The authors focused on nitrous oxide, a greenhouse gas emitted as a result of fertilizer use on crops. More than half of nitrous oxide emissions caused by human activities in 2005 was due to agriculture, and emissions are expected to increase even more as the planet’s population rises. Researchers predict that developing countries will also consume more meat, dairy, and cereals per person in the future.

The researchers wondered whether reducing food waste could make a dent in these emissions. For example, UK residents threw out about 360,000 tonnes of raw milk in 2009, often because they had poured too large a portion or the milk had gone bad. By reducing waste of milk, poultry, potatoes, and meat from sheep and pigs, the world could cut agriculture-related nitrous oxide emissions by about 3 percent, the team estimated.

Changing people’s diets could also have a substantial effect. If developed countries reduced their poultry consumption to the levels seen in Japan, they could decrease the world’s poultry-related nitrous oxide emissions by 19 percent. While it’s important to figure out ways to use nitrogen more efficiently, “we suggest that very significant emissions reductions may also be achieved by better addressing dietary choice and food wastage,” the authors write. — Roberta Kwok | 16 May 2012

Source: Reay, D.S. et al. 2012. Global agriculture and nitrous oxide emissions. Nature Climate Change doi: 10.1038/nclimate1458.

Image © SchulteProductions | iStockPhoto.com

Researchers have used satellite tracking to follow other marine animals and determine where protected areas should be located. But little is known about the habits of the manta ray (Manta birostris), a giant fish that can grow more than 7 meters wide. Fishermen sometimes catch these creatures — either accidentally or on purpose — and the International Union for Conservation of Nature has listed the species as “vulnerable.”

To learn more about these elusive animals, scientists attached satellite transmitting tags to six manta rays during a 13-day cruise in the Gulf of Mexico. The team was able to collect data for an average of 27 days per animal. The manta rays usually stayed more than 20 kilometers from the shore and travelled as far as 1,151 kilometers during the data collection period.

The animals were found in marine protected areas only 11.5 percent of the time, the authors report in PLoS ONE. However, areas where manta rays frequently travelled also contained major shipping lanes. The authors aren’t sure how the ships might be affecting the manta rays or whether these animals are able to migrate long distances. But the data could be one step toward designing protected areas for this species. — Roberta Kwok | 15 May 2012

Source: Graham, R.T. et al. 2012. Satellite tracking of manta rays highlights challenges to their conservation. PLoS ONE: doi 10.1371/journal.pone.0036834.

Image © JustinTHardine | iStockPhoto.com

Exotic fungi can trigger widespread damage to crops and ecosystems. For example, chestnut blight and Dutch elm disease are both caused by fungi. These invading pests can enter countries on timber and packaging materials, so many of these products are inspected. But some manufactured wood products can breeze through without inspection because they are thought to be unlikely hosts of pests.

A team of researchers analyzed boxes of wooden utensils imported to Italy from China and tested them for contamination. Some of the boxes and utensils were discolored or contaminated, and the authors were able to identify five species of fungus growing on the wood. One species, Fusarium oxysporum, is a known plant pathogen.

These fungi are already present in Europe, so this particular shipment posed no great danger. But the results suggest that “the hidden movement of fungi during the unrestricted trading of woody products should be considered a common and high risk pathway of invasion,” the authors write. And kitchen utensils may be particularly fungus-friendly because they often become wet when used, encouraging fungi to grow and produce spores. — Roberta Kwok | 14 May 2012

Source: Vannini, A., S. Franceschini, and A.M. Vettraino. 2012. Manufactured wood trade to Europe: a potential uninspected carrier of alien fungi. Biological Invasions doi: 10.1007/s10530-012-0222-0.

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There are more than half a billion domestic dogs in the world, and many are free to roam beyond their owners’ homes. Previous studies have suggested that dogs may threaten other species by killing them, spreading disease, or causing stress. A team of researchers wondered if dogs were also changing the distribution of wild animals, which might flee to other areas.

