

The link between domestic ducks and geese and chickens is seen by many experts as one of the major underlying factors in outbreaks of HPAI in disease-entrenched countries. “We are particularly concerned about the Black Sea area, which has a high concentration of chickens, ducks and geese,” said FAO senior animal health officer Jan Slingenbergh. “In the Ukraine alone, the number of domestic ducks is estimated at around 20 million birds. In Romania, 4 million domestic ducks and 4 million domestic geese are found in the Danube delta. These figures compare easily with chicken and waterfowl densities in Asia, where the virus continues to circulate among chickens and has found a niche in countries with tens of millions of domestic ducks and geese,” Slingenbergh said. Importantly, the Black Sea area serves as a main wintering area for migratory birds coming from Siberia and moving also to the Mediterranean and other regions. All countries bordering the Black Sea have experienced outbreaks of avian influenza in the past, favored by traditional open poultry systems with poor separation between wild and domestic birds.

The link between the H5N1 virus and domestic ducks and geese has recently been confirmed in Germany. Scientists of the Friedrich-Loeffler-Institut in Riems detected the H5N1 virus in diseased young ducks on a farm at the end of August 2007. Further scrutiny at 2 other farms revealed that, despite the absence of clinical signs and mortality in these ducks, the animals had been in contact with the H5N1 virus, because their immune defense system showed antibodies developed in response to the virus. Intensified monitoring finally confirmed pockets of H5N1 on one of the farms. Based on its experience in fighting avian influenza around the world over the past 3 years, FAO considers that risk assessment, surveillance and virus search strategies should be reviewed, Domenech said. Countries with significant domestic duck and geese populations in Western and Central Europe as well as the Black Sea region should consider the incident in Germany as a wake-up call and should not limit the virus search to chickens. Good surveillance is already in place in many European countries, and the European Commission issued in 2007 very comprehensive guidelines. But there are countries in which more monitoring is urgently needed, including more focus on ducks and geese, which should be considered as particularly risky populations.

“It could well be that there is more virus circulation in Europe than currently assumed,” Slingenbergh said. “We are not saying that the virus is widely spread in European countries; in fact, most of the countries are currently virus-free. But undetected localized virus spots in countries with significant waterfowl may pose a continuous risk. “After Asia and Africa, Europe could become the 3rd continent in which H5N1 could become endemic in some areas, FAO said.

ProMed mail
December 11, 2007

Original web page at ProMed mail

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Gene implicated in human language affects song learning in songbirds

Do special “human” genes provide the biological substrate for uniquely human traits, like language? Genetic aberrations of the human FoxP2 gene impair speech production and comprehension, yet the relative contributions of FoxP2 to brain development and function are unknown. Songbirds are a useful model to address this because, like human youngsters, they learn to vocalize by imitating the sounds of their elders. Previously, Dr. Constance Sharff and colleagues found that, when young zebra finches learn to sing or when adult canaries change their song seasonally, FoxP2 is up-regulated in Area X, a brain region important for song learning.

Dr. Sebastian Haesler, Dr. Scharff, and colleagues experimentally reduce FoxP2 levels in Area X before zebra finches started to learn their song. They used a virus-mediated RNA interference for the first time in songbird brains. The birds, with lowered levels of FoxP2, imitated their tutor’s song imprecisely and sang more variably than controls. FoxP2 thus appears to be critical for proper song development. These results suggest that humans and birds may employ similar molecular substrates for vocal learning, which can now be further analyzed in an experimental animal system.

Science Daily
December 11, 2007

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Scientists monitor the brains of homing pigeons on the wing

Neuroscientists have fitted pigeons with recorders that pick up brain activity as the birds fly. The devices confirm that the birds really do use features from a landscape to find their way home. And researchers hope that they will be able to use the caps to unpick how birds use other types of navigational signals at different points in a journey. Scientists are pretty sure from tracking experiments that pigeons use the Sun, Earth’s magnetic field and possibly smells as guiding cues when navigating. In 2004, Hans-Peter Lipp, a behavioural neuroscientist from the University of Zürich in Switzerland, showed that pigeons probably also use visual information. He noted that the birds tend to turn when they hit obvious landmarks like a highway exit. These tracking experiments collected good information about the birds’ location, by fitting modern global positioning system (GPS) loggers to the pigeons’ backs. But no-one has been able to measure directly what information the pigeon are using to navigate — no one has accessed the pigeons’ thoughts in flight.

“If we see a bird continuing along its path after crossing a bump in the magnetic field that would normally cause it to change direction — is this because it failed to sense the information or had a good reason to ignore it?” asks Lipp. “What’s going on in their minds?” To find out, Lipp teamed up with Alexei Vyssotski, a biological engineer, to develop tiny electroencephalogram (EEG) recorders that can pick up electrical signals from the brain, and coupled them to GPS loggers. They fitted devices on the heads of anaesthetized pigeons that lived in a loft inland of the Italian coast, near Rome. Tiny screws kept the instrument in place on the birds skulls, and served as EEG electrodes. Tracking reveals how brain patterns change over geographic features. Then they sailed the pigeons across the Mediterranean and released them some 50 kilometres from home. When they analysed the simultaneous GPS positions and the EEG-recorded brain waves, the team found only low and high frequency waves as the birds flew over the featureless sea — probably a sign of normal brain activity. But fluctuating levels of mid-frequency waves emerged as soon as the birds began to fly over the land. The mid-frequency waves they saw (of 12–60 Hertz) are the same as those seen in mammals when they start to pay attention to something. To be sure that these frequencies really were relevant to the navigational task, the team did another series of experiments closer to home. The researchers released the birds 5 kilometres away from their loft, requiring them to fly over a highway exit that Lipp knew, from his 2004 study, the birds used as a major landmark. The intensity of the mid-frequency band increased when the pigeons approached and crossed this highway exit.

