using hay bucket for bathroom?

Hello all.. I new behavior has arose with mister callaway. He was prone to knocking his hay container over so I used the clips on the back to secure it to the cage because I was tired of cleaning it up. Haha. So I did that about two weeks ago. This past week, while cleaning his cage, I noticed poops in the container. I cleaned out the hay container and replaced the hay. Its been a continuation. So, today while cleaning his cage, I noticed that he has also peed in the hay container. I have no idea how he is doing this! The container is clipped and its a good inch off the bottom of the cage. Whenever he goes to the bathroom, he sits next to the container, hunches over, lifts his tail, and goes. My guess is that he is doing it at night time. Is this normal behavior? If so, how can I get him to stop or alter the behavior. He has a litter box he uses sometimes but other than that, he just uses his cage which is set up sort of like a litter box. There is a grid in the bottom to let the droppings go through. PS he is never in there. He is only in there if we are gone for extended periods of time and over night.

Bunnies naturally nibble and poop to some extent all the time. It just goes hand in hand. Alot of people train their bunny to a litter box but still put hay in it. It goes against all veterinary rules of cleanlieness to go putting hay in the box then right where they're peeing and pooping-then they'll continually being eating contaminated food. Many bunny people argue that this encourages the bunny to use the litter. I find a hay wrack next to/above it better so they're not eating the same stuff they're peeing in.

Plus, if the bunny isn't altered that can cause them to all the more pee and poop everywhere.