Tough problem. If you are sure they are starlings, then you can be aggressive in their control, as they are not a native species and are not protected. I had a BB gun as a kid.
Some people put up owl decoys, with mixed success.
There are two companies that make bird deterrent products. I have never used any off their products so can not comment on how effective they are or if they are environmental friendly. Some options use sound, but are fairly expensive.http://birdbgone.comhttp://www.bird-x.com