How To Make A Simple (but effective) Owl & Crow Guard
(by Kent Justus)

Following is a simple to make owl/crow guard made by cutting squares of the 2"x4" steel hardwire cloth to fit the front of your martin house (you will need to measure). Simply attach this square to the front of the house using plastic cable tie wraps. You can buy a bag or cannister of these at your local electrical supply store. I get mine from HQ Warehouse. - Kent

gm1001.jpg (61336 bytes) Photo #1: My TG-12 before installing the owl/crow guards. Scroll down...
gm2001.jpg (63824 bytes) Photo #2: Cut a section of 2"x4" steel hardwire cloth (dog fence wire) to fit the front of your martin house.  Also get about 4 plastic cable tie wraps to use.  These are simple to remove to conduct nest checks.  Just cut them off and replace with new ones when your nest check is complete.  You can buy a whole canister full of them.
Photo #3: Position the guard on the front of the house and then attach the cable wraps to the railing on the house.
gm4001.jpg (62356 bytes) Photo #4: After the cable wraps are tightened down, snip the excess off with cutters.
gm5001.jpg (62516 bytes) Photo #5: Another view.  This is a very simple guard, and yet very effective to deter predation on martins (especially nestlings) from crows and large owls.  Please do your martins a favor and attach guards to all housing to prevent loss to these predators.  Also, note the green bean stake attached to the lower porch also with the plastic cable tie wraps.  This provides extra perching space for the martins and they love it!  My martins (six pairs in this house last year) would sit on the perches and preen in the morning.