February 13, 2013
Indonesia’s numerous islands (18,307 to be exact) house a wealth of avian biodiversity, yet scientists speculate that many of the country’s bird species have yet to be discovered or categorized. But ornithologists are celebrating today as a new species of owl joins the list, taking filling in one more spot in the catalog of the archipelago’s animals.
In 2003, George Sangster, a Dutch ornithologist from Stockholm University, and his wife were exploring the forested foothills of Lombak, an island just east of Bali. While traipsing through the forest at night, Sangster picked up on an owl call he did not recognize. Coincidentally, just a few days later Ben King, an ornithologist from the American Museum of Natural History, heard those same calls from the jungle and also suspected they came from an unknown species.
“It was quite a coincidence that two of us identified this new bird species on different parts of the same island, within a few days of being on the island, especially considering that no-one had noticed anything special about these owls in the previous 100 years,” Sangster said in a statement.
Locals on Lombak, it turned out, were familiar with the species. Known as burung pok–roughly translated as “pook,” a mimic of the owl’s hoots–the birds turned out to be a common feature of the nocturnal landscape. But locals on neighboring islands, however, said they had never heard of the bird and did not recognize its unusual call.
Here, you can hear the little Indonesian owl hooting into the night, which the researchers describe as “a single whistle without overtones:
Although birders and scientists alike love owls, surprisingly not much is known about those species’ biology, including how they relate to one another on an evolutionary scale. Lately, however, researchers have been working double time to get a grip on owls. In 1975, for example, scientists knew of 146 species, and that number leapt to 250 as of 2008. One driver behind this jump in species numbers was the realization that owl calls could lend clues (PDF) to classifying different types of owls. Owls hoot to attract mates and recognize one another as the same, so animals evolved calls unique to their species. In some cases, owls previously classified as the same species were split in two primarily on the basis of their calls.
Sangster, King and two other researchers from Sweden and Australia got together and were able to photograph the owls by playing back recordings of the call to attract several of the hooting culprits. Digging through old records, the researchers found that the owls matched specimens collected back in 1896 by Alfred Everett, a British administrator who was based in Borneo and spent his spare time collecting natural history curios. That same year, Ernest Hartlet, a naturalist who reported on Everett’s field work, accurately noted that “the cry is a clear but not very loud ‘pwok,’ like that of [O.] lempiji, but somewhat different in tone.”
Though Hartlet and Everett came close to identifying the new species, they fell just short of making the leap. Since then, no one had collected or observed this type of owl, according to records from the American Museum of Natural History and the Natural History Museum at Tring, in the U.K.
All of this evidence, the team concluded in a PLoS ONE paper, pointed to the discovery of a new species of owl.
Because the new owl shows dramatically less individual variation to its brown and cream-speckled feather patterns than similar species found on neighboring islands, the scientists hypothesize that ancestors of the Lombok owls may have been isolated and trapped on their island many years before by a catastrophic volcanic eruption. Starting with just a handful of individuals, the animals then could have slowly rebuilt their populations, eventually evolving into a unique lineage.
The species, they report, is the first bird known to be unique to Lombok. The authors named the new bird Otus jolandae, after Sangster’s wife, Jolanda.
February 8, 2013
In the coming years, the birds of Asia’s Eastern Himalaya and Lower Mekong Basin, considered biodiversity hotspots by scientists, will need to relocate within the region to find viable habitat, according to a new study published in the journal Global Change Biology. The reason? Climate change. Researchers at England’s Durham University tested 500 different climate-change scenarios for each of 370 Asian bird species and found that every possible climatic outcome–even the least extreme–would have an adverse effect on the birds.
The researchers honed in on sensitive habitat in Bhutan, Laos, Cambodia, Vietnam and parts of Nepal and India, where development and population growth are occurring at a rapid clip and the effects of climate shifts are expected to be significant, with both wet and dry seasons intensifying. Portions of the region will suffer drastically, the study authors wrote, and certain climates will have “no present-day analogues” by 2100.
This will send birds in search of food. “Food availability [could become] more seasonal, meaning that in some periods there is an over-abundance of food, in others the birds starve,” lead author Robert Bagchi, formerly of Durham University and now a senior scientist at ETH Zürich, told Surprising Science. Species in the Lower Mekong Basin, which includes Laos, Cambodia and Vietnam, will be most vulnerable to these shifts.
In the most extreme cases, the research showed, birds will need to be physically relocated–an outcome scientists are hoping to avoid. Instead, they’re recommending proactive conservation. “Maintaining forest patches and corridors through agricultural landscapes is likely to be a far more effective and affordable long term solution than translocation,” Bagchi said. Linking bird habitat will be key so that species can move between sites that are currently viable and those that will suit them in the future.
