careful pruning your cherry anymore, pruning cherries tend to make them overreact in growth the next year, and also makes them more susceptible to fireblight. and agree with the others, lichen isn't generally harmful. By itself, it certainly is not. the only thing I've heard of is that it can serve as habitat for pests that might hurt the tree. but not worth working so hard on.
as far as birds on a cherry that size? man, what can you do? Ive always wanted to chain a housecat in the tree, see how that would do....