The study authors focused on a forested region near Valdivia, Chile, covering four communities and almost 10,000 hectares. The team interviewed 93 households about interactions between dogs and the southern pudu, a small deer that is classified as vulnerable on the IUCN Red List of Threatened Species. The researchers also set up camera traps at 254 locations to look for dogs and pudus.

More than 160 known domestic dogs lived in the area, the team found. When a dog and pudu encountered each other, there was an 88 percent chance that the dog would attack the pudu, according to interviews. If people didn’t stop the attack, the pudu had a 50 percent chance of being killed.

The camera trap observations also showed that pudus tended to avoid areas with a lot of dogs. When pudus are unlucky enough to cross paths with dogs, “they are often harassed or killed,” the authors write in Biological Conservation. While wild pumas also hunt pudus, there are far fewer of them per square kilometer than domestic dogs.

Avoiding dogs could take a toll on prey species, since the time that these animals spend staying alert for predators might reduce time spent looking for food. And in areas where human development has fragmented the forest, wild animals may run out of places to hide. — Roberta Kwok | 11 May 2012

Source: Silva-Rodriguez, E.A. and K.E. Sieving. 2012. Domestic dogs shape the landscape-scale distribution of a threatened forest ungulate. Biological Conservation doi: 10.1016/j.biocon.2012.03.008.

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The North Pacific Subtropical Gyre is a huge collection of plastic debris floating in the ocean. Much of the debris is made up of small particles called “microplastic,” which can be swallowed by fish or help transport invasive species. Scientists wondered if microplastic might also affect populations of invertebrates. Such changes “could have ecosystem-wide consequences,” the authors note.

To investigate, the team compared North Pacific microplastic levels in 1972-1987 to levels in 1999-2010. The researchers also examined samples of the insect Halobates sericeus collected in 1972-1973 and 2009-2010.

Microplastic concentrations increased a hundred-fold over the last four decades, the authors report. In 2009-2010, microplastic concentration was linked to the number of H. sericeus eggs on the plastic bits, as well as numbers of adult and juvenile insects. The researchers found the insects’ eggs on microplastic pieces about 0.002 to 0.054 square centimeters in size.

If the amount of plastic continues to rise, species that live or breed on hard surfaces could flourish, the authors suggest. Meanwhile, their prey species, such as zooplankton, could suffer. — Roberta Kwok | 9 May 2012

Source: Goldstein, M.C., M. Rosenberg and L. Cheng. 2012. Increased oceanic microplastic debris enhances oviposition in an endemic pelagic insect. Biology Letters doi: 10.1098/rsbl.2012.0298.

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Many invasive species have appeared on dinner plates before. There are entire cookbooks devoted to recipes using non-native plants or animals, and Louisiana chefs have incorporated nutria, an invasive rodent, into meals. But the idea of eradicating or controlling invasive species by eating them has become even more popular recently, with government agencies advocating the consumption of Asian carp and lionfish. The strategy makes sense at first glance: after all, humans’ appetites have decimated species such as Atlantic cod in the past.

However, such programs “could produce some unintended consequences, and they may produce results opposite to those proposed,” the authors write. To make a dent in the population, harvesters will need to remove enough individuals of the right ages. This task might not be easy; for example, lionfish populations may be tough to reduce since they recover quickly and are spread over a large area. If a campaign fails, frustrated participants may lose faith in the idea that invasive species can be controlled at all, the authors say.

People might also start to value an invasive species more if it is successfully integrated into local cuisine. Once residents start making money by hunting or raising these animals, they may oppose removing the species entirely, the researchers suggest. Some invasive species could even become an important part of local culture. The non-native wild boar, for instance, is now strongly linked to cultural traditions in the Hawaiian Islands.

Gastronomy campaigns do have the potential to raise conservation awareness, quickly detect the spread of invasive species, and funnel money into local economies. But the authors urge managers to proceed with caution, noting that “sometimes doing nothing (do not eat them) may be better than promoting their incorporation into the local culture or creating a market that can be a problem for future management programs.” — Roberta Kwok | 8 May 2012

Source: Nunez, M.A. et al. 2012. Invasive species: To eat or not to eat, that is the question. Conservation Letters (Accepted Article) doi: 10.1111/j.1755-263X.2012.00250.x.

