Urban Ski Slope to Raise Profile of Europe's Waste-to-Energy Drive

Thomas K. Grose

Copenhagen, with a waterfront already famous for bike lanes, pedestrian walkways, and offshore wind turbines, is adding another clean energy feature to its urban landscape: a ski resort.

Perhaps the man-made slope will never rival the summits of Sweden or the Alps, where residents of Denmark's capital city typically travel to ski. But it will draw attention to Copenhagen's world-leading effort to cut fossil energy and waste. The ski slope will rest atop a $389 million (500 million euro), 60-megawatt power station fueled entirely by the city's garbage. (See related: "Quiz: What You Don't Know About Electricity.")

The Amager Bakke incinerator, now under construction, will contribute to Copenhagen's ambitious goal of becoming carbon-neutral by 2025. When finished in 2017, it will produce heat for 160,000 households and electricity for 62,500 residences. It is perhaps the flashiest example yet of Europe's effort to deploy cutting-edge waste-to-energy technology in the effort to cut greenhouse gas emissions. While some critics in Europe's green movement question the environmental benefits, and cost also can be an obstacle, cities like Copenhagen are convinced that producing megawatts is better than piling trash in landfills. (See related story: "On Mount Everest, Seeking Biogas Energy in a Mountain of Waste.")

Turning Trash to Treasure

The move toward waste-to-energy (WTE) plants was kick-started in 1999, with a European Union directive requiring member states to greatly reduce the amount of garbage going to landfills. As of 2010 (the most current year for which statistics are available), there were 451 WTE facilities in Europe, up from 390 in 2001, according to the Confederation of European Waste-to-Energy Plants (CEWEP). The plants annually incinerate 73 million metric tons of waste, producing 44 million megawatt-hours (MWH) of electricity and 61 million MWH of heat, or enough power to keep 13 million people wired and another 13 million warm. (See related story: "Waste Wattage: Cities Aim to Flush Heat Energy Out of Sewers.")

And more waste-to-energy projects are starting up, or are on the way. One market research firm says the EU's tightening standards on waste are a key driver behind world growth in WTE that it says will accelerate in the next five years, with 250 new plants and installed capacity on track to increase 21 percent by 2016. Ireland, which opened its first WTE plant in County Meath in 2011, is already expanding its capacity and more proposals are being debated. Several projects recently have been approved in the United Kingdom, including a modernistic WTE facility in the countryside between York and Harrowgate. It's not clear, though, if the Allerton Park energy recovery park will go forward, since the government withdrew £65 million in waste infrastructure credits for the controversial project earlier this year. (See related story: "Whisky a Go Go: Can Scotland's Distillery Waste Boost Biofuels? ")

In Copenhagen, the Amager Bakke plant also saw its share of controversy. Back in late 2011, city officials initially rejected the slick-looking, slope-topped facility—the design of hot Danish architect Bjarke Ingels—because of concerns that it wasn't environmentally friendly enough. But the utility, Amager Resource Center (ARC), overcame those objections. A key was the improvement compared to the existing 40-year-old waste-to-energy (WTE) plant that housed two generators, one that produced 20 MW and another that generated 9 MW. (See related story: "Can Nuclear Waste Spark an Energy Solution?")

While the new plant will increase carbon-dioxide emissions by 43 percent—from 140,000 tons a year to 200,000 tons—ARC says new technologies will make the plant 25 percent more efficient than the old one. In other words, it says, 3 kilos of incinerated waste will keep a light bulb burning for five hours instead of four. "It's not about size, it's about how you use it," said ARC spokeswoman Signe Josephsen. (See related story: "While Energy Policy Falters, Plastic Bag Laws Multiply.")

The burning of trash for power is hardly a new technology, but the current state-of-the-art plants—which use the heat created from the garbage inferno to make steam for heat or to run turbines for electricity—use expensive filters that scrub the flue gases to greatly reduce the amount of dangerous pollutants, such as dioxins, that are emitted. Because about half of the CO2 emitted is from biowaste, not fossil fuels, proponents say the plants are partly powered by renewable fuel, making them cleaner than fossil-fuel plants.

