The bug
The foxes are working as normal, but there's a weird behaviour with it after it attacks/kills the rabbit/chicken.

To reproduce the bug:
1: Get a fox (at least 5 or 6 of them)
2: Get a chicken or a rabbit. (used a rabbit for this one)
3: If luckily, the weird behaviour begins!

(Since it couldn't be reproduced, I think that only 1 fox would jump once and kill it after when in walking mode. So I added 2 other attachments (video) to see the difference of the rabbit and the chicken with more foxes going after it).