Animal Winners, Losers in Arctic Oil Fields

雪儿 · 发表于: 2011-11-11 17:04:25

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Something to Squawk About

Photograph courtesy WCS

Greater white-fronted geese defend their nest against a raiding arctic fox in a dramatic camera-trap photo from the tundra of Alaska's Prudhoe Bay oil fields. "These cameras allow us to paint a picture, sometimes quite graphic, of which predators are raiding nests and which aren't," said biologist Joe Liebezeit of the Wildlife Conservation Society (WCS) program in Arctic Alaska. "We gain a more complete view of the predator/prey dynamic with the use of these cameras"

The geese won this battle, but Liebezeit and his colleagues found that foxes and other predators are thriving at Prudhoe Bay thanks to "subsidies" from energy infrastructure-and some ground-nesting birds are paying a price. "We're seeing that certain predators like arctic fox are more numerous in the oil fields and seem to be doing well where people are," Liebezeit said. "And they are impacting the ability of some nesting birds to produce young successfully."

雪儿 · 发表于: 2011-11-11 17:04:51

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A Feast for Predators

Photograph courtesy WCS

Caught in the act, a red fox feasts on a Lapland Longspur nestling. The sparrow-like songbird is one of the migrating species that nest in the Arctic each summer, but its young are born blind, featherless, and vulnerable to predators old and new. "In the seventies or eighties it was sort of noteworthy when you'd see a red fox rather than an arctic fox and now that's almost reversed," said Dick Shideler, biologist with the Alaska Department of Fish & Game.

Climate change may be luring the bigger, stronger red foxes here in greater numbers. Once in the neighborhood of the oil fields they--like their relatives the arctic foxes-find excellent shelter in an extreme climate by denning in culverts and under buildings dotted about the oil fields. These "generalist" species also find extra food by consuming inevitable road kills or garbage scraps found in proximity to human development.

雪儿 · 发表于: 2011-11-11 17:05:38

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The Color of Survival

Photograph by Joel Sartore, National Geographic

Ptarmigan live year-round in the Arctic, changing their plumage from winter white to darker summer hues. While these birds are tough enough to reside in the north, and their populations appear healthy around the oil fields, they are less numerous than the millions of migratory birds who flock to the Arctic each summer to breed and rear their young.

Liebezeit and his colleagues compared migrating birds' ability to raise young in the oil fields of Prudhoe Bay with their success in the undeveloped Teshekpuk Lake area of the National Petroleum Reserve-Alaska. "In 2011 we documented that some, not all, birds had less ability to produce young successfully (in Prudhoe Bay)," he said. "But it's a complicated picture. Some birds seem to do fine near the infrastructure." Ptarmigans (Lagopus mutus) roosting on a rock in Prudhoe Bay, AK.

雪儿 · 发表于: 2011-11-11 17:06:11

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Drilling Down into Wildlife Impact

Photograph from Alaska Stock Images/National Geographic

Prudhoe Bay, on northern Alaska's Arctic Ocean coastline, is home to North America's largest oil field. The infrastructure required to extract oil, and support the people living and working here, is providing unanticipated benefits to local predator species like arctic fox and ravens.

"Whenever people change the landscape there are certain impacts and the question is how does one manage for specific objectives?" said University of Alaska Fairbanks biologist Matthew Cronin. "If foxes and ravens are abundant, then ground nests are going to get preyed upon, so you may have to do something about it. In the Lower 48, wildlife officials manage predators all the time with programs like coyote control. If the fox predation on birds is too heavy you might trap them or try to reduce access to denning sites." Cronin studies the genetics and evolution of wild animal populations. He's served as a consultant to the energy industry and to government policy makers.

雪儿 · 发表于: 2011-11-11 17:06:26

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Sniffing Out a Next Meal

Photograph courtesy WCS

A grizzly bear sniffs around a bird's nest and, unbeknownst to the bruin, a hidden camera trap. The bears are common around Prudhoe Bay. "The field includes a bunch of natural habitat, so bears would be here with or without the oil development," said Alaska Fish & Game's Dick Shideler.

Learning how energy development impacts both prey and predators is increasingly important so that management agencies have the tools to balance wildlife needs with the wider expansion of oil and gas development into areas like the National Petroleum Reserve-Alaska.

