After reading this forum and this site's other resources, I have decided to modify my PM house to 6"X12" compartments. I am in my second year of trying to attract PMs and am wondering if I need to go ahead and install the SREHs or wait until the birds are established.
Below is a sample pic from the retailer's website of my PM house
Hi Phillip,
IMO, if you have Starlings, put in the SREHs. That just gives you one less thing to worry about. Most Martins figure them out pretty quickly. Good Luck!
Phillip, on slick surfaces, put a thin layer of caulking inside
and outsid the entrances, then mark across with a course comb,
this gives them the traction they need to learn the sreh.
When converting to the larger compartments, can I cut an opening, say, 3"X3" in the center wall, and use that piece of plastic to cover the other hole? Is it safe to use small screws to attach it as long as the screws enter from the inside?