Question 107·Medium·Central Ideas and Details
Every winter since 1900, thousands of volunteers across North America have participated in the Christmas Bird Count, a citizen-science project in which people tally the birds they observe in a single 24-hour period. The data collected help ornithologists track population changes, identify at-risk species, and better understand how climate and habitat shifts affect bird life.
Which choice best states the main idea of the text?
For SAT main-idea questions on short passages, first quickly restate the passage in your own words, focusing on (1) who or what the passage is mainly about and (2) what is being said about them, especially the purpose or outcome. Then eliminate answer choices that (a) zoom in on a minor detail, (b) introduce emotional reactions or facts the passage never mentions, or (c) contradict the text. The correct answer will be a broad, accurate summary that combines the key elements from the whole passage without adding or twisting information.
Hints
Restate the passage in one sentence
Try to say in your own words, in a single sentence, what the passage as a whole is describing and why it matters.
Pay attention to both sentences
Look at what the first sentence explains about who is participating and what they are doing, and what the second sentence says about the purpose of that activity.
Watch out for extra or extreme claims
Check each option for ideas that are not stated in the passage, such as emotional reactions, absolute statements (like "only"), or specific outcomes (like a decline) that the text does not mention.
Step-by-step Explanation
Identify the basic topic
First, restate in your own words what the passage is about. The first sentence introduces the Christmas Bird Count, a winter event where thousands of volunteers across North America tally the birds they see in a 24-hour period. It is called a citizen-science project, meaning ordinary people (not just professional scientists) help collect scientific data.
Notice what happens with the data
The second sentence explains why the data are collected: they "help ornithologists track population changes, identify at-risk species, and better understand how climate and habitat shifts affect bird life." So the key idea is that scientists use the volunteers' data to monitor and study bird populations and their responses to environmental changes.
Decide what the main idea emphasizes
A main-idea answer must cover both the volunteers' counting activity and the scientific purpose of that activity. Eliminate any option that:
- Focuses only on volunteers' personal experience or enjoyment.
- Contradicts the passage about who gathers data.
- Makes a claim about climate change or bird declines that the passage does not state. Then choose the option that correctly summarizes: an annual bird count using volunteers, whose data scientists use to study bird populations and environmental effects. That description matches choice D.