I raised my toilet lid to use the bathroom, but there was a dead bird in there. The bird must have been alive at some point because the lid, rim, seat were all splashed with water. How did the bird get in there? The lid was down.

Tongue in cheek... please pardon me... Maybe it's a Toilet Duck?

OMG! Was there any scuba gear in there?

It is likely the lid was up when he hit it and fell in and the lid fell down. He struggled because he felt trapped then died of exhaustion. Next question is... how did he get in the house?

It might have come down the vent-- not been able to go back up and thought that was the route to freedom --Savage

It can be a sign of a gang coming to kill you, a friend had the same problem and knew of the gang sign and immediately called the police, they told her to get in her car, lock the doors, open the garage and leave. Apparently they do very very bad things. Scary things can happen. Also, another bad sign from the Mafia is that they will put a dead fish on your porch. That would typically mean they are searching for you and going to kill you, pretty scary!! Don't mean to scare anyone but that's what I've heard.

Been there! Done that! Some years back I was on a stopped toilet call. When I augered the bowl I brought back a dead bird that had flown down the vent into the bowl. Cheers, Tom