Every fall Croton's jays migrate south. The jays always join flocks of

Hello, Nandini21. In an effort to assist you and the larger community, I will provide a full analysis of the question. Since we are looking to strengthen the argument, we have to keep an eye on just what that argument says. The passage:


This seems a fitting passage for the beginning of fall (in the northern hemisphere), when a lot of birds begin their annual southward migrations. Anyway, notice the extreme language in the second line: the [Croton's jays] always join flocks of migrating crookbeaks (my italics). The third sentence follows up on this absolute truth within a conditional: even if a jay cannot keep up with the flock of crookbeaks, it wanders until it comes across another flock. Then, we get the conclusion, which you have identified above: Croton's jays lack the navigational ability to find their way south on their own.

To strengthen this assertion, we need to find an answer choice that addresses at least one of two angles:

1) Croton's jays cannot migrate (at all) on their own;

2) Croton's jays cannot migrate south on their own.

What do the answer choices have in store for us?


Although there is some information about a southern migration at the tail-end of the answer choice, we are not concerned with what happens after the migration. This information about Croton's jays being parasitic nesters has nothing to do with their migratory habits. This should be an easy elimination.


For the uninitiated, this answer choice might sound reasonable—if crookbeak-like birds do not migrate, then the jays must be following the crookbeaks, so the thinking may go—but the argument itself is not based on the migratory habits of any bird other than Croton's jays. We are not concerned with relatives of crookbeaks.


Now, I agree that it can be off-putting to see north in the answer choice when the argument is based on the jays migrating south. But remember what we outlined above. Perhaps the direction is less important than the overarching point that Croton's jays cannot migrate unaccompanied by other birds. We cannot ignore that this answer choice lays out just such a scenario, in which the jays are riding the coattails of the warblers to make their way to a different location. If the direction bothers you—and I will admit that it gave me pause—then simply place this option on hold while you assess the others.


First off, the argument is not based on birds besides Croton's jays, so these other birds fall outside the scope of the argument. I extended the red text, however, to point out another common problem that pops up in incorrect answer choices: vague, unqualified language. The word occasionally here acts in the capacity of a sometimes or a some in a different question, and unless the argument is based on an absolute condition (e.g., something always or never happens), this sort of vague language will not affect the argument one way or the other. Think about it: if something occasionally occurs, then we could just as easily say that that event sometimes does not occur. All of this is to say that you need to watch for unqualified language. It may not be the most apparent target here, but it may very well be in another question.


Notice the direction: north. The argument, of course, is based on the jays flying southward with the crookbeaks. Just because the crookbeaks flock north ahead of the jays does not mean the jays could not hitch a ride with the crookbeaks on their way south at the end of the season. Unfortunately, we are unable with the information in this answer choice to supply any explanation as to how Croton's jays migrate northward. Is it by making their own way (a fact that would fly in the face of the argument), or by finding some other bird to follow? Without any information to lean on, we cannot say that (E) strengthens the argument, so we need to abandon it.

There you have it. Of the five answer choices presented, a single one provides information that the Croton's jays migrate in the company of other birds, thereby strengthening the notion that the jays may lack the navigational ability to find their way... on their own. That is why we need to choose (C).

I hope my explanation proves useful. Good luck with your studies.

- Andrew