Last winter was mild enough to allow most bird species to forage natur

Hello,
Let me explain how C is the right answer.
It is a strengthen question so we can bring outside information.
The argument says:
The mild winter allowed birds to collect food naturally rather than visiting feeders.Also the mild winters prevented the birds from migrating south.
The argument says these two factors are responsible for larger than usual bird population this year.

So we need to strengthen it.So we need to prove that these two factors only are responsible for the increase ,using the outside info.

Now C says :

There are more predators in feeders than natural environment so there are more chances of them being killed in feeders and since they did not go to feeders this year,there is less probability of them getting killed so

mild winter--less visit to feeders--so less attacks--so more population thus mild winter is responsible for population.

We need to fill in the reasoning gap.

mild winter---more population.

Fill this gap:

Mild winter--leads to natural food availabilty---leads to less visits to feeder--leads to less attack --leads to more population.

Here assumption is vulnerability will lead to death but since no other option fits in,C makes perfect sense.
Hope this helps.

Premises:

Last year's mild winter led to more natural foraging and less feeder visiting.
Last year's mild winter also led to no migration and hence limited the accompanying reduction in numbers.

Conclusion: Last year’s mild winter is responsible for this year’s larger-than-usual bird population

We need to strengthen that mild winter is the reason behind larger than usual bird population right now.

(A) Increases in bird populations sometimes occur following unusual weather patterns.

We need to strengthen that mild winter led to increase in bird population. We don't know what unusual weather pattern is being talked about here. Also, we are given that SOMETIMES unusual weather pattern leads to increase. Is it one of those times, we don't know.

(B) When birds do not migrate south, the mating behaviors they exhibit differ from those they exhibit when they do migrate.

We don't know how the mating behaviour differs. Do they multiply faster or slower? - Does not tell us.

(C) Birds eating at feeders are more vulnerable to predators than are birds foraging naturally.

This tells us that birds foraging naturally are less likely to be killed by predators. We know that mild winters led to more natural foraging and less feeding at feeders. So this helps strengthen that mild winters led to a higher bird population this time.

(D) Birds that remain in their summer range all winter often exhaust that range’s food supply before spring.

Irrelevant. What will happen in spring is not our concern.

(E) Birds sometimes visit feeders even when they are able to find sufficient food for survival by foraging naturally.

Doesn't help strengthen our conclusion. Even if some birds visited feeders, the number was less than before and that the argument tells us. It doesn't help connect mild winter with increase in bird population.

Answer (C)

c is the correct answer because if the predators wouldn't be able to kill the birds the population of birds will increase and the predators are not able to kill the birds because of the weather change so it is the correct answer

Hi KarishmaB

At best, option C strengthen the "Conclusion". But it doesn't seem to strengthen the "Reasoning" the question is asking for. The reasoning is that because of limitation in migration the population increased, and the option C doesn't reinforce this argument, but put forwards another reasoning for the outcome.

Thanks

That is what we require the strengthener to do - add new info that strengthens the CONCLUSION. It could even directly give a new point in favour of the conclusion - nothing wrong with that.
We are given that 'the proportion of birds visiting feeders was much lower than usual' in the argument. Option (C) explains how it could have led to an increase in bird population too and how last year’s mild winter is responsible for this year’s larger-than-usual bird population.

Last winter was mild enough to allow most bird species to forage naturally, which explains why the proportion of birds visiting feeders was much lower than usual. The mild winter also allowed many species to stay in their summer range all winter without migrating south, thereby limiting the usual attrition accompanying migration. Hence, last year’s mild winter is responsible for this year’s larger-than-usual bird population.

Which one of the following, if true, would most strengthen the reasoning in the argument?
(A) Increases in bird populations sometimes occur following unusual weather patterns. - WRONG. Nothing as such faulty with this one unless we pay attention to the word "sometimes". Also, is "mild enough" counted as unusual. If yes, then we need further assumption which is why this option is wrong.
(B) When birds do not migrate south, the mating behaviors they exhibit differ from those they exhibit when they do migrate. - WRONG. Differing can go on either side. So, no the right choice.
(C) Birds eating at feeders are more vulnerable to predators than are birds foraging naturally. - CORRECT.
(D) Birds that remain in their summer range all winter often exhaust that range’s food supply before spring. - WRONG. Exhausting food is a weakening aspect in the passage's situation.
(E) Birds sometimes visit feeders even when they are able to find sufficient food for survival by foraging naturally. - WRONG. It's neutral and doesn't help.

What may help increase the population. One reason may be the genuine population increase due to mild winter and another could be less mortality rate because of some reason. C touches upon the latter reason and thus the right answer.

Answer C.