Yeah, I had two cats that grew up together. Over a year ago, one died and the other one just hasn't been right since.
Some people say animals don't have the same feeling we human's do. I can't speak for earthworms, but I would say most of the mammals out there share some if not all of the basic emotions of the human race. And birds are definitely more intelligent than people would like to think.
Sorry about your bird, TFB.
Bart