The recent decline in numbers of the Tennessee warbler

[dwsiegel]

CR q:

Kate: The recent decline in numbers of the Tennessee warbler, a North American songbird that migrates each fall to coffee plantations in South America, is due to the elimination of dense tree cover that formerly was a feature of most South American coffee plantations.

Scott: The population of the spruce budworm, the warbler's favourite prey in North America, has been dropping. This is a more likely explanation of the warbler's decline.

Question: Which of the following, if true, most seriously calls Scott's hypothesis into question?

1). The numbers of the Baltimore oriole, a songbird that does not eat budworms but is as dependent on South America coffee plantations as is the Tennessee warbler, are declining

2). The spruce budworm population has dropped because of a disease that can infect budworms but not Tennessee warblers

3). The drop in the population of the spruce budworm is expected to only be temporary

4). Many Tennessee warblers have begun migrating in the fall to places other than traditional coffee plantations

5). Although many North American songbirds have declined in numbers, no other species has experienced as great a decline as has the Tennessee warbler.

I am stuck on this one as I feel that no answer choice "kills" Scott's argument but 1 and 4 both knock at it in the same way. 1 = there is another bird that is declining without eating the BW. But perhaps it could be declining for any other reason, such as its prey is in decline. Slight knock to Scott. 4= Warblers are now moving to new places, presumably to find more tree cover. Slight plus to Kate.

I guess better to go with a knock to Scott's argument than a plus to Kate's, as this is what the question is asking. But I did not feel confident that 1 is a strong knock to Scott. Please explain?

[sunny.jain]

Well, I did this Question Yesterday. This Question is from GMAT Prep.

Kate: Decline of Bird ---> because of Decline in coffee tree plantation.

Scott:Decline of Bird ---> because of Decline in prey.

We have to put a Question on Scott hypothesis? or we can say weaken it?

What could be the possible ways?
Decline of Bird is not dependent on prey?
or
decline of Bird is dependent on coffee tree plantation?


Options
A) Another Bird --> not dependent on that prey, but dependent on coffee plantation --> declining.
things to note down here is that:
this new bird is declining irrespective of prey and it was dependent on coffee plantation. so even though this bird is declining of may be some other X,Y or Z reason, but it is definitely not declining because of shortage of prey.

B) talking about prey? --> irrelevant.
C) hmm but this temporary drop may cause decline in warbler.
D) warbler are migrating to other places where coffee plant doesn't exist, but we can not say whether at those places we have prey or not.
E) comparing other species with warbler.

Although A is very light, but i found this is most closest answer.

[RonPurewal]

I am stuck on this one as I feel that no answer choice "kills" Scott's argument

that's much too strong a standard. you don't have to "kill" the argument; you just have to provide counterevidence. that is what "call into question" means.

1 = there is another bird that is declining without eating the BW. But perhaps it could be declining for any other reason, such as its prey is in decline. Slight knock to Scott.

you absolutely cannot do this.

when you do strengthening/weakening questions:
AS SOON AS YOU SAY "PERHAPS", STOP. YOU CANNOT REASON FURTHER FROM THAT POINT.
if you go any further, then here's what you are doing: you're essentially just making stuff up at random ("perhaps..."), AND THEN USING THOSE RANDOM HYPOTHETICALS AS THE BASIS FOR AN ARGUMENT.
i think you can see why this is invalid reasoning. if you're going to do that, then you could argue absolutely any position at all in any argument (except positions that directly contradict existing premises).

this statement is direct evidence against the idea that budworms are the source of the problem, since it provides an example of a species that doesn't eat budworms but has experienced exactly the same decline.

4= Warblers are now moving to new places, presumably to find more tree cover. Slight plus to Kate.

the problem here is that you have to assume, without any real justification, that tree cover is the issue. that's another "perhaps", so the same advice applies as above.

[RonPurewal]

I am stuck on this one as I feel that no answer choice "kills" Scott's argument

that's much too strong a standard. you don't have to "kill" the argument; you just have to provide counterevidence. that is what "call into question" means.

