A while back, I found a British documentary series called "Burrowers: Animals Underground" on YouTube. They build enclosures for European Badger, Water Voles, and European Rabbits to see what they did underground. I found this fascinating. They also said they did it with Common Moles, but it never actually showed this.
I am curious to know what happened to the enclosures afterwards. Do they still exist? Can you visit them? Have studies like this been done for other animal species?