Seeing how I'm one of the people who enjoys predictions, old wives tales, random nonsense, and symbolism, I think it'd be fitting to go through some of the animals which are associated with evil or are simply bad omens. If you use them in your writing, do you think you have to believe in it as well? No, but some of your readers might so you better study up on whatever animal you want to consider for your story/book.
Bat
Guardian of the night, cleaner
Bats were oftentimes considered evil due to the misconception that all bats live off of blood or turn into vampires. Neither is true and only one specific vampire bat sucks blood. However, for stories, they are a welcome symbol of evil.
Coyote
The master trickster, laughter, humor, foolishness
As for these dog-looking creatures, the short version seems rather sufficient enough as an explanation. For the purpose of writing, main fact about these animals is that they are smart. They run in packs even though it might be a single one luring your pet outside its comfort zone to use it for dinner.
Crow
The keeper of sacred law
Crows and ravens might look similar but the crow is smaller in size. I am unfamiliar with their sacred law, but I can tell you that I've seen hundreds of them in my yard, perched up on trees, looking formidable. In many ways I don't see them as a good omen on a large scale, because when you see a 10 acre field covered in black, it's a bit freaky.
Owl
Can see what others can’t, essence of true wisdom, deception
Ah, the ever graceful owl. Where I'm from the owl is a bringer of sickness and death. Mind you, I live in the country now so the chances of spotting or hearing an owl are greater, but still. When an owl landed on my mom's car in the middle of the day, in the middle of a city, it didn't bring good news. Also, at some point I started hearing an owl on a regular basis in our yard. My husband's grandma passed away soon after that. I have not heard it since. Real or not, I'm not sure but I don't like them in close proximity to me.
Ram
Sense of self worth, assures an increase in flocks
Aside from the fact that it's a rather lazy animal and has but one use, rams, like goats, are also considered evil in some cultures.
Raven
Magic, the messenger of the great mystery, a change in consciousness
Raven as much as the crow has a purpose. Edgar Allan Poe's poem
The Raven is considered a mournful remembrance of his wife, some have said, but the animal itself is rather majestic in its beauty.
Sheep
Charity, elegance, passion
Aren't sheep considered sacrifice?
Snake
Power of creation, of transmutation, life, death and rebirth
Don't believe me if you don't want to but while actual snakes are part of nature and some are good for getting rid of poisonous ones - ask the two black snakes I have under my porch - dreaming of snakes has never nor will it ever be a good sign. It means that someone wishes you ill will. Like I said, you don't have to believe me.
Wolf
Teacher, pathfinder, sharing of knowledge, never-ending journey
Ah, the night creature that is magnificent and also shrouded in more mystery than one believes. Smart, kind, and they have the ability to see into your soul.
What do you think? Are all these true or false or perhaps half-truths? There's something to each. You can bring their abilities to life through your writing and make even a non-believer believe. After all, black cats bring good luck inside a house but beware if one crosses your path.
'til next time!