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  3. Wolves have been disappearing mysteriously in Sweden. Between 1999 and 2009, 18 of the animals—or about 17% of the individuals t

Wolves have been disappearing mysteriously in Sweden. Between 1999 and 2009, 18 of the animals—or about 17% of the individuals t

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问题     Wolves have been disappearing mysteriously in Sweden. Between 1999 and 2009, 18 of the animals—or about 17% of the individuals that researchers have actively followed—have gone missing; the global positioning system(GPS)collars used to track them suddenly blinked off, and the wolves never reemerged. Researchers suspected poaching, but it’s been hard to determine how much of a toll such clandestine kills have taken. Now, by using a new mathematical analysis, scientists have estimated that poaching accounts for half the deaths of Scandinavian wolves, potentially stymieing the rare predator’s recovery.
    As recently as the 1970s, not a single wolf lived in Norway or Sweden, says Guillaume Cha-pron, a conservation scientist at the Swedish University of Agricultural Sciences in Riddarhyttan and a co-author of the new study. DNA evidence has shown that those carnivores living in the region today descend from a single male-female pair that made the treacherous trek from Finland in the early 1980s and a second male that arrived in 1991. Packs have grown steadily from those three founders; in 2009, Sweden and Norway were home to 263 wolves.
    To keep an eye on their numbers, Scandinavian researchers fitted 104 wolves with GPS collars between 1999 and 2009. When a GPS blip goes dead, conservationists with the Scandinavian Wolf Project SKANDULV go looking. Some teams circle wolf territories in helicopters, whereas others set out on skis or snowmobiles to follow tracks and locate scat for DNA testing. If these extensive searches turn up nothing, as happened with 18 wolves that disappeared over the past 10 years, Chapron and his colleagues suspect foul play. "We cannot find any other mortality cause that would destroy the wolf and the radio-tracking collar other than poaching," he says.
    But bodies still haven’t turned up for any of the lost wolves. Chapron suspects that poachers disposed of their remains and the GPS collars to cover up the crimes. So instead, the researchers turned to ecology to show the extent of poaching in Scandinavia. Chapron and his colleagues projected how fast the Scandinavian wolf packs should have grown between 1999 and 2009. Had wolves died only from known causes—illnesses, speeding cars, and a few cases of confirmed poaching—numbers would have grown from 74 animals to nearly 700. But in 2009, researchers counted fewer than 300 wolves in Sweden and Norway.
    Poachers didn’t kill 400 wolves directly but took out an unknown number of males and females that would’ve otherwise been able to breed and multiply. "You cannot really explain the population counts," Chapron says. "You need an extra source of mortality. " In other words, hidden poaching.
    Regardless of the motive, illegal kills account for about 50% of total wolf deaths in Scandinavia, Chapron and colleagues estimate. In two-thirds of those cases, poachers seem to be killing and ditching the evidence without anyone knowing. Such "cryptic poaching" takes a whopping toll on the population, and it’s one that has gone unrecognized until now.
According to the ecology method, the growth of Scandinavian wolves
选项 A、has failed to attain the estimated number.
B、has been severely affected by various reasons.
C、has been underestimated during the past decade.
D、has helped researchers to locate the extent of poaching.
答案A
解析 推理判断题。根据题干关键词ecology method定位到第四段。由该段最后两句可知，根据生态研究，科学家发现若仅死于已知的原因，如疾病、被超速行驶的汽车撞死以及几宗已经得到证实的偷猎案，狼的数量应从74只增长到将近700只。但在2009年，研究者统计表明瑞典和挪威的狼的总数不足300只。由此可推断，目前该地区狼的实际数目远远低于估算的数目，因此[A]“没有达到预计数目”与原文意思相符，故为答案。本段讨论狼的数目减少的原因，矛头直指偷猎，因此[B]与原文不符；而[C]与原文意思相反；[D]原文未提及，故排除。
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