Nature
November 27, 2007

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For migrating sparrows, kids have a compass, but adults have the map

Even bird brains can get to know an entire continent — but it takes them a year of migration to do so, suggests a Princeton research team. The scientists have shown that migrating adult sparrows can find their way to their winter nesting grounds even after being thrown off course by thousands of miles, adjusting their flight plan to compensate for the displacement. However, similarly displaced juvenile birds, which have not yet made the complete round trip, are only able to orient themselves southward, indicating that songbirds’ innate sense of direction must be augmented with experience if they are to find their way home. “This is the first experiment to show that when it comes to songbird migration, age makes a difference,” said team member Martin Wikelski, an associate professor of ecology and evolutionary biology. “The results indicate that the adult birds possess a navigational map that encompasses at least the continental U.S., and possibly the entire globe.”

Two longstanding questions about migrant songbirds are how quickly they recover when thrown off course — as they can be when they encounter powerful winds — and just what navigational tools they use to do so. To address the two questions, the team decided to fit a group of white-crowned sparrows with tiny radio transmitters no heavier than a paper clip and track their movements from a small plane. The team first brought 30 sparrows to Princeton from northern Washington state, where the birds had been in the process of migrating southward from their summer breeding grounds in Alaska. Half the birds were juveniles of about three months in age that had never migrated before, while the other half were adults that had made the round trip to their wintering site in the southwestern United States at least once. After the birds were released, they attempted to resume their migration, but both age groups grew disoriented quickly. “All the birds scattered at first,” Wikelski said. “It was clear they were turned around for a couple of days. But while the adults eventually realized they had to head southwest, the younger birds resumed flying straight southward as though they were still in Washington.”

The adults, said team member Richard Holland, recovered their bearings because they possess something the younger birds do not, which is an internal map. “These birds need two things to know where they are and migrate effectively: a ‘map’ and a ‘compass,'” said Holland, a postdoctoral research associate in Wikelski’s lab. “What we’ve found is that juveniles use their compass, but the adults also use their map.” Holland said the birds do not lose the compass as they age, but somehow develop the map, eventually applying both tools to keep on track during migratory flights. Scientists already have determined that the compass is based on the sun or the magnetic field, but where the map comes from remains a mystery — one that the team will be exploring in coming years. “It could be the map also derives from the planet’s magnetic field,” Holland said. “But there are so many local magnetic anomalies in the Earth’s crust that it’s also possible they are navigating by sense of smell. It sounds crazy, but there’s a lot of evidence that homing pigeons navigate this way, so we need to investigate that idea further.”

Science Daily
November 27, 2007

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Cell death in sparrow brains may provide clues in age-related human diseases

A remarkable change takes place in the brains of tiny songbirds every year, and some day the mechanism controlling that change may help researchers develop treatments for age-related degenerative diseases of the brain such as Parkinson’s and dementia. Writing in the Proceedings of the National Academy of Sciences, researchers from the University of Washington and the University of California, Berkeley, report a striking shrinkage in the size of the brain regions that control singing behavior of Gambel’s white-crowned sparrows. This transformation is triggered by the withdrawal of testosterone, a naturally occurring steroid hormone, and is apparent within 12 hours. The study is the first to report such rapid regression of brain nuclei caused by the withdrawal of a hormone and a change in daylight conditions in adult animals.

“The changes are substantial,” said Christopher Thompson, lead author of the study and a UW doctoral student in neurobiology and behavior. “First, the volume of a song-control region called the HVC collapses 12 hours after testosterone is removed from circulation. Then, by four days, thousands of HVC neurons are lost. We have good reason to believe that they are killed by a cell suicide program call apoptosis.” Co-authors of the study are Eliot Brenowitz, a UW professor of psychology and biology, and George Bentley, a former UW postdoctoral researcher who is now a UC Berkeley assistant professor of integrative biology. The research mimicked the natural seasonal changes that occur in the brains of the sparrows. Their song-control regions expand in the spring and summer leading up to the breeding season, as they use songs to establish territories and attract mates in Alaska. Later in the summer, as the birds get ready to migrate back to California, the same brain regions shrink.

