PT56, S2, Q4 The song of the yellow warbler signals to other

[ManhattanPrepLSAT1]

4. (C)
Question Type: Assumption
This argument states that the territory of a molting warbler will not be encroached upon by other warblers, and then uses this information to conclude that the molting yellow warbler will have no competition for food in its area. This assumes that the molting warbler will not have to compete with other kinds of animals (besides warblers) for food in its area. Answer choice (C) states this assumption.

(A) is not assumed. The amount of food contained in a core area has no bearing on whether the molting warbler will face any competition for the food.
(B) is not assumed. Whether or not other birds lay claim to territories by singing has no bearing on whether the molting warbler will face competition for the food in its area.
(D) is tempting, as it implies that these birds who share the warbler’s territory wouldn’t be competing for the same food (they eat different foods). However, it is not necessary to assume that the warblers do not share their food with these birds in order to conclude that there will be no competition with any other animals.
(E) is not assumed. The relative size of the core area has no bearing on whether the molting warbler will face competition for the food in its own area.

[andrewgong01]

For the negation of Choice "D" we have two verbs to choose and one seems to destroy the argument and the other negation does not :

Negations :

1) Warblers do not often (i.e. rarely, less than 50% etc ) share feeding areas with other kinds of birds, which don't eat the same stuff as Warblers do

vs

2) Warblers often share their feeding areas with other birds, which do eat the same stuff warblers do.

The latter one seems to me would destroy the argument because it is saying Warblers still face competition from other bird types who eat the same stuff.

The first negation does not destroy it because wether it is rarely or often does not in itself say why in one case there is and in the other case there isn't the threat of competition as you either have competition or you do not have competition.

Updated Edit: Since "D" is wrong I am assuming the first negation is correct. However, why is the second negation wrong?

[ohthatpatrick]

This is a very atypical answer choice, because it DOES make two claims.

Two claims: A and B.

If we're saying "It's not the case that 'A and B'."
we're saying "Either ~A, ~B or ~both."

If we say,

IT'S NOT TRUE THAT
warblers often share their feeding area with birds who have at least a somewhat different diet,

we might mean: they don't share their feeding area with birds
or
we might mean: the birds they share with DO eat the same type of diet

Since we don't know which one we mean, we can't get any logical force out of arbitrarily choosing one of them.

We can't "choose" to hear the negation of this as "They DO share their feeding areas with other birds who DO eat the same kind"

========

Our OBJECTION to the "therefore, YW's have no competition for their food supply" might have been

OBJECTION: sure, other YW's won't encroach on the inner territory, but maybe OTHER birds will, and maybe THOSE birds compete for the same food supply.

If we say that as a NECESSARY ASSUMPTION, it would sound like
(D) There are not other types of birds who eat similar insects or seeds as warblers do who would be willing to enter the smaller core territory.

[EmilyL849]

Hi, teachers

Would you say that another assumption here is,

“The distance that the birds fly while they are molting does not significantly exceed their molting territory”

Even if the birds do fly above their molting territory, in order for this fact to really weaken the conclusion, we would require an additional assumption that they will search for food in this above range. However, the author does seem to rely on the fact that the birds fly only short distance in their molting time to conclude no food competition.
And sometimes answers to necessary questions just point out the unspoken thinking process of the author in drawing a conclusion. So, I want to check if my understanding is correct.

Thank you.

[ohthatpatrick]

I think you're right.

The argument has to assume that
"the short distances that a yellow warbler can fly during molting are all within their smaller core territory"