This happens every spring and fall-birds,
usually starlings come down our furnace pipe and into the basement.
Usually it's pretty easy for me to get them out-just open the basement
door and turn off the lights and they head right outside.
Sometimes, though-the door to our upstairs is open and they come up and
make a mess-flapping around, knocking stuff over, and pooping on
everything. This one made it all the way to our upstairs bathroom,
behind the door. I put on some gloves, grabbed him and set him free.
Glad I got a pic first, though.