As mentioned in an earlier question of mine, my particular world has a class of humanoids which have the magical ability to change into a single animal form at will. As detailed in the linked question, only clothing disappears and reappears on transformation, other items tend to fall off the animal body.
Since my world takes place in a story, there is going to be a fair amount of strife. Part of that will include enemies capturing some of these shapeshifters. Now holding a shapeshifter with a large animal form (such as a lion or a wolf) is not too hard. However, smaller creatures, particularly those which fly, becomes much more difficult. Particularly in the throes of combat.
Take, for example, a shapeshifter bat. Ideally a human-sized cage with very small holes or other such item would be used for capturing such enemies. However, when participating in frequent/guerilla combat, carrying a large cage around is simply not practical.
What kind of method using more portable materials (ropes, nets, etc.) could be used to capture humans that had the ability to change into small creatures? Ideally this is not too specific to a particular kind of animal (a mouse-shaped trap would not be very helpful against sparrows).
- The containing element (ropes, nets, etc.) would not transform with the shapeshifter. Shapeshifting is based on self-image. Ropes are not part of that.
- Shapeshifting occurs quickly (within seconds) and does not change the size of materials near the changing.
- Animal forms have human intelligence.
- Each shapeshifter has only one animal form. That is, a person with a bat form will never have a lion form.
- Shapeshifters only have reasonably large forms. No microscopic parasites or insects. Assume that all shapeshifters are at least the size of small mammals (mice, rats, etc).
- Shapeshifters can transform at will, but cannot be forced by outside measures. (There's no "button" to press to make them transform.)