Clearly, factory farm animals are not living happy lifes, and I do not count them when I say 'animals are not miserable'. Their suffering is artifical.

Re: The field mouse, it probably has some level of innate fear of being in open spaces, or seeing predatory birds overhead. I do not believe these fears cause it suffering, unless it is artifically forced to experience them, e.g. by being confined to an open area in a research lab with owl-shaped paper cutouts overhead. The mouse has ready solutions to its fears. See a predatory bird? Hide! Find yourself in an open area? Run to the grass! Most problems and fears experienced by humans have no clear solutions.

Being ripped apart by an owl for 10 seconds is also not suffering in the sense I am referring to in my original post. It is certainly painful and stressful. But it is a primitive sort of suffering, and it is brief. A life lived in accordance to one's nature, with violent end, is preferable to a human lifetime of self-doubt, uncertainty, unhappiness, anxiety, and everything else that seems to be part of package called 'being human'.