1 = there is another bird that is declining without eating the BW. But perhaps it could be declining for any other reason, such as its prey is in decline. Slight knock to Scott.

you absolutely cannot do this.

when you do strengthening/weakening questions:
AS SOON AS YOU SAY "PERHAPS", STOP. YOU CANNOT REASON FURTHER FROM THAT POINT.
if you go any further, then here's what you are doing: you're essentially just making stuff up at random ("perhaps..."), AND THEN USING THOSE RANDOM HYPOTHETICALS AS THE BASIS FOR AN ARGUMENT.
i think you can see why this is invalid reasoning. if you're going to do that, then you could argue absolutely any position at all in any argument (except positions that directly contradict existing premises).

this statement is direct evidence against the idea that budworms are the source of the problem, since it provides an example of a species that doesn't eat budworms but has experienced exactly the same decline.

4= Warblers are now moving to new places, presumably to find more tree cover. Slight plus to Kate.

the problem here is that you have to assume, without any real justification, that tree cover is the issue. that's another "perhaps", so the same advice applies as above.

[velascojh]

I got a little confused... waht is the OA ? Thank you

[RonPurewal]

I got a little confused... waht is the OA ? Thank you

the answer is (a).

[muralik.abm]

Ron,

Please confirm my below analysis if it is correct.

4) Many Tennessee warblers have begun migrating in the fall to places other than traditional coffee plantations

Option "4" actually weakens Kates' argument in a way that migration of the warblers is not due to the decline of traditional coffee plantations but due to some other factor and is not relevant to Scott's argument as it does not talk about the prey.

Regards,
Murali.

[RonPurewal]

Ron,

Please confirm my below analysis if it is correct.

4) Many Tennessee warblers have begun migrating in the fall to places other than traditional coffee plantations

Option "4" actually weakens Kates' argument in a way that migration of the warblers is not due to the decline of traditional coffee plantations but due to some other factor and is not relevant to Scott's argument as it does not talk about the prey.

Regards,
Murali.

i'm lost on the red part -- help me out here with a little more explanation.
i'm mostly lost because the migration isn't at issue; what's at issue is why the population is declining. is that what you meant to type?

[susmod]

Could someone explain why #4 does not weaken Scott's argument but #1 does? I don't get it.

[saptadeepc]

Kate : Decline of TW due to elimination of tree
Scott : Decline due to lack of prey

How to weaken Scott : What he says is not important to the decline of a bird, which is similar to the one in question(TW) ! Here the option says, more than the prey, these type of birds depend on trees ! Hence it opposes / weakens Scott's point.

Option 4 has no correlation between prey, declining of birds and migration. It is irrelevant I guess. Even if they are going to different places, how does the lack of prey matter ?

[aasim2k6]

I chose D as it strengthens Kate's argument. Warblers wouldn't have migrated elsewhere if the coffee plantations din't lose dense tree cover. So coffee plantations lacking dense tree cover is fair enough reason for decline in population. Let me know where I went wrong in this reasoning. The stem asks to undermine Scott's hypothesis. When two people argue, to undermine one Is it sufficient If we provide evidence that supports other?

[kvitkod]

D does not relevant to Scott's statement. If D is true, it supports Kate's statment, but does not weaken the Scott's one as the argument requests.

I chose D as it strengthens Kate's argument. Warblers wouldn't have migrated elsewhere if the coffee plantations din't lose dense tree cover. So coffee plantations lacking dense tree cover is fair enough reason for decline in population. Let me know where I went wrong in this reasoning. The stem asks to undermine Scott's hypothesis. When two people argue, to undermine one Is it sufficient If we provide evidence that supports other?

[RonPurewal]

Could someone explain why #4 does not weaken Scott's argument but #1 does? I don't get it.

those two choices are discussed earlier in the thread, so, if you don't understand what is discussed above, you'll have to specify what you don't understand.

[RonPurewal]

When two people argue, to undermine one Is it sufficient If we provide evidence that supports other?

no. if you need to weaken someone's hypothesis, then you actually have to weaken the hypothesis.

[aliassad]

Would A still be a weakener if it were written like this

A. The numbers of the Baltimore oriole, a songbird that does not eat budworms, are declining

rather than

A. The numbers of the Baltimore oriole, a songbird that does not eat budworms but is as dependent on South America coffee plantations as is the Tennessee warbler, are declining

The point is due we need to boost the argument of Kate as well ?

Thanks in advance.