The ramifications of bird relocation on plants and other animals has yet to be examined, but the shifts likely won’t bode well. Plant species that rely on birds to disperse seeds may not be able to survive, according to Bagchi. “Understanding how species interactions are going to change is very much at the cutting edge of what ecologists are trying to understand at the moment,” he said.
The study joins a growing body of research into how changes in climate affect food and water supplies, ranges, breeding habits and life cycles for birds and a variety of wildlife. Among those studied and deemed at risk are California’s threatened and endangered bird species. Research published last year showed that sea-level rise and changes in precipitation will most seriously imperil wetlands birds.
Investigators with the National Science Foundation are currently studying the prospects of Antarctica’s Adélie penguins for surviving climate change; the birds rely on floating sea ice, and if warmer temperatures melt that ice, the penguins will vanish. The top swimmers and foragers among their ranks have the best chances of survival, according to researchers, whose work is detailed in this video.
Among mammals, the adverse impacts of global warming on polar bear habitat has been well documented. A 2011 study showed the bears must swim longer distances in search of stable sea ice and that cubs are 27 percent more likely to die as a result of the extended plunges. New research published in the journal Ecology reveals that elephants are also vulnerable: Higher temperatures and lower precipitation have created an acute threat to Myanmar’s endangered Asian elephants, particularly babies.
Land-dwelling North American animals have also been affected. The snowmelt required by wolverines for reproduction is so greatly diminished that federal wildlife officials nominated the animal for Endangered Species Act listing earlier this month. And climate-change-induced, late-spring snowfalls have caused the Columbian ground squirrel to extend its Rocky Mountains hibernation by ten days over the past 20 years, according to Canadian researchers. By emerging later, the animals lose valuable time to stock up on the food they need to survive the next winter.
Conversely, another hibernator, the yellow-bellied marmot, was shown in a 2010 study to actually thrive in the face of climate alterations–a phenomenon scientists attributed to earlier-spring plant growth. But they predicted the benefits would be short-lived due to an increasingly serious climatic pitfall: drought.
Meanwhile, as temperatures continue to rise, other wildlife and insects are expected to flourish outright, including certain invasive species that will be able to expand their ranges and survive winters in new places, as well as non-invasive species. A recent Discovery news article highlighting climate-change winners focused on the brown argus butterfly, which has found a new host plant and a larger range; the albatross, whose food-finding ability has gotten a boost from shifting wind patterns; and the Australian gray nurse shark, whose population could boom if warmer waters reunite two separate populations. Also, melting Arctic ice could provide new feeding opportunities for orcas–but if so, two species it preys on, belugas and narwhals, would move into the climate-change losers column.
January 29, 2013
There are so many ways for a little bird or squirrel to die these days–they can be squished by cars, splattered into buildings, run over by bulldozers, poisoned or even shot. But if you have ever had to clean up a mangled “present” left on your doorstep by a kitty, you’ll know that little creatures can also be killed by pets.
Cats in particular have earned a nasty reputation for themselves as blood thirsty killers of wildlife. They have been named among the top 100 worst invasive species (PDF) in the world. Cats have also earned credit for countless island extinctions. Arriving onto the virgin specks of land alongside sailors, the naive native fauna didn’t stand a chance against these clever, efficient killers. All said, cats claim 14 percent of modern bird, amphibian and mammal island extinctions. But what about the mainland?
A recent study aimed to find out just that. Now the stats are in, and it’s much worse than we thought. But before bird lovers rush to declaw pets, the study’s scientists also found that feral cats and strays–not house cats–are responsible for the majority of the killings.
To arrive at the new findings, researchers from the Smithsonian’s Migratory Bird Center and the U.S. Fish and Wildlife Center assembled a systematic review of every U.S.-based cat predation study known in the scientific literature (excluding Hawaii and Alaska). Based on figures the authors verified as scientifically rigorous, they statistically quantified the total bird and small mammal mortality estimate caused by cats, further breaking the categories down into domestic versus unowned cats, that latter of which the authors define as barnyard kitties, strays that receive food from kind humans and cats that are completely wild.
Their results paint a grim picture for wildlife. In a paper published today in Nature Communications, they write that between 1.4 to 3.7 billion birds lose their lives to cats each year in the United States. Around 33 percent of the birds killed are non-native species (read: unwelcome). Even more startlingly, between 6.9 to 20.7 billion small mammals succumb to the predators. In urban areas, most of the mammals were pesky rats and mice, though rabbit, squirrel, shrew and vole carcasses turned up in rural and suburban locations. Just under 70 percent of those deaths, the authors calculate, occur at the paws of unowned cats, a number about three times the amount domesticated kitties slay.
