During a thunderstorm, all of my foxes outside of a enclosure run west, and attempt to cross a gigantic ocean to do so. This behavior does not seem normal at all and it ends up with foxes getting lost, and the baby foxes drowning.

It actually looks like they are attempting to find a village (despite the island already having a registered village), but they are crossing a massive ocean to get to it. However, they get distracted by the fish mobs and I haven't observed any of them succesfully making it to the other side.