Boat bunnies - random thoughts before I fall alseep

I'm just in bed trying to drift off (ru doesn't help!) and I had a memory from when I used to live in battersea on the river.

There were perm house boats parked up and one of them had a bunny pair on top of it! As in they lived on the roof in the open! They had a shelter in the form of a small hutch and were always snuggled up but how strange! I wonder what they did with them at night? I always thought they were really cute but wondered how they never jumped off the boat/got attacked by predators...