Cats may also be impacting reptile and amphibian populations, although calculating those figures remains difficult due to a lack of studies. Based upon data taken from Europe, Australia and New Zealand and extrapolated to fit the United States, the authors think that between 258 to 822 million reptiles and 95 to 299 million amphibians may die by cat each year nationwide, although additional research would be needed to verify those extrapolations.
These estimates, especially for birds, far exceed any previous figures for cat killings, they write, and also exceed all other direct sources of anthropogenic bird deaths, such as cars, buildings and communication towers.
The authors conclude:
The magnitude of wildlife mortality caused by cats that we report here far exceeds all prior estimates. Available evidence suggests that mortality from cat predation is likely to be substantial in all parts of the world where free-ranging cats occur.
Our estimates should alert policy makers and the general public about the large magnitude of wildlife mortality caused by free-ranging cats.
Although our results suggest that owned cats have relatively less impact than un-owned cats, owned cats still cause substantial wildlife mortality; simple solutions to reduce mortality caused by pets, such as limiting or preventing outdoor access, should be pursued.
The authors write that trap-neuter/spay-return programs–or those in which feral cats are caught, “fixed,” and released back into the wild unharmed–are undertaken throughout North American and are carried out largely without consideration towards to native animals and without widespread public knowledge. While cat lovers claim that these methods reduce wildlife mortality by humanely limiting the growth of feral colonies, the authors point out that the scientific literature does not support this assumption. Therefore, such colonies should be a “wildlife management priority,” they write. They don’t come out and say it but the implication is that feral cat colonies should be exterminated.
But feral cats, some animal rights advocates argue, are simply trying to eke out a living in a tough, unloving world. As the Humane Society explains, simply removing the cats may not be the most efficient means of solving the problem because cats that are inevitably left behind repopulate the colony, surrounding colonies may move in to replace the old and “the ongoing abandonment of unaltered pet cats…can also repopulate a vacated territory.” Feral cats, after all, are the “offspring of lost or abandoned pet cats or other feral cats who are not spayed or neutered.” Targeting irresponsible humans may provide a different solution, although spay/neuter laws are controversial.
In Washington D.C. alone, for example, there are more than 300 known feral cat colonies. Wildlife are victims of this problem, but feral cats are too as conditions for survival are tough. And as with so many other environmental banes, the root of the problem neatly traces back to a single source: humans. As the authors write in their paper, feral cats are the single greatest source of anthropogenic (human-driven) mortality for U.S. birds and mammals.
January 14, 2013
Beneath massive communication towers, fallen bird bodies pile up like confetti. They collide with the steel structures—which can reach heights twice that of the Empire State Building—or fly into the miles of cables radiating around the beacons. Each year, nearly 7 million birds lose their lives to these web-like traps of wire and metal—27 times more birds than were killed in the infamous 1989 Exxon Valdez spill.
The killing season peaks during the time nocturnal migratory birds make their way between Canada and the U.S. Flying in the darkness, they spot the tower lights, become disoriented and begin circling the beams. After a storm, when natural navigational cues like the stars or moon are obscured, mortalities are particularly high.
While the magnitude of causalities is worrying, until now researchers did not know whether or not the avian victims were species of conservation concern or just common sparrows. Research recently published in the journal Biological Conservation, however, confirms scientists’ fears. Members of thirteen threatened North American species succumb each year to the towers. The fallen birds represent between 1 and 9 percent of those species’ total population numbers.
“Certain species of birds, including many already in decline, are killed at communication towers in far greater proportions than their abundance would suggest,” said lead author Travis Longcore, the science director of the Urban Wildlands Group and an associate professor of research at the Spatial Science Institute at the University of Southern California, in an email. “And it’s not just these thirteen species we have to worry about—they’re just the ones being killed at the highest rates,” he continued. “Many more species of concern are killed at lower rates, too.”
To figure out mortality by species and regions, Longcore and his co-authors constructed a database of species deaths based on verifiable, available records. Then, they calculated the mean proportion of each species killed and compared those statistics with overall mortality rates for each species’ total population in the U.S. and Canada.
All in all, they found, 97 percent of the birds being killed are passerines, or songbirds. Among the threatened birds that are dying are the Yellow Rail, with 2,200 annuals mortalities, representing 8.9 percent of the species’ total population; the Golden-winged Warbler, with 5,300 annual deaths, representing 2.5 percent of the population; and the Swainson’s Warbler, with 7,500 annual deaths, representing 8.9 percent of the population. Other species, though not currently of conservation concern, still suffer formidable losses. Red-eyed Vireos, for example, relinquish 581,000 lives to communication towers each year, and around 499,000 Ovenbirds die this way, too.
