But the question is why would a cat leave a perfectly good rabbit in the cairn?
Not that I have an answer -- I still haven't figured out why mine leave dead animals every day on my doorstep.
Some they leave half eaten -- that makes sense, carrying food back to the den, instinct, there would be kittens in the wild but they're all neutered.
Some of the things they bring back, they leave untouched, but these are nasty things that taste bad like moles and voles that have scent glands.
But they think rabbits are yummy, and all they ever leave is a half-eaten carcass.
Easy question, really. The cat is actually leaving part of its kill for you - as a ceremonial offering.