题目内容：
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
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