But the main argument in favor of WTE plants is that if the tons of trash that they burn had instead been buried in landfills, the decomposition would have led to greater atmospheric harm through the release of methane, a greenhouse gas that is 25 times more potent than CO2 as a heat-trapping gas. According to the U.S. Environmental Protection Agency, greenhouse gas emissions from landfills are two to six times higher than those generated from plants that burn waste, when measured per unit of electricity generated. Moreover, metals that would have been buried are instead easily plucked from the ashes and recycled. That's one big reason why in April the Center for American Progress (CAP), a progressive think tank based in Washington, D.C., issued a report urging the United States to build more WTE plants to help cut the nation's greenhouse gas emissions. (There are currently just 26 in the United States, which has 56 times the population of Denmark, where there are 30 operating WTE facilities.) (See related interactive map: "The Global Electricity Mix.")

The Environmental Debate

Not everyone, however, thinks incinerators are such a hot idea. Nearby communities often fear air pollution from smokestacks and traffic impacts from trash hauling to the facilities. Some green groups, including Brussels-based Friends of the Earth Europe (FOEE), fear that burning trash for power stunts efforts to encourage recycling. "The only way to reduce CO2 emissions when it comes to waste policy is by preventing, reusing, and recycling," said Ariadna Rodrigo, a FOEE resource use campaigner.

But WTE proponents argue that extracting power from waste goes hand-in-hand with recycling efforts. "There does not have to be a choice between the two solutions. We're very much into recycling," said Rasmus Meyer, also of ARC. Moreover, CEWEP claims, 100 percent recycling is not possible. Some materials degrade after repeated recycling, some are too filthy (diapers, vacuum cleaner bags), some are too mixed to be sorted, and there's no demand for some recycled products.

And, to be sure, countries that are the biggest users of waste power tend to have very impressive recycling rates, too. Germany produces more waste power than any European country—a total of 26 MWH in 2010—and it recycles 62 percent of its municipal solid waste, while incinerating 37 percent of it. Denmark, meanwhile, recycles 43 percent of its rubbish and burns 54 percent of it. Across the EU, on average, 40 percent of urban refuse is recycled and 23 percent is used for energy. Meanwhile, the U.S. manages to recycle just 23 percent of its garbage. Nevertheless, Rodrigo insists, incineration still places inherent limits on recycling, because once a plant is built it has to operate for 20 to 30 years to recoup its investment. "And you still have to feed that monster."

The dash for trash-power has also resulted in a thriving pan-European import-export market for rubbish. "Waste is a commodity, and there's a well-functioning waste market in Europe today," said Pål Spillum, head of the waste recovery and hazardous waste section of the Norwegian Environment Agency. Norway, particularly its capital city Oslo, was spotlighted earlier this year when Britain's Guardian newspaper and the New York Times both ran stories about how it was shipping in trash from Britain, Ireland and Sweden to help power its WTE plants.

Several other countries, particularly Germany, import even more rubbish than Norway.The size of this market, however, is hard to determine. The import and export of nonhazardous waste doesn't have to be reported, so the European Environmental Agency has no statistics available. Spillum maintains that Norway, which burned 1.3 million tons of refuse for energy in 2011, exports more waste than it imports. In 2011, it imported about 90,000 tons of nonhazardous waste, but it exported 1.7 million tons. Overall, Norway has 17 WTE plants. The two in Oslo burn about 410,000 tons of waste a year, and provide 840 GWh of heat—enough to heat 30 percent of the city's 300,000 households and to provide an additional 160 GWh of electricity. (See related story: "A Fuel That Doesn't Go to Waste.")

Measuring Costs

Does all that shipping of garbage, and the resulting CO2 emissions from transportation, undercut the green edge that WTE plants have over landfills? A 2011 study by Swedish consulting firm Profu looked at six Northern European countries-Norway, Denmark, Sweden, Germany, the Netherlands, and Belgium-that were big consumers of rubbish from Eastern Europe. It concluded that WTE was still a net benefit for the atmosphere; each metric ton of municipal waste burned for energy prevented the emission from landfills of more than 600 kilograms of CO2 equivalent.

One possible drawback, in the United States at least, could be high construction costs. Harrisburg, Pennsylvania, was driven to the brink of bankruptcy over a $345 million debt largely racked up by the costs of overhauling and expanding a power-generating incinerator. But the CAP study says that, by and large, WTE plants in the United States, which could cost between $100 million to $300 million to build, depending on size, should be able to recoup building costs from fees and from the sale of power to the grid, as well as from the sale of recovered recyclable metals.

