I always loved the mud swallows that moved into our old chicken coop, they made cool nests and nice songs.
Not familiar with your mud swallows, here we have barn swallows. I had birdhouse hanging in my front pin oak tree a couple years ago and one day whilw walking under it I heard a scratching noise coming from it.
When I took it down to see what was inside, it was a barn swallow who had entered it but couldn't get out.
Fortunately the bird was still healthy and he flew away but I threw the house into the garbage. Prior to that poor thing, all I would get was the damn sparrows and as soon as I removed a nest they would build another one........they're vermin.
I have since built a new house with a smaller hole and installed it on the side of my house hoping to entice another swallow to come and make it its home.......
I look at swallows as the “Blue Angels” of the bird community..............They’re acrobatic jets.
They are interesting. Didn’t realize there was such a thing. :)