Question 146·Medium·Command of Evidence
Average Date of First Egg Laid by Two Arctic Bird Species
| Species | Average date in 2000 | Average date in 2020 | Change 2000–2020 |
|---|---|---|---|
| Arctic tern (Sterna paradisaea) | 15 June | 5 June | 10 days earlier |
| Snow bunting (Plectrophenax nivalis) | 20 June | 11 June | 9 days earlier |
To investigate how rising Arctic temperatures are affecting bird reproduction, ornithologist Leila Farooq compared long-term nesting records for two migratory species. She found that both the Arctic tern and the snow bunting began laying eggs earlier in 2020 than they had in 2000.
Which statement is best supported by the information in the table?
For SAT table-and-graph questions asking what is “best supported,” ignore background story details and focus on the exact numbers in the relevant column (often labeled “change,” “difference,” or a specific year). First, identify the key comparison the question cares about (here, how much each species’ timing changed). Then, read those numbers carefully and translate them into simple facts (which is larger, by how much, are they equal?). Finally, eliminate any answer that exaggerates, rounds too aggressively, claims equality when numbers differ, or adds extra claims not shown by the data, and select the choice that matches the numbers exactly.
Hints
Focus on the right part of the table
Look carefully at the "Change 2000–2020" column rather than just the dates themselves. That column already calculates how many days earlier each species laid eggs.
Compare the size of the changes
Ask yourself: which species shows a bigger shift in days, and by how much? Are the changes equal, almost two weeks, or just a bit different?
Eliminate options that misread the numbers
Check each answer for claims about "almost two weeks," "the same number of days," or "the same time." Do those claims match the exact numbers and dates in the table?
Step-by-step Explanation
Understand what the table is showing
The table compares, for two bird species:
- Their average first egg date in 2000
- Their average first egg date in 2020
- How many days earlier they laid eggs in 2020 than in 2000 (the "Change 2000–2020" column).
Read the exact numerical changes
Look at the "Change 2000–2020" column:
- Arctic tern: 10 days earlier
- Snow bunting: 9 days earlier So both species are laying earlier, and one species shifted by 1 more day than the other.
Match the question to the data
The question asks which statement is best supported by the information in the table. That means the correct choice must:
- Use the right size of change (around 9–10 days, not something much bigger)
- Correctly compare the two species (which changed more, which less)
- Not claim anything the table does not show (such as exact equality or identical dates).
Check each option against the table and choose
Now compare each choice with the numbers:
- A says snow buntings laid almost two weeks earlier and that Arctic terns showed no significant change. The table shows snow buntings only 9 days earlier (not nearly 14), and Arctic terns did change (10 days earlier), so A is wrong.
- B says both species shifted by the same number of days. The table shows 10 vs. 9 days, so B is wrong.
- D says Arctic terns now lay at the same time as snow buntings and that the five-day gap is gone. In 2020, terns lay on 5 June and buntings on 11 June, so there is still a gap, and D is wrong.
- C correctly matches the data: Arctic terns moved earlier by 10 days and snow buntings by 9 days, so terns advanced their breeding by slightly more days than snow buntings between 2000 and 2020. This is the statement best supported by the table.