Meanwhile, back in Denmark, the Amager Bakke incinerator-at 80 meters (260 feet), it will be one of the tallest buildings in Copenhagen-aims to stand as an example of WTE potential. Another unique feature of the Amager Bakke incinerator-and-ski-slope-if the technology's ready-will be a smokestack that belches out a giant smoke ring each time a ton of carbon dioxide is emitted. "It's a way to demonstrate to the people of Copenhagen that they are responsible for the environment," ARC's Meyer says. And if too many Copenhageners pay heed to the 200,000 smoke rings wafting over their city each year and deeply cut back on their waste streams? Well, there's still plenty of Eastern European garbage available to keep the fires beneath Amager Bakke's snow-covered slope fully stoked.

This story is part of a special series that explores energy issues. For more, visit The Great Energy Challenge.

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What We Do—and Don't—Know About Brain-Eating Amoebas

A 12-year-old Arkansas girl has been in a hospital for over a week after being infected with a typically fatal parasite that enters through the nose and consumes brain tissue.

A news release Friday from the Arkansas Department of Health says the source of the parasite is most likely a sandy-bottom lake at Willow Springs Water Park in Little Rock. A similar case was linked to the park in 2010.

This rare form of parasitic meningitis—primary amebic meningoencephalitis (PAM)—is caused by an amoeba called Naegleria fowleri. That microscopic amoeba—part of the class of life called protozoans—is a naturally occurring organism that normally feeds on bacteria and tends to live in the sedimentary layer of warm lakes and ponds.

(See "Giant Amoebas Found in Deepest Place on Earth.")

To find out more about Naegleria fowleri, National Geographic got in touch with Jonathan Yoder, an epidemiologist at the Centers for Disease Control and Prevention who collects and analyzes data on the microscopic amoeba.

How does this amoeba called Naegleria fowleri infect a human?

Under certain conditions, Naegleria fowleri can develop flagella—threadlike structures that enable it to rapidly move around and look for more favorable conditions. When people swim in warm freshwater during the summer, water contaminated with the moving amoeba can be forced up the nose and into the brain.

This causes headache, stiff neck, and vomiting, which progresses to more serious symptoms. Between exposure and onset, infection generally results in a coma and death after around five days.

Where is it found?

We see it in warm freshwater or in places with minimal chlorination. It is not uncommon to detect the amoeba if you sample freshwater in warm weather states.

Can it live in swimming pools?

There have been no evident cases of contamination in the United States in well-maintained, properly treated swimming pools. Filtration and chlorination or other types of disinfectant should reduce or eliminate the risk.

But it does get a bit trickier—there was a case in Arizona about ten years ago where a kid swam in a pool filled with water from a geothermal hot water source before it was treated. Unfortunately, the kid became ill and died.

Are cases of infection becoming more common?

We don't have data that says infection from Naegleria fowleri is becoming more common. In the last few years there have been four to five cases per year.

What has changed recently is that cases have appeared in places we had never seen before—like Minnesota, Indiana, and Kansas. This is evidence that the amoeba is moving farther north. In the past it was always found in warmer weather states.

Why does the amoeba enter the nose of some people but not others?

That is a very good question we don't know the answer to. Millions of people swim in these bodies of water every year and don't become ill. So it is difficult for us to say why one person would become ill and other people who swam in the same place and did the same activities did not. It certainly can affect anyone.

What is the chance of survival?

Since 1962, there have been 128 cases of Naegleria fowleri [infection] and only one survivor, not including the current case. Back in 1978, a patient survived after being treated with antibiotics. The same regimen has been tried unsuccessfully on other patients.

How can people stay safe?

If people want to reduce their risk of becoming infected—even though this is a rare event— the thing to think about is holding their nose shut or wearing nose clips when swimming in warm, untreated freshwater. Keep your head above water in hot springs or other thermally heated bodies of water, and during activities where water is forced up the nose, like water sports and diving.

Another way to reduce the risk of infection is to avoid stirring up the sediment in lakes and ponds, where the amoeba may live.

This is a tragic event for someone who becomes infected, as well as their family. We feel it is important for us to be involved even though it does not affect lots of people each year.

This interview has been edited and condensed.

Follow Jaclyn Skurie on Twitter.

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How Old Is That Lion? A Guide to Aging Animals

It seems like every year, the world discovers a newest oldest animal.