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People are living in increasingly developed areas that lack a rich variety of species. The authors of the study wondered if this biodiversity deprivation was linked to another “global megatrend,” the rise in allergies and autoimmune diseases. Scientists have speculated that the species in our surroundings could influence the bacteria in or on our bodies, which in turn could affect how our immune system functions.

The team tested the idea by studying 118 teenagers in eastern Finland. First, the researchers determined whether each person’s home was surrounded by forest, farmland, developed areas, bodies of water, or wetlands. They also analyzed the plants in the teenagers’ yards and the types of bacteria living on the teenagers’ skin. Finally, each person was tested for an inflammatory disorder called atopic sensitization, or a disposition toward allergies.

Teenagers who lived near forests and farmland were less likely to have the disorder, the team reports in Proceedings of the National Academy of Sciences. Higher diversity of uncommon native flowering plants in the person’s yard was also linked to lower levels of atopic sensitization. And teenagers with the disorder tended to have fewer types of a certain class of bacteria on their skin.

The missing bacteria, which are common in flowering plants, might help stave off allergies, the team suggests. “These results raise fundamental questions about the consequences of biodiversity loss for both allergic conditions and public health in general,” the authors write. — Roberta Kwok | 7 May 2012

Source: Hanski, I. et al. 2012. Environmental biodiversity, human microbiota, and allergy are interrelated. Proceedings of the National Academy of Sciences. doi: 10.1073/pnas.1205624109.

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Organic farming is on the rise in the U.S., with sales of organic products growing more than five-fold from 1997 to 2008. Converting conventional to organic farms can lower pollution, increase biodiversity, and improve the quality of water and soil. But farmers face several barriers to going organic: they can’t market their products as organic for the first three years, and yields can be more unpredictable.

A team investigated whether organic farmers might get a payoff in terms of higher household income. The researchers analyzed 2,689 observations from the 2008 Agricultural Resource Management Survey, which includes financial and household data on farms.

Certified organic farms did have higher gross earnings than traditional farms, bringing in an average of about $1 million more. But organic farmers also spent more on costs such as labor, marketing, and insurance, so their overall household income wasn’t significantly different. The higher insurance costs might reflect the greater risks involved in organic farming, the authors say.

The study suggests that “the lack of economic incentives can be an important barrier to conversion to organic farming,” the team writes in Ecological Economics. The researchers recommend policy changes to cover some of the extra costs and “hedge extra risk and uncertainty inherent in organic farming.” — Roberta Kwok | 4 May 2012

Source: Uematsu, Hiroki and Ashok K. Mishra. 2012. Organic farmers or conventional farmers: Where’s the money? Ecological Economics doi: 10.1016/j.ecolecon.2012.03.013.

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Models have predicted that wind farms could change local temperatures, but these simulations “only crudely represent the effects of wind turbines,” the authors write. A previous study found a night-time warming effect at one wind farm over a couple of months, but bigger, longer-term studies have been missing.

The team analyzed satellite data of a region in west-central Texas with 2,358 wind turbines. First, the researchers categorized areas based on whether they contained one or more wind turbines, had no wind farms, or were near wind farms. Then they compared surface temperatures from 2009-2011 to temperatures from 2003-2005.

Areas with wind farms showed a much stronger warming trend at night than nearby regions, the authors found. Relative to surrounding areas without wind farms, the warming rate could be as high as 0.72 degrees Celsius per decade. Factors such as land cover and surface reflectivity could not explain the changes.

The effect might be more pronounced at night because of stronger winds, which cause more turbulence, the researchers speculate. “To the best of our knowledge, this research is the first in quantifying the impacts of large wind farms on surface temperature using satellite data,” they write. — Roberta Kwok | 1 May 2012

Source: Zhou, L. et al. 2012. Impacts of wind farms on land surface temperature. Nature Climate Change doi: 10.1038/nclimate1505.

