Ava peered through her binoculars at the wooden birdhouse her grandfather had built. For three springs, she had documented the robin family that returned to nest there. But this year, the house remained empty even though other birds sang in nearby trees. "Maybe they found a better spot," her grandfather suggested, noticing her disappointment. Ava flipped through her nature journal, stopping at last year's photos of baby birds. She frowned as she noticed the crack that had appeared in the birdhouse roof.
What evidence tells us how long Ava has been watching the birdhouse?
"For three springs, she had documented the robin family that returned to nest there""She frowned as she noticed the crack that had appeared in the birdhouse roof""Other birds sang in nearby trees"Based on the text, what might explain why the robins didn't return this year?
They migrated to a different regionThe birdhouse is damagedOther birds scared them away