Almost a decade ago, it was Ming, the 405-year-old clam. Then there was Jonathan, a giant tortoise who was touted as the world's oldest living creature—until questions later emerged about his identity. There are accounts of 150-year-old whales and 115-year-old reptiles. They make Lonesome George—the famous Galápagos tortoise who died last year at 100—seem relatively young in comparison.

Determining the ages of these particular animals was not overly difficult. Like all clams, Ming grew tree-like rings for every year it was alive. Jonathan and George—the tortoises—were well documented, having appeared in diaries and photographs over the years. The bowhead whale—called the longest-living mammal on Earth—was found with a century-old harpoon pin lodged inside of it.

But determining the age of other animals—particularly those born in the wild—is not such an easy task. Zoologists can take x-rays to look for growth markers in the skeletal structure. And they can easily find out how old an animal is after death, by examining certain biological markers on an autopsy.

Without x-rays or tissue samples, however, determining the age of an animal becomes a lot more difficult. Zoologists must rely on visual cues, with a little bit of guesswork thrown in. Below, a guide to what they look for in various species to determine age.

Orangutans Get Wrinkles Too

A lot of primate aging has to do with teeth, says Meredith Bastian, curator of primates and small mammals at the Philadelphia Zoo.

"If I look at teeth, I have a pretty accurate idea of how old an animal is," she says.

Specifically, Bastian is looking at a primate's molars. Worn-down molars may indicate that a primate is older—or it may indicate that a primate eats food that requires a lot of heavy-duty chewing.

She also looks at a primate's skin.

"There are indications that are very similar to humans," says Bastian. "It's very clear—you can differentiate a baby versus a juvenile versus later stages of life, by looking at wrinkly skin."

In wild male orangutans, zoologists look for something called a flange—or cheek pads—which are only visible on sexually mature dominant males. As they age and become over-the-hill orangutans, their flanges sag—much like our jowls.

But that's not always 100 percent accurate, says Bastian, because unflanged sexually mature males also exist.

"It used to be thought that only flanged males could mate because the flange helps them emit long calls to attract females," she says. "That's the dominant male strategy. Unflanged males have a sneakier strategy. They basically mate away from the flanged males and try not to get caught."

Female orangutans don't have flanges. They do wrinkle and lose bone density, much the way older humans do.

"They might have less hair if they're more stressed," adds Bastian.

One last marker? The whites of orangutan eyes. Babies have white circles around their eyes that disappear gradually over time. So if you can see whites it means that an orangutan hasn't finished weaning yet.

Another Use for Cat Hair

For dating cats, you want to start out with the hair, says Tammy Schmidt, curator of carnivores and ungulates at the Philadelphia Zoo.

"Hair gets dry and brittle and gray as it ages," she says. "That's true for everything from house cats to big cats like an elderly lion or tiger."

Of course, you don't want to get too close to an elderly lion or tiger. But it is possible to see changes in their fur coats from a distance.

"The hair becomes duller," says Schmidt. "A cat is going to take less care and time with their fur coat [as it ages]."

There are other clues, but they may be harder to see.

"A carnivore like a lion or tiger is made to be secret and sly about what's happening to them," says Schmidt. "You need to put all of the pieces of the puzzle together."

Those pieces include things like muscle tone—animals become less toned as they age—and how the tail fits between an animal's hips.

"You look at how full the rump is," she says. "Can you see ribs? You look at how they're moving. Older animals are going to have more pronounced stepping because their eyesight is diminishing."

Only Dead Fish Admit Their Ages

The secret to aging fish is in the ear, reveals Kara Hilwig, the supervisor for the Alaska State Fish and Game lab. Hilwig was part of the team who recently aged a 200-year-old rockfish captured in Alaska.

To age the rockfish, Hilwig sliced through the animal's head and removed two tiny ear bones called otoliths. The otoliths have annual growth rings—like a clam or a tree—which can be counted to determine how old a fish is.

One caveat: The fish must be dead.

"We break the bones in half and then put them over a flame," says Hilwig. "And that's how you can discern this annual feature."

Want to age a fish without slicing its head off and digging around for ear bones? You're out of luck, she says.

"It would be very hard to determine a fish's actual age without the otolith," she says.

It's also important to make sure fish live in an environment where temperatures fluctuate. The otoliths only grow in the summertime.

