?
?"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 lead 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 it 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).
?
?"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 lead 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 it 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).
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.
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