Any number you want, quite tame but certainly more active at night, especially when you're lying in your sleeping bag. Endless hours of fun trying to catch the little blighters and great for your flexibility as they reach places no other beastie has reached before.
The wife will love them, especially when they run up her arm to greet her as she's putting your shooting clothes into the washing machine, I know mine was thrilled to bits. Also great for introducing to the in-laws when they've overstayed their welcome.
Unfortunately the wife tell's me I have too many pets and as she's quite attached to the spaniel, the keds will have to go. Postage shouldn't be too high but all homes will be vetted prior to transfer. A couple of the younger ones are showing great promise and I'm sure with patience, time and training they could be the most annoying little buggers you've ever met in your life.