"For fish down in the tropics, there's no distinct signature," she says. "So it's much harder to determine growth."

Follow Melody Kramer on Twitter.

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Inca Child Sacrifice Victims Were Drugged

Three Inca mummies found near the lofty summit of Volcán Llullaillaco in Argentina were so well preserved that they put a human face on the ancient ritual of capacocha—which ended with their sacrifice.

Now the bodies of 13-year-old Llullaillaco Maiden and her younger companions Llullaillaco Boy and Lightning Girl have revealed that mind-altering substances played a part in their deaths and during the year-long series of ceremonial processes that prepared them for their final hours.

Under biochemical analysis, the Maiden's hair yielded a record of what she ate and drank during the last two years of her life. This evidence seems to support historical accounts of a few selected children taking part in a year of sacred ceremonies—marked in their hair by changes in food, coca, and alcohol consumption—that would ultimately lead to their sacrifice. (Related: "Lofty Ambitions of the Inca.")

In Inca religious ideology, the authors note, coca and alcohol could induce altered states associated with the sacred. But the substances likely played a more pragmatic role as well, disorienting and sedating the young victims on the high mountainside to make them more accepting of their own grim fates.

Well-Preserved History

The Maiden and her young counterparts, found in 1999, exist in a remarkable state of natural preservation due to frigid conditions just below the mountain's 22,110-foot (6,739-meter) summit.

"In terms of mummies that are known around the world, in my opinion she has to be the best preserved of any of the mummies that I'm aware of," said forensic and archaeological expert Andrew Wilson, of the University of Bradford (U.K.). "She looks almost as if she's just fallen asleep."

It is this incredible level of preservation that made possible the kinds of technical analysis that, paired with the pristine condition of the artifacts and textiles arrayed in the tomb-like structure, allowed experts to re-create the events that took place in this thin air some 500 years ago.

"I suppose that's what makes this all the more chilling," Wilson added. "This isn't a desiccated mummy or a set of bones. This is a person; this is a child. And this data that we've generated in our studies is really pointing to some poignant messages about her final months and years."

(Photos: "Frozen Inca Mummy Goes On Display.")

Before the Final Day

Because hair grows about a centimeter a month and remains unchanged thereafter, the Maiden's long, braided locks contain a time line of markers that record her diet, including consumption of substances like coca and alcohol in the form of chicha, a fermented brew made from maize.

The markers show she appears to have been selected for sacrifice a year before her actual death, Wilson explained. During this period her life changed dramatically, as did her surging consumption of both coca and alcohol, which were then controlled substances not available for everyday use. "We suspect the Maiden was one of the acllas, or chosen women, selected around the time of puberty to live away from her familiar society under the guidance of priestesses," he said, noting that this practice is described in the accounts of Spaniards who chronicled information on such rites given to them by the Inca.

A previous DNA and chemical study, also led by Wilson, examined changes in the Maiden's diet and found marked improvements during the year before her death, including the consumption of elite foods like maize and animal protein, perhaps llama meat. Now it's clear that the Maiden's consumption of coca also rose heavily throughout the year before her death, spiking dramatically 12 months before her death and again 6 months before her death. (Related: "Thousands of Inca Mummies Raised From Their Graves.")

"These data fit with the suggestion that she was perhaps leading an ordinary or even peasant lifestyle up to that point, but a year before her death she's selected, effectively removed from that existence and the lifestyle that was familiar to her, and projected into a different existence," Wilson said. "And now we see a massive change in terms of the use of coca."

The Maiden consistently used coca at a high level during the last year of her life, but her alcohol consumption surged tellingly only in her last weeks.

"We're probably talking about the last six to eight weeks, which show that very altered existence, that she's either compliant in taking this or is being made to ingest such a large quantity of alcohol. Certainly in her final weeks she's again entering a different state, probably one in which these chemicals, the coca and the chicha alcohol, might be used in almost a controlling way in the final buildup to the culmination of this capacocha rite and her sacrifice."

On the day of the Maiden's death the drugs may have made her more docile, putting her in a stupor or perhaps even rendering her unconscious. That theory seems to be supported by her relaxed, seated position inside the tomb-like structure, and the fact that the artifacts around her were undisturbed as was the feathered headdress she wore as she drifted off to death. Chewed coca leaves were found in the mummy's mouth upon her discovery in 1999.

