You shouldn't be holding calls for long enough to take your breath away. Rabbits have very small lungs, so when you're blowing your lungs out, you're giving the WRONG sounds. Shrieks should be quick, like your lungs are only the size of your mouth. Hit sharp little shrieks with some lower pitched squeals for only about 30-45 seconds continuously, then break for a minute or so, then hit it again. Make sure to make your sound appear to "run around" while you're calling too, so you sound more realistic.

GOTTA LOVE THAT MARLIN MAGIC!!!!