beak shape eye position feather pattern tail-feather length
I gave my students this multiple choice question: A birdwatcher wants to identify an eastern bluebird. What feature of a bird should the birdwatcher evaluate first to identify an eastern bluebird?

Only one answer is correct among these 4 choices:
- beak shape
- eye position
- feather pattern
- tail-feather length

Could you tell me which one is correct?

feather pattern