How to protect mason bees from woodpeckers?

Are birds a problem? How can I protect my mason bees against woodpeckers?

ALSO

If I build a "guard" for the front of the bee box, what material should I use? Any design ideas?

Use some hardware cloth. I would think that 2" Poultry wire should work. Look for more information on crownbees.com. I know I mention that site a LOT but I have learned most everything I know about the bees there. Look for him on You Tube as well.

You can purchase protective screens. But I just got some wire mesh and attached it in a sort of U-shape to the front of the mason bee house, so birds are kept at a couple inches distance.

Here is a design for mason bee house with hardware cloth to protect the tubes... http://boingboing.net/2014/05/16/build-your-own-mason-bee-house.html