The birds are in no danger. Like doerscheln said, the cats just watch the birds...they love them! They grew up together and I have trained them that they are siblings. I also don't give them any toys that look like birds or have feathers on them, so they don't get mixed messages!
Yes, that is so sweet ! My father had budgies all his life and sometimes it happend that the cats went into the room with the birds. They just watched them and then went out of the room again. Outdoors they were hunting and eating birds..... unfortunately.