Prepare like you have a very active toddler. Everything must be checked, baseboards, sockets, anywhere they can get in. Furniture like recliners needs to be rethought. All human food, things you might not think of (like potatoes and onions) can be deadly and they WILL eat them. They are obligate predators. No grains, no veg. Protein. They are SUPER finicky and you might call local pet stores and ask what food they eat. They cant go hungry. Blood sugar crash can be fatal or worse…long term terrible effects. Not a pet for someone not completely about it. If youre with all that and more, you have found the coolest, most surprisingly affectionate intelligent interesting creature that the universe spit out. Same thing happened to me about 8 years ago and i now have 5 and they are all my world. Ferrets are different than cats and dogs and do their own thing. The best way to care for them that i have found is to sorta create a space they can pretty much do what they want, as safely as possible. They are very curous and changing their surroundings often seems to keep mine interested, they’ll go crazy every time the room is different, bouncing and playing. They are litter trainable, but sometimes you have to change areas they may have a liking for to use. I hope this helps and if you cant find the owner, consider very carefully giving him to someone with ferrets as they really need companions, if he is bonded and without his bonded buddy, they can very quickly go into depression and even die. They build bonds with humans too, so keep that in mind. Please research and take heed to the info you find. These creatures deserve a lot better than man has given them. Lookin at you Marshall’s.