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 ele

共用题干
第二篇

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 that 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 ele-
phant 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 of-
ten 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,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 Came-
roon.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 ele-
phant's natural range."The usual technique of monitoring only small,protected areas distorts numbers be-
cause elephants move in and out of these regions,"he says."If the elephant population increases within the
protected area,you cannot 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 evi--
dence such as nests,tracks or burrows（地洞）.

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 all over the region
C:they are different in decay rate
D:they are different in quality

共用题干
第二篇

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 that 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 ele-
phant 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 of-
ten 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,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 Came-
roon.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 ele-
phant's natural range."The usual technique of monitoring only small,protected areas distorts numbers be-
cause elephants move in and out of these regions,"he says."If the elephant population increases within the
protected area,you cannot 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 evi--
dence 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

共用题干
第二篇

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 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）.

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.

共用题干
第二篇

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 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 word "threatened" in the first sentence of the first paragraph could be best replaced by
A:"endangered".
B:"frightened".
C:"killed".
D:"angered".

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 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).
文章(31~35)

The word "threatened" in the first sentence of the first paragraph could be best replaced by

A "endangered".
B "frightened".
C "killed".
D "angered".

共用题干
第二篇

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 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）.

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 all over the region.
C:they are different in decay rate.
D:they are different in quality.

共用题干
第二篇

Don't Count on Dung（粪便）

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 percent 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 cannot 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）.

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

共用题干
第二篇

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 that 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 ele-
phant 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 of-
ten 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,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 Came-
roon.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 ele-
phant's natural range."The usual technique of monitoring only small,protected areas distorts numbers be-
cause elephants move in and out of these regions,"he says."If the elephant population increases within the
protected area,you cannot 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 evi--
dence such as nests,tracks or burrows（地洞）.

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

共用题干
第二篇

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 that 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 ele-
phant 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 of-
ten 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,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 Came-
roon.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 ele-
phant's natural range."The usual technique of monitoring only small,protected areas distorts numbers be-
cause elephants move in and out of these regions,"he says."If the elephant population increases within the
protected area,you cannot 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 evi--
dence such as nests,tracks or burrows（地洞）.

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.

共用题干
第二篇

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 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）.

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.

共用题干
第二篇

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 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.

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 all over the region.
C they are different in decay rate.
D they are different in quality.

共用题干
第二篇

Don't Count on Dung（粪便）

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 percent 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 cannot 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）.

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

共用题干
第二篇

Don't Count on Dung（粪便）

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 percent 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 cannot 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）.

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 anitnals.