Challenging TOEFL Reading Question
Passage
Given that predators can make it costly to beg for food, what benefit do begging nestlings derive from their communications? One possibility is that a noisy baby bird provides accurate signals of its real hunger and good health, making it worthwhile for the listening parent to give it food in a nest where several other offspring are usually available to be fed. If this hypothesis is true, then it follows that nestlings should adjust the intensity of their signals in relation to the signals produced by their nestmates, who are competing for parental attention. When experimentally deprived baby robins are placed in a nest with normally fed siblings, the hungry nestlings beg more loudly than usual – but so do their better‑fed siblings, though not as loudly as the hungrier birds.
If parent birds use begging intensity to direct food to healthy offspring capable of vigorous begging, then parents should make food delivery decisions on the basis of their offspring’s calls. Indeed, if you take baby tree swallows out of the nest for an hour, feeding half the set and not feeding the other half, when the birds are replaced in the nest, the unfed youngsters beg more loudly than the fed birds, and the parent birds feed the active beggars more than those who beg less vigorously.
Question
In paragraphs 4 and 5, what evidence supports the claim that the intensity of nestling begging calls is a good indicator of which offspring in a nest would most benefit from a feeding?
When placed in a nest with hungry robins, well‑fed robins did not beg for food.
Among robin nestlings, the intensity of begging decreased the more the nestlings were fed.
C. Hungry tree swallow nestlings begged louder than well‑fed nestlings in the same nest.
D. Hungry tree swallow nestlings continued to beg loudly until they were fed, whereas well‑fed nestlings soon stopped begging.
Lecture Script
Hi everyone. Let’s work together on how to solve this TOEFL Reading question, which was asked on Facebook. It’s good preparation for both the 2025 and 2026 versions of the test. This is a hard question because it asks for something that doesn’t have an exact corresponding keyword in the passage, so you might not be sure what to look for.
The question is this: In paragraphs 4 and 5, what evidence supports the claim that the intensity of nestling begging calls is a good indicator of which offspring in a nest would most benefit from a feeding? So you need to look for words relating to claim and evidence.
Identifying Synonyms
If you skim the passage, you don’t see the words "claim" or "evidence." This means other synonym words are used instead. Let’s read the passage looking for similar meaning words for evidence and claim.
The passage starts with a question.
Why do baby birds cry loudly to beg for food, even though this noise can attract predators like snakes?
Next, the passage gives one possible answer.
A loud baby bird may be showing that it is hungry and healthy. Because of this, parents think it is worth feeding that baby.
Then the passage uses the phrase “this hypothesis.”
A hypothesis is the same as a claim.
So the claim is: loud begging means a baby bird is hungry and healthy, and parents should feed it.
After that, the passage explains what we should see if this claim is true.
If the claim is correct, baby birds in the same nest should change how loudly they cry based on their siblings. In other words, baby birds compete with each other by adjusting their crying volume.
To test this idea, scientists did an experiment with baby robins.
Some baby robins were taken out of the nest and not fed for one hour. Then they were put back into the nest with their siblings, who had already eaten.
The result was clear.
The hungry baby robins cried louder than their fed siblings.
This result supports the claim.
It shows that hungrier baby birds beg more loudly than their siblings, which is evidence for the hypothesis.
Let’s look at the next paragraph. It states: “If parent birds use begging intensity to direct food to healthy offspring capable of vigorous begging, then parents should make food delivery decisions on the basis of their offspring’s calls.” In the previous experiment with baby robins, the test was about whether hungry ones beg louder than the fed ones, and it turned out to be true. But the experiment didn’t test whether parents will give more food to the hungry ones—that is, the louder ones.
To test this, another experiment was conducted with baby tree swallows. This time, you take out all babies from the nest for an hour, feeding only half the set of the babies. When all the baby birds are replaced in the nest, the unfed babies beg more loudly than the fed birds, and the parent birds feed the active beggars more than those who beg less vigorously. So the hypothesis is confirmed: noisy baby bird = hungry and healthy → worth for parent birds to feed them.
Now that we understand the passage, let’s look at the question again:
"In paragraphs 4 and 5, what evidence supports the claim that the intensity of nestling begging calls is a good indicator of which offspring in a nest would most benefit from a feeding?"
First, let’s restate the claim.
The claim says that how loud baby birds beg helps parent birds decide which baby needs food the most.
The passage gives evidence from two experiments.
In the first experiment, baby robins that were hungry begged more loudly than those that were already fed.
In the second experiment, parent tree swallows gave food to the babies that begged more loudly.
Together, these experiments support the claim: hungry babies beg louder, and parents respond to louder begging.
Now let’s check each answer choice.
A. When placed in a nest with hungry robins, well-fed robins did not beg for food.
This is incorrect. The well-fed robins did beg, just not as loudly. The experiment is about loudness, not begging versus not begging. So A is wrong.
B. Among robin nestlings, the intensity of begging decreased the more the nestlings were fed.
This sounds reasonable, but the experiment did not test gradual changes. It only compared hungry birds and fed birds. So B is wrong.
C. Hungry tree swallow nestlings begged louder than well-fed nestlings in the same nest.
This matches the second experiment exactly. This choice correctly describes the evidence.
This is the correct answer.
D. Hungry tree swallow nestlings continued to beg loudly until they were fed, whereas well-fed nestlings soon stopped begging.
This is incorrect. All nestlings continued to beg. The difference was only how loudly they begged. So D is wrong.