My feeding experience is more limited than Fran's, but I would guess that 
the attractiveness of the feeders to rats will partly depend on what you're 
putting in them.  Assuming the feeders are not directly accessible to the 
rats, the rats are probably depending on the birds to scatter seed on the 
ground.  Seed mixes are bad because some birds (especially House Sparrows, 
which are messy eaters anyway) will scatter large amounts of the seeds they 
don't like while picking out the ones they do like.  Non-mixed seed with low 
waste is the best bet, and I'm sure there's some seeds rats don't like as 
much--safflower, maybe?  In my case, my feeders are only a few feet from my 
neighbors' yards, so I avoid feeding entirely in summer, when rats seem to 
be most active.  I don't know if any of this is new info for someone who's 
been feeding for 14 years, though!

If the rats have moved in for the first time after 14 prior years of 
feeding, I'd guess there's a good chance they've got other food sources, so 
even taking away the feeders may not cause them to leave.

Jason Waanders
NW DC
jwaandersATstarpower.net