“We’ve seen seasonal changes in the brains of fish, reptiles, amphibians, birds and mammals such as gerbils, mice, and even in humans,” said Brenowitz. “However, the magnitude of changes in birds far exceeds that seen in other animals.” To better understand what happens in the sparrows’ brain, the researchers received federal and state permits to capture 25 of the migrating male birds in Eastern Washington. Next, they housed the birds for 12 weeks before exposing them to 20 days of long-day conditions comparable to the natural lighting the sparrows would experience in Alaska during the breeding season. The birds were also implanted with testosterone. At the end of 20 days, six of the birds were euthanized and the remaining 19 were castrated and testosterone implants were removed so there would not be any circulating testosterone in their systems. After 12 hours five more birds were euthanized and the remainder were euthanized at 2, 4, 7 and 20 days. These procedures were done with the approval of the UW’s Institutional Animal Care and Use Committee and the National Institute of Mental Health. The latter funded the research.

The researchers found that the size of the HVC region decreased 22 percent within 12 hours after the withdrawal of testosterone and that the number of neurons in this song-control region fell by 26 percent after four days. In addition, the size of two other song-control regions called Area X and the RA significantly regressed after 7 and 20 days, respectively. Thompson said there are a number of potential medical implications relating to age-related degenerative diseases and conditions marked by declining mental abilities from this study. “Having an animal model system with such robust neurodegeneration could be very useful in uncovering the mechanisms that underlie these kinds of diseases,” he said. “We will be looking at the molecular mechanisms of what happens when testosterone is removed. As men age, circulating levels of testosterone decrease, and other researchers have shown that this decline may contribute to cognitive impairment, brain disorders and neuron death.” Brenowitz added: “There is no reason to think that these processes are restricted to birds. They are very similar to what happens in some mammals. This study shows that regions of the brain that are hormonally sensitive are going to regress without testosterone. The flip side is that hormones such as testosterone protect neurons, so perhaps some form of hormone therapy may provide protection. Steroids such as testosterone are very potent and have wide implications for effects on the brain.”

Science Daily Health & Medicine
October 2, 2007

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Birds may ‘see’ magnetic north

How do migrating birds perceive which way is north? Research now points to the idea that they actually ‘see’ the Earth’s magnetic fields, rather than feeling or sensing them in some other way. Previous work has suggested that the Earth’s magnetic field might act on the sensitivity of a migratory bird’s eye, so that sight might be involved in finding magnetic north. Now researchers have firmed that up with evidence that molecules in the eyes of migratory birds are connected to the part of the brain that guides their direction of flight. Dominik Heyers, at the University of Oldenburg, Germany, and colleagues injected migratory garden warblers (Sylvia borin) with a tracer capable of travelling along neuronal fibres along with nerve signals. They injected one tracer into the part of the forebrain known to be the only active area when birds orient themselves (known as Cluster N), and a different tracer into the retina.

After a bird experienced a desire to migrate, both tracers ended up in the same place, the researchers report in the Public Library of Science One — a part of the thalamus responsible for vision. This anatomical link strongly supports the notion that the birds probably experience magnetic fields as a visual sensation, say the researchers. It has previously been suggested that proteins called cryptochromes in the eyes of migratory birds might play a role in their compass-like ability. The idea is that these cryptochromes might be sensitive to the electronic state of radical pairs. These pairs can exist as singlet or triplet states, and the relative proportions of these states is in turn influenced by the orientation of the molecules in the eye relative to the Earth’s magnetic field or any other magnetic field that the birds are exposed to. “This means that if a bird looks in a certain direction, the magnetic north might be seen as a dark spot,” says Heyers, although he adds that the precise way the birds see that magnetic field is subject to a bit of guess work: “we cannot ask the birds how they see it.”

Heyers’s work showing a connection between the retina and Cluster N is a “great result”, says Miriam Liedvogel, who studies migration at the University of Oxford, UK. But in her opinion it isn’t enough to prove the hypothesis that birds can ‘see’ magnetic fields, she adds. She’d like to see experiments where changing the magnetic field is conclusively shown to change neuronal activity in the thalamus, she says. And this will not to be the end of the story of how birds find their way. Other work has shown that migratory birds also have magnetic crystals in their beaks that are involved in navigation. Heyers thinks that the two systems probably exist to complement each other, with the beak being used to measure the strength of magnetic field as a kind of map, and the cryptochromes in the eyes acting as a compass.

Nature
October 2, 2007

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Old eggs show Adélie penguins switched from fish to shrimp 200 years ago

Ancient eggshell fragments show that Adélie penguins living in Antarctica switched from eating fish to krill around the time that humans began hunting seals and whales. The finding suggests that when humans removed krill-eating predators the penguins exploited the resulting shrimp surplus. Steven Emslie of the University of North Carolina in Wilmington, and William Patterson of the University of Saskatchewan in Saskatoon, analysed more than 220 fossil eggshell pieces ranging from 100 to 38,000 years old, and compared them with samples from modern nests. By comparing the proportion of certain forms of carbon and nitrogen in the shells with the proportions found in fish and krill, the researchers could tell what the birds had been eating. Emslie expected to find changes in diet matching climate change. Instead, the penguin menu remained biased towards fish until about 200 years ago, when the birds switched to krill. Recent global warming and the rise in krill fisheries has reduced krill stocks and could be contributing to the decline in Adélie penguin populations on the Antarctic Peninsula, says Emslie. The study is published in the Proceedings of the National Academy of Sciences.

