During a lightning storm, I heard a very loud lightning strike (close by, it was in fact right above me), and heard the death sounds of parrots and a dog (and, perhaps coincidentally, the feathers from the dead birds appeared by my feet, even though I was one floor lower than the parrots, and the floor separating us was made of solid blocks), when I went upstairs, I found two of my parrots, one of my dogs, and one cat was missing. I reverted the realm to the backup from 11 hours ago (I had just started playing today, thankfully I hadn't really done any progress since then)