Killing a bird in a dream is read symbolically, never literally — as cutting off a hope, silencing a voice or ending an idea. Dream books often see it as guilt or the end of a phase you have outgrown.
Where in your waking life have you met something like this lately?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.