From 1793 to 1807, an estimated 3.2 million seals were taken from the Southern Ocean. The resulting crash in the seal population — including the Antarctic fur seal Arctocephalus gazella, which fed primarily on krill — caused the industry to collapse. Whaling took off in the 1800s and continued until the mid-twentieth century, eventually depleting baleen whale populations by more than 90%. It’s estimated that the combined harvest of seals and whales resulted in more than 150 million tonnes of extra krill each year. Krill is an attractive food for penguins because it is high in protein and tends to travel in swarms. “The birds can capture lots of high-energy prey in a short time,” says Emslie. “This implies a huge ecological dietary response by the penguins in relation to some change in their environment,” says Keith Hobson of the Canadian Wildlife Service in Saskatchewan. But the reasons behind this switch are less obvious, he says.

“Abundance of a secondary food item does not necessarily explain this unless it was accompanied by a reduction in fish,” says Hobson. “Why does it matter that krill became more abundant to a predator that previously happily made eggs from fish?” The switch might be explained by an increase in fishing, says David Ainley of the California ecological consulting firm H. T. Harvey & Associates. “Not only were whales and seals removed,” he says, “there was a massive removal of fish from the Scotia Sea and western Antarctic Peninsula region at the same time.” Many of these fish ate krill, so their removal would have further boosted krill supplies. Their dietary flexibility demonstrates the penguins’ ability to adjust to large ecological changes, but that doesn’t mean they’ll survive the changes to come, says Hobson. “I remain a pessimist when it comes to how they may now cope with the onslaught of climate change,” he says.

Nature
August 21, 2007

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Chernobyl hits birds hard

Entire populations of birds have dwindled because of radiation from the nuclear power plant in Chernobyl, but some species are declining in number at a rate far greater than others are, a new study finds. The greatest drops are in species whose lifestyle or appearance, such as vibrant plumage, calls for plenty of antioxidants–a substance also needed to protect against radiation. Ionizing radiation creates free radicals that can wreak havoc on a cell’s DNA, sometimes killing the organism. A class of antioxidants called carotenoids, however, can swoop in and neutralize free radicals. Carotenoids also perform lots of other functions in many birds, such as coloring dazzling plumage, sustaining metabolism during long migrations, and nourishing the eggs birds lay. Some evidence suggests birds that make heavy use of carotenoids have lower levels of carotenoids–for example, birds that have just completed a migration.

An event like the Chernobyl disaster mobilizes a body’s antioxidant supply to quell the sudden surge of free radicals. Evolutionary ecologists Anders Møller at Pierre and Marie Curie University in Paris and Tim Mousseau at the University of South Carolina in Columbia wondered if bird species that rely heavily on carotenoids for other purposes may suffer more from radiation exposure. The two decided to investigate whether radiation had different effects on different bird communities within 50 km of the reactor. Møller recorded all birds seen or heard in a span of 5 minutes at 254 places near Chernobyl, with some of the places having high levels of radiation and some of them having normal levels of background radiation. They counted half as many brightly colored orioles, blackbirds, and blue tits, for example, than predicted from bird counts in the places with little radiation. Yet birds with duller plumage–such as tree pipits, coal tits, and chaffinches–had roughly the same size populations throughout the area. Similar patterns held for migratory birds: Orioles, blackbirds, and robins had reduced numbers, whereas homebodies like great tits, coal tits, and song thrushes didn’t, Møller and Mousseau report today in Journal of Applied Ecology.

Interestingly, resident birds fared better than those that migrate in and out of the Chernobyl area. Mousseau suggests it’s because migrating birds exhaust so much of their antioxidant supply on their high metabolism. “It’s not the exposure to radiation that’s most important,” he explains. “It’s whether defenses”–carotenoid stores–“are diminished.” Based on earlier studies of barn swallows, they theorize that the birds either died out or had drops in reproduction, and did not simply settle in other areas with lower radiation. Mousseau says they hope to test that theory by tracking populations of birds and measuring their carotenoid levels. Jonathan Blount, a physiological ecologist at the University of Exeter in Cornwall, U.K., agrees that the research “shows certain species of birds are more vulnerable than others to effects of radiation.” He adds that plumage color may serve as an indicator of population health, which would offer an easy way to monitor vulnerable species.

ScienceNow
August 21, 2007

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Fighting for flamingos

The world’s most important breeding site for lesser flamingos, whose colorful gatherings at East Africa’s Rift Valley lakes are one of the continent’s greatest spectacles, will be threatened if an industrial building plan in Tanzania goes forward, conservationists are alleging. Although the proposal has not yet gained government approval, the first public presentation of the plan’s details at a meeting yesterday brought protests from conservation groups, which dispute claims that the birds’ breeding sites would not be harmed. Fast Africa hosts about 2 million lesser flamingos (Phoenicopterus minor), about 75% of the world’s population. In recent years, unexplained mass die-offs of thousands of the birds at various Rift Valley lakes have alarmed conservationists (Science, 22 September 2006, p. 1724). Now they are crying foul over a plan, first aired last year, to build a soda-ash plant at Lake Natron, the only known East African breeding place for the species.

