Last winter was mild enough to allow most bird species to forage naturally, which explains why the proportion of bird...

shunhe on August 7, 2020

Hi @liz_hassett,

Thanks for the question! Let’s go over this stimulus first. We’re told that last winter was mild and so most bird species could forage naturally, so birds didn’t visit feeders as much. The mild winter also allowed species to stay in summer ranges all winter without going south, which limits attrition (birds dying) accompanying migration. Thus, the argument concludes, there’s more birds this year because of the mild winter.

Now we’re asked for something that would strengthen the reasoning in this argument; in other words, we want to make it seem more likely that the mild winter last year is the reason for more birds now. (B) tells us that the following statement strengthens: when birds don’t migrate south, the mating behaviors they exhibit differ from those they exhibit when they do migrate. As you noted, it doesn’t tell us how the mating patterns differ, so we can’t say that it strengthens the argument. Maybe the mating patterns differ and make it less likely for the birds to mate, and then that would weaken the argument. (B) would be more likely to be correct if it read what you suggested, that birds mated more when they don’t migrate south. (C), the correct answer choice, doesn’t have this ambiguity and so is a better answer than (B).

Hope this helps! Feel free to ask any other questions that you might have.