Hmm, a bit of flickering is unavoidable, but if you're getting serious flickering that may indicate a problem.
Check to make sure you are doing the steps in the right order:
- Print the blank lines.
- Print the owls
- Pause one second.
If you switch the order if steps 2 and 3 you will get horrible flickering, because mostly you only get to see the blank lines, and the owl text scrolls by too quickly.