The plan is a joint venture between Tata Chemicals, of Mumbai, India, and Tanzania’s National Development Corporation, a federal economic development agency. It calls for a new road and power station, as well as facilities for the 1200 workers needed to build the plant, which would extract sodium carbonate from the alkaline lake for export. At Thursday’s meeting in Tanzania’s capital, Dar es Salaam, consultants for the industrial group presented sections of its draft environmental impact report and sought comments from conservationists, including ornithologist Brooks Childress of the British-based Wildfowl and Wetlands Trust. He contends that even minor changes to Lake Natron’s water level, chemistry, or quiet environment could interfere with flamingo breeding. The lake’s “protection and preservation are crucial to the survival of the lesser flamingo,” he told ScienceNOW in an e-mail. Childress heads the Wetlands International specialist group that is drafting a flamingo protection plan that could be added to international migratory bird treaties.

Another critic of the project, Chris Mangin of the British-based Royal Society for the Protection of Birds, said in a statement “the chances of lesser flamingos continuing to breed at Lake Natron in the face of such mayhem are next to zero.” Lota Melamari, chief executive of Tanzania’s Wildlife Conservation Society, told ScienceNOW after the meeting that representatives of the joint venture promised to consider conservationists’ objections in refining the plan. But he says more details about the project are needed for an accurate assessment of its impact on wildlife. A representative for Tata Chemicals in Tanzania declined to comment; the company hopes for a government decision on the project by year’s end.

ScienceNow
August 21, 2007

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Cats could be scaring birds out of our cities

Are cats frightening birds so much that they don’t breed? Andy Beckerman and colleagues from the University of Sheffield, UK, think fear of cats may explain the ongoing fall in urban bird numbers. Many accusatory fingers point to the cat, and in areas of high cat density, predation may indeed be the sole reason for the decline. It might not be cats’ only effect, however. Beckerman’s team built a model that took both kills and the fear factor into account, and found that apprehension could explain the decrease even where predation is low. A reduction of just one chick per breeding pair per year per cat can lead to a fall in bird numbers of up to 95 per cent (Animal Conservation). “What’s cool about the model is that with no mortality you still get a large decline through mechanisms of fear,” says Beckerman.

New Scientist
July 10, 2007

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Early penguins liked it hot

A newly found fossil indicates that giant 1.5-meter-tall penguins with enormous beaks waddled about the tropics 36 million years ago. This and another new fossil species are shaking up early penguin history, because they suggest that ancient species headed north earlier than supposed and thrived in balmy climes during one of Earth’s warm spells Until now, penguin history has been written from scattered fossil fragments found mostly in New Zealand, Antarctica, and Australia. From those fragments, researchers deduced that penguins first appeared about 61 million years ago, venturing north to the tropics once Earth cooled in the last few million years. A single 40-million-year-old bone fragment found at the southernmost tip of South America indicates that the birds may have dispersed into new territory but still kept to chillier latitudes.

Now, fossils found in southern Peru suggest a rewrite is needed. A near-complete skeleton, the best preserved ancient penguin to date, reveals the 10th known species of extinct giant penguin, Icadyptes salasi. Its skull, the first found of these ancient birds, had a bigger, sharper beak than any previously seen. The notion of a species twice the size of an Emperor penguin in warm latitudes contradicts the trend in birds linking colder climates with larger body size. The other new species, Perudyptes devriesi, stood nearly a meter high–about as tall as today’s King penguin. And at 42 million years, the newly found fossil smashes the record for first penguin in the tropics. The penguins seem to have found their way to Peru in separate waves from Antarctica and New Zealand, possibly driven by changes brought about by new ocean circulation patterns with the opening of Drake’s Passage. The team, led by vertebrate paleontologist Julia Clarke of North Carolina State University in Raleigh, reports its findings online this week in the Proceedings of the National Academy of Sciences.

“No one predicted that penguins reached the equator before about 10 million years ago,” says Clarke, “and here we show them at 42 million years at least.” The two newly described species, along with unpublished data indicating the presence of three others, suggest that penguins diversified in the heat, not after chillier temperatures set in. The Peruvian discoveries expand the early geographic range significantly, says Ewan Fordyce, a vertebrate paleontologist at the University of Otago in Dunedin, New Zealand. Despite some patchy parts to the fossil record, he agrees with Clarke’s theory that today’s penguins evolved some 10 to 12 million years ago, in contrast to molecular data that pegs their origins at 40 million years ago. He notes that the early diversity and range of giant penguins strengthens the argument that they evolved large bodies as an adaptation unrelated to a cooling climate.

ScienceNow
July 10, 2007

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Candid call

There is truth in advertising, at least in the bird world. Female birds judge a male by the number of songs he knows, and new research shows they’re on the right track. The larger the repertoire of a male song sparrow, the more physically fit he is, the stronger his immune system, and the more diverse his genes, researchers report online the week of 11 June in Proceedings of The Royal Society B. Because these advantages would be passed on to offspring, female sparrows do best when they listen before they leap into love.

