I see this isnt by my area but is this oak and are those hollowed-out rounds subject to some kind of disease or bug?
To be honest, I'm not sure. I've seen plenty of hollowed logs/trees. More than once I've found large black ants in them. And on more than one occasion I've thought it was due to a poor tree trim. Not sure if I can find a pic as an example. Too flush of a cut opens up the tree to rot/bugs and it'll hollow out. My neighbor across the street has a very large maple that's been hacked over the years. I imagine it's worse that the pictures above in the add. It harbors starlings and I hate them birds!
I have seen oaks that look like they were just hollowed out and the tree still lives but the main trunk was just this dead and dried out shell. It grew well in the past it shows but like the ad shows, something took the heart out of the tree. If anything those birds may be gorging on those ants in your neighbors tree. I gather you'd prefer to pack their homes with a little tnt eh?
I have a large maple with 2 small cavities from previous trims that they try to nest it. I've filled with rock, sand, limbs, mouse poison, expanding insulation and I finally gave up. Now I let them get a little comfy, the get this out. Gamo Buckmaster Squirrel Terminator. This this is crazy deadly!