雪儿 · 发表于: 2011-11-11 17:06:47

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Walking a Fine Line

Photograph by Joel Sartore, National Geographic

Experts say that grizzlies have adapted well to energy infrastructure in Prudhoe Bay. "The net effect on the population I think has been pretty minor," said Alaska Fish & Game's Dick Shideler. "I think they adapt to all the human activity and learn how to pretty much ignore it. We've trained the oil field security guards in hazing techniques so they have a good way to train bears to stay away from activity and it works out pretty well. For the most part they continue to use the habitat just like they did in the past and should be just fine-as long as we can get the garbage under control."

雪儿 · 发表于: 2011-11-11 17:07:01

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Living Off Industry Spoils

Photograph by Joel Sartore, National Geographic

A mama grizzly bear and her two cubs scavenge for food in a Prudhoe Bay Dumpster and illustrate a major issue around Prudhoe Bay-animals becoming accustomed to feeding on human trash.

Prudhoe Bay is operated by BP, and ConocoPhillips and ExxonMobil are also major owners of the oil field. Management has taken serious steps to try to control scavenging animals, like switching to Dumpsters with lids on them and educating workers not to feed bears or foxes.

"The oil companies did a really great job from the late 1990s until the last four or five years, and they are still doing pretty well in the oil field itself. But in the community of Deadhorse, which is right outside of the fields, things have really been slipping a bit," said Dick Shideler. Shideler fears that local bears, which were painstakingly and sometimes lethally weaned off scavenging in the late 1990s, may become food-conditioned all over again with a growing influx of new workers.

雪儿 · 发表于: 2011-11-11 17:07:16

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Multiplying Amid Change

Photograph courtesy WCS

This mother caribou and her calf were captured by a camera-trap shot aimed at the bird's nest beneath their feet. Scientists have closely studied the impacts of Prudhoe Bay infrastructure on the Central Arctic caribou herd. Research has shown that during calving season the animals may try to avoid roads and other unsettling infrastructure to the detriment of nutrition and reproductive success. The herd has moved its main local calving grounds to the south, away from the traditional site's oil and gas development-but its numbers, which had dwindled to perhaps 5,000 animals in the mid-1970s, are estimated at more than 65,000 today.

"If you stick to the data you can see it's kind of a mixed story," said Matthew Cronin. "There may be local impacts, avoidance of activity or deflection of movements, but the herd has grown dramatically." Such growth also has been seen in caribou groupings elsewhere, like the important herd near Teshekpuk Lake, some 150 miles (240 kilometers) to the east on the coastal plain -- an area with similar climatic conditions but no current oil and gas development.

雪儿 · 发表于: 2011-11-11 17:07:30

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Never Flitting, Still Sitting

Photograph courtesy WCS

A raven prepares to dine on the egg of a Lapland Longspur that it has just plucked from a nest with its beak. Ravens are one of the species benefiting from the presence of Alaskan energy infrastructure like that seen on the distant horizon. "The ravens occur historically up on the North Slope but they don't really have many places to nest because they require some vertical structure and there are no trees on the Arctic coastal plain," Liebezeit said.

"They've been able to take advantage of human structures, nesting on towers, the eaves of buildings, and other structures. Their numbers have increased in the oil fields so it's not surprising to see that they are also preying on the eggs of the birds that nest in the oil fields." The birds now live year-round in the oil field area where they were once rare in winter.

雪儿 · 发表于: 2011-11-11 17:07:45

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Forage Fit for Foxes

Photograph by Joel Sartore, National Geographic

Playing its role in a long-standing cycle of predator and prey, an arctic fox carries a freshly caught bird. But Dick Shideler, biologist with the Alaska Department of Fish & Game, says traditional behaviors have shifted for arctic foxes in the vicinity of the Prudhoe Bay oil field.

"In the summer they typically feed on lemmings, birds, bird eggs, or carcasses," he said. "Usually they go offshore in the winter, following polar bears onto the ice and scavenging their kills. That life history for the foxes here in the oil fields has changed. They just stay here in the winter because they now have access to road kills or garbage."

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[2011年] Animal Winners, Losers in Arctic Oil Fields

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