ScienceNow
June 26, 2007

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Life decisions separate ‘hawk’ from ‘dove’

Ask anyone who has regular contact with animals – from farmers to pet owners – and they will tell you that animals have personalities. Some are docile, some are tetchy. Animals are individuals, with a range of temperaments, from aggressive to shy. Explaining the evolution of personality has been difficult. Now it seems the decisions animals make about how to live their lives and when to reproduce may be what gives them their personalities. “The decisions animals make about how to live their lives and reproduce may be what gives them their personalities”. To test the idea, Max Wolf of the theoretical biology group at the University of Groningen, the Netherlands, and colleagues built an evolutionary model based on trade-offs animals face during their lives. For example, young oystercatchers have to decide whether to move into a vacant territory with a poor food supply and start breeding, or wait for higher quality territory to become available. “We predict that the ones that delay reproduction will be more risk-averse, and more shy and non-aggressive, than the ones that start reproducing immediately,” says Wolf. This example is in birds, but all animals face similar decisions.

The model incorporates this dilemma over current or future reproduction, and looks at how behavioural traits evolve over many generations. Individuals in the model are confronted with a risky situation in which they might get injured but where there is also a chance of a high pay-off. This is similar to the famous “hawk-dove” game in which an individual who behaves aggressively has a higher chance of winning a fight over a resource than one who behaves meekly. Hawks, however, are more likely than doves to die in the attempt. The team also examined how animals forage when there are predators around. Bolder individuals get more food because they don’t waste time hiding – but they also run the risk of being eaten. In other words, individuals that live fast do risk dying young.

In the model, individuals can differ in their aggressiveness, boldness and intensity of exploratory behaviour. These behaviour traits are linked to the probability of obtaining resources and successfully reproducing (Nature, vol 447, p 581). “We find that evolution results in personalities,” says Wolf. “Individuals that have more to lose evolve to be more risk-averse in the different risk situations.” Individuals that put more emphasis on future reproduction evolve to have low levels of aggression and behave shyly. In contrast, individuals that invest more in current reproduction evolve to be more aggressive risk-takers. It is the first time that a formal mathematical model has been produced incorporating these different parameters to explain why individual animals have different personalities. The model also explains consistency in behaviour, says Wolf.

New Scientist
June 12, 2007

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Tropical birds have slow pace of life compared to Northern species

Tropical birds expend less energy at rest than do birds living in more northern climates, according to a study published online in the Proceedings of the National Academy of Sciences. “We found that tropical birds have a slow pace of life which is reflected in how much energy they spend to stay alive,” said Joseph Williams, co-author of the study and associate professor of evolution, ecology and organismal biology at Ohio State University. “This is the first time this has been confirmed in birds.” The findings of a slower pace of life in tropical birds correspond to other aspects of the lives of tropical birds, such as their longer life and slower growth. “Lower energy use fits with the life history of these tropical birds, which is different than those living in temperate climates,” said co-author Popko Wiersma, a postdoctoral researcher at Ohio State. Tropical birds live longer, lay fewer eggs and their chicks grow slower than those of temperate birds.

The researchers traveled to Panama where they captured 69 species of tropical birds and measured their basal metabolic rate (BMR) – the minimum amount of energy they expend at rest, solely to maintain their vital bodily functions. This was the largest data set ever collected of metabolic rates of tropical birds. They compared these measurements with the BMRs of 59 species of temperate birds. They found that tropical birds used about 18 percent less energy, as measured by BMR, when compared with temperate birds. To further test this association, the researchers also compared BMRs in related species pairs. These were birds from the same genus or family, such as flycatchers or swallows, in which one of the pair lived its life in the tropics and one lived in temperate zones. Even here, the tropical species had BMR scores about 13 percent lower than their relatives from temperate regions.

The researchers also tested neotropical migrants – those birds that live in the tropics much of the year, but migrate north to temperate climates such as the United States and Canada to breed. Results showed these birds expended more energy than those species that live year-round in the tropics, but still used less energy than birds that were permanent residents in Ohio. “These birds have a tropical lifestyle, even though they come up north to breed, and that tropical lifestyle is consistent with a reduced metabolic rate,” Williams said. In another experiment, the researchers tested peak metabolic rate (PMR)– how much energy birds expended to keep warm when exposed to cold temperatures. Results showed tropical birds had a PMR that was 34 percent lower than temperate birds. This suggests the physiology of tropical birds is indeed different from that of temperate birds and this affects their metabolism.

“Tropical birds are unable to create as much heat as temperate species through shivering. Their bodies are not built for that,” Wiersma said. To measure BMR and PMR, the researchers used a standard test in which they placed the birds in airtight steel containers with airflow in and out carefully controlled and monitored. The birds were allowed to get accustomed to the container, and then the researchers measured their oxygen consumption, which leads to the BMR and PMR values. (PMR is measured at very cold temperatures, while BMR is natural temperatures.) Scientists have believed that tropical birds may have a slower pace of life because it fits with the rest of their life history, Williams said. Tropical birds, compared to those from temperate regions, tend to live longer, and produce fewer offspring which develop slowly and mature relatively late in life. Among other species, this slower pace of life is associated with lower energy expenditures, but there has not been conclusive evidence of this in birds. The next step in their research, Williams said, is to learn how and why tropical birds expend less energy.