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Conditioning animals to eat food discarded or offered by humans can lead to major problems, including property damage and injuries to people and the animals themselves. A team of researchers wondered if animals were learning to exploit these food sources from their peers. Social animals, such as primates or cetaceans, might be especially prone to following the cues of fellow animals.

The team studied bottlenose dolphins in Cockburn Sound, Australia, which were often fed by recreational fishers. Previous research had shown that from 1993 to 2003, the number of dolphins seeking and accepting food from humans increased from 1 to 14. To find out whether this trend was partly driven by social learning, the researchers examined behavioral surveys of about 70 dolphins conducted from 1993 to 1997 and determined how frequently individual dolphins interacted with each other.

The more time a dolphin spent with other dolphins that sought and took food from humans, the more likely it was to start doing the same, the team found. The results suggest that social learning can “facilitate the transmission of harmful or maladaptive behaviours,” the authors write in Animal Conservation, noting that dolphins that accept people’s handouts also run a higher risk of being hit by boats or entangled in gear. The information could help wildlife managers identify animals that are more likely to learn such dangerous habits. — Roberta Kwok | 30 April 2012

Source: Donaldson, R. et al. 2012. The social side of human-wildlife interaction: wildlife can learn harmful behaviours from each other. Animal Conservation doi: 10.1111/j.1469-1795.2012.00548.x.

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Tracking mammal species is difficult and costly, particularly for rare or elusive animals. But obtaining accurate information about mammals’ locations is critical, since many of these species are threatened.

Researchers turned to a humble assistant for help: the leech. Since leeches eat the blood of mammals, the authors reasoned that they might be able to extract the DNA of the leech’s last meal. To test the idea, the team fed goat blood to 26 leeches. Goat DNA could be recovered from the leeches even four months later.

Next, the team collected 25 leeches from forests in Vietnam. Twenty-one of the leeches contained viable mammal DNA, the authors report in Current Biology. The leeches had feasted on animals such as the Truong Son muntjac, Annamite striped rabbit, small-toothed ferret-badger, and serow.

The method “has potential to revolutionise mammal detection surveys in tropical habitats,” the authors write. Leeches feed on many different animals, are easy to catch, and are common in Southeast Asian forests. Scientists could use aquatic leeches for similar purposes, the team suggests. — Roberta Kwok | 27 April 2012

Source: Schnell, I.B. et al. 2012. Screening mammal biodiversity using DNA from leeches. Current Biology doi: 10.1016/j.cub.2012.02.058.

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Climate models have forecasted that the water cycle, or patterns of precipitation and evaporation, will become more intense as the planet warms. But confirming that this trend is occurring has been difficult. Scientists have little long-term data showing how much rain has fallen over the oceans, which gets most of the Earth’s rain, and satellites have been gathering this information for only about 15 to 30 years.

The study authors took a different tack. They studied the salinity, or saltiness, of the oceans, which fluctuates depending on rainfall and evaporation. Areas with more evaporation have saltier waters, while rainy areas have fresher waters.

After examining salinity records from 1950 to 2000, the team concluded that salty parts of the ocean “are getting saltier, whereas fresh regions are getting fresher.” These results suggest that the globe’s water cycle has indeed intensified over the last half-century. And the rate of intensification was about twice as high as predicted by climate models. Such rapid changes in the water cycle are even more cause for concern than warming, the authors say. — Roberta Kwok | 26 April 2012

Source: Durack, P.J., S.E. Wijffels, and R.J. Matear. 2012. Ocean salinities reveal strong global water cycle intensification during 1950 to 2000. Science doi: 10.1126/science.1212222.

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The majority of people now live in urban areas, and carnivores are taking advantage of these new habitats. In addition to the more familiar raccoons and opossums, cities are seeing a rise in red foxes, coyotes, badgers, and mongooses. Even grey wolves, black bears, and hyenas have been spotted in or near urban areas, scientists note in a Journal of Zoology review article.

