A team of climate scientists hypothesizes that recent shifts in the timing of bird migration in eastern North America are driven by warming spring temperatures rather than by changes in day length.
Which finding, if true, would most strongly support the team's hypothesis?
- Acheck_circle
Migration arrival dates have advanced in regions where spring temperatures have risen most, but have remained stable in regions where temperatures have changed little, even though day length has shifted in the same way everywhere.
- B
Some birds migrate at night.
- C
Bird migration has been studied for many years.
- D
Day length is determined by the position of the Earth relative to the Sun.
Explanation
A links the variable shift (temperature) to the timing change while showing day-length cues are constant across regions, supporting the hypothesis. B, C, and D are tangential.