The crows in Passage 1 and the ravens in Passage 2 shared which trait?
Choice A is the best answer. Both bird species studied modified their behavior in response to changes in their environment. The researchers described in Passage 1 “had gotten wild crows used to finding meat tidbits in holes in a log” (Passage 1, lines 13–14). In other words, the researchers had repeatedly placed meat in the log—that is, changed the crows’ environment—and the birds had responded by modifying their behavior, a point reinforced in Passage 1, line 14, which note that the birds began “checking the log reliably.” The ravens in Passage 2 act in analogous fashion, responding to the introduction of new objects in their environment by “pick[ing] them out at a rate of up to tens of thousands of times greater than background or previously contacted objects” (Passage 2, lines 19–20).
Choice B is not the best answer because while there is some evidence that the ravens described in Passage 2 formed a bond with the author, going on walks with him and possibly viewing him as their “teacher,” there is no evidence that a similar bond formed between the researchers described in Passage 1 and the crows they studied. Indeed, these researchers “hid behind a blind” (Passage 1, line 16) in an effort to avoid contact with their subjects.
Choice C is not the best answer because while crows’ tool manufacture is the central focus of the experiment described in Passage 1, there is no evidence that the ravens in Passage 2 did anything similar. Passage 1 does mention that “some ravens” use “seemingly insightful string-pulling solutions” (Passage 1, line 29), but nothing in Passage 2 suggests that the ravens in that particular study had or displayed tool-making abilities.
Choice D is not the best answer because while there is some evidence that the ravens described in Passage 2 mimicked human behavior, going on walks with the author and possibly viewing him as their “teacher,” there is no evidence that the crows in Passage 1 did any mimicking. Passage 1, in fact, suggests that the ability of the crow to produce the meat-fishing tool was innate rather than a skill it had acquired from either humans or other birds.