Science Daily
June 12, 2007

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Virus disaster for US birds

Crows are associated with death, but not like this. Numbers of crows and the related blue jay in the north-eastern US are down by nearly half in some places. The cause is West Nile virus, responsible for 179 human deaths since it arrived in North America in 1999, and which is carried mainly by birds. “We knew the mosquitoes that carry the virus feed heavily on certain birds, yet we weren’t finding survivors with antibodies,” says Marm Kilpatrick of the Consortium for Conservation Medicine in New York. “That suggested they were dying.” Sure enough, surveys have showed abrupt declines after 1999 in titmice, wrens, chickadees and American robins – but also, unexpectedly, bluebirds. This may mean that other species not in the surveys are also suffering. Birds of prey are a particular worry, Kilpatrick says.
Source: Nature

New Scientist
May 29, 2007

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Many male blackbirds in Europe no longer migrate to the south

More than a century ago, some European Blackbirds gave up the commuting life. The traditional routine was to nest in northern forests but head for southern Europe or northern Africa at the first sign of winter. Then some populations discovered that winter in the city isn’t half-bad: The microclimate is warm with plenty of tasty leftovers. So strong is the appeal of city life, according to a research team in Germany, that it is has not only changed the blackbirds’ behavior, but their genetics, too. “It’s a very cool study, with a simple message: Urbanization is an important evolutionary force,” says Roarke Donnelly, an ornithologist at Oglethorpe University in Atlanta, Georgia. “We’ve been thinking about this stuff for a long time, but it isn’t easy to test. And they’ve done it with a simple but elegant experiment.”

Jesko Partecke, an ornithologist at the Max Planck Institute for Ornithology in Erling, Germany, knew that European blackbirds (Turdus merula) in Munich stayed put in winter while ones living nearby forests still migrated. To see if the urbanized birds had evolved, Partecke and Eberhard Gwinner (now deceased) collected chicks from the two settings in the spring of 1998. They raised them in their lab in individual cages with light and temperatures mimicking Munich’s. As summer gave way to fall, and winter to spring, they recorded the birds’ nocturnal activity; this “migratory restlessness” is inherited and correlates with the distance a bird travels on its migrations. The urban males were the least active of all the birds, preferring to sit quietly in their cages while other birds hopped about. In contrast, the urban females were just as active at night as their forest counterparts, indicating that the Munich females continue to migrate. “We were completely surprised by the females,” says Partecke. “We naturally assumed that both males and females had changed.” The difference may be bullying; males, which are larger, are known to drive the females away from food and warmth, says Partecke. As a result, he speculates, city-females who try to stay in town through winter may end up dying.

Another benefit of city life for males is that they reach sexual maturity earlier there than in the forest. Because blackbirds have multiple broods, this means they may have more offspring. “The shift to being sedentary seems to be adaptive in urban habitats,” the authors say. The findings are described in this month’s Ecology. “It’s good to see a study that’s looking at the evolutionary pressures caused by these pseudotropical bubbles, our cities,” says Eyal Shochat, an urban ecologist at Arizona State University in Tempe.

ScienceNow
May 29, 2007

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Parasites may help put songbirds on this European sparrowhawk’s dinner plate

In natural selection’s dance of predator and prey, predators have long been thought to target the weak and sick. But this idea has seldom been tested because it’s not easy to know the health of the prey, and how this correlates with the possibility it will be killed by a predator. However, two researchers have now zeroed in on what may make certain songbirds more likely to end up in a raptor’s talons: parasites. Danish songbirds infected with either of two parasites were more likely to end up a meal. The study also sheds light on how predation may keep such parasites in check. To determine the health of the raptors’ prey, Jan Tottrup Nielsen, an ornithologist in Sindal, Denmark, spent 27 years collecting and identifying the remains of nearly 46,000 birds from some 3200 nests of European sparrowhawks and Eurasian goshawks in the forests of northern Denmark. The sparrowhawks targeted small songbirds from 64 species including tits, thrushes, finches, sparrows, and buntings. In contrast, the goshawks went after larger prey, such as gulls, pheasants, partridges, pigeons, and starlings, killing 76 different species.

To find out whether parasites played a role in the deaths of these birds, Nielsen’s colleague, Anders Pape Møller, an evolutionary biologist at the University of Pierre and Marie Curie in Paris, calculated how prevalent such parasites are in European birds overall by compiling several published and unpublished data sets. After taking into account such factors as the abundance and size of the prey, Møller’s analysis showed that the risk of predation for prey targeted by goshawks and sparrowhawks increased by a factor of 25 if the prey birds were infected with the protozoan blood parasite Leucocytozoon. Further, birds infected with the avian malaria parasite were 16 times more likely to find themselves in the talons of a sparrowhawk.

Besides bolstering the theory that weak and sick prey are more vulnerable to being eaten, the study indicates that predation may ultimately keep the malaria parasite in check, the authors note. The severity of a malaria infection correlates with the parasite’s replication rate: The higher the rate, the more virulent the infection. In essence, Møller and Nielsen argue in their study published in this month’s issue of Ecology, the sparrowhawks are helping to keep the malaria parasite relatively benign by killing songbirds with the most virulent form of the disease. The organism is spread via mosquito bites, and so once the host is dead, so is the parasite.