The younger children show lower levels of coca and alcohol use, perhaps due to their lesser status in the ritual itself, or to their differences in age and size. "Perhaps as an older child there was a greater need to bring the Maiden to that point of sedation," Wilson said.

And while other capacocha sites show evidence of violence, like cranial trauma, these children were left to slip off peacefully. "Either they got it right, in terms of perfecting the mechanisms of performing this type of sacrifice, or these children went much more quietly," Wilson explained.

State-Sanctioned Sacrifices

Kelly Knudson, an archaeological chemist at Arizona State University, wasn't involved with the research but said the exciting study shows how archaeological science can help us understand both the intimate details of human lives and larger ancient societies.

"Seeing increases in both the consumption of alcohol and coca is very interesting, both in terms of the capacocha sacrifices and their lives before they died, and also in terms of what it can tell us about Inca coercion and control," Knudson said.

The system of control that brought these children to a remote mountaintop at extreme altitude shows all the hallmarks of state support at the highest level, the study's authors suggest, and may have occurred as part of a military and political expansion of the Cuzco-based empire that took place just prior to the arrival of the Spanish.

"The sort of logistical support needed even today to work at this altitude is extensive," Wilson explained. "And here we're talking about evidence that points to the highest possible, imperial-level support. There are artifacts and clothes that are elite and refined products coming from effectively the four corners of the Inca Empire."

Such artifacts include figures made of spondylus shells, brought from the coast, and feathered headdresses from the Amazon Basin. Well-crafted statues of gold and silver, adorned with finely woven miniature clothing, were also available only to the highest levels of society. "I think the whole assemblage represents their status and also the symbolism that this was undertaken under the highest possible sanction," he added. Wilson and his co-authors suggest that such sacrifices may have been a highly stratified means to help exert social control over large areas of conquered territories.

(Last year a study published in PloS ONE showed that the Maiden was suffering from a lung infection at the time of the sacrifice.)

Evidence Supports Early Spanish Chronicles

Johan Reinhard, a National Geographic Society Explorer-in-Residence, discovered the mummies in 1999 with colleague Constanza Ceruti, of the Catholic University of Salta (Argentina).

Reinhard, a co-author of the new study, said he's particularly interested in how the findings compare to what's been written in the historical chronicles of such ceremonies, penned by early Spanish explorers to the New World. "They describe how these ceremonies took place, but they weren't firsthand accounts; no Spanish ever saw one of these personally," Reinhard said. "They depended on what the Inca had told them about what happened."

(In the mid-16th century, for example, Juan de Betanzos wrote of widespread child sacrifices, up to a thousand individuals, on the testimony of his wife—who had previously been married to none other than the Inca Emperor Atahualpa.)

Now the data appear to match the kinds of events described in the chronicles, Reinhard said. "All of a sudden you have this picture where you can almost see what they are going through. Increased attention is paid to them in terms of better food and coca, which was used in ceremonies and wasn't in very common use. This kind of increased attention paid to these children is exactly what you read in the chronicles."

For example, Reinhard said, it's not surprising to see an increase in coca consumption during the year before the death of a chosen child like the Maiden because of the tales told in the chronicles.

"They talk about pilgrimages going to Cuzco and a series of ceremonies during which these children would be sent from one place to another on long pilgrimages. I think it's also interesting that there is a six-month period associated with these largest spikes in coca use," he added. "It could be six months related to something else, but a hypothesis to throw out there is that this corroborates historical accounts that some of these Virgins of the Sun were taken to solstice ceremonies during the year before they were taken off to their deaths."

Today the mummies reside in the Museo de Arqueología de Alta Montaña (MAAM) in Salta, Argentina. The extent to which their physical remains may support historical and archaeological records is exciting, Wilson added, but it is also chilling that the children remain so recognizably human even in death.

"For me it's almost like the children are able to reach out to us to tell us their own stories," he said. "Hair, especially, is such a personal thing, and here it's able to provide some compelling evidence and tell us a very personal story even after five centuries."

The study was published July 29 in the PNAS Early Edition journal.

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Wolves Identified by Unique Howls, May Help Rare Species

A gray wolf peers from a bush in Idaho's Sawtooth Mountains.

Photograph by Jim and Jamie Dutcher, National Geographic

Jennifer S. Holland

If any gray wolves are howling their discontent with a recent proposal to remove what remains of their U.S. federal protection, scientists can now identify the outspoken.