Urban carnivores have adapted readily to man-made sources of shelter and food. For example, red foxes have made homes in British inter-war housing, using the surrounding gardens as cover. In the Tokyo suburbs, Japanese badgers have established resting sites under the floors of buildings. And the abundance of pets, roadkill, and discarded food may offer carnivores a more reliable food source than natural habitats. In one California park, a resident was feeding red foxes seven kilograms of meat per day.

This cushy environment is allowing some carnivores to flourish even more than they would in a natural habitat. In some areas, urban raccoons and coyotes have higher survival rates than their rural counterparts. One team found seven times more coyotes per square kilometer in urban parts of southern California than rural areas, and raccoons have reached an “astonishing” 333 animals per square kilometer in one Fort Lauderdale, Florida park, about four to 400 times their density in the countryside.

The authors suggest that medium-sized carnivores do best in urban areas. Large animals may not cope well with fragmented habitats, while small animals may be killed by cats and dogs. The recent rise in urban carnivores “may mark the future for the coexistence of carnivores with man,” the authors write. — Roberta Kwok | 24 April 2012

Source: Bateman, P.W. and P.A. Fleming. 2012. Big city life: carnivores in urban environments. Journal of Zoology doi: 10.1111/j.1469-7998.2011.00887.x.

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The researchers examined 13,072 records of ants from 353 regions, scouring everything from scientific studies to museum collections. Next, the team identified areas that were likely to contain the most unreported ant diversity, considering factors such as biodiversity in nearby regions or climate. These “hotspots of discovery” included places in west and southeast Africa, northeastern Brazil, southern Mexico, and southeastern Asia.

“One might hope that these tend to be regions that are difficult to access geographically and, hence, relatively well preserved,” the authors write in the Proceedings of the National Academy of Sciences. “Unfortunately, our results indicate otherwise.” The team found that average deforestation rates over the last two decades were actually higher in these unexplored areas. One discovery hotspot, Togo, lost more than half of its forests during that time.

The researchers also compared their map of hotspots to the list of regions considered high-priority conservation targets by Conservation International. Some unexplored areas, such as Benin, Roraima, and Guizhou, were not on Conservation International’s list. “We hope that our study will encourage a new burst of scientific exploration in and conservation of the most poorly known regions of the Earth,” the team writes. — Roberta Kwok | 23 April 2012

Source: Guenard, B., M.D. Weiser, and R.R. Dunn. 2012. Global models of ant diversity suggest regions where new discoveries are most likely are under disproportionate deforestation threat. Proceedings of the National Academy of Sciences doi: 10.1073/pnas.1113867109.

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Allergies have been increasing around the world for the last 50 years, but scientists don’t fully understand why. Air pollution isn’t enough to explain the rise in snifflers. And while it’s possible that warmer weather could affect plant flowering times, research on pollen levels hasn’t revealed clear patterns.

The study authors decided to analyze the annual pollen index (API), or the average pollen concentration each day added up over one year. The team studied 1,221 pollen data sets spread over 97 locations in Europe, covering 10 to 28 years.

Fourteen percent of the data sets showed a statistically significant increase in pollen levels over time, while 8 percent showed a statistically significant decrease, the authors report in PLoS ONE. When the team examined APIs for 23 types of plants, nine went up and only two went down. The pollen increases didn’t seem to be linked to changes in temperature, but the problem did appear worse in urban areas.

The researchers speculate that the high carbon dioxide levels in cities might be boosting pollen production. Since scientists expect CO₂ levels to keep rising, we could see “greater exposure of humans to pollen allergens, with potentially serious consequences for public health,” the team writes. — Roberta Kwok | 20 April 2012

Source: Ziello, C. et al. 2012. Changes to airborne pollen counts across Europe. PLoS ONE doi: 10.1371/journal.pone.0034076.

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Poaching is a major problem in Southeast Asia, where bears, tigers, leopards, deer, and other animals are valued for medicine, pelts, and food. Even protected areas are “far from safe from poachers,” the authors write. To fight the problem, Khao Yai National Park in Thailand has established ranger stations along the park’s edge.

