A、During the spring. B、During the courtship. C、During the winter. D、During breeding season. B

Scientists have discovered a species of songbird that performs a tap dance so fast that it can’t be seen by the naked eye. Researchers from Japan and Germany slow down footages of the blue capped cordon-blue songbirds during courtship. Scientists have discovered that tap dance is in the courtship performance of both male and female cordon-blues. The next step for the researchers is to try and pick whether the birds mate is moved by the sight, the sound or the vibrations of this fancy foot work.
   Such is the agility of the songbirds show stopping quickstep that could only be fully appreciated in super-slow motion.
1. When does the songbird perform a tap dance?
2. How can songbirds’ tap dance be seen?