A new, more sophisticated method for analyzing sound recordings of wild wolf howls can, with absolute accuracy, tell individual wolves apart-and may even help save the old dog, according to a new paper in the journal Bioacoustics.

Study leader Holly Root-Gutteridge and colleagues at Nottingham Trent University in the U.K., working with recordings of wild wolves mostly from Algonquin Provincial Park (map) in Ontario, Canada, also found the technique can distinguish a single animal from a chorus of howlers with 97.4 percent accuracy. The team had previously used the method with captive wolves, but this is the first time it's worked with wild wolf songs and all the ambient sounds that go with them.

Specifically, the team's more thorough howl analysis looks at pitch—also considered by previous howl-analyzing tools—but also at amplitude, or the acoustic energy, of recorded howls.

"This is like trying to describe the human voice by saying 'Sandra has a high voice, and Jane has a high voice,'" said Root-Gutteridge, "then refining it by saying 'Sandra has a soft-spoken voice, but Jane has a loud voice.' The highness still matters, but if you add the detail about vocal intensity, you're less likely to confuse Sandra and Jane."

What's more, the technology is able to scrutinize howl recordings and throw out extra, unneeded noises like wind and water that might otherwise confuse the data.

Tracking Wolves a Challenge

These majestic canids—which once roamed most of the northern Rockies of the United States and Canada and the forests along the Great Lakes—nearly went extinct in the early 1960s, when they were considered vermin and all but eradicated by hunters. After the shooting stopped, only about 300 gray wolves remained, skulking through the deep woods of upper Michigan and Minnesota.

With protection under the Endangered Species Act, gray wolves have come back from the brink—one of the biggest success stories in U.S. conservation history. (Related: "Wolf Wars" in National Geographic magazine.)

Though nowhere near the historical estimate of more than 400,000 gray wolves in the United States, now as many as 5,000 live in Michigan, Wisconsin, and Minnesota, with another 7,000 in Alaska. Smaller numbers of reintroduced wolves live in Montana, Idaho, and Wyoming.

But monitoring their populations, which remains a vital part of management, has always been an inexact and labor-intensive science.

Methods include tracking the animals based on pawprints and other marks in the snow, which works quite well-when it snows. GPS collaring lets you know where an individual is, but not with whom it spends its time.

Plus, collars are expensive and collaring requires capturing wolves first-a huge and stressful undertaking for all involved, said Root-Gutteridge. (See an interactive on the return of the wolf.)

Finally, you can play howl recordings to wolves and listen to their replies-which can carry six miles (ten kilometers)-but you can't identify individuals and don't know when one animal is repeating itself or when a new howler has joined in.

DNA analysis of scat has its place, but it is costly and requires finding the wolves first.

Wolves Out of the Woods?

Now that the new technique has been shown to succeed with wild animals, the team sees it as a tool to help conserve wolves in their natural habitats. (See more wolf pictures.)

For instance, tracking howls accurately could make future wolf counts and monitoring of individuals much more precise. If plans go forward to fully drop the gray wolf from the U.S. Endangered Species list and let states do as they please regarding hunting, better monitoring could over time help determine if it was too soon to strip away those last protective rules, as many conservationists argue.

The technology could also be put to use with other canids like African wild dogs and Ethiopian wolves, both of which are endangered in their habitats, said Root-Gutteridge.

"If it howls, the code can extract it and we can identify it."

Follow Jennifer S. Holland on Twitter or check out her website at cuttlefishprose.com.

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Indian Tigers Trapped in "Human Sea" Escape to Find Mates

The tiger Shere Khan was lord in Rudyard Kipling's Jungle Book, but his modern-day descendants are king no more: The big cats have seen their central Indian forests dwindle and fracture.

The remaining tigers are only surviving by moving through critical—but unprotected—corridors of land that link distant populations, a new study says.

Using hair and fecal samples, Sandeep Sharma, of the Smithsonian Conservation Biology Institute, and team studied genes from 273 individual tigers that live in four distinct locations within India's 17,375-square-mile (45,000-square-kilometer) Satpura-Maikal region.

Tigers once roamed across Asia from Turkey to the Russian Far East, but have vanished from over 93 percent of that range. (See tiger pictures.)

