Interesting observation...

[Mommy2many]

Do the starlings destroy only bluebird nests or other bird's nests as well?

[ConcinusMan]

Do the starlings destroy only bluebird nests or other bird's nests as well?

Any bird. The only thing that stops them is if it is a very small bird, and the hole is too small for them.

Once a few years ago I discovered woodpeckers nesting in a hole in the wall of an abandoned building which I thought was really cool. After a while of seeing them come and go, I started hearing the cries of newborns. Shortly thereafter, I watched in horror as a couple of starlings got in there, picked the babies to shreds, and threw them out. A few weeks later, all that was there was a nest full of squawking, crapping starlings.