Ornithologist: This bird species is widely thought to subsist

Question

Ornithologist: This bird species is widely thought to subsist primarily on vegetation, but my research shows that this belief is erroneous.While concealed in a well-camouflaged blind, I have observed hundreds of these birds every morning over a period of months, and I estimate that over half of what they ate consisted of insects and other animal food sources.

The reasoning in the ornithologist’s argument is most vulnerable to criticism on the grounds that the argument

(A) assumes, without providing justification, that the feeding behavior of the birds observed was not affected by the ornithologist’s act of observation
(B) fails to specify the nature of the animal food sources, other than insects, that were consumed by the birds
(C) adopts a widespread belief about the birds’ feeding habits without considering the evidence that led to the belief
(D) neglects the possibility that the birds have different patterns of food consumption during different parts of the day and night
(E) fails to consider the possibility that the birds’ diet has changed since the earlier belief about their diet was formed

siddharthkapoor · Answer

The conclusion is concerned with primary food of a concerned bird species. The flaw in the ornithologist argument is that he is basing it on his observation during morning hours and assuming the same eating pattern in the concerned bird species all through the day. Option D points out this flaw, and therefore is the correct answer.

Jsuhani15 · Answer

Can someone explain how r we eliminating E as i was confused between D and E.
Thanks

Posted from my mobile device

siddhantvarma · Answer

Can someone please explain how to eliminate A? 
 GMATNinja   KarishmaB

zlishz · Answer

A says that the birds must have changed their feeding behaviour (chosen to eat insects) because of the act of observation of the ornithologist.

However, the passage states that the ornithologist was 'concealed in a well-camouflaged blind', this probably breaks the possibility of the birds being affected by the presence of the ornithologist.

napolean92728 · Answer

The correct answer is  (D)  neglects the possibility that the birds have different patterns of food consumption during different parts of the day and night.

Reasoning for the correct answer: 
The ornithologist observed the birds "every morning over a period of months" and based their conclusion about the birds' overall diet on these morning observations alone. This is problematic because the birds might consume different foods at different times of day. By only observing morning feeding habits, the ornithologist could be missing important dietary patterns that occur during afternoon, evening, or night. To make a claim about the birds' overall diet, observation throughout the full day/night cycle would be necessary.
Reasons for eliminating the incorrect options:

(A) is incorrect because the argument doesn't depend on whether the birds' behavior was affected by being observed. The ornithologist was "concealed in a well-camouflaged blind," suggesting steps were taken to minimize observer impact. Nothing in the passage suggests that the birds' behavior was altered by the ornithologist's presence.

(B) is incorrect because the specific nature of non-insect animal food sources is irrelevant to the ornithologist's main claim, which is about the proportion of animal vs. vegetable matter in the birds' diet. The lack of detail about these other animal food sources doesn't weaken the argument.

(C) is incorrect because the ornithologist doesn't adopt the widespread belief - they explicitly challenge it ("this belief is erroneous"). The ornithologist is disagreeing with, not adopting, the common view about the birds' feeding habits.

(E) is incorrect because there's no indication of a temporal change in the birds' diet. The argument is about what the birds currently eat versus what people believe they eat, not about how their diet might have changed over time.

Ornithologist: This bird species is widely thought to subsist

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Ornithologist: This bird species is widely thought to subsist

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