Don't Count on Dung
Conservationists（自然保护主义者）may be miscalculating the numbers of the threatened animals such as elephants．say African and American researchers．The error occurs because of a flaw in the way they estimate animal numbers from the piles of dung（粪）the creatures leave behind．
The mistake could 1ead researchers to think that there are twice as many elephants as there really are in some regions according to Andrew Plumptre of the Wildlife Conservation Society（wcs） in New York
Biologist Katy Payne of Cornell University in Ithaca，New York，agrees．''We really need to know elephant numbers and the evidence that we have is quite indirect，“says Payne，who electronically tracks elephants
Counting elephants from planes is impossible in the vast rainforests of Central Africa．So researchers often estimate elephant numbers by counting dung piles in a given area．They also need to know the rate at which dung decays Because it's extremely difficult to determine these rates．however，researchers counting elephants in one region tend to rely on standard decay rates established elsewhere
But researchers at the WCS have found that this decay rate varies from region to region depending on the climate and environment Using the wrong values can lead the census astray（离开正道），says Plumptre
He and his colleague Anthony Chifu Nchanji studied decaying elephant dung in the forests of Cameroon They found that the dung decayed between 55 and 65 per cent more slowly than the dung in the rainforests of neighbouring Gabon．If researchers use decay rates from Gabon to count elephants in Cameroon，they would probably find more elephants than are actually around．This could mean estimates in Cameroon are at least twice as high as those derived from decay rates calculated locally，says Plumptre“However accurate your dung density estimate might be．the decay rate can severely affect the result”
Plumptre also says that the dung—pile census should be carried out over a region similar in size to an elephant's natural range The usual technique of monitoring only small，protected areas distorts numbers because elephants move in and out of these regions，he says“If the elephant population increases within the protected area，you can not determine whether 1t is a real increase or whether it is due to elephants moving in because they are being poached（入侵偷猎）outside．”
Plumptre says that similar problems may also affect other animal census studies that rely on indirect evidence such as nests，tracks or burrows（地洞）
36 The word“threatened”in the first sentence of the first paragraph could be best replaced by
A “endangered”
B “frightened”
C “killed”
D “angered”
37 Why do researchers estimate elephant numbers in an area by counting dung piles?
A Because elephants are difficult to catch
B Because it is not possible to count elephants from a plane．
C Because it is not possible to keep track of elephants．
D Because elephants are shy animals
38 Piles of dung can't be relied upon when it comes to estimating elephant numbers because
A they are different in size
B they scatter an over the region．
C they are different in decay rate．
D they are different in quality．
39 According to Plumptre，the region over which a dung—pile census is carried out should be
A small enough
B well protected．
C carefully monitored．
D large enough
40 The first word“He”in paragraph 6 refers to
A Andrew Plumptre
B Katy Payne．
C Anthony Chifu Nchanji．
D the writer of the article．
参考答案
36 A threatened：有灭绝危险的。threatened animals：有灭绝危险的动物。endangered：有灭绝危险的；有生命危险的。an endangered species：一个有灭绝危险的物种。frightened：受惊的。killed：杀死了的。angered：激怒了的。
37 B 该题问的是：为什么研究人员通过数粪堆估计一个地区的象数?第三段有这么一个句子，意思是说：从飞机上数中非广阔的赤道雨林中的象是不可能的，研究人员通过数粪堆估计一个特定地区的粪堆估计该区域的象数。因此B是正确答案。
38 c 该题问的是：不可依据粪堆数估计象数的原因是什么?文章第五段第一句话是这么说的：……这种取决于气候和环境的腐烂速率在不同的地区是不一样的。可见c是正确的答案。A说的是：它们的大小是不一样的。B说的是：它们散布在整个地区。D说的是：它们的质量是不一样的。
39 D 该题问的是：根据Plumptre的观点，选择粪堆普查的地区应符合什么样的条件?倒数第二段提到了P1umDtre的观点，即普查的地区应该大到不能使象自由出入，也就是说，必须足够大。A说的是：足够小。B说的是：得到了很好的保护。c说的是：得到了密切的监控。