The 20th century was especially tough on the now-endangered beasts, when three subspecies became extinct, leaving six—all of which are at risk. (See a National Geographic magazine interactive of big cats in danger.)

At a glance the region's tigers seem to live in four populations, each occupying its own territory in what's called a designated tiger conservation landscape, or TCL. Those are Kanha-Phen, Pachmari-Satpura-Bori, Melghat, and Pench.

But the genetic study suggests otherwise: Corridors of woods and undeveloped land up to 125 miles (200 kilometers) long actually link Kanha and Pench into a single genetic unit, and Satpura-Melghat into a second.

That means the four populations of tigers are breeding as two much larger populations—and keeping their genetic diversity alive in the process.

Corridors also aid tiger survival on the ground, Sharma said, making the cats more likely to withstand many types of threats. (Related:"Tigers Making a Comeback in Parts of Asia.")

"If one of two connected populations drops, say because of poaching or some other factor, the other can expand and repopulate the area," he explained. But if these corridors aren't protected as wildlife habitat by the government or other entities, the land may be developed and leave the tigers in "islands."

If this happens, "eventually they are doomed."

Tiger Family Tree

Sharma and colleagues looked at the tiger population tree in the Satpura-Maikal region, which has seen dramatic declines in tiger habitat. (Read "A Cry for the Tiger" in National Geographic magazine.)

The team found two distinct periods in which tigers' genetic populations divided rapidly, and each was tied to known historical events.

"One was about 700 years ago, and that's [around] the time when Mughal invaders came into the region and they started clearing river valleys and intensified agriculture in those valleys," he said, noting that the major threat facing tigers at that time was habitat loss.

The second period was about 200 years ago, Sharma said, when the British Empire not only felled trees to fulfill its enormous need for timber, but also introduced a vast arsenal of firearms that dramatically increased the number of tigers killed by hunters.

"You can really see these two distinct patterns of genetic subdivision in this population," said Sharma, whose study appeared July 30 in Proceedings of the Royal Society B: Biological Sciences.

Sharma and colleagues also used their data to look back in time some 2,000 years and compare the present situation with ancient patterns of tiger gene flow.

Only tigers in those populations still connected by these corridors are maintaining similar levels of gene flow [to what] we saw historically," he explained.

In areas "that have lost the corridors, the gene flow has significantly decreased."

Living With Tigers

By illuminating the past and present the study provides a roadmap for where future conservation efforts must be focused—keeping the fragile links open between different population groups, according to the authors.

Today, however, these tiger corridors have no legal protection. They are simply forest landscapes, used by local peoples and subject to development, including mining in one of India's prime coal regions.

Earlier this year the Indian Ministry of Environment and Forests gave Coal India Limited permission for coal-mining development in the crucial Satpura-Pench wildlife corridor.

Officials stated publicly that the mine is an underground rather than open facility, and thus shouldn't interfere with the tigers' migratory corridor.

But Sharma is unconvinced, suggesting that mining brings with it settlements, roads, and infrastructure, which can be a major threat to the corridors just at the time when hard genetic data have shown that tigers are using them to travel and reproduce.

Conservationist Luke Dollar, a National Geographic Society Emerging Explorer who manages the society's Big Cats Initiative, said the tough decisions faced here are common where big cats prowl.

"India has half of all the remaining tigers on Earth, but it's also a perfect example of what we face in big-cat conservation, whether it be here or in Africa," he said. "The cats and people are colliding in a struggle for space and existence."

Dramatic Interventions

Where populations become very isolated, dramatic human interventions may be necessary to save inbred cats, Dollar added.

For instance, in 1995 Texas cougars were released to breed with and revitalize a Florida panther population so small and inbred that Dollar described them as "walking dead."

Protecting wildlife corridors is the best way to avoid such drastic measures and offers a better chance of success as well.

"In conservation it's not individuals or individual populations that we worry about if we're going to play the long game," he said.

"We worry about the overall genetic integrity of the species, which is exactly where corridors are critical as the mechanism for genetic exchange that can maintain a robust population."

"Floating in a Human Sea"

Sharma stressed that tigers need to be managed not with a myopic approach, as isolated populations, but as one big population connected by corridors.

"India has the second largest human population in the world, and these tigers are floating in a human sea," he said.

"We can't create new tiger habitat, and there is no hope outside these areas. The only hope is these corridors. If you cut them down, and fragment these populations, eventually they will only exist in history books."

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