The team wondered whether these stations were actually keeping poachers out. To investigate, rangers set up camera-traps at 217 spots in the park, gathering 650 photos over 6,260 nights. The photos revealed more ungulates such as deer near the ranger stations, suggesting that the stations were offering some protection.

But the authors also found many poachers within 1 kilometer of park headquarters and along the park’s eastern boundary. The poachers near headquarters might have been filching from a nearby plot of aloewood trees, which are used for incense. And a highway might have provided easy access to the eastern part of the park.

The study suggests that “ranger stations have not been able to sufficiently reduce poacher presence,” the authors write. Instead of setting up more ranger stations, the team says, the park should increase patrols along its edges. — Roberta Kwok | 19 April 2012

Source: Jenks, K.E., J. Howard, and P. Leimgruber. 2012. Do ranger stations deter poaching activity in national parks in Thailand? Biotropica doi: 10.1111/j.1744-7429.2012.00869.x.

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The chytrid fungus Batrachochytrium dendrobatidis is a well-known killer of amphibians around the world. How the pathogen is transmitted, though, is less clear. Infected amphibians without symptoms are probably contributing to the spread, but scientists haven’t been sure if other species are also to blame.

Researchers tested 397 wild geese from Belgium and found that 76 birds were carrying B. dendrobatidis on their toes. Lab tests showed that goose toe scales tended to attract the fungus, the team reports in PLoS ONE. The fungus could also survive in dry conditions on the toe scales for half an hour, long enough for geese to fly 30 kilometers.

Geese might not come into contact with amphibians that often: the birds flock to wetlands, rivers, and lakes rather than ponds. But when the two groups of animals do mix, the geese’s funky feet may be helping to transmit the pathogen. — Roberta Kwok | 17 April 2012

Source: Garmyn, A. et al. 2012. Waterfowl: Potential environmental reservoirs of the chytrid fungus Batrachochytrium dendrobatidis. PLoS ONE doi: 10.1371/journal.pone.0035038.

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The team studied the Karakoram mountains, which span China, Pakistan and India and have almost 20,000 square kilometers of glaciers. Previous research had suggested these glaciers were not receding and might be getting bigger, unlike other glaciers in the Hindu-Kush-Karakoram-Himalaya region. But the results were “debatable in a world where nearly all glaciers are shedding mass,” wrote Graham Cogley of Trent University in Peterborough, Canada in an accompanying Nature Geoscience article.

To resolve the question, the study authors used remote sensing data to analyze 5,615 square kilometers of the Karakoram mountains. The glaciers’ mass increased slightly from 1999 to 2008, perhaps because of higher precipitation in winter and cooler summers, the team reports in Nature Geoscience. The researchers estimate that the Karakoram glaciers therefore contributed about 0.05 millimeters less per year to sea level rise than previously thought. — Roberta Kwok | 16 April 2012

Source: Gardelle, J., E. Berthier, and Y. Arnaud. 2012. Slight mass gain of Karakoram glaciers in the early twenty-first century. Nature Geoscience doi: 10.1038/ngeo1450.

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Scientists are keen to track emperor penguin populations because these animals could suffer declines due to sea ice loss caused by climate change. Coming up with an accurate count is challenging, since many of the birds’ Antarctic breeding sites are far from research stations. Researchers have estimated there are about 135,000 to 175,000 emperor penguin pairs, but that study is almost twenty years old.

To pin down some better numbers, a team searched images of the Antarctic coastline for emperor penguin colonies. Then the researchers analyzed high-resolution satellite images of those sites taken during the species’ 2009 breeding season and classified features as penguins, shadows, snow, or guano.

There were roughly 238,000 breeding pairs at the colonies, which suggests the total number of adult birds is about 595,000, the study authors report in PLoS ONE. Scientists could use similar methods to study populations of other animals, such as large herbivores, the team says. — Roberta Kwok | 16 April 2012

Source: Fretwell, Peter T. et al. 2012. An emperor penguin population estimate: The first global, synoptic survey of a species from space. PLoS ONE doi: 10.1371/journal.pone.0033751.