Last year, the same team found that around 1,000 of the towers, used for television and radio broadcast, are responsible for 70 percent of the bird deaths. Those 1,000 towers, the team noted, stand 900 feet or higher, representing the largest of North America’s 70,000-odd communication towers included in the original study. In their follow up study, they identified the deadliest sites, which are in Texas, Louisiana, Florida and the Midwest. The findings are no surprise; the Southeastern coastal plain and the Midwest regions contain the highest concentrations of the tallest towers on the continent.
The Migratory Bird Treaty Act of 1918 makes it illegal to kill migratory birds in the U.S., so the researchers hope their findings may be used to better regulate communication towers. Eliminating the steady-glow red lights from the towers and replacing them with blinking lights—the same fix adopted by the Federal Aviation Administration—may reduce bird mortality by 50 to 70 percent.
The study also carries another lesson, Longcore said. Simply counting up the total number of birds killed by wind turbines, cats, windows, pesticides or communication towers across the country and then making crude comparisons between mortality sources can be misleading, he pointed out. The most impactful data—the types of species killed, and where, and when and how—often lurk beneath those surface figures. “Simple estimates of total ‘bird’ mortality are insufficient; it matters which species are being killed,” he said. “Each mortality source may be significant, but for different species and in different places.”
October 3, 2012
A little over two years ago, marine researchers set sail aboard the French schooner Tara as part of a plan to create the first comprehensive global picture of plankton ecosystems. By the time the journey concluded earlier this year, they had observed roughly 1 million previously unidentified species of plankton, giving an unprecedented window into the diversity of marine life at the most basic level of the food chain.
Unfortunately, the group’s findings weren’t all rosy. If, as they note, “studying plankton is like taking the pulse of our planet,” then Tara‘s journey also included the discovery of something like an irregular heartbeat. Last week, the researchers revealed that while collecting samples in the Southern Ocean (the waters that encircle Antarctica), they detected remarkably high levels of plastic pollutants in a habitat that was widely considered to be unspoiled.
“We had always assumed that this was a pristine environment, very little touched by human beings,” Chris Bowler, one of the team’s scientists, told The Guardian. ”The fact that we found these plastics is a sign that the reach of human beings is truly planetary in scale.”
The researchers expected to find some level of plastic in the waters, as all of the world’s oceans contain pieces of plastic debris—most are microscopic particles that result from the degradation of objects like plastic bags and bottles. But the team’s samples, collected from four different locations in the Southern Ocean and Antarctica, revealed concentrations of plastic far higher than they would have predicted: roughly 50,000 fragments per square kilometer, a figure that was considered a “high” amount just a couple of years ago but is now simply the world average for oceanic plastic concentration. The group says that they had expected to find concentrations of plastic somewhere around 5,000 fragments per square kilometer in the remote waters near Antarctica.
Although the Great Pacific Garbage Patch is the most notorious area of concentrated waste debris in the ocean, the North Atlantic and North Sea are also home to high amounts of floating plastic and garbage. What makes the discovery of such debris near Antarctica such a concern is that, unlike these areas near Europe and Asia, the Southern Ocean is distant from most human activity, indicating just how far this type of pollution has spread over time.
“Discovering plastic at these very high levels was completely unexpected because the Southern Ocean is relatively separated from the world’s other oceans and does not normally mix with them,” Bowler said. It’s difficult to know exactly where the plastic in these waters originated, but based on ocean currents, the Tara researchers speculate that the majority came from Australia, Africa and South America.
Floating plastic debris harms wildlife in a number of ways. For birds and fish, larger pieces are mistaken for food, and consumption of enough plastic can be toxic. On the Midway Islands, nearby the Great Pacific Patch, researchers have determined that all 2 million resident Laysan albatrosses have some quantity of plastic in their stomach, and that about a third of albatross chicks die due to being mistakenly fed plastic by their parents.
On a smaller level, UV light and the salt in seawater cause microscopic particles of plastic to emit toxic chemicals such as PCBs and DDT. When ingested by many types of marine species, these can be mistaken for estradiol, a sex hormone, causing a variety of symptoms related to endocrine disruption. Additionally, the chemicals tend to bioaccumulate in organisms as they move up the food chain, and can eventually lead to tainted populations of fish that humans regularly consume.
These sorts of problems have led Charles Moore, an oceanographer and racing boat captain who played a significant role in discovering and publicizing the great Pacific Garbage Patch, to argue that plastic pollution has become a more urgent problem for ocean life than climate change. “The sad thing is we thought Antarctic waters were clean,” he told the Australian Associated Press after the Tara‘s findings were announced. ”We no longer have an ocean anywhere that is free of pollution.”