Looks can be deceiving
This is the cover of the famous book in which Hitchcock was based to make 'The birds'. Although the movie has nothing to do with the book, only the part about the strange and violent behavior of the birds, both are equally creepy.
Solution
My challenge was to catch the reader by surprise, and just like in the story, first introduce some calm birds like the ones you see in a park, to move on to some creepy and bloody birds.
For this I have created two covers, one with the calm birds for the book jacket, and another more bloody one for the book cover. I think the result is interesting and encourages you to remove and put the jacket back and forth to see the creepy change.