My 5 month-old neutered bunny has all of a sudden started to poop and pee into his food bowl, which is fairly small (about 1/2 cup). It started a few days ago and I notice it happens at night when I'm sleeping and when there is little to no food left in the bowl. The bowl sits in his litterbox because he likes to be able to eat and go to the bathroom at the same time, so I'm wondering if he's doing it intentionally or just accidentally backing up too far next to the bowl. Thanks!

Is there any chance you can hang the bowl on the side of his cage/pen so that it's right above the litter box? Bunnies do love to poo and eat and the same time, so that might be one solution.

It's possible that he chose that corner as his favorite, I'm with Cinnabun, but if you can't hang it maybe switch it to an opposite corner and see if that works

This is just starting to happen with my bunny too! I can't figure out why. His food bowl is in the opposite corner of his litter box. :/

I would take the food bowl out of the litter box. Put hay in the litter box for him to munch.