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The Raso lark is a small bird that lives only on Raso, a tiny island in the Cape Verdes archipelago. Discovered in 1898, the species is now listed as critically endangered. To monitor its population, researchers began taking an annual census of larks on the island.

In 2004, there were only 65 Raso larks. That number doubled in 2005, then continued to rise until the population reached 1,490 in 2011. The growth appeared to be linked to increasing rainfall, showing “the dramatic effect that natural changes in climatic conditions may have on the recovery of endangered species,” the authors write in Animal Conservation.

It’s very rare for a critically endangered species to make such a strong comeback on its own, the team says, and the lark is a “remarkable example” of a natural recovery. But that doesn’t mean the birds are safe yet, since rain levels could vary in the future. The authors recommend establishing another population on Santa Luzia, an island about 20 kilometers away that also used to house Raso larks. — Roberta Kwok | 12 April 2012

Source: Brooke, Michael de L. et al. 2012. Rainfall-related population growth and adult sex ratio change in the Critically Endangered Raso lark (Alauda razae). Animal Conservation doi: 10.1111/j.1469-1795.2012.00535.x.

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Fishery managers already let a certain number of salmon slip away so those fish can spawn. But it’s not clear which “escapement” level is best for the fisheries and the ecosystem. Grizzly bears eat salmon and often leave the remains of their meals by streams, providing nutrients for plants and animals. And the number of spawning fish also affects fishery yields down the line.

Researchers tackled the problem by modelling the effects of different escapement levels for four coastal sockeye salmon stocks and two inland stocks in Alaska and British Columbia, Canada. In the coastal systems, leaving more salmon to spawn would increase bear density by 8 to 44 percent. Fishery yields would jump as well — “an apparent win-win situation,” the authors write.

The situation wasn’t as rosy for the two inland stocks in Fraser River, Canada, where few salmon species besides sockeye exist. Bears would benefit from more sockeye salmon escaping, but fishery yields would drop.

Nevertheless, the team suggests that the research offers a way to balance ecosystem and fishery trade-offs. While a system that values ecosystems and fisheries equally “might not be socio-politically possible,” the researchers write, the model “allows estimation of costs and benefits associated with adjustments to escapement in either direction.” — Roberta Kwok | 10 April 2012

Source: Levi, Taal et al. 2012. Using grizzly bears to assess harvest-ecosystem tradeoffs in salmon fisheries. PLoS Biology doi: 10.1371/journal.pbio.1001303.

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The aptly-named fungus Geomyces destructans causes white-nose syndrome, a disease that has decimated bats in the U.S. and Canada over the past several years. But European bats haven’t suffered from massive die-offs, even though some bats are infected with the pathogen. Researchers weren’t sure if the fungus arrived in North America from Europe, possibly carried by a tourist visiting a bat cave, or if the fungus lived in North America all along and evolved into a more deadly form.

To find out, the study authors infected 18 bats with G. destructans isolated from North America and 18 bats with G. destructans from Europe. Both types of infections caused bats to rouse more often from hibernation, the team reports in the Proceedings of the National Academy of Sciences. Most of the infected bats died, and autopsies showed that the animals’ fat reserves were almost completely gone.

These experiments suggest that the fungus likely invaded North America from Europe, the authors write. European bats may be less vulnerable to the pathogen because they have evolved ways to withstand infection. That’s good news, because it means that scientists probably don’t have to worry about the North American fungus crossing the pond and killing European bats. — Roberta Kwok | 9 April 2012

Source: Warnecke, Lisa et al. 2012. Inoculation of bats with European Geomyces destructans supports the novel pathogen hypothesis for the origin of white-nose syndrome. Proceedings of the National Academy of Sciences doi: 10.1073/pnas.1200374109.

Image courtesy Ryan von Linden/New York Department of Environmental Conservation

Illegal trade can affect biodiversity and drive some species close to extinction. According to some estimates, people hunt or trade more than 400 threatened bird species. But exactly how many animals are traded — and for how much money — is hard to determine.

