Bird feeder

Hi,

I was wondering if anyone had a suggestion for a bird feeder which I could use to stop crows eating the feed before any other birds can get there?

At the moment we have feeders with anti squirrel cages on the fat ball and tray feeder, but I didn't want to cage the peanuts as we get nuthatch and greater spotted woodpeckers.

So we we're looking for something that would allow the greater spotted woodpecker and nuthatch but not the crows.

Regards,

Mark