Songbird Migration

This topic has expert replies
User avatar
Legendary Member
Posts: 1665
Joined: Thu Nov 03, 2011 7:04 pm
Thanked: 165 times
Followed by:70 members

Songbird Migration

by karthikpandian19 » Sun Jan 08, 2012 4:35 am
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 elimination of the dense tree cover that formerly was a feature of South American coffee plantations.

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

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

a.The number of the Baltimore oriole, a songbird that does not eat bud worms but is as dependent on South American coffee plantations as is the Tennessee warbler, are declining.

b.The spruce bud worm population has dropped because of disease that can infect bud worms but not Tennessee warblers.

c.The drop in the population of spruce bud worm is expected to be only temporary.

d.Many Tennessee warblers have began migrating in the fall to places other than traditional coffee plantations.

e.Although many North American songbirds have declined in numbers, no other species has experienced as great a decline as has Tennessee warbler.
Source: — Critical Reasoning |

Master | Next Rank: 500 Posts
Posts: 382
Joined: Thu Mar 31, 2011 5:47 pm
Thanked: 15 times

by ArunangsuSahu » Sun Jan 08, 2012 1:26 pm
(A) is the answer

(D)--weakens kate's answer
(E)--Irrelevant
(C)--The effect of (C) is not known as there are no statistics that after the spruce worm population (which ever happened before) came back to normal what happened..no instances of that
(B)--Irrelevant

User avatar
Newbie | Next Rank: 10 Posts
Posts: 9
Joined: Wed Aug 10, 2011 3:40 pm

by bajjuri6 » Sun Jan 08, 2012 1:33 pm
The objective here is to undermine Scott's theory that the decline in numbers is due to shortage of prey. Choice A best defies this argument by presenting an example of another species with similar characteristics.

User avatar
Legendary Member
Posts: 1665
Joined: Thu Nov 03, 2011 7:04 pm
Thanked: 165 times
Followed by:70 members

by karthikpandian19 » Sun Jan 08, 2012 5:18 pm
OA is A

User avatar
Legendary Member
Posts: 1239
Joined: Tue Apr 26, 2011 6:25 am
Thanked: 233 times
Followed by:26 members
GMAT Score:680

by sam2304 » Sun Jan 08, 2012 6:50 pm
IMO A.

Provides alternate reason which weakens scott's hypothesis.
Getting defeated is just a temporary notion, giving it up is what makes it permanent.
https://gmatandbeyond.blogspot.in/

User avatar
Master | Next Rank: 500 Posts
Posts: 130
Joined: Fri Apr 20, 2012 8:13 am
Location: Toronto, Ontario
Thanked: 16 times
Followed by:4 members
GMAT Score:650

by tisrar02 » Mon May 14, 2012 2:08 pm
This is a comparison question. We need to undermine Scotts theory so A would be the best answer choice as it is said that there is another bird that lives in almost constant circumstances that is also declining. Therefore the best answer choice for this question is A.

Hope this helps!