[Maine-birds] B-H Cowbirds Question

Hi.  Wondering about methods to discourage large numbers of Cowbirds.  They are cleaning me out.  I remember seeing suggestion to stop filling feeders.  Has anyone tried this method?  Does it work?  How long should I leave them empty?  Do they just return when they are refilled?  And most important - what's the impact on the other birdie visitors?  Will they also seek greener pastures?  Trying to balance the cost benefit.

Thanks in advance.

Judy Scher