To investigate, researcher Rodrigo Farias Silva Regueira of the Universidade Federal de Pernambuco visited 10 street markets in Recife, a metropolitan area in Brazil, and pretended to be a potential buyer. Using a pen camera hidden in a shirt collar, the team recorded images of wild birds for sale.

The researchers saw 2,130 birds from more than 50 species, including yellow-bellied seedeaters, saffron finches, and red-cowled cardinals. Eighty-two percent of the birds appeared stressed, usually because they were kept in crowded cages or roughly handled by vendors. These markets likely sell about 40,000 birds per year for an average value of about $505,000, the team estimates in Biological Conservation.

Since many animals probably die before being sold, the number of birds captured from the wild could be much higher, the authors say. “Such sites are real biodiversity sinks,” they write, “and both society and authorities are underestimating the mid and long-term damage those sites are causing.” — Roberta Kwok | 6 April 2012

Source: Regueira, R.F.S. and E. Bernard. 2012. Wildlife sinks: Quantifying the impact of illegal bird trade in street markets in Brazil. Biological Conservation doi: 10.1016/j.biocon.2012.02.009.

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Caribbean coral reef cover has plunged by about 80 percent in the last few decades, and scientists have linked the decline to climate change. Early surveys hinted that some species may have started to dwindle about a century ago, but researchers didn’t have enough data to know for sure.

In a study in Ecology Letters, scientists collected fossils of corals and molluscs from lagoons and offshore reefs near Panama. Using radiocarbon dating, the team determined the age of each sample. Next, the researchers analyzed how reef species had changed over time.

The team found several shifts that had taken place before 1960. In seven excavated pits, the average abundance of the coral Acropora cervicornis fell from 28 percent to 6 percent of corals. In lagoons, the abundance of an oyster species, Dendrostrea frons, dropped from 40 percent to 18 percent. Since those oysters attach to corals called gorgonians, their decline suggests that gorgonians also died during that time. And the average weight of bivalve shells fell by more than 50 percent.

The study suggests that the reefs “experienced substantial ecological change before 1960 that was very likely underway by the 19th century,” the authors write. Cutting down trees, which would have caused more sediment and pollutants to flow into coral reefs, likely contributed, as did overfishing. While climate change made the situation even worse, the results “highlight the importance of managing local impacts such as fishing and land clearing to stem the tide of reef decline.” — Roberta Kwok | 5 April 2012

Source: Cramer, K.L. et al. 2012. Anthropogenic mortality on coral reefs in Caribbean Panama predates coral disease and bleaching. Ecology Letters doi: 10.1111/j.1461-0248.2012.01768.x.

Image © vilainecrevette | iStockPhoto.com

Roundup is one of the world’s most popular herbicides and is used to kill weeds on farms. To find out how Roundup might affect amphibians, researcher Rick Relyea at the University of Pittsburgh set up artificial wetlands in tanks and added wood frog, northern leopard frog, and American toad tadpoles. Then he outfitted the tanks with cages containing newts or dragonflies, both predators of tadpoles. Finally, he added varying amounts of Roundup.

Surprisingly, the herbicide was less deadly to the amphibians when predators were present. The tadpoles swam deeper into the water to avoid predators at the surface, and Relyea speculates that the herbicide was less concentrated near the bottom of the tanks.

The frog tadpoles developed wider tails in response to predators, a trait that may help them dodge attacks. Relyea also saw changes in the frog tadpoles’ tail shape when the herbicide was added, which were “nearly identical to the morphological changes induced by the caged dragonflies,” he writes. The results suggest that “the world’s most widely applied herbicide may have much further-reaching effects on nontarget species” than previously realized. — Roberta Kwok | 3 April 2012

Source: Relyea, Rick A. 2012. New effects of Roundup on amphibians: Predators reduce herbicide mortality; herbicides induce antipredator morphology. Ecological Applications doi: http://dx.doi.org/10.1890/11-0189.1.

Image © Brian Gratwicke | Wikimedia Commons