I found a headless chicken?

City chickens are getting very common (when I fix the drainage in my backyard I'm building a coop myself!) and cats, and also foxes (you'd be surprised how many foxes live in cities and you'll never see them) will happily kill them, and regularly just eat the head. I have a decapitating cat of my own. Brings me headless rats and birds.

On top of that, small hawks will regularly steal such kills, and travel quite a distance with them.

Cat, coincidence. Voodoo/witchcraft, do you have many enemies. If you think it is the second, seek either help from a medium, psychiatrist or some kind of law enforcement.

Possibly garbage or a sick joke.

Unless you know someone that practices Voodoo and they are mad at you putting a curse on you. No.Is anyone in the neighborhood mad at you? Probably just some kids messing with you or someone lost their dinner out of the window

Yes.