#26 - At night, a flock of crows will generally perch close

[robertoc92]

Hi:

I was going through Lesson 5 of the Advance Logical Reasoning Course this morning, and I am a little stuck on Question #2 of the Cannot Be True section. The question about the flock of crows settling roosts.

In particular, I do not understand why the stimulus proves the flock of birds cannot move the five miles in response to food depletion. For the sake of argument, the birds could only move 5 miles because their newborns are limited to a certain distance. So the birds pick up and move that 5 miles with their kids, settle another roost, and then continue to scavenge that far range. Obviously, it would be best for the crows to pick up and move out of their original location, but there may be limitations preventing them from moving them that far. Limitations that even the stimulus doesn't prevent from being true.

I apologize for maybe taking this too far, and I realize that you guys didn't make the test, but I am just playing devil's advocate here.

[Dave Killoran]

Hi Rob,

Good to hear from you. Let's take a closer look at this question, which is from the June 1998 LSAT, Section 4, #25. I suspect there's something in the answer that you might be de-emphasizing or overlooking, but before we reach that point, let's first look at the stimulus.

In this question, we get a set of facts about crow habits. Of interest to us in understanding this question is the statement that "the crows’ hunting extends as far as 100 to 130 kilometers (60 to 80 miles) from the roost." Then, as you note, when they move, they usually only move 5 miles away.

Answer choice (E) basically contains an explanation of why the crows would move from one roost to another. But is it an explanation that is valid based on what we know? It isn't.

The crows hunt out in a range of up to 80 miles, which in my head I see as a big circle around that central roost. If "the area in which it has hunted and scavenged has been depleted of food sources," that means this entire area is now seriously lacking food. A move of just 5 miles (thus creating another big circular hunting range) would overlap significantly with the original hunting area, and thus the new roost would be in the middle of an area without much food. and the "new" area with food would still be some distance away. It doesn't make sense that a flock would move such a short distance if the reason was lack of food, because they'd still be facing the same problem, by and large.

Now, could it occur on occasion that a flock might just move 5 miles even in the face of food depletion? Sure--maybe they're sickly, or there's some other problem as you mention. But, answer choice (E) says "it generally does so..." and it wouldn't make sense that that would be the usual reason they moved such a short distance. I suspect it is the "generally" part that you might have overlooked in the answer, because it does allow for the possibility that once in a while a flock of crows moves a short distance.

There are times I disagree with certain things I see in questions, or feel like the problem could have been constructed in a better or more efficient manner. This isn't one of those times, though--I think this question is solid.

Please let me know if that helps. Thanks!

[robertoc92]

Hey Dave,

Thanks for your quick reply.

I didn't quite see the "generally" part of the answer choice, and I kind of see what role that word plays in the overall structure. I guess I still have trouble seeing why the hypothetical situation that I presented with the newborns couldn't generally be true for even all birds? All birds have babies, and this fact could limit the flock to how far it could move its roost site, but not necessarily how far the elder birds can travel to get food. Obviously not the ideal situation for them, but one they would have to live with to continue that bird species.

I am not trying to argue this idea (especially over a forum haha), but I just thought it may be something interesting to consider that could put the answer choice (E) in the "could be true" category.

Again thanks for your help, and I am really learning a lot from this course. I will be taking the October 5th LSAT, so prep is really ramping up.

[Dave Killoran]

Hey Rob,

I don't see this as an argument at all, more like an investigation of various possibilities

I'm certainly no bird expert, but birds don't have newborns year-round, so it could even be that bird flocks don't change roosts until breeding season is over. Either way, we don't have information on how that works, so we can't assume that they are limited in this fashion. We also don't have a timeline for how long a roost change takes (1 day? 1 week?). Maybe fledgling birds can fly 5 miles a day, and, if required, could relocate a significant distance over a matter of weeks if needed. there's also the issue where the stimulus states that, "the crows leave the roost and fan out in small groups to hunt and scavenge the surrounding area." In a sense, by saying that crows can range up to 80 miles, it could be interpreted that they took this baby/weakling/limited relocation range issue off the table. With the point above in mind, it's hard to make a determination that all birds would be limited in the way you describe.

Could the reason cited in (E) be possible? Yes, we both agree on that. I just don't see it as a consistent explanation for relocation, and that's what makes (E) problematic.

Glad to hear the Advanced LR Course is helping! It's always nice to get positive feedback. Thanks!

[al_godnessmary]

I've picked D for this question a couple of times around now, and although now I finally see why E is the better answer, I just want to know:

Is the key word marking D unsuitable "force"? Because I kept reasoning that "It's not difficult to get them to move again since they do so every few years, which shows that they don't have much difficulty abandoning a site for another." Maybe I should have crossed D off on the basis that I know nothing about actively FORCING a roost to move?

[David Boyle]

I've picked D for this question a couple of times around now, and although now I finally see why E is the better answer, I just want to know:

Is the key word marking D unsuitable "force"? Because I kept reasoning that "It's not difficult to get them to move again since they do so every few years, which shows that they don't have much difficulty abandoning a site for another." Maybe I should have crossed D off on the basis that I know nothing about actively FORCING a roost to move?

Hello,

That makes some sense. Indeed, the passage says nothing about force.

David