The team examined “an impressive sample size,” says Dennis Murray, a population ecologist at Trent University in Peterborough, Canada. But he cautions that the duo’s reliance on the databases of other researchers to calculate both the prevalence of parasites in prey species and the relative vulnerability to predation of prey species is correlative and risky. “Ideally, one would find a partially eaten prey, test it to see if it actually has malaria, and then compare prevalence of malaria in predator-killed prey to that found in live songbirds,” he notes. “That would make their case stronger.” Still, Murray acknowledges, Møller and Nielsen have shown for a great variety of birds that a heavy load of parasites is likely to put you in natural selection’s cross-hairs.

ScienceNow
May 15, 2007

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A condor crosses the border

A lone California condor flew into the United States from Mexico last week, apparently on an exploratory, 160-kilometer journey from its home in the remote mountains of Baja California. Although the bird stayed only 3 days in San Diego County, its arrival marks the first documented sighting of a wild California condor in the area in nearly a century and suggests that recovery efforts for the once highly endangered bird may attain a key goal: re-establishing a population that spans Baja to central California. “It’s a momentous occasion,” says Mike Wallace, an ornithologist and the team leader of the California Condor Recovery Program at the San Diego Zoo. Dubbed the “bird with one wing in the grave,” the California condor nearly went extinct in the late 20th century. In 1983, only 22 birds were left in the wild. But captive breeding efforts by the San Diego Zoo have paid off: Since 1992, the recovery program has been releasing young condors into protected areas of California and Arizona. In 2002 and 2005, it freed a total of 10 captive-raised condors in Baja’s Sierra San Pedro Martir range, where the birds had survived until 1945. There are now 280 California condors, with 135 living in the wild in California, Arizona, and Mexico.

The bird that made the flight last week was hatched in 2004 at the San Diego Zoo and released in Baja the following year. Young condors are known for their exploratory flights. “They’re more adventurous,” notes Wallace, adding that in 2005, three 4-year-old condors from the Baja population flew within 24 km of the border. Ultimately, the Recovery Program hopes to re-establish the scavenging birds throughout their former range, from Baja to the Canadian border. But although the flight is encouraging, it should not be taken as a sign that California condors are ready to resume a free and wild life on their own, some caution. “I fear for them,” says Steve Beissinger, a conservation biologist at the University of California, Berkeley. “If they stay, they’re very likely to encounter lead-tainted food,” such as the carcasses of animals shot by hunters. The Center for Biological Diversity (CBD) in San Francisco and other groups have sued the California Fish and Game Commission for not banning the use of lead bullets, which are toxic to the birds. “Until we end the use of lead ammunition, condors will not be safe in the wild,” says CBD spokesperson Jeff Miller.

ScienceNow
May 1, 2007

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Chernobyl-based birds avoid radioactive nests

Birds in Chernobyl choose to nest in sites with lower levels of background radioactivity, researchers discover, but how they can tell remains a mystery. Anders Møller at Pierre and Marie Curie University in Paris, France, and Tim Mousseau at the University of South Carolina in Columbia, US, erected more than 200 nest boxes in the Red Forest, about 3 kilometres away from the nuclear reactor that exploded in 1986. Using these artificial nests, they studied at the nesting habits of two species of birds – the great tit Parus major and the pied flycatcher Ficedula hypoleuca – between 2002 and 2003. Møller and Mousseau wanted to see if either species would differentiate between nesting sites that had high and low levels of background radioactivity. The patchy distribution of background radioactivity in the area (due to the fact that radioactive material from the explosion did not settle uniformly) meant the nest boxes could be in very similar locations, with similar food supplies, but have widely varying levels of background radioactivity. Levels at some nest sites were as much as 2000 times natural levels elsewhere in the world.

The researchers found that both species had a definite preference for nest boxes with low radioactivity, with the pied flycatcher seemingly more sensitive than the great tit. Previous research done by Mousseau and colleagues (Trends in Ecology and Evolution, DOI: 10.1016/j.tree.2006.01.008) showed that higher radioactivity results in lower levels of antioxidants and also deformed sperm in barn swallows around Chernobyl. It therefore makes sense for birds to avoid more radioactive sites. “It is not entirely clear exactly how the birds are able to tell which boxes are most contaminated”, says Mousseau, adding that determining this will be very difficult without experimental manipulations. A spokesperson for the Royal Society for the Protection of Birds told New Scientist that the study is interesting, but points out the unexpected benefits of the Chernobyl explosion. Reports show that the large human exclusion zone around the site has led to a boom in animal populations, including eagles, wolves and bears.

“Whatever effect the radioactivity is having, it seems to be less of a threat than human activities, such as agriculture,” said the spokesperson. “There have been few rigorous scientific analyses of background radiation and the natural abundance of species,” responds Mousseau. “But every rock we turn over, every survey we do, we find some previously unreported effect of background radiation. “Mousseau believes that the reports of sustained animal populations around Chernobyl mask fluctuations within the populations. He says studies he has carried out looking at where the barn swallow populations in Chernobyl come from suggest that “the populations are mostly sustained by immigrant birds”, rather than birds returning to their nesting sites as they normally would. So an overall picture showing constant population size could hide the fact that the local population is dwindling but being constantly replenished by neighbouring ones.
Source: Proceedings for the Royal Society for Protection of Birds

New Scientist
April 17, 2007

Original web page at New Scientist