1)
A. techniques used in certain experiments on social learning in birds
There is a lot of discussion of experiments, but notice, the results are discussed more than are the techniques.
B. reasons for the differences between social learning in birds and in mammals
Only that they "may be fundamentally different" is mentioned. There is no discussion of the reasons for any differences. This answer could trap someone who is just going with what sounds right. Mammals and birds are mentioned and reasons for differences in social learning among birds are mentioned. So as usual you have to be careful and really notice what is being said and what is not being said in order to get this question right.
C. question of how social learning manifests itself in birds
There is extensive discussion of this topic. Different kinds of birds and their particular types of social learning are discussed. In fact, the passage is mostly about a particular question, the question of whether birds can, like mammals, "can develop preferences for palatable food through social learning." While this answer choice does not say that exactly, it is the choice closest to what the passage is about.
D. basis for a widespread belief about a difference in behavior between birds and mammals
The basis, some experiments, for the belief that mammals and birds learn different things from each other about food is discussed, but much more is going on.
E. possible reasons why birds may or may not learn from each other in a particular
way. This is only briefly discussed in the part about chickens.
The correct answer is C.
2)
A. Only a small number of observer hens appeared to learn to avoid food that was
demonstrated by other hens to be noxious. - Incorrect. It is not shown that even a small number of observer hens appeared to learn to avoid food.
B. Observer hens ingested food preferentially only after numerous instances of
witnessing demonstrator hens preferentially ingest that type of food. - Incorrect. Nothing like this is indicated in the passage.
C. Observer hens appeared unable to recognize when demonstrator hens found a
particular food especially palatable. - Incorrect. Again, nothing like this is indicated. In fact, the passage does not indicate any difficulty in recognition by observer hens.
D. Demonstrator hens reacted adversely to ingesting certain novel foods. - Correct. Refer to the following lines. Even when demonstrator hens reacted with obvious disgust to a specific food, via vigorous head shaking and bill wiping
E. Demonstrator hens altered their behavior less obviously in response to noxious
foods than in response to highly palatable foods. - Incorrect. Quite the contrary. It is shown that demonstrator hens nade their body language very clear when given noxious food.
Answer:
3)It can be inferred…
"Sherwin’s research team speculated that ecological or social constraints during the evolution of this species might have resulted in there being little benefit from the social learning of unpalatability "
AND
"These results confirmed that avian species can develop preferences for palatable food through social learning"
Option (E) clearly describes the above two excerpts and is therefore correct.
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Thanks & Regards,
Anaira Mitch

GMATNinjaTwo Could you help with Q1?

1. The primary purpose of the passage is to discuss the

(A) techniques used in certain experiments on social learning in birds
(B) reasons for the differences between social learning in birds and in mammals
(C) question of how social learning manifests itself in birds
(D) basis for a widespread belief about a difference in behavior between birds and mammals
(E) possible reasons why birds may or may not learn from each other in a particular way
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E: Demonstrator hens altered their behavior less obviously in response to noxious foods than in response to highly palatable foods.

the above behavior is shown by observer hen and not the demonstrator hen hence E is wrong.

But Sherwin's recent experiments with domestic hens do not support the notion that avian social learning necessarily facilitates aversion to novel foods that are noxious or toxic.
Even when demonstrator hens reacted with obvious disgust to a specific food,
there was no evidence that observers subsequently avoided eating that food.

Demonstrator hens reacted adversely to ingesting certain novel foods. hence D is the answer